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gerrit-public.fairphone.software / platform / external / libpng / bbd17bd7c41b8544695dffe76e742b8bb8cc1ff7 / . / pngvalid.c
blob: 5525f551517472095d0c4dc1206a25de9674c57e [file] [log] [blame]
/* pngvalid.c - validate libpng by constructing then reading png files.
*
* Last changed in libpng 1.5.5 [(PENDING RELEASE)]
* Copyright (c) 2011 Glenn Randers-Pehrson
* Written by John Cunningham Bowler
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* NOTES:
* This is a C program that is intended to be linked against libpng. It
* generates bitmaps internally, stores them as PNG files (using the
* sequential write code) then reads them back (using the sequential
* read code) and validates that the result has the correct data.
*
* The program can be modified and extended to test the correctness of
* transformations performed by libpng.
*/
#define _POSIX_SOURCE 1
#include "png.h"
#if PNG_LIBPNG_VER < 10500
/* This delibarately lacks the PNG_CONST. */
typedef png_byte *png_const_bytep;
/* This is copied from 1.5.1 png.h: */
#define PNG_INTERLACE_ADAM7_PASSES 7
#define PNG_PASS_START_ROW(pass) (((1U&~(pass))<<(3-((pass)>>1)))&7)
#define PNG_PASS_START_COL(pass) (((1U& (pass))<<(3-(((pass)+1)>>1)))&7)
#define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
#define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
#define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
-1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
#define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
-1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
#define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
(((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
#define PNG_COL_FROM_PASS_COL(xIn, pass) \
(((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
#define PNG_PASS_MASK(pass,off) ( \
((0x110145AFU>>(((7-(off))-(pass))<<2)) & 0xFU) | \
((0x01145AF0U>>(((7-(off))-(pass))<<2)) & 0xF0U))
#define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
#define PNG_COL_IN_INTERLACE_PASS(x, pass) \
((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
/* These are needed too for the default build: */
#define PNG_WRITE_16BIT_SUPPORTED
#define PNG_READ_16BIT_SUPPORTED
/* This comes from pnglibconf.h afer 1.5: */
#define PNG_FP_1 100000
#define PNG_GAMMA_THRESHOLD_FIXED\
((png_fixed_point)(PNG_GAMMA_THRESHOLD * PNG_FP_1))
#endif
#include "zlib.h" /* For crc32 */
#include <float.h> /* For floating point constants */
#include <stdlib.h> /* For malloc */
#include <string.h> /* For memcpy, memset */
#include <math.h> /* For floor */
/* Unused formal parameter errors are removed using the following macro which is
* expected to have no bad effects on performance.
*/
#ifndef UNUSED
# if defined(__GNUC__) || defined(_MSC_VER)
# define UNUSED(param) (void)param;
# else
# define UNUSED(param)
# endif
#endif
/***************************** EXCEPTION HANDLING *****************************/
#include "contrib/visupng/cexcept.h"
#ifdef __cplusplus
# define this not_the_cpp_this
# define new not_the_cpp_new
# define voidcast(type, value) static_cast<type>(value)
#else
# define voidcast(type, value) (value)
#endif /* __cplusplus */
struct png_store;
define_exception_type(struct png_store*);
/* The following are macros to reduce typing everywhere where the well known
* name 'the_exception_context' must be defined.
*/
#define anon_context(ps) struct exception_context *the_exception_context = \
&(ps)->exception_context
#define context(ps,fault) anon_context(ps); png_store *fault
/******************************* UTILITIES ************************************/
/* Error handling is particularly problematic in production code - error
* handlers often themselves have bugs which lead to programs that detect
* minor errors crashing. The following functions deal with one very
* common class of errors in error handlers - attempting to format error or
* warning messages into buffers that are too small.
*/
static size_t safecat(char *buffer, size_t bufsize, size_t pos,
PNG_CONST char *cat)
{
while (pos < bufsize && cat != NULL && *cat != 0)
buffer[pos++] = *cat++;
if (pos >= bufsize)
pos = bufsize-1;
buffer[pos] = 0;
return pos;
}
static size_t safecatn(char *buffer, size_t bufsize, size_t pos, int n)
{
char number[64];
sprintf(number, "%d", n);
return safecat(buffer, bufsize, pos, number);
}
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
static size_t safecatd(char *buffer, size_t bufsize, size_t pos, double d,
int precision)
{
char number[64];
sprintf(number, "%.*f", precision, d);
return safecat(buffer, bufsize, pos, number);
}
#endif
static PNG_CONST char invalid[] = "invalid";
static PNG_CONST char sep[] = ": ";
static PNG_CONST char *colour_types[8] =
{
"greyscale", invalid, "truecolour", "indexed-colour",
"greyscale with alpha", invalid, "truecolour with alpha", invalid
};
/* Convert a double precision value to fixed point. */
static png_fixed_point
fix(double d)
{
d = floor(d * PNG_FP_1 + .5);
return (png_fixed_point)d;
}
/* Generate random bytes. This uses a boring repeatable algorithm and it
* is implemented here so that it gives the same set of numbers on every
* architecture. It's a linear congruential generator (Knuth or Sedgewick
* "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
* Hill, "The Art of Electronics".
*/
static void
make_random_bytes(png_uint_32* seed, void* pv, size_t size)
{
png_uint_32 u0 = seed[0], u1 = seed[1];
png_bytep bytes = voidcast(png_bytep, pv);
/* There are thirty three bits, the next bit in the sequence is bit-33 XOR
* bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
*/
size_t i;
for (i=0; i<size; ++i)
{
/* First generate 8 new bits then shift them in at the end. */
png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
u1 <<= 8;
u1 |= u0 >> 24;
u0 <<= 8;
u0 |= u;
*bytes++ = (png_byte)u;
}
seed[0] = u0;
seed[1] = u1;
}
static void
make_four_random_bytes(png_uint_32* seed, png_bytep bytes)
{
make_random_bytes(seed, bytes, 4);
}
static void
randomize(void *pv, size_t size)
{
static png_uint_32 random_seed[2] = {0x56789abc, 0xd};
make_random_bytes(random_seed, pv, size);
}
#define RANDOMIZE(this) randomize(&(this), sizeof (this))
static unsigned int
random_mod(unsigned int max)
{
unsigned int x;
RANDOMIZE(x);
return x % max; /* 0 .. max-1 */
}
static int
random_choice(void)
{
unsigned char x;
RANDOMIZE(x);
return x & 1;
}
/* A numeric ID based on PNG file characteristics. The 'do_interlace' field
* simply records whether pngvalid did the interlace itself or whether it
* was done by libpng. Width and height must be less than 256. 'palette' is an
* index of the palette to use for formats with a palette (0 otherwise.)
*/
#define FILEID(col, depth, palette, interlace, width, height, do_interlace) \
((png_uint_32)((col) + ((depth)<<3) + ((palette)<<8) + ((interlace)<<13) + \
(((do_interlace)!=0)<<15) + ((width)<<16) + ((height)<<24)))
#define COL_FROM_ID(id) ((png_byte)((id)& 0x7U))
#define DEPTH_FROM_ID(id) ((png_byte)(((id) >> 3) & 0x1fU))
#define PALETTE_FROM_ID(id) ((int)(((id) >> 8) & 0x1f))
#define INTERLACE_FROM_ID(id) ((int)(((id) >> 13) & 0x3))
#define DO_INTERLACE_FROM_ID(id) ((int)(((id)>>15) & 1))
#define WIDTH_FROM_ID(id) (((id)>>16) & 0xff)
#define HEIGHT_FROM_ID(id) (((id)>>24) & 0xff)
/* Utility to construct a standard name for a standard image. */
static size_t
standard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type,
int bit_depth, int npalette, int interlace_type,
png_uint_32 w, png_uint_32 h, int do_interlace)
{
pos = safecat(buffer, bufsize, pos, colour_types[colour_type]);
if (npalette > 0)
{
pos = safecat(buffer, bufsize, pos, "[");
pos = safecatn(buffer, bufsize, pos, npalette);
pos = safecat(buffer, bufsize, pos, "]");
}
pos = safecat(buffer, bufsize, pos, " ");
pos = safecatn(buffer, bufsize, pos, bit_depth);
pos = safecat(buffer, bufsize, pos, " bit");
if (interlace_type != PNG_INTERLACE_NONE)
{
pos = safecat(buffer, bufsize, pos, " interlaced");
if (do_interlace)
pos = safecat(buffer, bufsize, pos, "(pngvalid)");
else
pos = safecat(buffer, bufsize, pos, "(libpng)");
}
if (w > 0 || h > 0)
{
pos = safecat(buffer, bufsize, pos, " ");
pos = safecatn(buffer, bufsize, pos, w);
pos = safecat(buffer, bufsize, pos, "x");
pos = safecatn(buffer, bufsize, pos, h);
}
return pos;
}
static size_t
standard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id)
{
return standard_name(buffer, bufsize, pos, COL_FROM_ID(id),
DEPTH_FROM_ID(id), PALETTE_FROM_ID(id), INTERLACE_FROM_ID(id),
WIDTH_FROM_ID(id), HEIGHT_FROM_ID(id), DO_INTERLACE_FROM_ID(id));
}
/* Convenience API and defines to list valid formats. Note that 16 bit read and
* write support is required to do 16 bit read tests (we must be able to make a
* 16 bit image to test!)
*/
#ifdef PNG_WRITE_16BIT_SUPPORTED
# define WRITE_BDHI 4
# ifdef PNG_READ_16BIT_SUPPORTED
# define READ_BDHI 4
# define DO_16BIT
# endif
#else
# define WRITE_BDHI 3
#endif
#ifndef DO_16BIT
# define READ_BDHI 3
#endif
/* The following defines the number of different palettes to generate for
* each log bit depth of a colour type 3 standard image.
*/
#define PALETTE_COUNT(bit_depth) ((bit_depth) > 4 ? 1 : 16)
static int
next_format(png_bytep colour_type, png_bytep bit_depth, int* palette_number)
{
if (*bit_depth == 0)
{
*colour_type = 0, *bit_depth = 1, *palette_number = 0;
return 1;
}
if (*colour_type == 3)
{
/* Add multiple palettes for colour type 3. */
if (++*palette_number < PALETTE_COUNT(*bit_depth))
return 1;
*palette_number = 0;
}
*bit_depth = (png_byte)(*bit_depth << 1);
/* Palette images are restricted to 8 bit depth */
if (*bit_depth <= 8
# ifdef DO_16BIT
|| (*colour_type != 3 && *bit_depth <= 16)
# endif
)
return 1;
/* Move to the next color type, or return 0 at the end. */
switch (*colour_type)
{
case 0:
*colour_type = 2;
*bit_depth = 8;
return 1;
case 2:
*colour_type = 3;
*bit_depth = 1;
return 1;
case 3:
*colour_type = 4;
*bit_depth = 8;
return 1;
case 4:
*colour_type = 6;
*bit_depth = 8;
return 1;
default:
return 0;
}
}
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
static unsigned int
sample(png_const_bytep row, png_byte colour_type, png_byte bit_depth,
png_uint_32 x, unsigned int sample_index)
{
png_uint_32 bit_index, result;
/* Find a sample index for the desired sample: */
x *= bit_depth;
bit_index = x;
if ((colour_type & 1) == 0) /* !palette */
{
if (colour_type & 2)
bit_index *= 3;
if (colour_type & 4)
bit_index += x; /* Alpha channel */
/* Multiple channels; select one: */
if (colour_type & (2+4))
bit_index += sample_index * bit_depth;
}
/* Return the sample from the row as an integer. */
row += bit_index >> 3;
result = *row;
if (bit_depth == 8)
return result;
else if (bit_depth > 8)
return (result << 8) + *++row;
/* Less than 8 bits per sample. */
bit_index &= 7;
return (result >> (8-bit_index-bit_depth)) & ((1U<<bit_depth)-1);
}
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
/* Copy a single pixel, of a given size, from one buffer to another -
* while this is basically bit addressed there is an implicit assumption
* that pixels 8 or more bits in size are byte aligned and that pixels
* do not otherwise cross byte boundaries. (This is, so far as I know,
* universally true in bitmap computer graphics. [JCB 20101212])
*
* NOTE: The to and from buffers may be the same.
*/
static void
pixel_copy(png_bytep toBuffer, png_uint_32 toIndex,
png_const_bytep fromBuffer, png_uint_32 fromIndex, unsigned int pixelSize)
{
/* Assume we can multiply by 'size' without overflow because we are
* just working in a single buffer.
*/
toIndex *= pixelSize;
fromIndex *= pixelSize;
if (pixelSize < 8) /* Sub-byte */
{
/* Mask to select the location of the copied pixel: */
unsigned int destMask = ((1U<<pixelSize)-1) << (8-pixelSize-(toIndex&7));
/* The following read the entire pixels and clears the extra: */
unsigned int destByte = toBuffer[toIndex >> 3] & ~destMask;
unsigned int sourceByte = fromBuffer[fromIndex >> 3];
/* Don't rely on << or >> supporting '0' here, just in case: */
fromIndex &= 7;
if (fromIndex > 0) sourceByte <<= fromIndex;
if ((toIndex & 7) > 0) sourceByte >>= toIndex & 7;
toBuffer[toIndex >> 3] = (png_byte)(destByte | (sourceByte & destMask));
}
else /* One or more bytes */
memmove(toBuffer+(toIndex>>3), fromBuffer+(fromIndex>>3), pixelSize>>3);
}
/* Compare pixels - they are assumed to start at the first byte in the
* given buffers.
*/
static int
pixel_cmp(png_const_bytep pa, png_const_bytep pb, png_uint_32 bit_width)
{
if (memcmp(pa, pb, bit_width>>3) == 0)
{
png_uint_32 p;
if ((bit_width & 7) == 0) return 0;
/* Ok, any differences? */
p = pa[bit_width >> 3];
p ^= pb[bit_width >> 3];
if (p == 0) return 0;
/* There are, but they may not be significant, remove the bits
* after the end (the low order bits in PNG.)
*/
bit_width &= 7;
p >>= 8-bit_width;
if (p == 0) return 0;
}
return 1; /* Different */
}
/*************************** BASIC PNG FILE WRITING ***************************/
/* A png_store takes data from the sequential writer or provides data
* to the sequential reader. It can also store the result of a PNG
* write for later retrieval.
*/
#define STORE_BUFFER_SIZE 500 /* arbitrary */
typedef struct png_store_buffer
{
struct png_store_buffer* prev; /* NOTE: stored in reverse order */
png_byte buffer[STORE_BUFFER_SIZE];
} png_store_buffer;
#define FILE_NAME_SIZE 64
typedef struct store_palette_entry /* record of a single palette entry */
{
png_byte red;
png_byte green;
png_byte blue;
png_byte alpha;
} store_palette_entry, store_palette[256];
typedef struct png_store_file
{
struct png_store_file* next; /* as many as you like... */
char name[FILE_NAME_SIZE];
png_uint_32 id; /* must be correct (see FILEID) */
png_size_t datacount; /* In this (the last) buffer */
png_store_buffer data; /* Last buffer in file */
int npalette; /* Number of entries in palette */
store_palette_entry* palette; /* May be NULL */
} png_store_file;
/* The following is a pool of memory allocated by a single libpng read or write
* operation.
*/
typedef struct store_pool
{
struct png_store *store; /* Back pointer */
struct store_memory *list; /* List of allocated memory */
png_byte mark[4]; /* Before and after data */
/* Statistics for this run. */
png_alloc_size_t max; /* Maximum single allocation */
png_alloc_size_t current; /* Current allocation */
png_alloc_size_t limit; /* Highest current allocation */
png_alloc_size_t total; /* Total allocation */
/* Overall statistics (retained across successive runs). */
png_alloc_size_t max_max;
png_alloc_size_t max_limit;
png_alloc_size_t max_total;
} store_pool;
typedef struct png_store
{
/* For cexcept.h exception handling - simply store one of these;
* the context is a self pointer but it may point to a different
* png_store (in fact it never does in this program.)
*/
struct exception_context
exception_context;
unsigned int verbose :1;
unsigned int treat_warnings_as_errors :1;
unsigned int expect_error :1;
unsigned int expect_warning :1;
unsigned int saw_warning :1;
unsigned int speed :1;
unsigned int progressive :1; /* use progressive read */
unsigned int validated :1; /* used as a temporary flag */
int nerrors;
int nwarnings;
char test[128]; /* Name of test */
char error[256];
/* Read fields */
png_structp pread; /* Used to read a saved file */
png_infop piread;
png_store_file* current; /* Set when reading */
png_store_buffer* next; /* Set when reading */
png_size_t readpos; /* Position in *next */
png_byte* image; /* Buffer for reading interlaced images */
png_size_t cb_image; /* Size of this buffer */
png_size_t cb_row; /* Row size of the image(s) */
png_uint_32 image_h; /* Number of rows in a single image */
store_pool read_memory_pool;
/* Write fields */
png_store_file* saved;
png_structp pwrite; /* Used when writing a new file */
png_infop piwrite;
png_size_t writepos; /* Position in .new */
char wname[FILE_NAME_SIZE];
png_store_buffer new; /* The end of the new PNG file being written. */
store_pool write_memory_pool;
store_palette_entry* palette;
int npalette;
} png_store;
/* Initialization and cleanup */
static void
store_pool_mark(png_bytep mark)
{
static png_uint_32 store_seed[2] = { 0x12345678, 1};
make_four_random_bytes(store_seed, mark);
}
/* Use this for random 32 bit values; this function makes sure the result is
* non-zero.
*/
static png_uint_32
random_32(void)
{
for(;;)
{
png_byte mark[4];
png_uint_32 result;
store_pool_mark(mark);
result = png_get_uint_32(mark);
if (result != 0)
return result;
}
}
static void
store_pool_init(png_store *ps, store_pool *pool)
{
memset(pool, 0, sizeof *pool);
pool->store = ps;
pool->list = NULL;
pool->max = pool->current = pool->limit = pool->total = 0;
pool->max_max = pool->max_limit = pool->max_total = 0;
store_pool_mark(pool->mark);
}
static void
store_init(png_store* ps)
{
memset(ps, 0, sizeof *ps);
init_exception_context(&ps->exception_context);
store_pool_init(ps, &ps->read_memory_pool);
store_pool_init(ps, &ps->write_memory_pool);
ps->verbose = 0;
ps->treat_warnings_as_errors = 0;
ps->expect_error = 0;
ps->expect_warning = 0;
ps->saw_warning = 0;
ps->speed = 0;
ps->progressive = 0;
ps->validated = 0;
ps->nerrors = ps->nwarnings = 0;
ps->pread = NULL;
ps->piread = NULL;
ps->saved = ps->current = NULL;
ps->next = NULL;
ps->readpos = 0;
ps->image = NULL;
ps->cb_image = 0;
ps->cb_row = 0;
ps->image_h = 0;
ps->pwrite = NULL;
ps->piwrite = NULL;
ps->writepos = 0;
ps->new.prev = NULL;
ps->palette = NULL;
ps->npalette = 0;
}
static void
store_freebuffer(png_store_buffer* psb)
{
if (psb->prev)
{
store_freebuffer(psb->prev);
free(psb->prev);
psb->prev = NULL;
}
}
static void
store_freenew(png_store *ps)
{
store_freebuffer(&ps->new);
ps->writepos = 0;
if (ps->palette != NULL)
{
free(ps->palette);
ps->palette = NULL;
ps->npalette = 0;
}
}
static void
store_storenew(png_store *ps)
{
png_store_buffer *pb;
if (ps->writepos != STORE_BUFFER_SIZE)
png_error(ps->pwrite, "invalid store call");
pb = voidcast(png_store_buffer*, malloc(sizeof *pb));
if (pb == NULL)
png_error(ps->pwrite, "store new: OOM");
*pb = ps->new;
ps->new.prev = pb;
ps->writepos = 0;
}
static void
store_freefile(png_store_file **ppf)
{
if (*ppf != NULL)
{
store_freefile(&(*ppf)->next);
store_freebuffer(&(*ppf)->data);
(*ppf)->datacount = 0;
if ((*ppf)->palette != NULL)
{
free((*ppf)->palette);
(*ppf)->palette = NULL;
(*ppf)->npalette = 0;
}
free(*ppf);
*ppf = NULL;
}
}
/* Main interface to file storeage, after writing a new PNG file (see the API
* below) call store_storefile to store the result with the given name and id.
*/
static void
store_storefile(png_store *ps, png_uint_32 id)
{
png_store_file *pf = voidcast(png_store_file*, malloc(sizeof *pf));
if (pf == NULL)
png_error(ps->pwrite, "storefile: OOM");
safecat(pf->name, sizeof pf->name, 0, ps->wname);
pf->id = id;
pf->data = ps->new;
pf->datacount = ps->writepos;
ps->new.prev = NULL;
ps->writepos = 0;
pf->palette = ps->palette;
pf->npalette = ps->npalette;
ps->palette = 0;
ps->npalette = 0;
/* And save it. */
pf->next = ps->saved;
ps->saved = pf;
}
/* Generate an error message (in the given buffer) */
static size_t
store_message(png_store *ps, png_structp pp, char *buffer, size_t bufsize,
size_t pos, PNG_CONST char *msg)
{
if (pp != NULL && pp == ps->pread)
{
/* Reading a file */
pos = safecat(buffer, bufsize, pos, "read: ");
if (ps->current != NULL)
{
pos = safecat(buffer, bufsize, pos, ps->current->name);
pos = safecat(buffer, bufsize, pos, sep);
}
}
else if (pp != NULL && pp == ps->pwrite)
{
/* Writing a file */
pos = safecat(buffer, bufsize, pos, "write: ");
pos = safecat(buffer, bufsize, pos, ps->wname);
pos = safecat(buffer, bufsize, pos, sep);
}
else
{
/* Neither reading nor writing (or a memory error in struct delete) */
pos = safecat(buffer, bufsize, pos, "pngvalid: ");
}
if (ps->test[0] != 0)
{
pos = safecat(buffer, bufsize, pos, ps->test);
pos = safecat(buffer, bufsize, pos, sep);
}
pos = safecat(buffer, bufsize, pos, msg);
return pos;
}
/* Verbose output to the error stream: */
static void
store_verbose(png_store *ps, png_structp pp, png_const_charp prefix,
png_const_charp message)
{
char buffer[512];
if (prefix)
fputs(prefix, stderr);
(void)store_message(ps, pp, buffer, sizeof buffer, 0, message);
fputs(buffer, stderr);
fputc('\n', stderr);
}
/* Log an error or warning - the relevant count is always incremented. */
static void
store_log(png_store* ps, png_structp pp, png_const_charp message, int is_error)
{
/* The warning is copied to the error buffer if there are no errors and it is
* the first warning. The error is copied to the error buffer if it is the
* first error (overwriting any prior warnings).
*/
if (is_error ? (ps->nerrors)++ == 0 :
(ps->nwarnings)++ == 0 && ps->nerrors == 0)
store_message(ps, pp, ps->error, sizeof ps->error, 0, message);
if (ps->verbose)
store_verbose(ps, pp, is_error ? "error: " : "warning: ", message);
}
/* Functions to use as PNG callbacks. */
static void
store_error(png_structp pp, png_const_charp message) /* PNG_NORETURN */
{
png_store *ps = voidcast(png_store*, png_get_error_ptr(pp));
if (!ps->expect_error)
store_log(ps, pp, message, 1 /* error */);
/* And finally throw an exception. */
{
struct exception_context *the_exception_context = &ps->exception_context;
Throw ps;
}
}
static void
store_warning(png_structp pp, png_const_charp message)
{
png_store *ps = voidcast(png_store*, png_get_error_ptr(pp));
if (!ps->expect_warning)
store_log(ps, pp, message, 0 /* warning */);
else
ps->saw_warning = 1;
}
/* These somewhat odd functions are used when reading an image to ensure that
* the buffer is big enough, the png_structp is for errors.
*/
/* Return a single row from the correct image. */
static png_bytep
store_image_row(PNG_CONST png_store* ps, png_structp pp, int nImage,
png_uint_32 y)
{
png_size_t coffset = (nImage * ps->image_h + y) * (ps->cb_row + 5) + 2;
if (ps->image == NULL)
png_error(pp, "no allocated image");
if (coffset + ps->cb_row + 3 > ps->cb_image)
png_error(pp, "image too small");
return ps->image + coffset;
}
static void
store_image_free(png_store *ps, png_structp pp)
{
if (ps->image != NULL)
{
png_bytep image = ps->image;
if (image[-1] != 0xed || image[ps->cb_image] != 0xfe)
{
if (pp != NULL)
png_error(pp, "png_store image overwrite (1)");
else
store_log(ps, NULL, "png_store image overwrite (2)", 1);
}
ps->image = NULL;
ps->cb_image = 0;
--image;
free(image);
}
}
static void
store_ensure_image(png_store *ps, png_structp pp, int nImages, png_size_t cbRow,
png_uint_32 cRows)
{
png_size_t cb = nImages * cRows * (cbRow + 5);
if (ps->cb_image < cb)
{
png_bytep image;
store_image_free(ps, pp);
/* The buffer is deliberately mis-aligned. */
image = voidcast(png_bytep, malloc(cb+2));
if (image == NULL)
{
/* Called from the startup - ignore the error for the moment. */
if (pp == NULL)
return;
png_error(pp, "OOM allocating image buffer");
}
/* These magic tags are used to detect overwrites above. */
++image;
image[-1] = 0xed;
image[cb] = 0xfe;
ps->image = image;
ps->cb_image = cb;
}
/* We have an adequate sized image; lay out the rows. There are 2 bytes at
* the start and three at the end of each (this ensures that the row
* alignment starts out odd - 2+1 and changes for larger images on each row.)
*/
ps->cb_row = cbRow;
ps->image_h = cRows;
/* For error checking, the whole buffer is set to '1' - this matches what
* happens with the 'size' test images on write and also matches the unused
* bits in the test rows.
*/
memset(ps->image, 0xff, cb);
/* Then put in the marks. */
while (--nImages >= 0)
{
png_uint_32 y;
for (y=0; y<cRows; ++y)
{
png_bytep row = store_image_row(ps, pp, nImages, y);
/* The markers: */
row[-2] = 190;
row[-1] = 239;
row[cbRow] = 222;
row[cbRow+1] = 173;
row[cbRow+2] = 17;
}
}
}
static void
store_image_check(PNG_CONST png_store* ps, png_structp pp, int iImage)
{
png_const_bytep image = ps->image;
if (image[-1] != 0xed || image[ps->cb_image] != 0xfe)
png_error(pp, "image overwrite");
else
{
png_size_t cbRow = ps->cb_row;
png_uint_32 rows = ps->image_h;
image += iImage * (cbRow+5) * ps->image_h;
image += 2; /* skip image first row markers */
while (rows-- > 0)
{
if (image[-2] != 190 || image[-1] != 239)
png_error(pp, "row start overwritten");
if (image[cbRow] != 222 || image[cbRow+1] != 173 ||
image[cbRow+2] != 17)
png_error(pp, "row end overwritten");
image += cbRow+5;
}
}
}
static void
store_write(png_structp pp, png_bytep pb, png_size_t st)
{
png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
if (ps->pwrite != pp)
png_error(pp, "store state damaged");
while (st > 0)
{
size_t cb;
if (ps->writepos >= STORE_BUFFER_SIZE)
store_storenew(ps);
cb = st;
if (cb > STORE_BUFFER_SIZE - ps->writepos)
cb = STORE_BUFFER_SIZE - ps->writepos;
memcpy(ps->new.buffer + ps->writepos, pb, cb);
pb += cb;
st -= cb;
ps->writepos += cb;
}
}
static void
store_flush(png_structp pp)
{
UNUSED(pp) /*DOES NOTHING*/
}
static size_t
store_read_buffer_size(png_store *ps)
{
/* Return the bytes available for read in the current buffer. */
if (ps->next != &ps->current->data)
return STORE_BUFFER_SIZE;
return ps->current->datacount;
}
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
/* Return total bytes available for read. */
static size_t
store_read_buffer_avail(png_store *ps)
{
if (ps->current != NULL && ps->next != NULL)
{
png_store_buffer *next = &ps->current->data;
size_t cbAvail = ps->current->datacount;
while (next != ps->next && next != NULL)
{
next = next->prev;
cbAvail += STORE_BUFFER_SIZE;
}
if (next != ps->next)
png_error(ps->pread, "buffer read error");
if (cbAvail > ps->readpos)
return cbAvail - ps->readpos;
}
return 0;
}
#endif
static int
store_read_buffer_next(png_store *ps)
{
png_store_buffer *pbOld = ps->next;
png_store_buffer *pbNew = &ps->current->data;
if (pbOld != pbNew)
{
while (pbNew != NULL && pbNew->prev != pbOld)
pbNew = pbNew->prev;
if (pbNew != NULL)
{
ps->next = pbNew;
ps->readpos = 0;
return 1;
}
png_error(ps->pread, "buffer lost");
}
return 0; /* EOF or error */
}
/* Need separate implementation and callback to allow use of the same code
* during progressive read, where the io_ptr is set internally by libpng.
*/
static void
store_read_imp(png_store *ps, png_bytep pb, png_size_t st)
{
if (ps->current == NULL || ps->next == NULL)
png_error(ps->pread, "store state damaged");
while (st > 0)
{
size_t cbAvail = store_read_buffer_size(ps) - ps->readpos;
if (cbAvail > 0)
{
if (cbAvail > st) cbAvail = st;
memcpy(pb, ps->next->buffer + ps->readpos, cbAvail);
st -= cbAvail;
pb += cbAvail;
ps->readpos += cbAvail;
}
else if (!store_read_buffer_next(ps))
png_error(ps->pread, "read beyond end of file");
}
}
static void
store_read(png_structp pp, png_bytep pb, png_size_t st)
{
png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
if (ps == NULL || ps->pread != pp)
png_error(pp, "bad store read call");
store_read_imp(ps, pb, st);
}
static void
store_progressive_read(png_store *ps, png_structp pp, png_infop pi)
{
/* Notice that a call to store_read will cause this function to fail because
* readpos will be set.
*/
if (ps->pread != pp || ps->current == NULL || ps->next == NULL)
png_error(pp, "store state damaged (progressive)");
do
{
if (ps->readpos != 0)
png_error(pp, "store_read called during progressive read");
png_process_data(pp, pi, ps->next->buffer, store_read_buffer_size(ps));
}
while (store_read_buffer_next(ps));
}
/* The caller must fill this in: */
static store_palette_entry *
store_write_palette(png_store *ps, int npalette)
{
if (ps->pwrite == NULL)
store_log(ps, NULL, "attempt to write palette without write stream", 1);
if (ps->palette != NULL)
png_error(ps->pwrite, "multiple store_write_palette calls");
/* This function can only return NULL if called with '0'! */
if (npalette > 0)
{
ps->palette = voidcast(store_palette_entry*, malloc(npalette *
sizeof *ps->palette));
if (ps->palette == NULL)
png_error(ps->pwrite, "store new palette: OOM");
ps->npalette = npalette;
}
return ps->palette;
}
static store_palette_entry *
store_current_palette(png_store *ps, int *npalette)
{
/* This is an internal error (the call has been made outside a read
* operation.)
*/
if (ps->current == NULL)
store_log(ps, ps->pread, "no current stream for palette", 1);
/* The result may be null if there is no palette. */
*npalette = ps->current->npalette;
return ps->current->palette;
}
/***************************** MEMORY MANAGEMENT*** ***************************/
/* A store_memory is simply the header for an allocated block of memory. The
* pointer returned to libpng is just after the end of the header block, the
* allocated memory is followed by a second copy of the 'mark'.
*/
typedef struct store_memory
{
store_pool *pool; /* Originating pool */
struct store_memory *next; /* Singly linked list */
png_alloc_size_t size; /* Size of memory allocated */
png_byte mark[4]; /* ID marker */
} store_memory;
/* Handle a fatal error in memory allocation. This calls png_error if the
* libpng struct is non-NULL, else it outputs a message and returns. This means
* that a memory problem while libpng is running will abort (png_error) the
* handling of particular file while one in cleanup (after the destroy of the
* struct has returned) will simply keep going and free (or attempt to free)
* all the memory.
*/
static void
store_pool_error(png_store *ps, png_structp pp, PNG_CONST char *msg)
{
if (pp != NULL)
png_error(pp, msg);
/* Else we have to do it ourselves. png_error eventually calls store_log,
* above. store_log accepts a NULL png_structp - it just changes what gets
* output by store_message.
*/
store_log(ps, pp, msg, 1 /* error */);
}
static void
store_memory_free(png_structp pp, store_pool *pool, store_memory *memory)
{
/* Note that pp may be NULL (see store_pool_delete below), the caller has
* found 'memory' in pool->list *and* unlinked this entry, so this is a valid
* pointer (for sure), but the contents may have been trashed.
*/
if (memory->pool != pool)
store_pool_error(pool->store, pp, "memory corrupted (pool)");
else if (memcmp(memory->mark, pool->mark, sizeof memory->mark) != 0)
store_pool_error(pool->store, pp, "memory corrupted (start)");
/* It should be safe to read the size field now. */
else
{
png_alloc_size_t cb = memory->size;
if (cb > pool->max)
store_pool_error(pool->store, pp, "memory corrupted (size)");
else if (memcmp((png_bytep)(memory+1)+cb, pool->mark, sizeof pool->mark)
!= 0)
store_pool_error(pool->store, pp, "memory corrupted (end)");
/* Finally give the library a chance to find problems too: */
else
{
pool->current -= cb;
free(memory);
}
}
}
static void
store_pool_delete(png_store *ps, store_pool *pool)
{
if (pool->list != NULL)
{
fprintf(stderr, "%s: %s %s: memory lost (list follows):\n", ps->test,
pool == &ps->read_memory_pool ? "read" : "write",
pool == &ps->read_memory_pool ? (ps->current != NULL ?
ps->current->name : "unknown file") : ps->wname);
++ps->nerrors;
do
{
store_memory *next = pool->list;
pool->list = next->next;
next->next = NULL;
fprintf(stderr, "\t%lu bytes @ %p\n",
(unsigned long)next->size, (PNG_CONST void*)(next+1));
/* The NULL means this will always return, even if the memory is
* corrupted.
*/
store_memory_free(NULL, pool, next);
}
while (pool->list != NULL);
}
/* And reset the other fields too for the next time. */
if (pool->max > pool->max_max) pool->max_max = pool->max;
pool->max = 0;
if (pool->current != 0) /* unexpected internal error */
fprintf(stderr, "%s: %s %s: memory counter mismatch (internal error)\n",
ps->test, pool == &ps->read_memory_pool ? "read" : "write",
pool == &ps->read_memory_pool ? (ps->current != NULL ?
ps->current->name : "unknown file") : ps->wname);
pool->current = 0;
if (pool->limit > pool->max_limit)
pool->max_limit = pool->limit;
pool->limit = 0;
if (pool->total > pool->max_total)
pool->max_total = pool->total;
pool->total = 0;
/* Get a new mark too. */
store_pool_mark(pool->mark);
}
/* The memory callbacks: */
static png_voidp
store_malloc(png_structp pp, png_alloc_size_t cb)
{
store_pool *pool = voidcast(store_pool*, png_get_mem_ptr(pp));
store_memory *new = voidcast(store_memory*, malloc(cb + (sizeof *new) +
(sizeof pool->mark)));
if (new != NULL)
{
if (cb > pool->max)
pool->max = cb;
pool->current += cb;
if (pool->current > pool->limit)
pool->limit = pool->current;
pool->total += cb;
new->size = cb;
memcpy(new->mark, pool->mark, sizeof new->mark);
memcpy((png_byte*)(new+1) + cb, pool->mark, sizeof pool->mark);
new->pool = pool;
new->next = pool->list;
pool->list = new;
++new;
}
else
store_pool_error(pool->store, pp, "out of memory");
return new;
}
static void
store_free(png_structp pp, png_voidp memory)
{
store_pool *pool = voidcast(store_pool*, png_get_mem_ptr(pp));
store_memory *this = voidcast(store_memory*, memory), **test;
/* First check that this 'memory' really is valid memory - it must be in the
* pool list. If it is, use the shared memory_free function to free it.
*/
--this;
for (test = &pool->list; *test != this; test = &(*test)->next)
{
if (*test == NULL)
{
store_pool_error(pool->store, pp, "bad pointer to free");
return;
}
}
/* Unlink this entry, *test == this. */
*test = this->next;
this->next = NULL;
store_memory_free(pp, pool, this);
}
/* Setup functions. */
/* Cleanup when aborting a write or after storing the new file. */
static void
store_write_reset(png_store *ps)
{
if (ps->pwrite != NULL)
{
anon_context(ps);
Try
png_destroy_write_struct(&ps->pwrite, &ps->piwrite);
Catch_anonymous
{
/* memory corruption: continue. */
}
ps->pwrite = NULL;
ps->piwrite = NULL;
}
/* And make sure that all the memory has been freed - this will output
* spurious errors in the case of memory corruption above, but this is safe.
*/
store_pool_delete(ps, &ps->write_memory_pool);
store_freenew(ps);
}
/* The following is the main write function, it returns a png_struct and,
* optionally, a png_info suitable for writiing a new PNG file. Use
* store_storefile above to record this file after it has been written. The
* returned libpng structures as destroyed by store_write_reset above.
*/
static png_structp
set_store_for_write(png_store *ps, png_infopp ppi,
PNG_CONST char * volatile name)
{
anon_context(ps);
Try
{
if (ps->pwrite != NULL)
png_error(ps->pwrite, "write store already in use");
store_write_reset(ps);
safecat(ps->wname, sizeof ps->wname, 0, name);
/* Don't do the slow memory checks if doing a speed test. */
if (ps->speed)
ps->pwrite = png_create_write_struct(PNG_LIBPNG_VER_STRING,
ps, store_error, store_warning);
else
ps->pwrite = png_create_write_struct_2(PNG_LIBPNG_VER_STRING,
ps, store_error, store_warning, &ps->write_memory_pool,
store_malloc, store_free);
png_set_write_fn(ps->pwrite, ps, store_write, store_flush);
if (ppi != NULL)
*ppi = ps->piwrite = png_create_info_struct(ps->pwrite);
}
Catch_anonymous
return NULL;
return ps->pwrite;
}
/* Cleanup when finished reading (either due to error or in the success case).
*/
static void
store_read_reset(png_store *ps)
{
if (ps->pread != NULL)
{
anon_context(ps);
Try
png_destroy_read_struct(&ps->pread, &ps->piread, NULL);
Catch_anonymous
{
/* error already output: continue */
}
ps->pread = NULL;
ps->piread = NULL;
}
/* Always do this to be safe. */
store_pool_delete(ps, &ps->read_memory_pool);
ps->current = NULL;
ps->next = NULL;
ps->readpos = 0;
ps->validated = 0;
}
static void
store_read_set(png_store *ps, png_uint_32 id)
{
png_store_file *pf = ps->saved;
while (pf != NULL)
{
if (pf->id == id)
{
ps->current = pf;
ps->next = NULL;
store_read_buffer_next(ps);
return;
}
pf = pf->next;
}
{
size_t pos;
char msg[FILE_NAME_SIZE+64];
pos = standard_name_from_id(msg, sizeof msg, 0, id);
pos = safecat(msg, sizeof msg, pos, ": file not found");
png_error(ps->pread, msg);
}
}
/* The main interface for reading a saved file - pass the id number of the file
* to retrieve. Ids must be unique or the earlier file will be hidden. The API
* returns a png_struct and, optionally, a png_info. Both of these will be
* destroyed by store_read_reset above.
*/
static png_structp
set_store_for_read(png_store *ps, png_infopp ppi, png_uint_32 id,
PNG_CONST char *name)
{
/* Set the name for png_error */
safecat(ps->test, sizeof ps->test, 0, name);
if (ps->pread != NULL)
png_error(ps->pread, "read store already in use");
store_read_reset(ps);
/* Both the create APIs can return NULL if used in their default mode
* (because there is no other way of handling an error because the jmp_buf
* by default is stored in png_struct and that has not been allocated!)
* However, given that store_error works correctly in these circumstances
* we don't ever expect NULL in this program.
*/
if (ps->speed)
ps->pread = png_create_read_struct(PNG_LIBPNG_VER_STRING, ps,
store_error, store_warning);
else
ps->pread = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, ps,
store_error, store_warning, &ps->read_memory_pool, store_malloc,
store_free);
if (ps->pread == NULL)
{
struct exception_context *the_exception_context = &ps->exception_context;
store_log(ps, NULL, "png_create_read_struct returned NULL (unexpected)",
1 /*error*/);
Throw ps;
}
store_read_set(ps, id);
if (ppi != NULL)
*ppi = ps->piread = png_create_info_struct(ps->pread);
return ps->pread;
}
/* The overall cleanup of a store simply calls the above then removes all the
* saved files. This does not delete the store itself.
*/
static void
store_delete(png_store *ps)
{
store_write_reset(ps);
store_read_reset(ps);
store_freefile(&ps->saved);
store_image_free(ps, NULL);
}
/*********************** PNG FILE MODIFICATION ON READ ************************/
/* Files may be modified on read. The following structure contains a complete
* png_store together with extra members to handle modification and a special
* read callback for libpng. To use this the 'modifications' field must be set
* to a list of png_modification structures that actually perform the
* modification, otherwise a png_modifier is functionally equivalent to a
* png_store. There is a special read function, set_modifier_for_read, which
* replaces set_store_for_read.
*/
typedef enum modifier_state
{
modifier_start, /* Initial value */
modifier_signature, /* Have a signature */
modifier_IHDR /* Have an IHDR */
} modifier_state;
typedef struct CIE_color
{
/* A single CIE tristimulus value, representing the unique response of a
* standard observer to a variety of light spectra. The observer recognizes
* all spectra that produce this response as the same color, therefore this
* is effectively a description of a color.
*/
double X, Y, Z;
} CIE_color;
static double
chromaticity_x(CIE_color c)
{
return c.X / (c.X + c.Y + c.Z);
}
static double
chromaticity_y(CIE_color c)
{
return c.Y / (c.X + c.Y + c.Z);
}
typedef struct color_encoding
{
/* A description of an (R,G,B) encoding of color (as defined above); this
* includes the actual colors of the (R,G,B) triples (1,0,0), (0,1,0) and
* (0,0,1) plus an encoding value that is used to encode the linear
* components R, G and B to give the actual values R^gamma, G^gamma and
* B^gamma that are stored.
*/
double gamma; /* Encoding (file) gamma of space */
CIE_color red, green, blue; /* End points */
} color_encoding;
static CIE_color
white_point(PNG_CONST color_encoding *encoding)
{
CIE_color white;
white.X = encoding->red.X + encoding->green.X + encoding->blue.X;
white.Y = encoding->red.Y + encoding->green.Y + encoding->blue.Y;
white.Z = encoding->red.Z + encoding->green.Z + encoding->blue.Z;
return white;
}
static void
normalize_color_encoding(color_encoding *encoding)
{
PNG_CONST double whiteY = encoding->red.Y + encoding->green.Y +
encoding->blue.Y;
if (whiteY != 1)
{
encoding->red.X /= whiteY;
encoding->red.Y /= whiteY;
encoding->red.Z /= whiteY;
encoding->green.X /= whiteY;
encoding->green.Y /= whiteY;
encoding->green.Z /= whiteY;
encoding->blue.X /= whiteY;
encoding->blue.Y /= whiteY;
encoding->blue.Z /= whiteY;
}
}
static size_t
safecat_color_encoding(char *buffer, size_t bufsize, size_t pos,
PNG_CONST color_encoding *e, double encoding_gamma)
{
if (e != 0)
{
if (encoding_gamma != 0)
pos = safecat(buffer, bufsize, pos, "(");
pos = safecat(buffer, bufsize, pos, "R(");
pos = safecatd(buffer, bufsize, pos, e->red.X, 4);
pos = safecat(buffer, bufsize, pos, ",");
pos = safecatd(buffer, bufsize, pos, e->red.Y, 4);
pos = safecat(buffer, bufsize, pos, ",");
pos = safecatd(buffer, bufsize, pos, e->red.Z, 4);
pos = safecat(buffer, bufsize, pos, "),G(");
pos = safecatd(buffer, bufsize, pos, e->green.X, 4);
pos = safecat(buffer, bufsize, pos, ",");
pos = safecatd(buffer, bufsize, pos, e->green.Y, 4);
pos = safecat(buffer, bufsize, pos, ",");
pos = safecatd(buffer, bufsize, pos, e->green.Z, 4);
pos = safecat(buffer, bufsize, pos, "),B(");
pos = safecatd(buffer, bufsize, pos, e->blue.X, 4);
pos = safecat(buffer, bufsize, pos, ",");
pos = safecatd(buffer, bufsize, pos, e->blue.Y, 4);
pos = safecat(buffer, bufsize, pos, ",");
pos = safecatd(buffer, bufsize, pos, e->blue.Z, 4);
pos = safecat(buffer, bufsize, pos, ")");
if (encoding_gamma != 0)
pos = safecat(buffer, bufsize, pos, ")");
}
if (encoding_gamma != 0)
{
pos = safecat(buffer, bufsize, pos, "^");
pos = safecatd(buffer, bufsize, pos, encoding_gamma, 5);
}
return pos;
}
typedef struct png_modifier
{
png_store this; /* I am a png_store */
struct png_modification *modifications; /* Changes to make */
modifier_state state; /* My state */
/* Information from IHDR: */
png_byte bit_depth; /* From IHDR */
png_byte colour_type; /* From IHDR */
/* While handling PLTE, IDAT and IEND these chunks may be pended to allow
* other chunks to be inserted.
*/
png_uint_32 pending_len;
png_uint_32 pending_chunk;
/* Test values */
double *gammas;
unsigned int ngammas;
unsigned int ngamma_tests; /* Number of gamma tests to run*/
double current_gamma; /* 0 if not set */
PNG_CONST color_encoding *encodings;
unsigned int nencodings;
PNG_CONST color_encoding *current_encoding; /* If an encoding has been set */
unsigned int encoding_counter; /* For iteration */
int encoding_ignored; /* Something overwrote it */
/* Control variables used to iterate through possible encodings, the
* following must be set to 0 and tested by the function that uses the
* png_modifier because the modifier only sets it to 1 (true.)
*/
unsigned int repeat :1; /* Repeat this transform test. */
unsigned int test_uses_encoding :1;
/* Lowest sbit to test (libpng fails for sbit < 8) */
png_byte sbitlow;
/* Error control - these are the limits on errors accepted by the gamma tests
* below.
*/
double maxout8; /* Maximum output value error */
double maxabs8; /* Absolute sample error 0..1 */
double maxcalc8; /* Absolute sample error 0..1 */
double maxpc8; /* Percentage sample error 0..100% */
double maxout16; /* Maximum output value error */
double maxabs16; /* Absolute sample error 0..1 */
double maxcalc16;/* Absolute sample error 0..1 */
double maxpc16; /* Percentage sample error 0..100% */
/* This is set by transforms that need to allow a higher limit, it is an
* internal check on pngvalid to ensure that the calculated error limits are
* not ridiculous; without this it is too easy to make a mistake in pngvalid
* that allows any value through.
*/
double limit; /* limit on error values, normally 4E-3 */
/* Log limits - values above this are logged, but not necessarily
* warned.
*/
double log8; /* Absolute error in 8 bits to log */
double log16; /* Absolute error in 16 bits to log */
/* Logged 8 and 16 bit errors ('output' values): */
double error_gray_2;
double error_gray_4;
double error_gray_8;
double error_gray_16;
double error_color_8;
double error_color_16;
double error_indexed;
/* Flags: */
/* Whether or not to interlace. */
int interlace_type :9; /* int, but must store '1' */
/* Run the standard tests? */
unsigned int test_standard :1;
/* Run the odd-sized image and interlace read/write tests? */
unsigned int test_size :1;
/* Run tests on reading with a combiniation of transforms, */
unsigned int test_transform :1;
/* When to use the use_input_precision option: */
unsigned int use_input_precision :1;
unsigned int use_input_precision_sbit :1;
unsigned int use_input_precision_16to8 :1;
/* If set assume that the calculation bit depth is set by the input
* precision, not the output precision.
*/
unsigned int calculations_use_input_precision :1;
/* If set assume that the calculations are done in 16 bits even if both input
* and output are 8 bit or less.
*/
unsigned int assume_16_bit_calculations :1;
/* Which gamma tests to run: */
unsigned int test_gamma_threshold :1;
unsigned int test_gamma_transform :1; /* main tests */
unsigned int test_gamma_sbit :1;
unsigned int test_gamma_scale16 :1;
unsigned int test_gamma_background :1;
unsigned int test_gamma_alpha_mode :1;
unsigned int test_gamma_expand16 :1;
unsigned int test_exhaustive :1;
unsigned int log :1; /* Log max error */
/* Buffer information, the buffer size limits the size of the chunks that can
* be modified - they must fit (including header and CRC) into the buffer!
*/
size_t flush; /* Count of bytes to flush */
size_t buffer_count; /* Bytes in buffer */
size_t buffer_position; /* Position in buffer */
png_byte buffer[1024];
} png_modifier;
/* This returns true if the test should be stopped now because it has already
* failed and it is running silently.
*/
static int fail(png_modifier *pm)
{
return !pm->log && !pm->this.verbose && (pm->this.nerrors > 0 ||
(pm->this.treat_warnings_as_errors && pm->this.nwarnings > 0));
}
static void
modifier_init(png_modifier *pm)
{
memset(pm, 0, sizeof *pm);
store_init(&pm->this);
pm->modifications = NULL;
pm->state = modifier_start;
pm->sbitlow = 1U;
pm->ngammas = 0;
pm->ngamma_tests = 0;
pm->gammas = 0;
pm->current_gamma = 0;
pm->encodings = 0;
pm->nencodings = 0;
pm->current_encoding = 0;
pm->encoding_counter = 0;
pm->encoding_ignored = 0;
pm->repeat = 0;
pm->test_uses_encoding = 0;
pm->maxout8 = pm->maxpc8 = pm->maxabs8 = pm->maxcalc8 = 0;
pm->maxout16 = pm->maxpc16 = pm->maxabs16 = pm->maxcalc16 = 0;
pm->limit = 4E-3;
pm->log8 = pm->log16 = 0; /* Means 'off' */
pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = 0;
pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0;
pm->error_indexed = 0;
pm->interlace_type = PNG_INTERLACE_NONE;
pm->test_standard = 0;
pm->test_size = 0;
pm->test_transform = 0;
pm->use_input_precision = 0;
pm->use_input_precision_sbit = 0;
pm->use_input_precision_16to8 = 0;
pm->calculations_use_input_precision = 0;
pm->test_gamma_threshold = 0;
pm->test_gamma_transform = 0;
pm->test_gamma_sbit = 0;
pm->test_gamma_scale16 = 0;
pm->test_gamma_background = 0;
pm->test_gamma_alpha_mode = 0;
pm->test_gamma_expand16 = 0;
pm->test_exhaustive = 0;
pm->log = 0;
/* Rely on the memset for all the other fields - there are no pointers */
}
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
/* If pm->calculations_use_input_precision is set then operations will happen
* with only 8 bit precision unless both the input and output bit depth are 16.
*
* If pm->assume_16_bit_calculations is set then even 8 bit calculations use 16
* bit precision. This only affects those of the following limits that pertain
* to a calculation - not a digitization operation - unless the following API is
* called directly.
*/
static double digitize(PNG_CONST png_modifier *pm, double value,
int sample_depth, int do_round)
{
/* 'value' is in the range 0 to 1, the result is the same value rounded to a
* multiple of the digitization factor - 8 or 16 bits depending on both the
* sample depth and the 'assume' setting. Digitization is normally by
* rounding and 'do_round' should be 1, if it is 0 the digitized value will
* be truncated.
*/
PNG_CONST unsigned int digitization_factor =
(pm->assume_16_bit_calculations || sample_depth == 16) ? 65535 : 255;
/* Limiting the range is done as a convenience to the caller - it's easier to
* do it once here than every time at the call site.
*/
if (value <= 0)
value = 0;
else if (value >= 1)
value = 1;
value *= digitization_factor;
if (do_round) value += .5;
return floor(value)/digitization_factor;
}
static double abserr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
{
/* Absolute error permitted in linear values - affected by the bit depth of
* the calculations.
*/
if (pm->assume_16_bit_calculations || (out_depth == 16 && (in_depth == 16 ||
!pm->calculations_use_input_precision)))
return pm->maxabs16;
else
return pm->maxabs8;
}
static double calcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
{
/* Error in the linear composition arithmetic - only relevant when
* composition actually happens (0 < alpha < 1).
*/
if (pm->assume_16_bit_calculations || (out_depth == 16 && (in_depth == 16 ||
!pm->calculations_use_input_precision)))
return pm->maxcalc16;
else
return pm->maxcalc8;
}
static double pcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
{
/* Percentage error permitted in the linear values. Note that the specified
* value is a percentage but this routine returns a simple number.
*/
if (pm->assume_16_bit_calculations || (out_depth == 16 && (in_depth == 16 ||
!pm->calculations_use_input_precision)))
return pm->maxpc16 * .01;
else
return pm->maxpc8 * .01;
}
/* Output error - the error in the encoded value. This is determined by the
* digitization of the output so can be +/-0.5 in the actual output value. In
* the expand_16 case with the current code in libpng the expand happens after
* all the calculations are done in 8 bit arithmetic, so even though the output
* depth is 16 the output error is determined by the 8 bit calculation.
*
* This limit is not determined by the bit depth of internal calculations.
*
* The specified parameter does *not* include the base .5 digitization error but
* it is added here.
*/
static double outerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
{
/* There is a serious error in the 2 and 4 bit grayscale transform because
* the gamma table value (8 bits) is simply shifted, not rounded, so the
* error in 4 bit greyscale gamma is up to the value below. This is a hack
* to allow pngvalid to succeed:
*
* TODO: fix this in libpng
*/
if (out_depth == 2)
return .73182-.5;
if (out_depth == 4)
return .90644-.5;
if (out_depth == 16 && (in_depth == 16 ||
!pm->calculations_use_input_precision))
return pm->maxout16;
/* This is the case where the value was calculated at 8-bit precision then
* scaled to 16 bits.
*/
else if (out_depth == 16)
return pm->maxout8 * 257;
else
return pm->maxout8;
}
/* This does the same thing as the above however it returns the value to log,
* rather than raising a warning. This is useful for debugging to track down
* exactly what set of parameters cause high error values.
*/
static double outlog(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
{
/* The command line parameters are either 8 bit (0..255) or 16 bit (0..65535)
* and so must be adjusted for low bit depth grayscale:
*/
if (out_depth <= 8)
{
if (pm->log8 == 0) /* switched off */
return 256;
if (out_depth < 8)
return pm->log8 / 255 * ((1<<out_depth)-1);
return pm->log8;
}
if (out_depth == 16 && (in_depth == 16 ||
!pm->calculations_use_input_precision))
{
if (pm->log16 == 0)
return 65536;
return pm->log16;
}
/* This is the case where the value was calculated at 8-bit precision then
* scaled to 16 bits.
*/
if (pm->log8 == 0)
return 65536;
return pm->log8 * 257;
}
/* This complements the above by providing the appropriate quantization for the
* final value. Normally this would just be quantization to an integral value,
* but in the 8 bit calculation case it's actually quantization to a multiple of
* 257!
*/
static int output_quantization_factor(PNG_CONST png_modifier *pm, int in_depth,
int out_depth)
{
if (out_depth == 16 && in_depth != 16
&& pm->calculations_use_input_precision)
return 257;
else
return 1;
}
/* One modification structure must be provided for each chunk to be modified (in
* fact more than one can be provided if multiple separate changes are desired
* for a single chunk.) Modifications include adding a new chunk when a
* suitable chunk does not exist.
*
* The caller of modify_fn will reset the CRC of the chunk and record 'modified'
* or 'added' as appropriate if the modify_fn returns 1 (true). If the
* modify_fn is NULL the chunk is simply removed.
*/
typedef struct png_modification
{
struct png_modification *next;
png_uint_32 chunk;
/* If the following is NULL all matching chunks will be removed: */
int (*modify_fn)(struct png_modifier *pm,
struct png_modification *me, int add);
/* If the following is set to PLTE, IDAT or IEND and the chunk has not been
* found and modified (and there is a modify_fn) the modify_fn will be called
* to add the chunk before the relevant chunk.
*/
png_uint_32 add;
unsigned int modified :1; /* Chunk was modified */
unsigned int added :1; /* Chunk was added */
unsigned int removed :1; /* Chunk was removed */
} png_modification;
static void
modification_reset(png_modification *pmm)
{
if (pmm != NULL)
{
pmm->modified = 0;
pmm->added = 0;
pmm->removed = 0;
modification_reset(pmm->next);
}
}
static void
modification_init(png_modification *pmm)
{
memset(pmm, 0, sizeof *pmm);
pmm->next = NULL;
pmm->chunk = 0;
pmm->modify_fn = NULL;
pmm->add = 0;
modification_reset(pmm);
}
static void
modifier_current_encoding(PNG_CONST png_modifier *pm, color_encoding *ce)
{
if (pm->current_encoding != 0)
*ce = *pm->current_encoding;
else
memset(ce, 0, sizeof *ce);
ce->gamma = pm->current_gamma;
}
static size_t
safecat_current_encoding(char *buffer, size_t bufsize, size_t pos,
PNG_CONST png_modifier *pm)
{
pos = safecat_color_encoding(buffer, bufsize, pos, pm->current_encoding,
pm->current_gamma);
if (pm->encoding_ignored)
pos = safecat(buffer, bufsize, pos, "[overridden]");
return pos;
}
/* Iterate through the usefully testable color encodings. An encoding is one
* of:
*
* 1) Nothing (no color space, no gamma).
* 2) Just a gamma value from the gamma array (including 1.0)
* 3) A color space from the encodings array with the corresponding gamma.
* 4) The same, but with gamma 1.0 (only really useful with 16 bit calculations)
*
* The iterator selects these in turn, the randomizer selects one at random,
* which is used depends on the setting of the 'test_exhaustive' flag. Notice
* that this function changes the colour space encoding so it must only be
* called on completion of the previous test. This is what 'modifier_reset'
* does, below.
*
* After the function has been called the 'repeat' flag will still be set; the
* caller of modifier_reset must reset it at the start of each run of the test!
*/
static unsigned int
modifier_total_encodings(PNG_CONST png_modifier *pm)
{
return 1 + /* (1) nothing */
pm->ngammas + /* (2) gamma values to test */
pm->nencodings + /* (3) total number of encodings */
/* The following test only works after the first time through the
* png_modifier code because 'bit_depth' is set when the IHDR is read.
* modifier_reset, below, preserves the setting until after it has called
* the iterate function (also below.)
*
* For this reason do not rely on this function outside a call to
* modifier_reset.
*/
((pm->bit_depth == 16 || pm->assume_16_bit_calculations) ?
pm->nencodings : 0); /* (4) encodings with gamma == 1.0 */
}
static void
modifier_encoding_iterate(png_modifier *pm)
{
if (!pm->repeat && /* Else something needs the current encoding again. */
pm->test_uses_encoding) /* Some transform is encoding dependent */
{
if (pm->test_exhaustive)
{
if (++pm->encoding_counter >= modifier_total_encodings(pm))
pm->encoding_counter = 0; /* This will stop the repeat */
}
else
{
/* Not exhaustive - choose an encoding at random; generate a number in
* the range 1..(max-1), so the result is always non-zero:
*/
if (pm->encoding_counter == 0)
pm->encoding_counter = random_mod(modifier_total_encodings(pm)-1)+1;
else
pm->encoding_counter = 0;
}
if (pm->encoding_counter > 0)
pm->repeat = 1;
}
else if (!pm->repeat)
pm->encoding_counter = 0;
}
static void
modifier_reset(png_modifier *pm)
{
store_read_reset(&pm->this);
pm->limit = 4E-3;
pm->pending_len = pm->pending_chunk = 0;
pm->flush = pm->buffer_count = pm->buffer_position = 0;
pm->modifications = NULL;
pm->state = modifier_start;
modifier_encoding_iterate(pm);
/* The following must be set in the next run. In particular
* test_uses_encodings must be set in the _ini function of each transform
* that looks at the encodings. (Not the 'add' function!)
*/
pm->test_uses_encoding = 0;
pm->current_gamma = 0;
pm->current_encoding = 0;
pm->encoding_ignored = 0;
/* These only become value after IHDR is read: */
pm->bit_depth = pm->colour_type = 0;
}
/* The following must be called before anything else to get the encoding set up
* on the modifier. In particular it must be called before the transform init
* functions are called.
*/
static void
modifier_set_encoding(png_modifier *pm)
{
/* Set the encoding to the one specified by the current encoding counter,
* first clear out all the settings - this corresponds to an encoding_counter
* of 0.
*/
pm->current_gamma = 0;
pm->current_encoding = 0;
pm->encoding_ignored = 0; /* not ignored yet - happens in _ini functions. */
/* Now, if required, set the gamma and encoding fields. */
if (pm->encoding_counter > 0)
{
/* The gammas[] array is an array of screen gammas, not encoding gammas,
* so we need the inverse:
*/
if (pm->encoding_counter <= pm->ngammas)
pm->current_gamma = 1/pm->gammas[pm->encoding_counter-1];
else
{
unsigned int i = pm->encoding_counter - pm->ngammas;
if (i >= pm->nencodings)
{
i %= pm->nencodings;
pm->current_gamma = 1; /* Linear, only in the 16 bit case */
}
else
pm->current_gamma = pm->encodings[i].gamma;
pm->current_encoding = pm->encodings + i;
}
}
}
/* Enquiry functions to find out what is set. Notice that there is an implicit
* assumption below that the first encoding in the list is the one for sRGB.
*/
static int
modifier_color_encoding_is_sRGB(PNG_CONST png_modifier *pm)
{
return pm->current_encoding != 0 && pm->current_encoding == pm->encodings &&
pm->current_encoding->gamma == pm->current_gamma;
}
static int
modifier_color_encoding_is_set(PNG_CONST png_modifier *pm)
{
return pm->current_gamma != 0;
}
/* Convenience macros. */
#define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
#define CHUNK_IHDR CHUNK(73,72,68,82)
#define CHUNK_PLTE CHUNK(80,76,84,69)
#define CHUNK_IDAT CHUNK(73,68,65,84)
#define CHUNK_IEND CHUNK(73,69,78,68)
#define CHUNK_cHRM CHUNK(99,72,82,77)
#define CHUNK_gAMA CHUNK(103,65,77,65)
#define CHUNK_sBIT CHUNK(115,66,73,84)
#define CHUNK_sRGB CHUNK(115,82,71,66)
/* The guts of modification are performed during a read. */
static void
modifier_crc(png_bytep buffer)
{
/* Recalculate the chunk CRC - a complete chunk must be in
* the buffer, at the start.
*/
uInt datalen = png_get_uint_32(buffer);
png_save_uint_32(buffer+datalen+8, crc32(0L, buffer+4, datalen+4));
}
static void
modifier_setbuffer(png_modifier *pm)
{
modifier_crc(pm->buffer);
pm->buffer_count = png_get_uint_32(pm->buffer)+12;
pm->buffer_position = 0;
}
/* Separate the callback into the actual implementation (which is passed the
* png_modifier explicitly) and the callback, which gets the modifier from the
* png_struct.
*/
static void
modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
{
while (st > 0)
{
size_t cb;
png_uint_32 len, chunk;
png_modification *mod;
if (pm->buffer_position >= pm->buffer_count) switch (pm->state)
{
static png_byte sign[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
case modifier_start:
store_read_imp(&pm->this, pm->buffer, 8); /* size of signature. */
pm->buffer_count = 8;
pm->buffer_position = 0;
if (memcmp(pm->buffer, sign, 8) != 0)
png_error(pm->this.pread, "invalid PNG file signature");
pm->state = modifier_signature;
break;
case modifier_signature:
store_read_imp(&pm->this, pm->buffer, 13+12); /* size of IHDR */
pm->buffer_count = 13+12;
pm->buffer_position = 0;
if (png_get_uint_32(pm->buffer) != 13 ||
png_get_uint_32(pm->buffer+4) != CHUNK_IHDR)
png_error(pm->this.pread, "invalid IHDR");
/* Check the list of modifiers for modifications to the IHDR. */
mod = pm->modifications;
while (mod != NULL)
{
if (mod->chunk == CHUNK_IHDR && mod->modify_fn &&
(*mod->modify_fn)(pm, mod, 0))
{
mod->modified = 1;
modifier_setbuffer(pm);
}
/* Ignore removal or add if IHDR! */
mod = mod->next;
}
/* Cache information from the IHDR (the modified one.) */
pm->bit_depth = pm->buffer[8+8];
pm->colour_type = pm->buffer[8+8+1];
pm->state = modifier_IHDR;
pm->flush = 0;
break;
case modifier_IHDR:
default:
/* Read a new chunk and process it until we see PLTE, IDAT or
* IEND. 'flush' indicates that there is still some data to
* output from the preceding chunk.
*/
if ((cb = pm->flush) > 0)
{
if (cb > st) cb = st;
pm->flush -= cb;
store_read_imp(&pm->this, pb, cb);
pb += cb;
st -= cb;
if (st == 0) return;
}
/* No more bytes to flush, read a header, or handle a pending
* chunk.
*/
if (pm->pending_chunk != 0)
{
png_save_uint_32(pm->buffer, pm->pending_len);
png_save_uint_32(pm->buffer+4, pm->pending_chunk);
pm->pending_len = 0;
pm->pending_chunk = 0;
}
else
store_read_imp(&pm->this, pm->buffer, 8);
pm->buffer_count = 8;
pm->buffer_position = 0;
/* Check for something to modify or a terminator chunk. */
len = png_get_uint_32(pm->buffer);
chunk = png_get_uint_32(pm->buffer+4);
/* Terminators first, they may have to be delayed for added
* chunks
*/
if (chunk == CHUNK_PLTE || chunk == CHUNK_IDAT ||
chunk == CHUNK_IEND)
{
mod = pm->modifications;
while (mod != NULL)
{
if ((mod->add == chunk ||
(mod->add == CHUNK_PLTE && chunk == CHUNK_IDAT)) &&
mod->modify_fn != NULL && !mod->modified && !mod->added)
{
/* Regardless of what the modify function does do not run
* this again.
*/
mod->added = 1;
if ((*mod->modify_fn)(pm, mod, 1 /*add*/))
{
/* Reset the CRC on a new chunk */
if (pm->buffer_count > 0)
modifier_setbuffer(pm);
else
{
pm->buffer_position = 0;
mod->removed = 1;
}
/* The buffer has been filled with something (we assume)
* so output this. Pend the current chunk.
*/
pm->pending_len = len;
pm->pending_chunk = chunk;
break; /* out of while */
}
}
mod = mod->next;
}
/* Don't do any further processing if the buffer was modified -
* otherwise the code will end up modifying a chunk that was
* just added.
*/
if (mod != NULL)
break; /* out of switch */
}
/* If we get to here then this chunk may need to be modified. To
* do this it must be less than 1024 bytes in total size, otherwise
* it just gets flushed.
*/
if (len+12 <= sizeof pm->buffer)
{
store_read_imp(&pm->this, pm->buffer+pm->buffer_count,
len+12-pm->buffer_count);
pm->buffer_count = len+12;
/* Check for a modification, else leave it be. */
mod = pm->modifications;
while (mod != NULL)
{
if (mod->chunk == chunk)
{
if (mod->modify_fn == NULL)
{
/* Remove this chunk */
pm->buffer_count = pm->buffer_position = 0;
mod->removed = 1;
break; /* Terminate the while loop */
}
else if ((*mod->modify_fn)(pm, mod, 0))
{
mod->modified = 1;
/* The chunk may have been removed: */
if (pm->buffer_count == 0)
{
pm->buffer_position = 0;
break;
}
modifier_setbuffer(pm);
}
}
mod = mod->next;
}
}
else
pm->flush = len+12 - pm->buffer_count; /* data + crc */
/* Take the data from the buffer (if there is any). */
break;
}
/* Here to read from the modifier buffer (not directly from
* the store, as in the flush case above.)
*/
cb = pm->buffer_count - pm->buffer_position;
if (cb > st)
cb = st;
memcpy(pb, pm->buffer + pm->buffer_position, cb);
st -= cb;
pb += cb;
pm->buffer_position += cb;
}
}
/* The callback: */
static void
modifier_read(png_structp pp, png_bytep pb, png_size_t st)
{
png_modifier *pm = voidcast(png_modifier*, png_get_io_ptr(pp));
if (pm == NULL || pm->this.pread != pp)
png_error(pp, "bad modifier_read call");
modifier_read_imp(pm, pb, st);
}
/* Like store_progressive_read but the data is getting changed as we go so we
* need a local buffer.
*/
static void
modifier_progressive_read(png_modifier *pm, png_structp pp, png_infop pi)
{
if (pm->this.pread != pp || pm->this.current == NULL ||
pm->this.next == NULL)
png_error(pp, "store state damaged (progressive)");
/* This is another Horowitz and Hill random noise generator. In this case
* the aim is to stress the progressive reader with truly horrible variable
* buffer sizes in the range 1..500, so a sequence of 9 bit random numbers
* is generated. We could probably just count from 1 to 32767 and get as
* good a result.
*/
for (;;)
{
static png_uint_32 noise = 1;
png_size_t cb, cbAvail;
png_byte buffer[512];
/* Generate 15 more bits of stuff: */
noise = (noise << 9) | ((noise ^ (noise >> (9-5))) & 0x1ff);
cb = noise & 0x1ff;
/* Check that this number of bytes are available (in the current buffer.)
* (This doesn't quite work - the modifier might delete a chunk; unlikely
* but possible, it doesn't happen at present because the modifier only
* adds chunks to standard images.)
*/
cbAvail = store_read_buffer_avail(&pm->this);
if (pm->buffer_count > pm->buffer_position)
cbAvail += pm->buffer_count - pm->buffer_position;
if (cb > cbAvail)
{
/* Check for EOF: */
if (cbAvail == 0)
break;
cb = cbAvail;
}
modifier_read_imp(pm, buffer, cb);
png_process_data(pp, pi, buffer, cb);
}
/* Check the invariants at the end (if this fails it's a problem in this
* file!)
*/
if (pm->buffer_count > pm->buffer_position ||
pm->this.next != &pm->this.current->data ||
pm->this.readpos < pm->this.current->datacount)
png_error(pp, "progressive read implementation error");
}
/* Set up a modifier. */
static png_structp
set_modifier_for_read(png_modifier *pm, png_infopp ppi, png_uint_32 id,
PNG_CONST char *name)
{
/* Do this first so that the modifier fields are cleared even if an error
* happens allocating the png_struct. No allocation is done here so no
* cleanup is required.
*/
pm->state = modifier_start;
pm->bit_depth = 0;
pm->colour_type = 255;
pm->pending_len = 0;
pm->pending_chunk = 0;
pm->flush = 0;
pm->buffer_count = 0;
pm->buffer_position = 0;
return set_store_for_read(&pm->this, ppi, id, name);
}
/******************************** MODIFICATIONS *******************************/
/* Standard modifications to add chunks. These do not require the _SUPPORTED
* macros because the chunks can be there regardless of whether this specific
* libpng supports them.
*/
typedef struct gama_modification
{
png_modification this;
png_fixed_point gamma;
} gama_modification;
static int
gama_modify(png_modifier *pm, png_modification *me, int add)
{
UNUSED(add)
/* This simply dumps the given gamma value into the buffer. */
png_save_uint_32(pm->buffer, 4);
png_save_uint_32(pm->buffer+4, CHUNK_gAMA);
png_save_uint_32(pm->buffer+8, ((gama_modification*)me)->gamma);
return 1;
}
static void
gama_modification_init(gama_modification *me, png_modifier *pm, double gammad)
{
double g;
modification_init(&me->this);
me->this.chunk = CHUNK_gAMA;
me->this.modify_fn = gama_modify;
me->this.add = CHUNK_PLTE;
g = fix(gammad);
me->gamma = (png_fixed_point)g;
me->this.next = pm->modifications;
pm->modifications = &me->this;
}
typedef struct chrm_modification
{
png_modification this;
PNG_CONST color_encoding *encoding;
png_fixed_point wx, wy, rx, ry, gx, gy, bx, by;
} chrm_modification;
static int
chrm_modify(png_modifier *pm, png_modification *me, int add)
{
UNUSED(add)
/* As with gAMA this just adds the required cHRM chunk to the buffer. */
png_save_uint_32(pm->buffer , 32);
png_save_uint_32(pm->buffer+ 4, CHUNK_cHRM);
png_save_uint_32(pm->buffer+ 8, ((chrm_modification*)me)->wx);
png_save_uint_32(pm->buffer+12, ((chrm_modification*)me)->wy);
png_save_uint_32(pm->buffer+16, ((chrm_modification*)me)->rx);
png_save_uint_32(pm->buffer+20, ((chrm_modification*)me)->ry);
png_save_uint_32(pm->buffer+24, ((chrm_modification*)me)->gx);
png_save_uint_32(pm->buffer+28, ((chrm_modification*)me)->gy);
png_save_uint_32(pm->buffer+32, ((chrm_modification*)me)->bx);
png_save_uint_32(pm->buffer+36, ((chrm_modification*)me)->by);
return 1;
}
static void
chrm_modification_init(chrm_modification *me, png_modifier *pm,
PNG_CONST color_encoding *encoding)
{
CIE_color white = white_point(encoding);
/* Original end points: */
me->encoding = encoding;
/* Chromaticities (in fixed point): */
me->wx = fix(chromaticity_x(white));
me->wy = fix(chromaticity_y(white));
me->rx = fix(chromaticity_x(encoding->red));
me->ry = fix(chromaticity_y(encoding->red));
me->gx = fix(chromaticity_x(encoding->green));
me->gy = fix(chromaticity_y(encoding->green));
me->bx = fix(chromaticity_x(encoding->blue));
me->by = fix(chromaticity_y(encoding->blue));
modification_init(&me->this);
me->this.chunk = CHUNK_cHRM;
me->this.modify_fn = chrm_modify;
me->this.add = CHUNK_PLTE;
me->this.next = pm->modifications;
pm->modifications = &me->this;
}
typedef struct srgb_modification
{
png_modification this;
png_byte intent;
} srgb_modification;
static int
srgb_modify(png_modifier *pm, png_modification *me, int add)
{
UNUSED(add)
/* As above, ignore add and just make a new chunk */
png_save_uint_32(pm->buffer, 1);
png_save_uint_32(pm->buffer+4, CHUNK_sRGB);
pm->buffer[8] = ((srgb_modification*)me)->intent;
return 1;
}
static void
srgb_modification_init(srgb_modification *me, png_modifier *pm, png_byte intent)
{
modification_init(&me->this);
me->this.chunk = CHUNK_sBIT;
if (intent <= 3) /* if valid, else *delete* sRGB chunks */
{
me->this.modify_fn = srgb_modify;
me->this.add = CHUNK_PLTE;
me->intent = intent;
}
else
{
me->this.modify_fn = 0;
me->this.add = 0;
me->intent = 0;
}
me->this.next = pm->modifications;
pm->modifications = &me->this;
}
typedef struct sbit_modification
{
png_modification this;
png_byte sbit;
} sbit_modification;
static int
sbit_modify(png_modifier *pm, png_modification *me, int add)
{
png_byte sbit = ((sbit_modification*)me)->sbit;
if (pm->bit_depth > sbit)
{
int cb = 0;
switch (pm->colour_type)
{
case 0:
cb = 1;
break;
case 2:
case 3:
cb = 3;
break;
case 4:
cb = 2;
break;
case 6:
cb = 4;
break;
default:
png_error(pm->this.pread,
"unexpected colour type in sBIT modification");
}
png_save_uint_32(pm->buffer, cb);
png_save_uint_32(pm->buffer+4, CHUNK_sBIT);
while (cb > 0)
(pm->buffer+8)[--cb] = sbit;
return 1;
}
else if (!add)
{
/* Remove the sBIT chunk */
pm->buffer_count = pm->buffer_position = 0;
return 1;
}
else
return 0; /* do nothing */
}
static void
sbit_modification_init(sbit_modification *me, png_modifier *pm, png_byte sbit)
{
modification_init(&me->this);
me->this.chunk = CHUNK_sBIT;
me->this.modify_fn = sbit_modify;
me->this.add = CHUNK_PLTE;
me->sbit = sbit;
me->this.next = pm->modifications;
pm->modifications = &me->this;
}
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
/***************************** STANDARD PNG FILES *****************************/
/* Standard files - write and save standard files. */
/* There are two basic forms of standard images. Those which attempt to have
* all the possible pixel values (not possible for 16bpp images, but a range of
* values are produced) and those which have a range of image sizes. The former
* are used for testing transforms, in particular gamma correction and bit
* reduction and increase. The latter are reserved for testing the behavior of
* libpng with respect to 'odd' image sizes - particularly small images where
* rows become 1 byte and interlace passes disappear.
*
* The first, most useful, set are the 'transform' images, the second set of
* small images are the 'size' images.
*
* The transform files are constructed with rows which fit into a 1024 byte row
* buffer. This makes allocation easier below. Further regardless of the file
* format every row has 128 pixels (giving 1024 bytes for 64bpp formats).
*
* Files are stored with no gAMA or sBIT chunks, with a PLTE only when needed
* and with an ID derived from the colour type, bit depth and interlace type
* as above (FILEID). The width (128) and height (variable) are not stored in
* the FILEID - instead the fields are set to 0, indicating a transform file.
*
* The size files ar constructed with rows a maximum of 128 bytes wide, allowing
* a maximum width of 16 pixels (for the 64bpp case.) They also have a maximum
* height of 16 rows. The width and height are stored in the FILEID and, being
* non-zero, indicate a size file.
*
* For palette image (colour type 3) multiple transform images are stored with
* the same bit depth to allow testing of more colour combinations -
* particularly important for testing the gamma code because libpng uses a
* different code path for palette images. For size images a single palette is
* used.
*/
/* Make a 'standard' palette. Because there are only 256 entries in a palette
* (maximum) this actually makes a random palette in the hope that enough tests
* will catch enough errors. (Note that the same palette isn't produced every
* time for the same test - it depends on what previous tests have been run -
* but a given set of arguments to pngvalid will always produce the same palette
* at the same test! This is why pseudo-random number generators are useful for
* testing.)
*
* The store must be open for write when this is called, otherwise an internal
* error will occur. This routine contains its own magic number seed, so the
* palettes generated don't change if there are intervening errors (changing the
* calls to the store_mark seed.)
*/
static store_palette_entry *
make_standard_palette(png_store* ps, int npalette, int do_tRNS)
{
static png_uint_32 palette_seed[2] = { 0x87654321, 9 };
int i = 0;
png_byte values[256][4];
/* Always put in black and white plus the six primary and secondary colors.
*/
for (; i<8; ++i)
{
values[i][1] = (i&1) ? 255 : 0;
values[i][2] = (i&2) ? 255 : 0;
values[i][3] = (i&4) ? 255 : 0;
}
/* Then add 62 greys (one quarter of the remaining 256 slots). */
{
int j = 0;
png_byte random_bytes[4];
png_byte need[256];
need[0] = 0; /*got black*/
memset(need+1, 1, (sizeof need)-2); /*need these*/
need[255] = 0; /*but not white*/
while (i<70)
{
png_byte b;
if (j==0)
{
make_four_random_bytes(palette_seed, random_bytes);
j = 4;
}
b = random_bytes[--j];
if (need[b])
{
values[i][1] = b;
values[i][2] = b;
values[i++][3] = b;
}
}
}
/* Finally add 192 colors at random - don't worry about matches to things we
* already have, chance is less than 1/65536. Don't worry about greys,
* chance is the same, so we get a duplicate or extra gray less than 1 time
* in 170.
*/
for (; i<256; ++i)
make_four_random_bytes(palette_seed, values[i]);
/* Fill in the alpha values in the first byte. Just use all possible values
* (0..255) in an apparently random order:
*/
{
store_palette_entry *palette;
png_byte selector[4];
make_four_random_bytes(palette_seed, selector);
if (do_tRNS)
for (i=0; i<256; ++i)
values[i][0] = (png_byte)(i ^ selector[0]);
else
for (i=0; i<256; ++i)
values[i][0] = 255; /* no transparency/tRNS chunk */
/* 'values' contains 256 ARGB values, but we only need 'npalette'.
* 'npalette' will always be a power of 2: 2, 4, 16 or 256. In the low
* bit depth cases select colors at random, else it is difficult to have
* a set of low bit depth palette test with any chance of a reasonable
* range of colors. Do this by randomly permuting values into the low
* 'npalette' entries using an XOR mask generated here. This also
* permutes the npalette == 256 case in a potentially useful way (there is
* no relationship between palette index and the color value therein!)
*/
palette = store_write_palette(ps, npalette);
for (i=0; i<npalette; ++i)
{
palette[i].alpha = values[i ^ selector[1]][0];
palette[i].red = values[i ^ selector[1]][1];
palette[i].green = values[i ^ selector[1]][2];
palette[i].blue = values[i ^ selector[1]][3];
}
return palette;
}
}
/* Initialize a standard palette on a write stream. The 'do_tRNS' argument
* indicates whether or not to also set the tRNS chunk.
*/
static void
init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
int do_tRNS)
{
store_palette_entry *ppal = make_standard_palette(ps, npalette, do_tRNS);
{
int i;
png_color palette[256];
/* Set all entries to detect overread errors. */
for (i=0; i<npalette; ++i)
{
palette[i].red = ppal[i].red;
palette[i].green = ppal[i].green;
palette[i].blue = ppal[i].blue;
}
/* Just in case fill in the rest with detectable values: */
for (; i<256; ++i)
palette[i].red = palette[i].green = palette[i].blue = 42;
png_set_PLTE(pp, pi, palette, npalette);
}
if (do_tRNS)
{
int i, j;
png_byte tRNS[256];
/* Set all the entries, but skip trailing opaque entries */
for (i=j=0; i<npalette; ++i)
if ((tRNS[i] = ppal[i].alpha) < 255)
j = i+1;
/* Fill in the remainder with a detectable value: */
for (; i<256; ++i)
tRNS[i] = 24;
if (j > 0)
png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
}
}
/* The number of passes is related to the interlace type. There was no libpng
* API to determine this prior to 1.5, so we need an inquiry function:
*/
static int
npasses_from_interlace_type(png_structp pp, int interlace_type)
{
switch (interlace_type)
{
default:
png_error(pp, "invalid interlace type");
case PNG_INTERLACE_NONE:
return 1;
case PNG_INTERLACE_ADAM7:
return PNG_INTERLACE_ADAM7_PASSES;
}
}
static unsigned int
bit_size(png_structp pp, png_byte colour_type, png_byte bit_depth)
{
switch (colour_type)
{
default: png_error(pp, "invalid color type");
case 0: return bit_depth;
case 2: return 3*bit_depth;
case 3: return bit_depth;
case 4: return 2*bit_depth;
case 6: return 4*bit_depth;
}
}
#define TRANSFORM_WIDTH 128U
#define TRANSFORM_ROWMAX (TRANSFORM_WIDTH*8U)
#define SIZE_ROWMAX (16*8U) /* 16 pixels, max 8 bytes each - 128 bytes */
#define STANDARD_ROWMAX TRANSFORM_ROWMAX /* The larger of the two */
#define SIZE_HEIGHTMAX 16 /* Maximum range of size images */
static size_t
transform_rowsize(png_structp pp, png_byte colour_type, png_byte bit_depth)
{
return (TRANSFORM_WIDTH * bit_size(pp, colour_type, bit_depth)) / 8;
}
/* transform_width(pp, colour_type, bit_depth) current returns the same number
* every time, so just use a macro:
*/
#define transform_width(pp, colour_type, bit_depth) TRANSFORM_WIDTH
static png_uint_32
transform_height(png_structp pp, png_byte colour_type, png_byte bit_depth)
{
switch (bit_size(pp, colour_type, bit_depth))
{
case 1:
case 2:
case 4:
return 1; /* Total of 128 pixels */
case 8:
return 2; /* Total of 256 pixels/bytes */
case 16:
return 512; /* Total of 65536 pixels */
case 24:
case 32:
return 512; /* 65536 pixels */
case 48:
case 64:
return 2048;/* 4 x 65536 pixels. */
# define TRANSFORM_HEIGHTMAX 2048
default:
return 0; /* Error, will be caught later */
}
}
/* The following can only be defined here, now we have the definitions
* of the transform image sizes.
*/
static png_uint_32
standard_width(png_structp pp, png_uint_32 id)
{
png_uint_32 width = WIDTH_FROM_ID(id);
UNUSED(pp)
if (width == 0)
width = transform_width(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
return width;
}
static png_uint_32
standard_height(png_structp pp, png_uint_32 id)
{
png_uint_32 height = HEIGHT_FROM_ID(id);
if (height == 0)
height = transform_height(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
return height;
}
static png_uint_32
standard_rowsize(png_structp pp, png_uint_32 id)
{
png_uint_32 width = standard_width(pp, id);
/* This won't overflow: */
width *= bit_size(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
return (width + 7) / 8;
}
static void
transform_row(png_structp pp, png_byte buffer[TRANSFORM_ROWMAX],
png_byte colour_type, png_byte bit_depth, png_uint_32 y)
{
png_uint_32 v = y << 7;
png_uint_32 i = 0;
switch (bit_size(pp, colour_type, bit_depth))
{
case 1:
while (i<128/8) buffer[i] = v & 0xff, v += 17, ++i;
return;
case 2:
while (i<128/4) buffer[i] = v & 0xff, v += 33, ++i;
return;
case 4:
while (i<128/2) buffer[i] = v & 0xff, v += 65, ++i;
return;
case 8:
/* 256 bytes total, 128 bytes in each row set as follows: */
while (i<128) buffer[i] = v & 0xff, ++v, ++i;
return;
case 16:
/* Generate all 65536 pixel values in order, which includes the 8 bit
* GA case as well as the 16 bit G case.
*/
while (i<128)
buffer[2*i] = (v>>8) & 0xff, buffer[2*i+1] = v & 0xff, ++v, ++i;
return;
case 24:
/* 65535 pixels, but rotate the values. */
while (i<128)
{
/* Three bytes per pixel, r, g, b, make b by r^g */
buffer[3*i+0] = (v >> 8) & 0xff;
buffer[3*i+1] = v & 0xff;
buffer[3*i+2] = ((v >> 8) ^ v) & 0xff;
++v;
++i;
}
return;
case 32:
/* 65535 pixels, r, g, b, a; just replicate */
while (i<128)
{
buffer[4*i+0] = (v >> 8) & 0xff;
buffer[4*i+1] = v & 0xff;
buffer[4*i+2] = (v >> 8) & 0xff;
buffer[4*i+3] = v & 0xff;
++v;
++i;
}
return;
case 48:
/* y is maximum 2047, giving 4x65536 pixels, make 'r' increase by 1 at
* each pixel, g increase by 257 (0x101) and 'b' by 0x1111:
*/
while (i<128)
{
png_uint_32 t = v++;
buffer[6*i+0] = (t >> 8) & 0xff;
buffer[6*i+1] = t & 0xff;
t *= 257;
buffer[6*i+2] = (t >> 8) & 0xff;
buffer[6*i+3] = t & 0xff;
t *= 17;
buffer[6*i+4] = (t >> 8) & 0xff;
buffer[6*i+5] = t & 0xff;
++i;
}
return;
case 64:
/* As above in the 32 bit case. */
while (i<128)
{
png_uint_32 t = v++;
buffer[8*i+0] = (t >> 8) & 0xff;
buffer[8*i+1] = t & 0xff;
buffer[8*i+4] = (t >> 8) & 0xff;
buffer[8*i+5] = t & 0xff;
t *= 257;
buffer[8*i+2] = (t >> 8) & 0xff;
buffer[8*i+3] = t & 0xff;
buffer[8*i+6] = (t >> 8) & 0xff;
buffer[8*i+7] = t & 0xff;
++i;
}
return;
default:
break;
}
png_error(pp, "internal error");
}
/* This is just to do the right cast - could be changed to a function to check
* 'bd' but there isn't much point.
*/
#define DEPTH(bd) ((png_byte)(1U << (bd)))
/* Make a standardized image given a an image colour type, bit depth and
* interlace type. The standard images have a very restricted range of
* rows and heights and are used for testing transforms rather than image
* layout details. See make_size_images below for a way to make images
* that test odd sizes along with the libpng interlace handling.
*/
static void
make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
png_byte PNG_CONST bit_depth, int palette_number, int interlace_type,
png_const_charp name)
{
context(ps, fault);
Try
{
png_infop pi;
png_structp pp = set_store_for_write(ps, &pi, name);
png_uint_32 h;
/* In the event of a problem return control to the Catch statement below
* to do the clean up - it is not possible to 'return' directly from a Try
* block.
*/
if (pp == NULL)
Throw ps;
h = transform_height(pp, colour_type, bit_depth);
png_set_IHDR(pp, pi, transform_width(pp, colour_type, bit_depth), h,
bit_depth, colour_type, interlace_type,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
#ifdef PNG_TEXT_SUPPORTED
{
static char key[] = "image name"; /* must be writeable */
size_t pos;
png_text text;
char copy[FILE_NAME_SIZE];
/* Use a compressed text string to test the correct interaction of text
* compression and IDAT compression.
*/
text.compression = PNG_TEXT_COMPRESSION_zTXt;
text.key = key;
/* Yuck: the text must be writable! */
pos = safecat(copy, sizeof copy, 0, ps->wname);
text.text = copy;
text.text_length = pos;
text.itxt_length = 0;
text.lang = 0;
text.lang_key = 0;
png_set_text(pp, pi, &text, 1);
}
#endif
if (colour_type == 3) /* palette */
init_standard_palette(ps, pp, pi, 1U << bit_depth, 1/*do tRNS*/);
png_write_info(pp, pi);
if (png_get_rowbytes(pp, pi) !=
transform_rowsize(pp, colour_type, bit_depth))
png_error(pp, "row size incorrect");
else
{
/* Somewhat confusingly this must be called *after* png_write_info
* because if it is called before, the information in *pp has not been
* updated to reflect the interlaced image.
*/
int npasses = png_set_interlace_handling(pp);
int pass;
if (npasses != npasses_from_interlace_type(pp, interlace_type))
png_error(pp, "write: png_set_interlace_handling failed");
for (pass=0; pass<npasses; ++pass)
{
png_uint_32 y;
for (y=0; y<h; ++y)
{
png_byte buffer[TRANSFORM_ROWMAX];
transform_row(pp, buffer, colour_type, bit_depth, y);
png_write_row(pp, buffer);
}
}
}
#ifdef PNG_TEXT_SUPPORTED
{
static char key[] = "end marker";
static char comment[] = "end";
png_text text;
/* Use a compressed text string to test the correct interaction of text
* compression and IDAT compression.
*/
text.compression = PNG_TEXT_COMPRESSION_zTXt;
text.key = key;
text.text = comment;
text.text_length = (sizeof comment)-1;
text.itxt_length = 0;
text.lang = 0;
text.lang_key = 0;
png_set_text(pp, pi, &text, 1);
}
#endif
png_write_end(pp, pi);
/* And store this under the appropriate id, then clean up. */
store_storefile(ps, FILEID(colour_type, bit_depth, palette_number,
interlace_type, 0, 0, 0));
store_write_reset(ps);
}
Catch(fault)
{
/* Use the png_store returned by the exception. This may help the compiler
* because 'ps' is not used in this branch of the setjmp. Note that fault
* and ps will always be the same value.
*/
store_write_reset(fault);
}
}
static void
make_transform_images(png_store *ps)
{
png_byte colour_type = 0;
png_byte bit_depth = 0;
int palette_number = 0;
/* This is in case of errors. */
safecat(ps->test, sizeof ps->test, 0, "make standard images");
/* Use next_format to enumerate all the combinations we test, including
* generating multiple low bit depth palette images.
*/
while (next_format(&colour_type, &bit_depth, &palette_number))
{
int interlace_type;
for (interlace_type = PNG_INTERLACE_NONE;
interlace_type < PNG_INTERLACE_LAST; ++interlace_type)
{
char name[FILE_NAME_SIZE];
standard_name(name, sizeof name, 0, colour_type, bit_depth,
palette_number, interlace_type, 0, 0, 0);
make_transform_image(ps, colour_type, bit_depth, palette_number,
interlace_type, name);
}
}
}
/* The following two routines use the PNG interlace support macros from
* png.h to interlace or deinterlace rows.
*/
static void
interlace_row(png_bytep buffer, png_const_bytep imageRow,
unsigned int pixel_size, png_uint_32 w, int pass)
{
png_uint_32 xin, xout, xstep;
/* Note that this can, trivially, be optimized to a memcpy on pass 7, the
* code is presented this way to make it easier to understand. In practice
* consult the code in the libpng source to see other ways of doing this.
*/
xin = PNG_PASS_START_COL(pass);
xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
for (xout=0; xin<w; xin+=xstep)
{
pixel_copy(buffer, xout, imageRow, xin, pixel_size);
++xout;
}
}
static void
deinterlace_row(png_bytep buffer, png_const_bytep row,
unsigned int pixel_size, png_uint_32 w, int pass)
{
/* The inverse of the above, 'row' is part of row 'y' of the output image,
* in 'buffer'. The image is 'w' wide and this is pass 'pass', distribute
* the pixels of row into buffer and return the number written (to allow
* this to be checked).
*/
png_uint_32 xin, xout, xstep;
xout = PNG_PASS_START_COL(pass);
xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
for (xin=0; xout<w; xout+=xstep)
{
pixel_copy(buffer, xout, row, xin, pixel_size);
++xin;
}
}
/* Build a single row for the 'size' test images; this fills in only the
* first bit_width bits of the sample row.
*/
static void
size_row(png_byte buffer[SIZE_ROWMAX], png_uint_32 bit_width, png_uint_32 y)
{
/* height is in the range 1 to 16, so: */
y = ((y & 1) << 7) + ((y & 2) << 6) + ((y & 4) << 5) + ((y & 8) << 4);
/* the following ensures bits are set in small images: */
y ^= 0xA5;
while (bit_width >= 8)
*buffer++ = (png_byte)y++, bit_width -= 8;
/* There may be up to 7 remaining bits, these go in the most significant
* bits of the byte.
*/
if (bit_width > 0)
{
png_uint_32 mask = (1U<<(8-bit_width))-1;
*buffer = (png_byte)((*buffer & mask) | (y & ~mask));
}
}
static void
make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
png_byte PNG_CONST bit_depth, int PNG_CONST interlace_type,
png_uint_32 PNG_CONST w, png_uint_32 PNG_CONST h,
int PNG_CONST do_interlace)
{
context(ps, fault);
Try
{
png_infop pi;
png_structp pp;
unsigned int pixel_size;
/* Make a name and get an appropriate id for the store: */
char name[FILE_NAME_SIZE];
PNG_CONST png_uint_32 id = FILEID(colour_type, bit_depth, 0/*palette*/,
interlace_type, w, h, do_interlace);
standard_name_from_id(name, sizeof name, 0, id);
pp = set_store_for_write(ps, &pi, name);
/* In the event of a problem return control to the Catch statement below
* to do the clean up - it is not possible to 'return' directly from a Try
* block.
*/
if (pp == NULL)
Throw ps;
png_set_IHDR(pp, pi, w, h, bit_depth, colour_type, interlace_type,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
if (colour_type == 3) /* palette */
init_standard_palette(ps, pp, pi, 1U << bit_depth, 0/*do tRNS*/);
png_write_info(pp, pi);
/* Calculate the bit size, divide by 8 to get the byte size - this won't
* overflow because we know the w values are all small enough even for
* a system where 'unsigned int' is only 16 bits.
*/
pixel_size = bit_size(pp, colour_type, bit_depth);
if (png_get_rowbytes(pp, pi) != ((w * pixel_size) + 7) / 8)
png_error(pp, "row size incorrect");
else
{
int npasses = npasses_from_interlace_type(pp, interlace_type);
png_uint_32 y;
int pass;
png_byte image[16][SIZE_ROWMAX];
/* To help consistent error detection make the parts of this buffer
* that aren't set below all '1':
*/
memset(image, 0xff, sizeof image);
if (!do_interlace && npasses != png_set_interlace_handling(pp))
png_error(pp, "write: png_set_interlace_handling failed");
/* Prepare the whole image first to avoid making it 7 times: */
for (y=0; y<h; ++y)
size_row(image[y], w * pixel_size, y);
for (pass=0; pass<npasses; ++pass)
{
/* The following two are for checking the macros: */
PNG_CONST png_uint_32 wPass = PNG_PASS_COLS(w, pass);
/* If do_interlace is set we don't call png_write_row for every
* row because some of them are empty. In fact, for a 1x1 image,
* most of them are empty!
*/
for (y=0; y<h; ++y)
{
png_const_bytep row = image[y];
png_byte tempRow[SIZE_ROWMAX];
/* If do_interlace *and* the image is interlaced we
* need a reduced interlace row; this may be reduced
* to empty.
*/
if (do_interlace && interlace_type == PNG_INTERLACE_ADAM7)
{
/* The row must not be written if it doesn't exist, notice
* that there are two conditions here, either the row isn't
* ever in the pass or the row would be but isn't wide
* enough to contribute any pixels. In fact the wPass test
* can be used to skip the whole y loop in this case.
*/
if (PNG_ROW_IN_INTERLACE_PASS(y, pass) && wPass > 0)
{
/* Set to all 1's for error detection (libpng tends to
* set unset things to 0).
*/
memset(tempRow, 0xff, sizeof tempRow);
interlace_row(tempRow, row, pixel_size, w, pass);
row = tempRow;
}
else
continue;
}
/* Only get to here if the row has some pixels in it. */
png_write_row(pp, row);
}
}
}
png_write_end(pp, pi);
/* And store this under the appropriate id, then clean up. */
store_storefile(ps, id);
store_write_reset(ps);
}
Catch(fault)
{
/* Use the png_store returned by the exception. This may help the compiler
* because 'ps' is not used in this branch of the setjmp. Note that fault
* and ps will always be the same value.
*/
store_write_reset(fault);
}
}
static void
make_size(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, int bdlo,
int PNG_CONST bdhi)
{
for (; bdlo <= bdhi; ++bdlo)
{
png_uint_32 width;
for (width = 1; width <= 16; ++width)
{
png_uint_32 height;
for (height = 1; height <= 16; ++height)
{
/* The four combinations of DIY interlace and interlace or not -
* no interlace + DIY should be identical to no interlace with
* libpng doing it.
*/
make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE,
width, height, 0);
make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE,
width, height, 1);
make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
width, height, 0);
make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
width, height, 1);
}
}
}
}
static void
make_size_images(png_store *ps)
{
/* This is in case of errors. */
safecat(ps->test, sizeof ps->test, 0, "make size images");
/* Arguments are colour_type, low bit depth, high bit depth
*/
make_size(ps, 0, 0, WRITE_BDHI);
make_size(ps, 2, 3, WRITE_BDHI);
make_size(ps, 3, 0, 3 /*palette: max 8 bits*/);
make_size(ps, 4, 3, WRITE_BDHI);
make_size(ps, 6, 3, WRITE_BDHI);
}
/* Return a row based on image id and 'y' for checking: */
static void
standard_row(png_structp pp, png_byte std[STANDARD_ROWMAX], png_uint_32 id,
png_uint_32 y)
{
if (WIDTH_FROM_ID(id) == 0)
transform_row(pp, std, COL_FROM_ID(id), DEPTH_FROM_ID(id), y);
else
size_row(std, WIDTH_FROM_ID(id) * bit_size(pp, COL_FROM_ID(id),
DEPTH_FROM_ID(id)), y);
}
/* Tests - individual test cases */
/* Like 'make_standard' but errors are deliberately introduced into the calls
* to ensure that they get detected - it should not be possible to write an
* invalid image with libpng!
*/
#ifdef PNG_WARNINGS_SUPPORTED
static void
sBIT0_error_fn(png_structp pp, png_infop pi)
{
/* 0 is invalid... */
png_color_8 bad;
bad.red = bad.green = bad.blue = bad.gray = bad.alpha = 0;
png_set_sBIT(pp, pi, &bad);
}
static void
sBIT_error_fn(png_structp pp, png_infop pi)
{
png_byte bit_depth;
png_color_8 bad;
if (png_get_color_type(pp, pi) == PNG_COLOR_TYPE_PALETTE)
bit_depth = 8;
else
bit_depth = png_get_bit_depth(pp, pi);
/* Now we know the bit depth we can easily generate an invalid sBIT entry */
bad.red = bad.green = bad.blue = bad.gray = bad.alpha =
(png_byte)(bit_depth+1);
png_set_sBIT(pp, pi, &bad);
}
static PNG_CONST struct
{
void (*fn)(png_structp, png_infop);
PNG_CONST char *msg;
unsigned int warning :1; /* the error is a warning... */
} error_test[] =
{
/* no warnings makes these errors undetectable. */
{ sBIT0_error_fn, "sBIT(0): failed to detect error", 1 },
{ sBIT_error_fn, "sBIT(too big): failed to detect error", 1 },
};
static void
make_error(png_store* volatile ps, png_byte PNG_CONST colour_type,
png_byte bit_depth, int interlace_type, int test, png_const_charp name)
{
context(ps, fault);
Try
{
png_structp pp;
png_infop pi;
pp = set_store_for_write(ps, &pi, name);
if (pp == NULL)
Throw ps;
png_set_IHDR(pp, pi, transform_width(pp, colour_type, bit_depth),
transform_height(pp, colour_type, bit_depth), bit_depth, colour_type,
interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
if (colour_type == 3) /* palette */
init_standard_palette(ps, pp, pi, 1U << bit_depth, 0/*do tRNS*/);
/* Time for a few errors; these are in various optional chunks, the
* standard tests test the standard chunks pretty well.
*/
# define exception__prev exception_prev_1
# define exception__env exception_env_1
Try
{
/* Expect this to throw: */
ps->expect_error = !error_test[test].warning;
ps->expect_warning = error_test[test].warning;
ps->saw_warning = 0;
error_test[test].fn(pp, pi);
/* Normally the error is only detected here: */
png_write_info(pp, pi);
/* And handle the case where it was only a warning: */
if (ps->expect_warning && ps->saw_warning)
Throw ps;
/* If we get here there is a problem, we have success - no error or
* no warning - when we shouldn't have success. Log an error.
*/
store_log(ps, pp, error_test[test].msg, 1 /*error*/);
}
Catch (fault)
ps = fault; /* expected exit, make sure ps is not clobbered */
#undef exception__prev
#undef exception__env
/* And clear these flags */
ps->expect_error = 0;
ps->expect_warning = 0;
/* Now write the whole image, just to make sure that the detected, or
* undetected, errro has not created problems inside libpng.
*/
if (png_get_rowbytes(pp, pi) !=
transform_rowsize(pp, colour_type, bit_depth))
png_error(pp, "row size incorrect");
else
{
png_uint_32 h = transform_height(pp, colour_type, bit_depth);
int npasses = png_set_interlace_handling(pp);
int pass;
if (npasses != npasses_from_interlace_type(pp, interlace_type))
png_error(pp, "write: png_set_interlace_handling failed");
for (pass=0; pass<npasses; ++pass)
{
png_uint_32 y;
for (y=0; y<h; ++y)
{
png_byte buffer[TRANSFORM_ROWMAX];
transform_row(pp, buffer, colour_type, bit_depth, y);
png_write_row(pp, buffer);
}
}
}
png_write_end(pp, pi);
/* The following deletes the file that was just written. */
store_write_reset(ps);
}
Catch(fault)
{
store_write_reset(fault);
}
}
static int
make_errors(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
int bdlo, int PNG_CONST bdhi)
{
for (; bdlo <= bdhi; ++bdlo)
{
int interlace_type;
for (interlace_type = PNG_INTERLACE_NONE;
interlace_type < PNG_INTERLACE_LAST; ++interlace_type)
{
unsigned int test;
char name[FILE_NAME_SIZE];
standard_name(name, sizeof name, 0, colour_type, 1<<bdlo, 0,
interlace_type, 0, 0, 0);
for (test=0; test<(sizeof error_test)/(sizeof error_test[0]); ++test)
{
make_error(&pm->this, colour_type, DEPTH(bdlo), interlace_type,
test, name);
if (fail(pm))
return 0;
}
}
}
return 1; /* keep going */
}
#endif
static void
perform_error_test(png_modifier *pm)
{
#ifdef PNG_WARNINGS_SUPPORTED /* else there are no cases that work! */
/* Need to do this here because we just write in this test. */
safecat(pm->this.test, sizeof pm->this.test, 0, "error test");
if (!make_errors(pm, 0, 0, WRITE_BDHI))
return;
if (!make_errors(pm, 2, 3, WRITE_BDHI))
return;
if (!make_errors(pm, 3, 0, 3))
return;
if (!make_errors(pm, 4, 3, WRITE_BDHI))
return;
if (!make_errors(pm, 6, 3, WRITE_BDHI))
return;
#else
UNUSED(pm)
#endif
}
/* This is just to validate the internal PNG formatting code - if this fails
* then the warning messages the library outputs will probably be garbage.
*/
static void
perform_formatting_test(png_store *volatile ps)
{
#ifdef PNG_TIME_RFC1123_SUPPORTED
/* The handle into the formatting code is the RFC1123 support; this test does
* nothing if that is compiled out.
*/
context(ps, fault);
Try
{
png_const_charp correct = "29 Aug 2079 13:53:60 +0000";
png_const_charp result;
png_structp pp;
png_time pt;
pp = set_store_for_write(ps, NULL, "libpng formatting test");
if (pp == NULL)
Throw ps;
/* Arbitrary settings: */
pt.year = 2079;
pt.month = 8;
pt.day = 29;
pt.hour = 13;
pt.minute = 53;
pt.second = 60; /* a leap second */
result = png_convert_to_rfc1123(pp, &pt);
if (result == NULL)
png_error(pp, "png_convert_to_rfc1123 failed");
if (strcmp(result, correct) != 0)
{
size_t pos = 0;
char msg[128];
pos = safecat(msg, sizeof msg, pos, "png_convert_to_rfc1123(");
pos = safecat(msg, sizeof msg, pos, correct);
pos = safecat(msg, sizeof msg, pos, ") returned: '");
pos = safecat(msg, sizeof msg, pos, result);
pos = safecat(msg, sizeof msg, pos, "'");
png_error(pp, msg);
}
store_write_reset(ps);
}
Catch(fault)
{
store_write_reset(fault);
}
#else
UNUSED(ps)
#endif
}
/* Because we want to use the same code in both the progressive reader and the
* sequential reader it is necessary to deal with the fact that the progressive
* reader callbacks only have one parameter (png_get_progressive_ptr()), so this
* must contain all the test parameters and all the local variables directly
* accessible to the sequential reader implementation.
*
* The technique adopted is to reinvent part of what Dijkstra termed a
* 'display'; an array of pointers to the stack frames of enclosing functions so
* that a nested function definition can access the local (C auto) variables of
* the functions that contain its definition. In fact C provides the first
* pointer (the local variables - the stack frame pointer) and the last (the
* global variables - the BCPL global vector typically implemented as global
* addresses), this code requires one more pointer to make the display - the
* local variables (and function call parameters) of the function that actually
* invokes either the progressive or sequential reader.
*
* Perhaps confusingly this technique is confounded with classes - the
* 'standard_display' defined here is sub-classed as the 'gamma_display' below.
* A gamma_display is a standard_display, taking advantage of the ANSI-C
* requirement that the pointer to the first member of a structure must be the
* same as the pointer to the structure. This allows us to reuse standard_
* functions in the gamma test code; something that could not be done with
* nested functions!
*/
typedef struct standard_display
{
png_store* ps; /* Test parameters (passed to the function) */
png_byte colour_type;
png_byte bit_depth;
png_byte red_sBIT; /* Input data sBIT values. */
png_byte green_sBIT;
png_byte blue_sBIT;
png_byte alpha_sBIT;
int interlace_type;
png_uint_32 id; /* Calculated file ID */
png_uint_32 w; /* Width of image */
png_uint_32 h; /* Height of image */
int npasses; /* Number of interlaced passes */
png_uint_32 pixel_size; /* Width of one pixel in bits */
png_uint_32 bit_width; /* Width of output row in bits */
size_t cbRow; /* Bytes in a row of the output image */
int do_interlace; /* Do interlacing internally */
int is_transparent; /* Transparency information was present. */
int speed; /* Doing a speed test */
struct
{
png_uint_16 red;
png_uint_16 green;
png_uint_16 blue;
} transparent; /* The transparent color, if set. */
int npalette; /* Number of entries in the palette. */
store_palette
palette;
} standard_display;
static void
standard_display_init(standard_display *dp, png_store* ps, png_uint_32 id,
int do_interlace)
{
memset(dp, 0, sizeof *dp);
dp->ps = ps;
dp->colour_type = COL_FROM_ID(id);
dp->bit_depth = DEPTH_FROM_ID(id);
if (dp->colour_type == 3)
dp->red_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT = 8;
else
dp->red_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT =
dp->bit_depth;
dp->interlace_type = INTERLACE_FROM_ID(id);
dp->id = id;
/* All the rest are filled in after the read_info: */
dp->w = 0;
dp->h = 0;
dp->npasses = 0;
dp->pixel_size = 0;
dp->bit_width = 0;
dp->cbRow = 0;
dp->do_interlace = do_interlace;
dp->is_transparent = 0;
dp->speed = ps->speed;
dp->npalette = 0;
/* Preset the transparent color to black: */
memset(&dp->transparent, 0, sizeof dp->transparent);
/* Preset the palette to full intensity/opaque througout: */
memset(dp->palette, 0xff, sizeof dp->palette);
}
/* Initialize the palette fields - this must be done later because the palette
* comes from the particular png_store_file that is selected.
*/
static void
standard_palette_init(standard_display *dp)
{
store_palette_entry *palette = store_current_palette(dp->ps, &dp->npalette);
/* The remaining entries remain white/opaque. */
if (dp->npalette > 0)
{
int i = dp->npalette;
memcpy(dp->palette, palette, i * sizeof *palette);
/* Check for a non-opaque palette entry: */
while (--i >= 0)
if (palette[i].alpha < 255)
break;
# ifdef __GNUC__
/* GCC can't handle the more obviously optimizable version. */
if (i >= 0)
dp->is_transparent = 1;
else
dp->is_transparent = 0;
# else
dp->is_transparent = (i >= 0);
# endif
}
}
/* Utility to read the palette from the PNG file and convert it into
* store_palette format. This returns 1 if there is any transparency in the
* palette (it does not check for a transparent colour in the non-palette case.)
*/
static int
read_palette(store_palette palette, int *npalette, png_structp pp, png_infop pi)
{
png_colorp pal;
png_bytep trans_alpha;
int num;
pal = 0;
*npalette = -1;
if (png_get_PLTE(pp, pi, &pal, npalette) & PNG_INFO_PLTE)
{
int i = *npalette;
if (i <= 0 || i > 256)
png_error(pp, "validate: invalid PLTE count");
while (--i >= 0)
{
palette[i].red = pal[i].red;
palette[i].green = pal[i].green;
palette[i].blue = pal[i].blue;
}
/* Mark the remainder of the entries with a flag value (other than
* white/opaque which is the flag value stored above.)
*/
memset(palette + *npalette, 126, (256-*npalette) * sizeof *palette);
}
else /* !png_get_PLTE */
{
if (*npalette != (-1))
png_error(pp, "validate: invalid PLTE result");
/* But there is no palette, so record this: */
*npalette = 0;
memset(palette, 113, sizeof palette);
}
trans_alpha = 0;
num = 2; /* force error below */
if ((png_get_tRNS(pp, pi, &trans_alpha, &num, 0) & PNG_INFO_tRNS) != 0 &&
(trans_alpha != NULL || num != 1/*returns 1 for a transparent color*/) &&
/* Oops, if a palette tRNS gets expanded png_read_update_info (at least so
* far as 1.5.4) does not zap the trans_alpha pointer, only num_trans, so
* in the above call we get a success, we get a pointer (who knows what
* to) and we get num_trans == 0:
*/
!(trans_alpha != NULL && num == 0)) /* TODO: fix this in libpng. */
{
int i;
/* Any of these are crash-worthy - given the implementation of
* png_get_tRNS up to 1.5 an app won't crash if it just checks the
* result above and fails to check that the variables it passed have
* actually been filled in! Note that if the app were to pass the
* last, png_color_16p, variable too it couldn't rely on this.
*/
if (trans_alpha == NULL || num <= 0 || num > 256 || num > *npalette)
png_error(pp, "validate: unexpected png_get_tRNS (palette) result");
for (i=0; i<num; ++i)
palette[i].alpha = trans_alpha[i];
for (num=*npalette; i<num; ++i)
palette[i].alpha = 255;
for (; i<256; ++i)
palette[i].alpha = 33; /* flag value */
return 1; /* transparency */
}
else
{
/* No palette transparency - just set the alpha channel to opaque. */
int i;
for (i=0, num=*npalette; i<num; ++i)
palette[i].alpha = 255;
for (; i<256; ++i)
palette[i].alpha = 55; /* flag value */
return 0; /* no transparency */
}
}
/* Utility to validate the palette if it should not have changed (the
* non-transform case).
*/
static void
standard_palette_validate(standard_display *dp, png_structp pp, png_infop pi)
{
int npalette;
store_palette palette;
if (read_palette(palette, &npalette, pp, pi) != dp->is_transparent)
png_error(pp, "validate: palette transparency changed");
if (npalette != dp->npalette)
{
size_t pos = 0;
char msg[64];
pos = safecat(msg, sizeof msg, pos, "validate: palette size changed: ");
pos = safecatn(msg, sizeof msg, pos, dp->npalette);
pos = safecat(msg, sizeof msg, pos, " -> ");
pos = safecatn(msg, sizeof msg, pos, npalette);
png_error(pp, msg);
}
{
int i = npalette; /* npalette is aliased */
while (--i >= 0)
if (palette[i].red != dp->palette[i].red ||
palette[i].green != dp->palette[i].green ||
palette[i].blue != dp->palette[i].blue ||
palette[i].alpha != dp->palette[i].alpha)
png_error(pp, "validate: PLTE or tRNS chunk changed");
}
}
/* By passing a 'standard_display' the progressive callbacks can be used
* directly by the sequential code, the functions suffixed "_imp" are the
* implementations, the functions without the suffix are the callbacks.
*
* The code for the info callback is split into two because this callback calls
* png_read_update_info or png_start_read_image and what gets called depends on
* whether the info needs updating (we want to test both calls in pngvalid.)
*/
static void
standard_info_part1(standard_display *dp, png_structp pp, png_infop pi)
{
if (png_get_bit_depth(pp, pi) != dp->bit_depth)
png_error(pp, "validate: bit depth changed");
if (png_get_color_type(pp, pi) != dp->colour_type)
png_error(pp, "validate: color type changed");
if (png_get_filter_type(pp, pi) != PNG_FILTER_TYPE_BASE)
png_error(pp, "validate: filter type changed");
if (png_get_interlace_type(pp, pi) != dp->interlace_type)
png_error(pp, "validate: interlacing changed");
if (png_get_compression_type(pp, pi) != PNG_COMPRESSION_TYPE_BASE)
png_error(pp, "validate: compression type changed");
dp->w = png_get_image_width(pp, pi);
if (dp->w != standard_width(pp, dp->id))
png_error(pp, "validate: image width changed");
dp->h = png_get_image_height(pp, pi);
if (dp->h != standard_height(pp, dp->id))
png_error(pp, "validate: image height changed");
/* Record (but don't check at present) the input sBIT according to the colour
* type information.
*/
{
png_color_8p sBIT = 0;
if (png_get_sBIT(pp, pi, &sBIT) & PNG_INFO_sBIT)
{
int sBIT_invalid = 0;
if (sBIT == 0)
png_error(pp, "validate: unexpected png_get_sBIT result");
if (dp->colour_type & PNG_COLOR_MASK_COLOR)
{
if (sBIT->red == 0 || sBIT->red > dp->bit_depth)
sBIT_invalid = 1;
else
dp->red_sBIT = sBIT->red;
if (sBIT->green == 0 || sBIT->green > dp->bit_depth)
sBIT_invalid = 1;
else
dp->green_sBIT = sBIT->green;
if (sBIT->blue == 0 || sBIT->blue > dp->bit_depth)
sBIT_invalid = 1;
else
dp->blue_sBIT = sBIT->blue;
}
else /* !COLOR */
{
if (sBIT->gray == 0 || sBIT->gray > dp->bit_depth)
sBIT_invalid = 1;
else
dp->blue_sBIT = dp->green_sBIT = dp->red_sBIT = sBIT->gray;
}
/* All 8 bits in tRNS for a palette image are significant - see the
* spec.
*/
if (dp->colour_type & PNG_COLOR_MASK_ALPHA)
{
if (sBIT->alpha == 0 || sBIT->alpha > dp->bit_depth)
sBIT_invalid = 1;
else
dp->alpha_sBIT = sBIT->alpha;
}
if (sBIT_invalid)
png_error(pp, "validate: sBIT value out of range");
}
}
/* Important: this is validating the value *before* any transforms have been
* put in place. It doesn't matter for the standard tests, where there are
* no transforms, but it does for other tests where rowbytes may change after
* png_read_update_info.
*/
if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, dp->id))
png_error(pp, "validate: row size changed");
/* Validate the colour type 3 palette (this can be present on other color
* types.)
*/
standard_palette_validate(dp, pp, pi);
/* In any case always check for a tranparent color (notice that the
* colour type 3 case must not give a successful return on the get_tRNS call
* with these arguments!)
*/
{
png_color_16p trans_color = 0;
if (png_get_tRNS(pp, pi, 0, 0, &trans_color) & PNG_INFO_tRNS)
{
if (trans_color == 0)
png_error(pp, "validate: unexpected png_get_tRNS (color) result");
switch (dp->colour_type)
{
case 0:
dp->transparent.red = dp->transparent.green = dp->transparent.blue =
trans_color->gray;
dp->is_transparent = 1;
break;
case 2:
dp->transparent.red = trans_color->red;
dp->transparent.green = trans_color->green;
dp->transparent.blue = trans_color->blue;
dp->is_transparent = 1;
break;
case 3:
/* Not expected because it should result in the array case
* above.
*/
png_error(pp, "validate: unexpected png_get_tRNS result");
break;
default:
png_error(pp, "validate: invalid tRNS chunk with alpha image");
}
}
}
/* Read the number of passes - expected to match the value used when
* creating the image (interlaced or not). This has the side effect of
* turning on interlace handling (if do_interlace is not set.)
*/
dp->npasses = npasses_from_interlace_type(pp, dp->interlace_type);
if (!dp->do_interlace && dp->npasses != png_set_interlace_handling(pp))
png_error(pp, "validate: file changed interlace type");
/* Caller calls png_read_update_info or png_start_read_image now, then calls
* part2.
*/
}
/* This must be called *after* the png_read_update_info call to get the correct
* 'rowbytes' value, otherwise png_get_rowbytes will refer to the untransformed
* image.
*/
static void
standard_info_part2(standard_display *dp, png_structp pp, png_infop pi,
int nImages)
{
/* Record cbRow now that it can be found. */
dp->pixel_size = bit_size(pp, png_get_color_type(pp, pi),
png_get_bit_depth(pp, pi));
dp->bit_width = png_get_image_width(pp, pi) * dp->pixel_size;
dp->cbRow = png_get_rowbytes(pp, pi);
/* Validate the rowbytes here again. */
if (dp->cbRow != (dp->bit_width+7)/8)
png_error(pp, "bad png_get_rowbytes calculation");
/* Then ensure there is enough space for the output image(s). */
store_ensure_image(dp->ps, pp, nImages, dp->cbRow, dp->h);
}
static void
standard_info_imp(standard_display *dp, png_structp pp, png_infop pi,
int nImages)
{
/* Note that the validation routine has the side effect of turning on
* interlace handling in the subsequent code.
*/
standard_info_part1(dp, pp, pi);
/* And the info callback has to call this (or png_read_update_info - see
* below in the png_modifier code for that variant.
*/
png_start_read_image(pp);
/* Validate the height, width and rowbytes plus ensure that sufficient buffer
* exists for decoding the image.
*/
standard_info_part2(dp, pp, pi, nImages);
}
static void
standard_info(png_structp pp, png_infop pi)
{
standard_display *dp = voidcast(standard_display*,
png_get_progressive_ptr(pp));
/* Call with nImages==1 because the progressive reader can only produce one
* image.
*/
standard_info_imp(dp, pp, pi, 1 /*only one image*/);
}
static void
progressive_row(png_structp pp, png_bytep new_row, png_uint_32 y, int pass)
{
PNG_CONST standard_display *dp = voidcast(standard_display*,
png_get_progressive_ptr(pp));
/* When handling interlacing some rows will be absent in each pass, the
* callback still gets called, but with a NULL pointer. This is checked
* in the 'else' clause below. We need our own 'cbRow', but we can't call
* png_get_rowbytes because we got no info structure.
*/
if (new_row != NULL)
{
png_bytep row;
/* In the case where the reader doesn't do the interlace it gives
* us the y in the sub-image:
*/
if (dp->do_interlace && dp->interlace_type == PNG_INTERLACE_ADAM7)
{
#ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
/* Use this opportunity to validate the png 'current' APIs: */
if (y != png_get_current_row_number(pp))
png_error(pp, "png_get_current_row_number is broken");
if (pass != png_get_current_pass_number(pp))
png_error(pp, "png_get_current_pass_number is broken");
#endif
y = PNG_ROW_FROM_PASS_ROW(y, pass);
}
/* Validate this just in case. */
if (y >= dp->h)
png_error(pp, "invalid y to progressive row callback");
row = store_image_row(dp->ps, pp, 0, y);
/* Combine the new row into the old: */
if (dp->do_interlace)
{
if (dp->interlace_type == PNG_INTERLACE_ADAM7)
deinterlace_row(row, new_row, dp->pixel_size, dp->w, pass);
else
memcpy(row, new_row, dp->cbRow);
}
else
png_progressive_combine_row(pp, row, new_row);
} else if (dp->interlace_type == PNG_INTERLACE_ADAM7 &&
PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
PNG_PASS_COLS(dp->w, pass) > 0)
png_error(pp, "missing row in progressive de-interlacing");
}
static void
sequential_row(standard_display *dp, png_structp pp, png_infop pi,
PNG_CONST int iImage, PNG_CONST int iDisplay)
{
PNG_CONST int npasses = dp->npasses;
PNG_CONST int do_interlace = dp->do_interlace &&
dp->interlace_type == PNG_INTERLACE_ADAM7;
PNG_CONST png_uint_32 height = standard_height(pp, dp->id);
PNG_CONST png_uint_32 width = standard_width(pp, dp->id);
PNG_CONST png_store* ps = dp->ps;
int pass;
for (pass=0; pass<npasses; ++pass)
{
png_uint_32 y;
png_uint_32 wPass = PNG_PASS_COLS(width, pass);
for (y=0; y<height; ++y)
{
if (do_interlace)
{
/* wPass may be zero or this row may not be in this pass.
* png_read_row must not be called in either case.
*/
if (wPass > 0 && PNG_ROW_IN_INTERLACE_PASS(y, pass))
{
/* Read the row into a pair of temporary buffers, then do the
* merge here into the output rows.
*/
png_byte row[STANDARD_ROWMAX], display[STANDARD_ROWMAX];
/* The following aids (to some extent) error detection - we can
* see where png_read_row wrote. Use opposite values in row and
* display to make this easier.
*/
memset(row, 0xff, sizeof row);
memset(display, 0, sizeof display);
png_read_row(pp, row, display);
if (iImage >= 0)
deinterlace_row(store_image_row(ps, pp, iImage, y), row,
dp->pixel_size, dp->w, pass);
if (iDisplay >= 0)
deinterlace_row(store_image_row(ps, pp, iDisplay, y), display,
dp->pixel_size, dp->w, pass);
}
}
else
png_read_row(pp,
iImage >= 0 ? store_image_row(ps, pp, iImage, y) : NULL,
iDisplay >= 0 ? store_image_row(ps, pp, iDisplay, y) : NULL);
}
}
/* And finish the read operation (only really necessary if the caller wants
* to find additional data in png_info from chunks after the last IDAT.)
*/
png_read_end(pp, pi);
}
static void
standard_row_validate(standard_display *dp, png_structp pp,
int iImage, int iDisplay, png_uint_32 y)
{
png_byte std[STANDARD_ROWMAX];
memset(std, 0xff, sizeof std);
standard_row(pp, std, dp->id, y);
/* At the end both the 'row' and 'display' arrays should end up identical.
* In earlier passes 'row' will be partially filled in, with only the pixels
* that have been read so far, but 'display' will have those pixels
* replicated to fill the unread pixels while reading an interlaced image.
* The side effect inside the libpng sequential reader is that the 'row'
* array retains the correct values for unwritten pixels within the row
* bytes, while the 'display' array gets bits off the end of the image (in
* the last byte) trashed. Unfortunately in the progressive reader the
* row bytes are always trashed, so we always do a pixel_cmp here even though
* a memcmp of all cbRow bytes will succeed for the sequential reader.
*/
if (iImage >= 0 && pixel_cmp(std, store_image_row(dp->ps, pp, iImage, y),
dp->bit_width) != 0)
{
char msg[64];
sprintf(msg, "PNG image row %d changed", y);
png_error(pp, msg);
}
/* In this case use pixel_cmp because we need to compare a partial
* byte at the end of the row if the row is not an exact multiple
* of 8 bits wide.
*/
if (iDisplay >= 0 && pixel_cmp(std, store_image_row(dp->ps, pp, iDisplay, y),
dp->bit_width) != 0)
{
char msg[64];
sprintf(msg, "display row %d changed", y);
png_error(pp, msg);
}
}
static void
standard_image_validate(standard_display *dp, png_structp pp, int iImage,
int iDisplay)
{
png_uint_32 y;
if (iImage >= 0)
store_image_check(dp->ps, pp, iImage);
if (iDisplay >= 0)
store_image_check(dp->ps, pp, iDisplay);
for (y=0; y<dp->h; ++y)
standard_row_validate(dp, pp, iImage, iDisplay, y);
/* This avoids false positives if the validation code is never called! */
dp->ps->validated = 1;
}
static void
standard_end(png_structp pp, png_infop pi)
{
standard_display *dp = voidcast(standard_display*,
png_get_progressive_ptr(pp));
UNUSED(pi)
/* Validate the image - progressive reading only produces one variant for
* interlaced images.
*/
standard_image_validate(dp, pp, 0, -1);
}
/* A single test run checking the standard image to ensure it is not damaged. */
static void
standard_test(png_store* PNG_CONST psIn, png_uint_32 PNG_CONST id,
int do_interlace)
{
standard_display d;
context(psIn, fault);
/* Set up the display (stack frame) variables from the arguments to the
* function and initialize the locals that are filled in later.
*/
standard_display_init(&d, psIn, id, do_interlace);
/* Everything is protected by a Try/Catch. The functions called also
* typically have local Try/Catch blocks.
*/
Try
{
png_structp pp;
png_infop pi;
/* Get a png_struct for reading the image. This will throw an error if it
* fails, so we don't need to check the result.
*/
pp = set_store_for_read(d.ps, &pi, d.id,
d.do_interlace ? (d.ps->progressive ?
"pngvalid progressive deinterlacer" :
"pngvalid sequential deinterlacer") : (d.ps->progressive ?
"progressive reader" : "sequential reader"));
/* Initialize the palette correctly from the png_store_file. */
standard_palette_init(&d);
/* Introduce the correct read function. */
if (d.ps->progressive)
{
png_set_progressive_read_fn(pp, &d, standard_info, progressive_row,
standard_end);
/* Now feed data into the reader until we reach the end: */
store_progressive_read(d.ps, pp, pi);
}
else
{
/* Note that this takes the store, not the display. */
png_set_read_fn(pp, d.ps, store_read);
/* Check the header values: */
png_read_info(pp, pi);
/* The code tests both versions of the images that the sequential
* reader can produce.
*/
standard_info_imp(&d, pp, pi, 2 /*images*/);
/* Need the total bytes in the image below; we can't get to this point
* unless the PNG file values have been checked against the expected
* values.
*/
{
sequential_row(&d, pp, pi, 0, 1);
/* After the last pass loop over the rows again to check that the
* image is correct.
*/
if (!d.speed)
standard_image_validate(&d, pp, 0, 1);
}
}
/* Check for validation. */
if (!d.ps->validated)
png_error(pp, "image read failed silently");
/* Successful completion. */
}
Catch(fault)
d.ps = fault; /* make sure this hasn't been clobbered. */
/* In either case clean up the store. */
store_read_reset(d.ps);
}
static int
test_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
int bdlo, int PNG_CONST bdhi)
{
for (; bdlo <= bdhi; ++bdlo)
{
int interlace_type;
for (interlace_type = PNG_INTERLACE_NONE;
interlace_type < PNG_INTERLACE_LAST; ++interlace_type)
{
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
interlace_type, 0, 0, 0), 0/*do_interlace*/);
if (fail(pm))
return 0;
}
}
return 1; /* keep going */
}
static void
perform_standard_test(png_modifier *pm)
{
/* Test each colour type over the valid range of bit depths (expressed as
* log2(bit_depth) in turn, stop as soon as any error is detected.
*/
if (!test_standard(pm, 0, 0, READ_BDHI))
return;
if (!test_standard(pm, 2, 3, READ_BDHI))
return;
if (!test_standard(pm, 3, 0, 3))
return;
if (!test_standard(pm, 4, 3, READ_BDHI))
return;
if (!test_standard(pm, 6, 3, READ_BDHI))
return;
}
/********************************** SIZE TESTS ********************************/
static int
test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
int bdlo, int PNG_CONST bdhi)
{
/* Run the tests on each combination.
*
* NOTE: on my 32 bit x86 each of the following blocks takes
* a total of 3.5 seconds if done across every combo of bit depth
* width and height. This is a waste of time in practice, hence the
* hinc and winc stuff:
*/
static PNG_CONST png_byte hinc[] = {1, 3, 11, 1, 5};
static PNG_CONST png_byte winc[] = {1, 9, 5, 7, 1};
for (; bdlo <= bdhi; ++bdlo)
{
png_uint_32 h, w;
for (h=1; h<=16; h+=hinc[bdlo]) for (w=1; w<=16; w+=winc[bdlo])
{
/* First test all the 'size' images against the sequential
* reader using libpng to deinterlace (where required.) This
* validates the write side of libpng. There are four possibilities
* to validate.
*/
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
PNG_INTERLACE_NONE, w, h, 0), 0/*do_interlace*/);
if (fail(pm))
return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
PNG_INTERLACE_NONE, w, h, 1), 0/*do_interlace*/);
if (fail(pm))
return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
PNG_INTERLACE_ADAM7, w, h, 0), 0/*do_interlace*/);
if (fail(pm))
return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
PNG_INTERLACE_ADAM7, w, h, 1), 0/*do_interlace*/);
if (fail(pm))
return 0;
/* Now validate the interlaced read side - do_interlace true,
* in the progressive case this does actually make a difference
* to the code used in the non-interlaced case too.
*/
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
PNG_INTERLACE_NONE, w, h, 0), 1/*do_interlace*/);
if (fail(pm))
return 0;
standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
PNG_INTERLACE_ADAM7, w, h, 0), 1/*do_interlace*/);
if (fail(pm))
return 0;
}
}
return 1; /* keep going */
}
static void
perform_size_test(png_modifier *pm)
{
/* Test each colour type over the valid range of bit depths (expressed as
* log2(bit_depth) in turn, stop as soon as any error is detected.
*/
if (!test_size(pm, 0, 0, READ_BDHI))
return;
if (!test_size(pm, 2, 3, READ_BDHI))
return;
/* For the moment don't do the palette test - it's a waste of time when
* compared to the greyscale test.
*/
#if 0
if (!test_size(pm, 3, 0, 3))
return;
#endif
if (!test_size(pm, 4, 3, READ_BDHI))
return;
if (!test_size(pm, 6, 3, READ_BDHI))
return;
}
/******************************* TRANSFORM TESTS ******************************/
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
/* A set of tests to validate libpng image transforms. The possibilities here
* are legion because the transforms can be combined in a combinatorial
* fashion. To deal with this some measure of restraint is required, otherwise
* the tests would take forever.
*/
typedef struct image_pixel
{
/* A local (pngvalid) representation of a PNG pixel, in all its
* various forms.
*/
unsigned int red, green, blue, alpha; /* For non-palette images. */
unsigned int palette_index; /* For a palette image. */
png_byte colour_type; /* As in the spec. */
png_byte bit_depth; /* Defines bit size in row */
png_byte sample_depth; /* Scale of samples */
int have_tRNS; /* tRNS chunk may need processing */
/* For checking the code calculates double precision floating point values
* along with an error value, accumulated from the transforms. Because an
* sBIT setting allows larger error bounds (indeed, by the spec, apparently
* up to just less than +/-1 in the scaled value) the *lowest* sBIT for each
* channel is stored. This sBIT value is folded in to the stored error value
* at the end of the application of the transforms to the pixel.
*/
double redf, greenf, bluef, alphaf;
double rede, greene, bluee, alphae;
png_byte red_sBIT, green_sBIT, blue_sBIT, alpha_sBIT;
} image_pixel;
/* Shared utility function, see below. */
static void
image_pixel_setf(image_pixel *this, unsigned int max)
{
this->redf = this->red / (double)max;
this->greenf = this->green / (double)max;
this->bluef = this->blue / (double)max;
this->alphaf = this->alpha / (double)max;
if (this->red < max)
this->rede = this->redf * DBL_EPSILON;
else
this->rede = 0;
if (this->green < max)
this->greene = this->greenf * DBL_EPSILON;
else
this->greene = 0;
if (this->blue < max)
this->bluee = this->bluef * DBL_EPSILON;
else
this->bluee = 0;
if (this->alpha < max)
this->alphae = this->alphaf * DBL_EPSILON;
else
this->alphae = 0;
}
/* Initialize the structure for the next pixel - call this before doing any
* transforms and call it for each pixel since all the fields may need to be
* reset.
*/
static void
image_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type,
png_byte bit_depth, png_uint_32 x, store_palette palette)
{
PNG_CONST png_byte sample_depth = (png_byte)(colour_type ==
PNG_COLOR_TYPE_PALETTE ? 8 : bit_depth);
PNG_CONST unsigned int max = (1U<<sample_depth)-1;
/* Initially just set everything to the same number and the alpha to opaque.
* Note that this currently assumes a simple palette where entry x has colour
* rgb(x,x,x)!
*/
this->palette_index = this->red = this->green = this->blue =
sample(row, colour_type, bit_depth, x, 0);
this->alpha = max;
this->red_sBIT = this->green_sBIT = this->blue_sBIT = this->alpha_sBIT =
sample_depth;
/* Then override as appropriate: */
if (colour_type == 3) /* palette */
{
/* This permits the caller to default to the sample value. */
if (palette != 0)
{
PNG_CONST unsigned int i = this->palette_index;
this->red = palette[i].red;
this->green = palette[i].green;
this->blue = palette[i].blue;
this->alpha = palette[i].alpha;
}
}
else /* not palette */
{
unsigned int i = 0;
if (colour_type & 2)
{
this->green = sample(row, colour_type, bit_depth, x, 1);
this->blue = sample(row, colour_type, bit_depth, x, 2);
i = 2;
}
if (colour_type & 4)
this->alpha = sample(row, colour_type, bit_depth, x, ++i);
}
/* Calculate the scaled values, these are simply the values divided by
* 'max' and the error is initialized to the double precision epsilon value
* from the header file.
*/
image_pixel_setf(this, max);
/* Store the input information for use in the transforms - these will
* modify the information.
*/
this->colour_type = colour_type;
this->bit_depth = bit_depth;
this->sample_depth = sample_depth;
this->have_tRNS = 0;
}
/* Convert a palette image to an rgb image. This necessarily converts the tRNS
* chunk at the same time, because the tRNS will be in palette form. The way
* palette validation works means that the original palette is never updated,
* instead the image_pixel value from the row contains the RGB of the
* corresponding palette entry and *this* is updated. Consequently this routine
* only needs to change the colour type information.
*/
static void
image_pixel_convert_PLTE(image_pixel *this)
{
if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
{
if (this->have_tRNS)
{
this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
this->have_tRNS = 0;
}
else
this->colour_type = PNG_COLOR_TYPE_RGB;
/* The bit depth of the row changes at this point too (notice that this is
* the row format, not the sample depth, which is separate.)
*/
this->bit_depth = 8;
}
}
/* Add an alpha channel; this will import the tRNS information because tRNS is
* not valid in an alpha image. The bit depth will invariably be set to at
* least 8. Palette images will be converted to alpha (using the above API).
*/
static void
image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
{
if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(this);
if ((this->colour_type & PNG_COLOR_MASK_ALPHA) == 0)
{
if (this->colour_type == PNG_COLOR_TYPE_GRAY)
{
if (this->bit_depth < 8)
this->bit_depth = 8;
if (this->have_tRNS)
{
this->have_tRNS = 0;
/* Check the input, original, channel value here against the
* original tRNS gray chunk valie.
*/
if (this->red == display->transparent.red)
this->alphaf = 0;
else
this->alphaf = 1;
}
else
this->alphaf = 1;
this->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA;
}
else if (this->colour_type == PNG_COLOR_TYPE_RGB)
{
if (this->have_tRNS)
{
this->have_tRNS = 0;
/* Again, check the exact input values, not the current transformed
* value!
*/
if (this->red == display->transparent.red &&
this->green == display->transparent.green &&
this->blue == display->transparent.blue)
this->alphaf = 0;
else
this->alphaf = 1;
this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
}
}
/* The error in the alpha is zero and the sBIT value comes from the
* original sBIT data (actually it will always be the original bit depth).
*/
this->alphae = 0;
this->alpha_sBIT = display->alpha_sBIT;
}
}
struct transform_display;
typedef struct image_transform
{
/* The name of this transform: a string. */
PNG_CONST char *name;
/* Each transform can be disabled from the command line: */
int enable;
/* The global list of transforms; read only. */
struct image_transform *PNG_CONST list;
/* The global count of the number of times this transform has been set on an
* image.
*/
unsigned int global_use;
/* The local count of the number of times this transform has been set. */
unsigned int local_use;
/* The next transform in the list, each transform must call its own next
* transform after it has processed the pixel successfully.
*/
PNG_CONST struct image_transform *next;
/* A single transform for the image, expressed as a series of function
* callbacks and some space for values.
*
* First a callback to add any required modifications to the png_modifier;
* this gets called just before the modifier is set up for read.
*/
void (*ini)(PNG_CONST struct image_transform *this,
struct transform_display *that);
/* And a callback to set the transform on the current png_read_struct:
*/
void (*set)(PNG_CONST struct image_transform *this,
struct transform_display *that, png_structp pp, png_infop pi);
/* Then a transform that takes an input pixel in one PNG format or another
* and modifies it by a pngvalid implementation of the transform (thus
* duplicating the libpng intent without, we hope, duplicating the bugs
* in the libpng implementation!) The png_structp is solely to allow error
* reporting via png_error and png_warning.
*/
void (*mod)(PNG_CONST struct image_transform *this, image_pixel *that,
png_structp pp, PNG_CONST struct transform_display *display);
/* Add this transform to the list and return true if the transform is
* meaningful for this colour type and bit depth - if false then the
* transform should have no effect on the image so there's not a lot of
* point running it.
*/
int (*add)(struct image_transform *this,
PNG_CONST struct image_transform **that, png_byte colour_type,
png_byte bit_depth);
} image_transform;
typedef struct transform_display
{
standard_display this;
/* Parameters */
png_modifier* pm;
PNG_CONST image_transform* transform_list;
/* Local variables */
png_byte output_colour_type;
png_byte output_bit_depth;
/* Modifications (not necessarily used.) */
gama_modification gama_mod;
chrm_modification chrm_mod;
srgb_modification srgb_mod;
} transform_display;
/* Set sRGB, cHRM and gAMA transforms as required by the current encoding. */
static void
transform_set_encoding(transform_display *this)
{
/* Set up the png_modifier '_current' fields then use these to determine how
* to add appropriate chunks.
*/
png_modifier *pm = this->pm;
modifier_set_encoding(pm);
if (modifier_color_encoding_is_set(pm))
{
if (modifier_color_encoding_is_sRGB(pm))
srgb_modification_init(&this->srgb_mod, pm, PNG_sRGB_INTENT_ABSOLUTE);
else
{
/* Set gAMA and cHRM separately. */
gama_modification_init(&this->gama_mod, pm, pm->current_gamma);
if (pm->current_encoding != 0)
chrm_modification_init(&this->chrm_mod, pm, pm->current_encoding);
}
}
}
/* Three functions to end the list: */
static void
image_transform_ini_end(PNG_CONST image_transform *this,
transform_display *that)
{
UNUSED(this)
UNUSED(that)
}
static void
image_transform_set_end(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
UNUSED(this)
UNUSED(that)
UNUSED(pp)
UNUSED(pi)
}
/* At the end of the list recalculate the output image pixel value from the
* double precision values set up by the preceding 'mod' calls:
*/
static unsigned int
sample_scale(double sample_value, unsigned int scale)
{
sample_value = floor(sample_value * scale + .5);
/* Return NaN as 0: */
if (!(sample_value > 0))
sample_value = 0;
else if (sample_value > scale)
sample_value = scale;
return (unsigned int)sample_value;
}
static void
image_transform_mod_end(PNG_CONST image_transform *this, image_pixel *that,
png_structp pp, PNG_CONST transform_display *display)
{
PNG_CONST unsigned int scale = (1U<<that->sample_depth)-1;
UNUSED(this)
UNUSED(pp)
UNUSED(display)
/* At the end recalculate the digitized red green and blue values according
* to the current sample_depth of the pixel.
*
* The sample value is simply scaled to the maximum, checking for over
* and underflow (which can both happen for some image transforms,
* including simple size scaling, though libpng doesn't do that at present.
*/
that->red = sample_scale(that->redf, scale);
/* The error value is increased, at the end, according to the lowest sBIT
* value seen. Common sense tells us that the intermediate integer
* representations are no more accurate than +/- 0.5 in the integral values,
* the sBIT allows the implementation to be worse than this. In addition the
* PNG specification actually permits any error within the range (-1..+1),
* but that is ignored here. Instead the final digitized value is compared,
* below to the digitized value of the error limits - this has the net effect
* of allowing (almost) +/-1 in the output value. It's difficult to see how
* any algorithm that digitizes intermediate results can be more accurate.
*/
that->rede += 1./(2*((1U<<that->red_sBIT)-1));
if (that->colour_type & PNG_COLOR_MASK_COLOR)
{
that->green = sample_scale(that->greenf, scale);
that->blue = sample_scale(that->bluef, scale);
that->greene += 1./(2*((1U<<that->green_sBIT)-1));
that->bluee += 1./(2*((1U<<that->blue_sBIT)-1));
}
else
{
that->blue = that->green = that->red;
that->bluef = that->greenf = that->redf;
that->bluee = that->greene = that->rede;
}
if ((that->colour_type & PNG_COLOR_MASK_ALPHA) ||
that->colour_type == PNG_COLOR_TYPE_PALETTE)
{
that->alpha = sample_scale(that->alphaf, scale);
that->alphae += 1./(2*((1U<<that->alpha_sBIT)-1));
}
else
{
that->alpha = scale; /* opaque */
that->alpha = 1; /* Override this. */
that->alphae = 0; /* It's exact ;-) */
}
}
/* Static 'end' structure: */
static image_transform image_transform_end =
{
"(end)", /* name */
1, /* enable */
0, /* list */
0, /* global_use */
0, /* local_use */
0, /* next */
image_transform_ini_end,
image_transform_set_end,
image_transform_mod_end,
0 /* never called, I want it to crash if it is! */
};
/* Reader callbacks and implementations, where they differ from the standard
* ones.
*/
static void
transform_display_init(transform_display *dp, png_modifier *pm, png_uint_32 id,
PNG_CONST image_transform *transform_list)
{
memset(dp, 0, sizeof dp);
/* Standard fields */
standard_display_init(&dp->this, &pm->this, id, 0/*do_interlace*/);
/* Parameter fields */
dp->pm = pm;
dp->transform_list = transform_list;
/* Local variable fields */
dp->output_colour_type = 255; /* invalid */
dp->output_bit_depth = 255; /* invalid */
}
static void
transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
{
/* Reuse the standard stuff as appropriate. */
standard_info_part1(&dp->this, pp, pi);
/* Now set the list of transforms. */
dp->transform_list->set(dp->transform_list, dp, pp, pi);
/* Update the info structure for these transforms: */
png_read_update_info(pp, pi);
/* And get the output information into the standard_display */
standard_info_part2(&dp->this, pp, pi, 1/*images*/);
/* Plus the extra stuff we need for the transform tests: */
dp->output_colour_type = png_get_color_type(pp, pi);
dp->output_bit_depth = png_get_bit_depth(pp, pi);
/* Validate the combination of colour type and bit depth that we are getting
* out of libpng; the semantics of something not in the PNG spec are, at
* best, unclear.
*/
switch (dp->output_colour_type)
{
case PNG_COLOR_TYPE_PALETTE:
if (dp->output_bit_depth > 8) goto error;
/*FALL THROUGH*/
case PNG_COLOR_TYPE_GRAY:
if (dp->output_bit_depth == 1 || dp->output_bit_depth == 2 ||
dp->output_bit_depth == 4)
break;
/*FALL THROUGH*/
default:
if (dp->output_bit_depth == 8 || dp->output_bit_depth == 16)
break;
/*FALL THROUGH*/
error:
{
char message[128];
size_t pos;
pos = safecat(message, sizeof message, 0,
"invalid final bit depth: colour type(");
pos = safecatn(message, sizeof message, pos, dp->output_colour_type);
pos = safecat(message, sizeof message, pos, ") with bit depth: ");
pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
png_error(pp, message);
}
}
/* Use a test pixel to check that the output agrees with what we expect -
* this avoids running the whole test if the output is unexpected.
*/
{
image_pixel test_pixel;
memset(&test_pixel, 0, sizeof test_pixel);
test_pixel.colour_type = dp->this.colour_type; /* input */
test_pixel.bit_depth = dp->this.bit_depth;
if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE)
test_pixel.sample_depth = 8;
else
test_pixel.sample_depth = test_pixel.bit_depth;
/* Don't need sBIT here */
test_pixel.have_tRNS = dp->this.is_transparent;
dp->transform_list->mod(dp->transform_list, &test_pixel, pp, dp);
if (test_pixel.colour_type != dp->output_colour_type)
{
char message[128];
size_t pos = safecat(message, sizeof message, 0, "colour type ");
pos = safecatn(message, sizeof message, pos, dp->output_colour_type);
pos = safecat(message, sizeof message, pos, " expected ");
pos = safecatn(message, sizeof message, pos, test_pixel.colour_type);
png_error(pp, message);
}
if (test_pixel.bit_depth != dp->output_bit_depth)
{
char message[128];
size_t pos = safecat(message, sizeof message, 0, "bit depth ");
pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
pos = safecat(message, sizeof message, pos, " expected ");
pos = safecatn(message, sizeof message, pos, test_pixel.bit_depth);
png_error(pp, message);
}
/* If both bit depth and colour type are correct check the sample depth.
* I believe these are both internal errors.
*/
if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE)
{
if (test_pixel.sample_depth != 8) /* oops - internal error! */
png_error(pp, "pngvalid: internal: palette sample depth not 8");
}
else if (test_pixel.sample_depth != dp->output_bit_depth)
{
char message[128];
size_t pos = safecat(message, sizeof message, 0,
"internal: sample depth ");
pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
pos = safecat(message, sizeof message, pos, " expected ");
pos = safecatn(message, sizeof message, pos, test_pixel.sample_depth);
png_error(pp, message);
}
}
}
static void
transform_info(png_structp pp, png_infop pi)
{
transform_info_imp(voidcast(transform_display*, png_get_progressive_ptr(pp)),
pp, pi);
}
static void
transform_range_check(png_structp pp, unsigned int r, unsigned int g,
unsigned int b, unsigned int a, unsigned int in_digitized, double in,
unsigned int out, png_byte sample_depth, double err, double limit,
PNG_CONST char *name, double digitization_error)
{
/* Compare the scaled, digitzed, values of our local calculation (in+-err)
* with the digitized values libpng produced; 'sample_depth' is the actual
* digitization depth of the libpng output colors (the bit depth except for
* palette images where it is always 8.) The check on 'err' is to detect
* internal errors in pngvalid itself.
*/
unsigned int max = (1U<<sample_depth)-1;
double in_min = ceil((in-err)*max - digitization_error);
double in_max = floor((in+err)*max + digitization_error);
if (err > limit || !(out >= in_min && out <= in_max))
{
char message[256];
size_t pos;
pos = safecat(message, sizeof message, 0, name);
pos = safecat(message, sizeof message, pos, " output value error: rgba(");
pos = safecatn(message, sizeof message, pos, r);
pos = safecat(message, sizeof message, pos, ",");
pos = safecatn(message, sizeof message, pos, g);
pos = safecat(message, sizeof message, pos, ",");
pos = safecatn(message, sizeof message, pos, b);
pos = safecat(message, sizeof message, pos, ",");
pos = safecatn(message, sizeof message, pos, a);
pos = safecat(message, sizeof message, pos, "): ");
pos = safecatn(message, sizeof message, pos, out);
pos = safecat(message, sizeof message, pos, " expected: ");
pos = safecatn(message, sizeof message, pos, in_digitized);
pos = safecat(message, sizeof message, pos, " (");
pos = safecatd(message, sizeof message, pos, (in-err)*max, 3);
pos = safecat(message, sizeof message, pos, "..");
pos = safecatd(message, sizeof message, pos, (in+err)*max, 3);
pos = safecat(message, sizeof message, pos, ")");
png_error(pp, message);
}
}
static void
transform_image_validate(transform_display *dp, png_structp pp, png_infop pi)
{
/* Constants for the loop below: */
PNG_CONST png_store* PNG_CONST ps = dp->this.ps;
PNG_CONST png_byte in_ct = dp->this.colour_type;
PNG_CONST png_byte in_bd = dp->this.bit_depth;
PNG_CONST png_uint_32 w = dp->this.w;
PNG_CONST png_uint_32 h = dp->this.h;
PNG_CONST png_byte out_ct = dp->output_colour_type;
PNG_CONST png_byte out_bd = dp->output_bit_depth;
PNG_CONST png_byte sample_depth = (png_byte)(out_ct ==
PNG_COLOR_TYPE_PALETTE ? 8 : out_bd);
PNG_CONST png_byte red_sBIT = dp->this.red_sBIT;
PNG_CONST png_byte green_sBIT = dp->this.green_sBIT;
PNG_CONST png_byte blue_sBIT = dp->this.blue_sBIT;
PNG_CONST png_byte alpha_sBIT = dp->this.alpha_sBIT;
PNG_CONST int have_tRNS = dp->this.is_transparent;
double digitization_error;
store_palette out_palette;
png_uint_32 y;
UNUSED(pi)
/* Check for row overwrite errors */
store_image_check(dp->this.ps, pp, 0);
/* Read the palette corresponding to the output if the output colour type
* indicates a palette, othewise set out_palette to garbage.
*/
if (out_ct == PNG_COLOR_TYPE_PALETTE)
{
/* Validate that the palette count itself has not changed - this is not
* expected.
*/
int npalette = (-1);
(void)read_palette(out_palette, &npalette, pp, pi);
if (npalette != dp->this.npalette)
png_error(pp, "unexpected change in palette size");
digitization_error = .5;
}
else
{
png_byte in_sample_depth;
memset(out_palette, 0x5e, sizeof out_palette);
/* assume-8-bit-calculations means assume that if the input has 8 bit
* (or less) samples and the output has 16 bit samples the calculations
* will be done with 8 bit precision, not 16.
*
* TODO: fix this in libpng; png_set_expand_16 should cause 16 bit
* calculations to be used throughout.
*/
if (in_ct == PNG_COLOR_TYPE_PALETTE || in_bd < 16)
in_sample_depth = 8;
else
in_sample_depth = in_bd;
if (sample_depth != 16 || in_sample_depth > 8 ||
!dp->pm->calculations_use_input_precision)
digitization_error = .5;
/* Else errors are at 8 bit precision, scale .5 in 8 bits to the 16 bits:
*/
else
digitization_error = .5 * 257;
}
for (y=0; y<h; ++y)
{
png_const_bytep PNG_CONST pRow = store_image_row(ps, pp, 0, y);
png_uint_32 x;
/* The original, standard, row pre-transforms. */
png_byte std[STANDARD_ROWMAX];
transform_row(pp, std, in_ct, in_bd, y);
/* Go through each original pixel transforming it and comparing with what
* libpng did to the same pixel.
*/
for (x=0; x<w; ++x)
{
image_pixel in_pixel, out_pixel;
unsigned int r, g, b, a;
/* Find out what we think the pixel should be: */
image_pixel_init(&in_pixel, std, in_ct, in_bd, x, dp->this.palette);
in_pixel.red_sBIT = red_sBIT;
in_pixel.green_sBIT = green_sBIT;
in_pixel.blue_sBIT = blue_sBIT;
in_pixel.alpha_sBIT = alpha_sBIT;
in_pixel.have_tRNS = have_tRNS;
/* For error detection, below. */
r = in_pixel.red;
g = in_pixel.green;
b = in_pixel.blue;
a = in_pixel.alpha;
dp->transform_list->mod(dp->transform_list, &in_pixel, pp, dp);
/* Read the output pixel and compare it to what we got, we don't
* use the error field here, so no need to update sBIT.
*/
image_pixel_init(&out_pixel, pRow, out_ct, out_bd, x, out_palette);
/* We don't expect changes to the index here even if the bit depth is
* changed.
*/
if (in_ct == PNG_COLOR_TYPE_PALETTE &&
out_ct == PNG_COLOR_TYPE_PALETTE)
{
if (in_pixel.palette_index != out_pixel.palette_index)
png_error(pp, "unexpected transformed palette index");
}
/* Check the colours for palette images too - in fact the palette could
* be separately verified itself in most cases.
*/
if (in_pixel.red != out_pixel.red)
transform_range_check(pp, r, g, b, a, in_pixel.red, in_pixel.redf,
out_pixel.red, sample_depth, in_pixel.rede,
dp->pm->limit + 1./(2*((1U<<in_pixel.red_sBIT)-1)), "red/gray",
digitization_error);
if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 &&
in_pixel.green != out_pixel.green)
transform_range_check(pp, r, g, b, a, in_pixel.green,
in_pixel.greenf, out_pixel.green, sample_depth, in_pixel.greene,
dp->pm->limit + 1./(2*((1U<<in_pixel.green_sBIT)-1)), "green",
digitization_error);
if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 &&
in_pixel.blue != out_pixel.blue)
transform_range_check(pp, r, g, b, a, in_pixel.blue, in_pixel.bluef,
out_pixel.blue, sample_depth, in_pixel.bluee,
dp->pm->limit + 1./(2*((1U<<in_pixel.blue_sBIT)-1)), "blue",
digitization_error);
if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0 &&
in_pixel.alpha != out_pixel.alpha)
transform_range_check(pp, r, g, b, a, in_pixel.alpha,
in_pixel.alphaf, out_pixel.alpha, sample_depth, in_pixel.alphae,
dp->pm->limit + 1./(2*((1U<<in_pixel.alpha_sBIT)-1)), "alpha",
digitization_error);
} /* pixel (x) loop */
} /* row (y) loop */
/* Record that something was actually checked to avoid a false positive. */
dp->this.ps->validated = 1;
}
static void
transform_end(png_structp pp, png_infop pi)
{
transform_display *dp = voidcast(transform_display*,
png_get_progressive_ptr(pp));
transform_image_validate(dp, pp, pi);
}
/* A single test run. */
static void
transform_test(png_modifier *pmIn, PNG_CONST png_uint_32 idIn,
PNG_CONST image_transform* transform_listIn, PNG_CONST char * volatile name)
{
transform_display d;
context(&pmIn->this, fault);
transform_display_init(&d, pmIn, idIn, transform_listIn);
Try
{
size_t pos = 0;
png_structp pp;
png_infop pi;
char full_name[256];
/* Make sure the encoding fields are correct and enter the required
* modifications.
*/
transform_set_encoding(&d);
/* Add any modifications required by the transform list. */
d.transform_list->ini(d.transform_list, &d);
/* Add the color space information, if any, to the name. */
pos = safecat(full_name, sizeof full_name, pos, name);
pos = safecat_current_encoding(full_name, sizeof full_name, pos, d.pm);
/* Get a png_struct for reading the image. */
pp = set_modifier_for_read(d.pm, &pi, d.this.id, full_name);
standard_palette_init(&d.this);
# if 0
/* Logging (debugging only) */
{
char buffer[256];
(void)store_message(&d.pm->this, pp, buffer, sizeof buffer, 0,
"running test");
fprintf(stderr, "%s\n", buffer);
}
# endif
/* Introduce the correct read function. */
if (d.pm->this.progressive)
{
/* Share the row function with the standard implementation. */
png_set_progressive_read_fn(pp, &d, transform_info, progressive_row,
transform_end);
/* Now feed data into the reader until we reach the end: */
modifier_progressive_read(d.pm, pp, pi);
}
else
{
/* modifier_read expects a png_modifier* */
png_set_read_fn(pp, d.pm, modifier_read);
/* Check the header values: */
png_read_info(pp, pi);
/* Process the 'info' requirements. Only one image is generated */
transform_info_imp(&d, pp, pi);
sequential_row(&d.this, pp, pi, -1, 0);
if (!d.this.speed)
transform_image_validate(&d, pp, pi);
}
modifier_reset(d.pm);
}
Catch(fault)
{
modifier_reset((png_modifier*)fault);
}
}
/* The transforms: */
#define ITSTRUCT(name) image_transform_##name
#define ITDATA(name) image_transform_data_##name
#define image_transform_ini image_transform_default_ini
#define IT(name)\
static image_transform ITSTRUCT(name) =\
{\
#name,\
1, /*enable*/\
&PT, /*list*/\
0, /*global_use*/\
0, /*local_use*/\
0, /*next*/\
image_transform_ini,\
image_transform_png_set_##name##_set,\
image_transform_png_set_##name##_mod,\
image_transform_png_set_##name##_add\
}
#define PT ITSTRUCT(end) /* stores the previous transform */
/* To save code: */
static void
image_transform_default_ini(PNG_CONST image_transform *this,
transform_display *that)
{
this->next->ini(this->next, that);
}
static int
image_transform_default_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(colour_type)
UNUSED(bit_depth)
this->next = *that;
*that = this;
return 1;
}
#ifdef PNG_READ_EXPAND_SUPPORTED
/* png_set_palette_to_rgb */
static void
image_transform_png_set_palette_to_rgb_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_palette_to_rgb(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_palette_to_rgb_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(that);
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_palette_to_rgb_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(bit_depth)
this->next = *that;
*that = this;
return colour_type == PNG_COLOR_TYPE_PALETTE;
}
IT(palette_to_rgb);
#undef PT
#define PT ITSTRUCT(palette_to_rgb)
#endif /* PNG_READ_EXPAND_SUPPORTED */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* png_set_tRNS_to_alpha */
static void
image_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_tRNS_to_alpha(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_tRNS_to_alpha_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
/* LIBPNG BUG: this always forces palette images to RGB. */
if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(that);
/* This effectively does an 'expand' only if there is some transparency to
* convert to an alpha channel.
*/
if (that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
/* LIBPNG BUG: otherwise libpng still expands to 8 bits! */
else
{
if (that->bit_depth < 8)
that->bit_depth =8;
if (that->sample_depth < 8)
that->sample_depth = 8;
}
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_tRNS_to_alpha_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(bit_depth)
this->next = *that;
*that = this;
/* We don't know yet whether there will be a tRNS chunk, but we know that
* this transformation should do nothing if there already is an alpha
* channel.
*/
return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
}
IT(tRNS_to_alpha);
#undef PT
#define PT ITSTRUCT(tRNS_to_alpha)
#endif /* PNG_READ_EXPAND_SUPPORTED */
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* png_set_gray_to_rgb */
static void
image_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_gray_to_rgb(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_gray_to_rgb_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
/* NOTE: we can actually pend the tRNS processing at this point because we
* can correctly recognize the original pixel value even though we have
* mapped the one gray channel to the three RGB ones, but in fact libpng
* doesn't do this, so we don't either.
*/
if ((that->colour_type & PNG_COLOR_MASK_COLOR) == 0 && that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
/* Simply expand the bit depth and alter the colour type as required. */
if (that->colour_type == PNG_COLOR_TYPE_GRAY)
{
/* RGB images have a bit depth at least equal to '8' */
if (that->bit_depth < 8)
that->sample_depth = that->bit_depth = 8;
/* And just changing the colour type works here because the green and blue
* channels are being maintained in lock-step with the red/gray:
*/
that->colour_type = PNG_COLOR_TYPE_RGB;
}
else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
that->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_gray_to_rgb_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(bit_depth)
this->next = *that;
*that = this;
return (colour_type & PNG_COLOR_MASK_COLOR) == 0;
}
IT(gray_to_rgb);
#undef PT
#define PT ITSTRUCT(gray_to_rgb)
#endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* png_set_expand */
static void
image_transform_png_set_expand_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_expand(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_expand_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
/* The general expand case depends on what the colour type is: */
if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(that);
else if (that->bit_depth < 8) /* grayscale */
that->sample_depth = that->bit_depth = 8;
if (that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_expand_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(bit_depth)
this->next = *that;
*that = this;
/* 'expand' should do nothing for RGBA or GA input - no tRNS and the bit
* depth is at least 8 already.
*/
return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
}
IT(expand);
#undef PT
#define PT ITSTRUCT(expand)
#endif /* PNG_READ_EXPAND_SUPPORTED */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* png_set_expand_gray_1_2_4_to_8
* LIBPNG BUG: this just does an 'expand'
*/
static void
image_transform_png_set_expand_gray_1_2_4_to_8_set(
PNG_CONST image_transform *this, transform_display *that, png_structp pp,
png_infop pi)
{
png_set_expand_gray_1_2_4_to_8(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_expand_gray_1_2_4_to_8_mod(
PNG_CONST image_transform *this, image_pixel *that, png_structp pp,
PNG_CONST transform_display *display)
{
image_transform_png_set_expand_mod(this, that, pp, display);
}
static int
image_transform_png_set_expand_gray_1_2_4_to_8_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
return image_transform_png_set_expand_add(this, that, colour_type,
bit_depth);
}
IT(expand_gray_1_2_4_to_8);
#undef PT
#define PT ITSTRUCT(expand_gray_1_2_4_to_8)
#endif /* PNG_READ_EXPAND_SUPPORTED */
#ifdef PNG_READ_EXPAND_16_SUPPORTED
/* png_set_expand_16 */
static void
image_transform_png_set_expand_16_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_expand_16(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_expand_16_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
/* Expect expand_16 to expand everything to 16 bits as a result of also
* causing 'expand' to happen.
*/
if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(that);
if (that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
if (that->bit_depth < 16)
that->sample_depth = that->bit_depth = 16;
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_expand_16_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(colour_type)
this->next = *that;
*that = this;
/* expand_16 does something unless the bit depth is already 16. */
return bit_depth < 16;
}
IT(expand_16);
#undef PT
#define PT ITSTRUCT(expand_16)
#endif /* PNG_READ_EXPAND_16_SUPPORTED */
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED /* API added in 1.5.4 */
/* png_set_scale_16 */
static void
image_transform_png_set_scale_16_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_scale_16(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_scale_16_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
if (that->bit_depth == 16)
{
that->sample_depth = that->bit_depth = 8;
if (that->red_sBIT > 8) that->red_sBIT = 8;
if (that->green_sBIT > 8) that->green_sBIT = 8;
if (that->blue_sBIT > 8) that->blue_sBIT = 8;
if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
}
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_scale_16_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(colour_type)
this->next = *that;
*that = this;
return bit_depth > 8;
}
IT(scale_16);
#undef PT
#define PT ITSTRUCT(scale_16)
#endif /* PNG_READ_SCALE_16_TO_8_SUPPORTED (1.5.4 on) */
#ifdef PNG_READ_16_TO_8_SUPPORTED /* the default before 1.5.4 */
/* png_set_strip_16 */
static void
image_transform_png_set_strip_16_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_strip_16(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_strip_16_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
if (that->bit_depth == 16)
{
that->sample_depth = that->bit_depth = 8;
if (that->red_sBIT > 8) that->red_sBIT = 8;
if (that->green_sBIT > 8) that->green_sBIT = 8;
if (that->blue_sBIT > 8) that->blue_sBIT = 8;
if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
/* Prior to 1.5.4 png_set_strip_16 would use an 'accurate' method if this
* configuration option is set. From 1.5.4 the flag is never set and the
* 'scale' API (above) must be used.
*/
# ifdef PNG_READ_ACCURATE_SCALE_SUPPORTED
# if PNG_LIBPNG_VER >= 10504
# error PNG_READ_ACCURATE_SCALE should not be set
# endif
/* The strip 16 algorithm drops the low 8 bits rather than calculating
* 1/257, so we need to adjust the permitted errors appropriately:
* Notice that this is only relevant prior to the addition of the
* png_set_scale_16 API in 1.5.4 (but 1.5.4+ always defines the above!)
*/
{
PNG_CONST double d = (255-128.5)/65535;
that->rede += d;
that->greene += d;
that->bluee += d;
that->alphae += d;
}
# endif
}
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_strip_16_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(colour_type)
this->next = *that;
*that = this;
return bit_depth > 8;
}
IT(strip_16);
#undef PT
#define PT ITSTRUCT(strip_16)
#endif /* PNG_READ_16_TO_8_SUPPORTED */
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
/* png_set_strip_alpha */
static void
image_transform_png_set_strip_alpha_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_strip_alpha(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_strip_alpha_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
that->colour_type = PNG_COLOR_TYPE_GRAY;
else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
that->colour_type = PNG_COLOR_TYPE_RGB;
that->have_tRNS = 0;
that->alphaf = 1;
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_strip_alpha_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(bit_depth)
this->next = *that;
*that = this;
return (colour_type & PNG_COLOR_MASK_ALPHA) != 0;
}
IT(strip_alpha);
#undef PT
#define PT ITSTRUCT(strip_alpha)
#endif /* PNG_READ_STRIP_ALPHA_SUPPORTED */
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* png_set_rgb_to_gray(png_structp, int err_action, double red, double green)
* png_set_rgb_to_gray_fixed(png_structp, int err_action, png_fixed_point red,
* png_fixed_point green)
* png_get_rgb_to_gray_status
*
* The 'default' test here uses values known to be used inside libpng:
*
* red: 6968
* green: 23434
* blue: 2366
*
* These values are being retained for compatibility, along with the somewhat
* broken truncation calculation in the fast-and-inaccurate code path. Older
* versions of libpng will fail the accuracy tests below because they use the
* truncation algorithm everywhere.
*/
#define data ITDATA(rgb_to_gray)
static struct
{
double gamma; /* File gamma to use in processing */
/* The following are the parameters for png_set_rgb_to_gray: */
# ifdef PNG_FLOATING_POINT_SUPPORTED
double red_to_set;
double green_to_set;
# else
png_fixed_point red_to_set;
png_fixed_point green_to_set;
# endif
/* The actual coefficients: */
double red_coefficient;
double green_coefficient;
double blue_coefficient;
/* Set if the coeefficients have been overridden. */
int coefficients_overridden;
} data;
#undef image_transform_ini
#define image_transform_ini image_transform_png_set_rgb_to_gray_ini
static void
image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
transform_display *that)
{
png_modifier *pm = that->pm;
PNG_CONST color_encoding *e = pm->current_encoding;
UNUSED(this)
/* Since we check the encoding this flag must be set: */
pm->test_uses_encoding = 1;
/* If 'e' is not NULL chromaticity information is present and either a cHRM
* or an sRGB chunk will be inserted.
*/
if (e != 0)
{
/* Coefficients come from the encoding, but may need to be normalized to a
* white point Y of 1.0
*/
PNG_CONST double whiteY = e->red.Y + e->green.Y + e->blue.Y;
data.red_coefficient = e->red.Y;
data.green_coefficient = e->green.Y;
data.blue_coefficient = e->blue.Y;
if (whiteY != 1)
{
data.red_coefficient /= whiteY;
data.green_coefficient /= whiteY;
data.blue_coefficient /= whiteY;
}
}
else
{
/* The default (built in) coeffcients, as above: */
data.red_coefficient = 6968 / 32768.;
data.green_coefficient = 23434 / 32768.;
data.blue_coefficient = 2366 / 32768.;
}
data.gamma = pm->current_gamma;
/* If not set then the calculations assume linear encoding (implicitly): */
if (data.gamma == 0)
data.gamma = 1;
/* The arguments to png_set_rgb_to_gray can override the coefficients implied
* by the color space encoding. If doing exhaustive checks do the override
* in each case, otherwise do it randomly.
*/
if (pm->test_exhaustive)
{
/* First time in coefficients_overridden is 0, the following sets it to 1,
* so repeat if it is set. If a test fails this may mean we subsequently
* skip a non-override test, ignore that.
*/
data.coefficients_overridden = !data.coefficients_overridden;
pm->repeat = data.coefficients_overridden != 0;
}
else
data.coefficients_overridden = random_choice();
if (data.coefficients_overridden)
{
/* These values override the color encoding defaults, simply use random
* numbers.
*/
png_uint_32 ru;
double total;
RANDOMIZE(ru);
data.green_coefficient = total = (ru & 0xffff) / 65535.;
ru >>= 16;
data.red_coefficient = (1 - total) * (ru & 0xffff) / 65535.;
total += data.red_coefficient;
data.blue_coefficient = 1 - total;
# ifdef PNG_FLOATING_POINT_SUPPORTED
data.red_to_set = data.red_coefficient;
data.green_to_set = data.green_coefficient;
# else
data.red_to_set = fix(data.red_coefficient);
data.green_to_set = fix(data.green_coefficient);
# endif
/* The following just changes the error messages: */
pm->encoding_ignored = 1;
}
else
{
data.red_to_set = -1;
data.green_to_set = -1;
}
/* Adjust the error limit in the png_modifier because of the larger errors
* produced in the digitization during the gamma handling.
*/
if (data.gamma != 1) /* Use gamma tables */
{
if (that->this.bit_depth == 16 || pm->assume_16_bit_calculations)
{
/* The 16 bit case ends up producing a maximum error of about
* +/-5 in 65535, allow for +/-8 with the given gamma.
*/
that->pm->limit += pow(8./65535, data.gamma);
}
else
{
/* Rounding to 8 bits in the linear space causes massive errors which
* will trigger the error check in transform_range_check. Fix that
* here by taking the gamma encoding into account.
*/
that->pm->limit += pow(1./255, data.gamma);
}
}
else
{
/* With no gamma correction a large error comes from the truncation of the
* calculation in the 8 bit case, allow for that here.
*/
if (that->this.bit_depth != 16)
that->pm->limit += 4E-3;
}
}
static void
image_transform_png_set_rgb_to_gray_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
PNG_CONST int error_action = 1; /* no error, no defines in png.h */
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_rgb_to_gray(pp, error_action, data.red_to_set, data.green_to_set);
# else
png_set_rgb_to_gray_fixed(pp, error_action, data.red_to_set,
data.green_to_set);
# endif
# ifdef PNG_READ_cHRM_SUPPORTED
if (that->pm->current_encoding != 0)
{
/* We have an encoding so a cHRM chunk may have been set; if so then
* check that the libpng APIs give the correct (X,Y,Z) values within
* some margin of error for the round trip through the chromaticity
* form.
*/
# ifdef PNG_FLOATING_POINT_SUPPORTED
# define API_function png_get_cHRM_XYZ
# define API_form "FP"
# define API_type double
# define API_cvt(x) (x)
# else
# define API_function png_get_cHRM_XYZ_fixed
# define API_form "fixed"
# define API_type png_fixed_point
# define API_cvt(x) ((double)(x)/PNG_FP_1)
# endif
API_type rX, gX, bX;
API_type rY, gY, bY;
API_type rZ, gZ, bZ;
if ((API_function(pp, pi, &rX, &rY, &rZ, &gX, &gY, &gZ, &bX, &bY, &bZ)
& PNG_INFO_cHRM) != 0)
{
double maxe;
PNG_CONST char *el;
color_encoding e, o;
/* Expect libpng to return a normalized result, but the original
* color space encoding may not be normalized.
*/
modifier_current_encoding(that->pm, &o);
normalize_color_encoding(&o);
/* Sanity check the pngvalid code - the coefficients should match
* the normalized Y values of the encoding unless they were
* overridden.
*/
if (data.red_to_set == -1 && data.green_to_set == -1 &&
(fabs(o.red.Y - data.red_coefficient) > DBL_EPSILON ||
fabs(o.green.Y - data.green_coefficient) > DBL_EPSILON ||
fabs(o.blue.Y - data.blue_coefficient) > DBL_EPSILON))
png_error(pp, "internal pngvalid cHRM coefficient error");
/* Generate a colour space encoding. */
e.gamma = o.gamma; /* not used */
e.red.X = API_cvt(rX);
e.red.Y = API_cvt(rY);
e.red.Z = API_cvt(rZ);
e.green.X = API_cvt(gX);
e.green.Y = API_cvt(gY);
e.green.Z = API_cvt(gZ);
e.blue.X = API_cvt(bX);
e.blue.Y = API_cvt(bY);
e.blue.Z = API_cvt(bZ);
/* This should match the original one from the png_modifier, within
* the range permitted by the libpng fixed point representation.
*/
maxe = 0;
el = "-"; /* Set to element name with error */
# define CHECK(col,x)\
{\
double err = fabs(o.col.x - e.col.x);\
if (err > maxe)\
{\
maxe = err;\
el = #col "(" #x ")";\
}\
}
CHECK(red,X)
CHECK(red,Y)
CHECK(red,Z)
CHECK(green,X)
CHECK(green,Y)
CHECK(green,Z)
CHECK(blue,X)
CHECK(blue,Y)
CHECK(blue,Z)
/* Here in both fixed and floating cases to check the values read
* from the cHRm chunk. PNG uses fixed point in the cHRM chunk, so
* we can't expect better than +/-.5E-5 on the result, allow 1E-5.
*/
if (maxe >= 1E-5)
{
size_t pos = 0;
char buffer[256];
pos = safecat(buffer, sizeof buffer, pos, API_form);
pos = safecat(buffer, sizeof buffer, pos, " cHRM ");
pos = safecat(buffer, sizeof buffer, pos, el);
pos = safecat(buffer, sizeof buffer, pos, " error: ");
pos = safecatd(buffer, sizeof buffer, pos, maxe, 7);
pos = safecat(buffer, sizeof buffer, pos, " ");
/* Print the color space without the gamma value: */
pos = safecat_color_encoding(buffer, sizeof buffer, pos, &o, 0);
pos = safecat(buffer, sizeof buffer, pos, " -> ");
pos = safecat_color_encoding(buffer, sizeof buffer, pos, &e, 0);
png_error(pp, buffer);
}
}
}
# endif /* READ_cHRM */
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
if ((that->colour_type & PNG_COLOR_MASK_COLOR) != 0)
{
double gray, err;
if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(that);
/* Image now has RGB channels... */
{
PNG_CONST png_modifier *pm = display->pm;
PNG_CONST unsigned int sample_depth = that->sample_depth;
int isgray;
double r, g, b;
double rlo, rhi, glo, ghi, blo, bhi, graylo, grayhi;
/* Do this using interval arithmetic, otherwise it is too difficult to
* handle the errors correctly.
*
* To handle the gamma correction work out the upper and lower bounds
* of the digitized value. Assume rounding here - normally the values
* will be identical after this operation if there is only one
* transform, feel free to delete the png_error checks on this below in
* the future (this is just me trying to ensure it works!)
*/
r = rlo = rhi = that->redf;
rlo -= that->rede;
rlo = digitize(pm, rlo, sample_depth, 1/*round*/);
rhi += that->rede;
rhi = digitize(pm, rhi, sample_depth, 1/*round*/);
g = glo = ghi = that->greenf;
glo -= that->greene;
glo = digitize(pm, glo, sample_depth, 1/*round*/);
ghi += that->greene;
ghi = digitize(pm, ghi, sample_depth, 1/*round*/);
b = blo = bhi = that->bluef;
blo -= that->bluee;
blo = digitize(pm, blo, sample_depth, 1/*round*/);
bhi += that->greene;
bhi = digitize(pm, bhi, sample_depth, 1/*round*/);
isgray = r==g && g==b;
if (data.gamma != 1)
{
PNG_CONST double power = 1/data.gamma;
PNG_CONST double abse = abserr(pm, sample_depth, sample_depth);
/* 'abse' is the absolute error permitted in linear calculations. It
* is used here to capture the error permitted in the handling
* (undoing) of the gamma encoding. Once again digitization occurs
* to handle the upper and lower bounds of the values. This is
* where the real errors are introduced.
*/
r = pow(r, power);
rlo = digitize(pm, pow(rlo, power)-abse, sample_depth, 1);
rhi = digitize(pm, pow(rhi, power)+abse, sample_depth, 1);
g = pow(g, power);
glo = digitize(pm, pow(glo, power)-abse, sample_depth, 1);
ghi = digitize(pm, pow(ghi, power)+abse, sample_depth, 1);
b = pow(b, power);
blo = digitize(pm, pow(blo, power)-abse, sample_depth, 1);
bhi = digitize(pm, pow(bhi, power)+abse, sample_depth, 1);
}
/* Now calculate the actual gray values. Although the error in the
* coefficients depends on whether they were specified on the command
* line (in which case truncation to 15 bits happened) or not (rounding
* was used) the maxium error in an individual coefficient is always
* 1/32768, because even in the rounding case the requirement that
* coefficients add up to 32768 can cause a larger rounding error.
*
* The only time when rounding doesn occur in 1.5.5 and later is when
* the non-gamma code path is used for less than 16 bit data.
*/
gray = r * data.red_coefficient + g * data.green_coefficient +
b * data.blue_coefficient;
{
PNG_CONST int do_round = data.gamma != 1 || sample_depth == 16;
PNG_CONST double ce = 1. / 32768;
graylo = digitize(pm, rlo * (data.red_coefficient-ce) +
glo * (data.green_coefficient-ce) +
blo * (data.blue_coefficient-ce), sample_depth, do_round);
if (graylo <= 0)
graylo = 0;
grayhi = digitize(pm, rhi * (data.red_coefficient+ce) +
ghi * (data.green_coefficient+ce) +
bhi * (data.blue_coefficient+ce), sample_depth, do_round);
if (grayhi >= 1)
grayhi = 1;
}
/* And invert the gamma. */
if (data.gamma != 1)
{
PNG_CONST double power = data.gamma;
gray = pow(gray, power);
graylo = digitize(pm, pow(graylo, power), sample_depth, 1);
grayhi = digitize(pm, pow(grayhi, power), sample_depth, 1);
}
/* Now the error can be calculated.
*
* If r==g==b because there is no overall gamma correction libpng
* currently preserves the original value.
*/
if (isgray)
err = (that->rede + that->greene + that->bluee)/3;
else
{
err = fabs(grayhi-gray);
if (fabs(gray - graylo) > err)
err = fabs(graylo-gray);
/* Check that this worked: */
if (err > display->pm->limit)
{
size_t pos = 0;
char buffer[128];
pos = safecat(buffer, sizeof buffer, pos, "rgb_to_gray error ");
pos = safecatd(buffer, sizeof buffer, pos, err, 6);
pos = safecat(buffer, sizeof buffer, pos, " exceeds limit ");
pos = safecatd(buffer, sizeof buffer, pos,
display->pm->limit, 6);
png_error(pp, buffer);
}
}
}
that->bluef = that->greenf = that->redf = gray;
that->bluee = that->greene = that->rede = err;
/* The sBIT is the minium of the three colour channel sBITs. */
if (that->red_sBIT > that->green_sBIT)
that->red_sBIT = that->green_sBIT;
if (that->red_sBIT > that->blue_sBIT)
that->red_sBIT = that->blue_sBIT;
that->blue_sBIT = that->green_sBIT = that->red_sBIT;
/* And zap the colour bit in the type: */
if (that->colour_type == PNG_COLOR_TYPE_RGB)
that->colour_type = PNG_COLOR_TYPE_GRAY;
else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
that->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA;
}
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_rgb_to_gray_add(image_transform *this,
PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
{
UNUSED(bit_depth)
this->next = *that;
*that = this;
return (colour_type & PNG_COLOR_MASK_COLOR) != 0;
}
#undef data
IT(rgb_to_gray);
#undef PT
#define PT ITSTRUCT(rgb_to_gray)
#undef image_transform_ini
#define image_transform_ini image_transform_default_ini
#endif /* PNG_READ_RGB_TO_GRAY_SUPPORTED */
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* png_set_background(png_structp, png_const_color_16p background_color,
* int background_gamma_code, int need_expand, double background_gamma)
* png_set_background_fixed(png_structp, png_const_color_16p background_color,
* int background_gamma_code, int need_expand,
* png_fixed_point background_gamma)
*
* As with rgb_to_gray this ignores the gamma (at present.)
*/
#define data ITDATA(background)
static image_pixel data;
static void
image_transform_png_set_background_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_byte colour_type, bit_depth;
png_byte random_bytes[8]; /* 8 bytes - 64 bits - the biggest pixel */
png_color_16 back;
/* We need a background colour, because we don't know exactly what transforms
* have been set we have to supply the colour in the original file format and
* so we need to know what that is! The background colour is stored in the
* transform_display.
*/
RANDOMIZE(random_bytes);
/* Read the random value, for colour type 3 the background colour is actually
* expressed as a 24bit rgb, not an index.
*/
colour_type = that->this.colour_type;
if (colour_type == 3)
{
colour_type = PNG_COLOR_TYPE_RGB;
bit_depth = 8;
}
else
bit_depth = that->this.bit_depth;
image_pixel_init(&data, random_bytes, colour_type,
bit_depth, 0/*x*/, 0/*unused: palette*/);
/* Extract the background colour from this image_pixel, but make sure the
* unused fields of 'back' are garbage.
*/
RANDOMIZE(back);
if (colour_type & PNG_COLOR_MASK_COLOR)
{
back.red = (png_uint_16)data.red;
back.green = (png_uint_16)data.green;
back.blue = (png_uint_16)data.blue;
}
else
back.gray = (png_uint_16)data.red;
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, 1/*need expand*/,
0);
# else
png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE,
1/*need expand*/, 0);
# endif
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_background_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
/* Check for tRNS first: */
if (that->have_tRNS && that->colour_type != PNG_COLOR_TYPE_PALETTE)
image_pixel_add_alpha(that, &display->this);
/* This is only necessary if the alpha value is less than 1. */
if (that->alphaf < 1)
{
/* Now we do the background calculation without any gamma correction. */
if (that->alphaf <= 0)
{
that->redf = data.redf;
that->greenf = data.greenf;
that->bluef = data.bluef;
that->rede = data.rede;
that->greene = data.greene;
that->bluee = data.bluee;
that->red_sBIT= data.red_sBIT;
that->green_sBIT= data.green_sBIT;
that->blue_sBIT= data.blue_sBIT;
}
else /* 0 < alpha < 1 */
{
double alf = 1 - that->alphaf;
that->redf = that->redf * that->alphaf + data.redf * alf;
that->rede = that->rede * that->alphaf + data.rede * alf +
DBL_EPSILON;
that->greenf = that->greenf * that->alphaf + data.greenf * alf;
that->greene = that->greene * that->alphaf + data.greene * alf +
DBL_EPSILON;
that->bluef = that->bluef * that->alphaf + data.bluef * alf;
that->bluee = that->bluee * that->alphaf + data.bluee * alf +
DBL_EPSILON;
}
/* Remove the alpha type and set the alpha (not in that order.) */
that->alphaf = 1;
that->alphae = 0;
if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
that->colour_type = PNG_COLOR_TYPE_RGB;
else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
that->colour_type = PNG_COLOR_TYPE_GRAY;
/* PNG_COLOR_TYPE_PALETTE is not changed */
}
this->next->mod(this->next, that, pp, display);
}
#define image_transform_png_set_background_add image_transform_default_add
#undef data
IT(background);
#undef PT
#define PT ITSTRUCT(background)
#endif /* PNG_READ_BACKGROUND_SUPPORTED */
/* This may just be 'end' if all the transforms are disabled! */
static image_transform *PNG_CONST image_transform_first = &PT;
static void
transform_enable(PNG_CONST char *name)
{
/* Everything starts out enabled, so if we see an 'enable' disabled
* everything else the first time round.
*/
static int all_disabled = 0;
int found_it = 0;
image_transform *list = image_transform_first;
while (list != &image_transform_end)
{
if (strcmp(list->name, name) == 0)
{
list->enable = 1;
found_it = 1;
}
else if (!all_disabled)
list->enable = 0;
list = list->list;
}
all_disabled = 1;
if (!found_it)
{
fprintf(stderr, "pngvalid: --transform-enable=%s: unknown transform\n",
name);
exit(1);
}
}
static void
transform_disable(PNG_CONST char *name)
{
image_transform *list = image_transform_first;
while (list != &image_transform_end)
{
if (strcmp(list->name, name) == 0)
{
list->enable = 0;
return;
}
list = list->list;
}
fprintf(stderr, "pngvalid: --transform-disable=%s: unknown transform\n",
name);
exit(1);
}
static void
image_transform_reset_count(void)
{
image_transform *next = image_transform_first;
int count = 0;
while (next != &image_transform_end)
{
next->local_use = 0;
next->next = 0;
next = next->list;
++count;
}
/* This can only happen if we every have more than 32 transforms (excluding
* the end) in the list.
*/
if (count > 32) abort();
}
static int
image_transform_test_counter(png_uint_32 counter, unsigned int max)
{
/* Test the list to see if there is any point contining, given a current
* counter and a 'max' value.
*/
image_transform *next = image_transform_first;
while (next != &image_transform_end)
{
/* For max 0 or 1 continue until the counter overflows: */
counter >>= 1;
/* Continue if any entry hasn't reacked the max. */
if (max > 1 && next->local_use < max)
return 1;
next = next->list;
}
return max <= 1 && counter == 0;
}
static png_uint_32
image_transform_add(PNG_CONST image_transform **this, unsigned int max,
png_uint_32 counter, char *name, size_t sizeof_name, size_t *pos,
png_byte colour_type, png_byte bit_depth)
{
for (;;) /* until we manage to add something */
{
png_uint_32 mask;
image_transform *list;
/* Find the next counter value, if the counter is zero this is the start
* of the list. This routine always returns the current counter (not the
* next) so it returns 0 at the end and expects 0 at the beginning.
*/
if (counter == 0) /* first time */
{
image_transform_reset_count();
if (max <= 1)
counter = 1;
else
counter = random_32();
}
else /* advance the counter */
{
switch (max)
{
case 0: ++counter; break;
case 1: counter <<= 1; break;
default: counter = random_32(); break;
}
}
/* Now add all these items, if possible */
*this = &image_transform_end;
list = image_transform_first;
mask = 1;
/* Go through the whole list adding anything that the counter selects: */
while (list != &image_transform_end)
{
if ((counter & mask) != 0 && list->enable &&
(max == 0 || list->local_use < max))
{
/* Candidate to add: */
if (list->add(list, this, colour_type, bit_depth) || max == 0)
{
/* Added, so add to the name too. */
*pos = safecat(name, sizeof_name, *pos, " +");
*pos = safecat(name, sizeof_name, *pos, list->name);
}
else
{
/* Not useful and max>0, so remove it from *this: */
*this = list->next;
list->next = 0;
/* And, since we know it isn't useful, stop it being added again
* in this run:
*/
list->local_use = max;
}
}
mask <<= 1;
list = list->list;
}
/* Now if anything was added we have something to do. */
if (*this != &image_transform_end)
return counter;
/* Nothing added, but was there anything in there to add? */
if (!image_transform_test_counter(counter, max))
return 0;
}
}
#ifdef THIS_IS_THE_PROFORMA
static void
image_transform_png_set_@_set(PNG_CONST image_transform *this,
transform_display *that, png_structp pp, png_infop pi)
{
png_set_@(pp);
this->next->set(this->next, that, pp, pi);
}
static void
image_transform_png_set_@_mod(PNG_CONST image_transform *this,
image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
{
this->next->mod(this->next, that, pp, display);
}
static int
image_transform_png_set_@_add(image_transform *this,
PNG_CONST image_transform **that, char *name, size_t sizeof_name,
size_t *pos, png_byte colour_type, png_byte bit_depth)
{
this->next = *that;
*that = this;
*pos = safecat(name, sizeof_name, *pos, " +@");
return 1;
}
IT(@);
#endif
/* png_set_quantize(png_structp, png_colorp palette, int num_palette,
* int maximum_colors, png_const_uint_16p histogram, int full_quantize)
*
* Very difficult to validate this!
*/
/*NOTE: TBD NYI */
/* The data layout transforms are handled by swapping our own channel data,
* necessarily these need to happen at the end of the transform list because the
* semantic of the channels changes after these are executed. Some of these,
* like set_shift and set_packing, can't be done at present because they change
* the layout of the data at the sub-sample level so sample() won't get the
* right answer.
*/
/* png_set_invert_alpha */
/*NOTE: TBD NYI */
/* png_set_bgr */
/*NOTE: TBD NYI */
/* png_set_swap_alpha */
/*NOTE: TBD NYI */
/* png_set_swap */
/*NOTE: TBD NYI */
/* png_set_filler, (png_structp png_ptr, png_uint_32 filler, int flags)); */
/*NOTE: TBD NYI */
/* png_set_add_alpha, (png_structp png_ptr, png_uint_32 filler, int flags)); */
/*NOTE: TBD NYI */
/* png_set_packing */
/*NOTE: TBD NYI */
/* png_set_packswap */
/*NOTE: TBD NYI */
/* png_set_invert_mono */
/*NOTE: TBD NYI */
/* png_set_shift(png_structp, png_const_color_8p true_bits) */
/*NOTE: TBD NYI */
static void
perform_transform_test(png_modifier *pm)
{
png_byte colour_type = 0;
png_byte bit_depth = 0;
int palette_number = 0;
while (next_format(&colour_type, &bit_depth, &palette_number))
{
png_uint_32 counter = 0;
size_t base_pos;
char name[64];
base_pos = safecat(name, sizeof name, 0, "transform:");
for (;;)
{
size_t pos = base_pos;
PNG_CONST image_transform *list = 0;
/* 'max' is currently hardwired to '1'; this should be settable on the
* command line.
*/
counter = image_transform_add(&list, 1/*max*/, counter,
name, sizeof name, &pos, colour_type, bit_depth);
if (counter == 0)
break;
/* The command line can change this to checking interlaced images. */
do
{
pm->repeat = 0;
transform_test(pm, FILEID(colour_type, bit_depth, palette_number,
pm->interlace_type, 0, 0, 0), list, name);
if (fail(pm))
return;
}
while (pm->repeat);
}
}
}
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
/********************************* GAMMA TESTS ********************************/
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Reader callbacks and implementations, where they differ from the standard
* ones.
*/
typedef struct gamma_display
{
standard_display this;
/* Parameters */
png_modifier* pm;
double file_gamma;
double screen_gamma;
double background_gamma;
png_byte sbit;
int threshold_test;
int use_input_precision;
int scale16;
int expand16;
int do_background;
png_color_16 background_color;
/* Local variables */
double maxerrout;
double maxerrpc;
double maxerrabs;
} gamma_display;
#define ALPHA_MODE_OFFSET 4
static void
gamma_display_init(gamma_display *dp, png_modifier *pm, png_uint_32 id,
double file_gamma, double screen_gamma, png_byte sbit, int threshold_test,
int use_input_precision, int scale16, int expand16,
int do_background, PNG_CONST png_color_16 *pointer_to_the_background_color,
double background_gamma)
{
/* Standard fields */
standard_display_init(&dp->this, &pm->this, id, 0/*do_interlace*/);
/* Parameter fields */
dp->pm = pm;
dp->file_gamma = file_gamma;
dp->screen_gamma = screen_gamma;
dp->background_gamma = background_gamma;
dp->sbit = sbit;
dp->threshold_test = threshold_test;
dp->use_input_precision = use_input_precision;
dp->scale16 = scale16;
dp->expand16 = expand16;
dp->do_background = do_background;
if (do_background && pointer_to_the_background_color != 0)
dp->background_color = *pointer_to_the_background_color;
else
memset(&dp->background_color, 0, sizeof dp->background_color);
/* Local variable fields */
dp->maxerrout = dp->maxerrpc = dp->maxerrabs = 0;
}
static void
gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi)
{
/* Reuse the standard stuff as appropriate. */
standard_info_part1(&dp->this, pp, pi);
/* If requested strip 16 to 8 bits - this is handled automagically below
* because the output bit depth is read from the library. Note that there
* are interactions with sBIT but, internally, libpng makes sbit at most
* PNG_MAX_GAMMA_8 when doing the following.
*/
if (dp->scale16)
# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
png_set_scale_16(pp);
# else
/* The following works both in 1.5.4 and earlier versions: */
# ifdef PNG_READ_16_TO_8_SUPPORTED
png_set_strip_16(pp);
# else
png_error(pp, "scale16 (16 to 8 bit conversion) not supported");
# endif
# endif
if (dp->expand16)
# ifdef PNG_READ_EXPAND_16_SUPPORTED
png_set_expand_16(pp);
# else
png_error(pp, "expand16 (8 to 16 bit conversion) not supported");
# endif
if (dp->do_background >= ALPHA_MODE_OFFSET)
{
# ifdef PNG_READ_ALPHA_MODE_SUPPORTED
{
/* This tests the alpha mode handling, if supported. */
int mode = dp->do_background - ALPHA_MODE_OFFSET;
/* The gamma value is the output gamma, and is in the standard,
* non-inverted, represenation. It provides a default for the PNG file
* gamma, but since the file has a gAMA chunk this does not matter.
*/
PNG_CONST double sg = dp->screen_gamma;
# ifndef PNG_FLOATING_POINT_SUPPORTED
PNG_CONST png_fixed_point g = fix(sg);
# endif
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_alpha_mode(pp, mode, sg);
# else
png_set_alpha_mode_fixed(pp, mode, g);
# endif
/* However, for the standard Porter-Duff algorithm the output defaults
* to be linear, so if the test requires non-linear output it must be
* corrected here.
*/
if (mode == PNG_ALPHA_STANDARD && sg != 1)
{
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_gamma(pp, sg, dp->file_gamma);
# else
png_fixed_point f = fix(dp->file_gamma);
png_set_gamma_fixed(pp, g, f);
# endif
}
}
# else
png_error(pp, "alpha mode handling not supported");
# endif
}
else
{
/* Set up gamma processing. */
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_gamma(pp, dp->screen_gamma, dp->file_gamma);
# else
{
png_fixed_point s = fix(dp->screen_gamma);
png_fixed_point f = fix(dp->file_gamma);
png_set_gamma_fixed(pp, s, f);
}
# endif
if (dp->do_background)
{
# ifdef PNG_READ_BACKGROUND_SUPPORTED
/* NOTE: this assumes the caller provided the correct background gamma!
*/
PNG_CONST double bg = dp->background_gamma;
# ifndef PNG_FLOATING_POINT_SUPPORTED
PNG_CONST png_fixed_point g = fix(bg);
# endif
# ifdef PNG_FLOATING_POINT_SUPPORTED
png_set_background(pp, &dp->background_color, dp->do_background,
0/*need_expand*/, bg);
# else
png_set_background_fixed(pp, &dp->background_color,
dp->do_background, 0/*need_expand*/, g);
# endif
# else
png_error(pp, "png_set_background not supported");
# endif
}
}
png_read_update_info(pp, pi);
/* Now we may get a different cbRow: */
standard_info_part2(&dp->this, pp, pi, 1 /*images*/);
}
static void
gamma_info(png_structp pp, png_infop pi)
{
gamma_info_imp(voidcast(gamma_display*, png_get_progressive_ptr(pp)), pp,
pi);
}
/* Validate a single component value - the routine gets the input and output
* sample values as unscaled PNG component values along with a cache of all the
* information required to validate the values.
*/
typedef struct validate_info
{
png_structp pp;
gamma_display *dp;
png_byte sbit;
int use_input_precision;
int do_background;
int scale16;
unsigned int sbit_max;
unsigned int isbit_shift;
unsigned int outmax;
double gamma_correction; /* Overall correction required. */
double file_inverse; /* Inverse of file gamma. */
double screen_gamma;
double screen_inverse; /* Inverse of screen gamma. */
double background_red; /* Linear background value, red or gray. */
double background_green;
double background_blue;
double maxabs;
double maxpc;
double maxcalc;
double maxout;
double maxout_total; /* Total including quantization error */
double outlog;
int outquant;
}
validate_info;
static void
init_validate_info(validate_info *vi, gamma_display *dp, png_struct *pp,
int in_depth, int out_depth)
{
PNG_CONST unsigned int outmax = (1U<<out_depth)-1;
vi->pp = pp;
vi->dp = dp;
if (dp->sbit > 0 && dp->sbit < in_depth)
{
vi->sbit = dp->sbit;
vi->isbit_shift = in_depth - dp->sbit;
}
else
{
vi->sbit = (png_byte)in_depth;
vi->isbit_shift = 0;
}
vi->sbit_max = (1U << vi->sbit)-1;
/* This mimics the libpng threshold test, '0' is used to prevent gamma
* correction in the validation test.
*/
vi->screen_gamma = dp->screen_gamma;
if (fabs(vi->screen_gamma-1) < PNG_GAMMA_THRESHOLD)
vi->screen_gamma = vi->screen_inverse = 0;
else
vi->screen_inverse = 1/vi->screen_gamma;
vi->use_input_precision = dp->use_input_precision;
vi->outmax = outmax;
vi->maxabs = abserr(dp->pm, in_depth, out_depth);
vi->maxpc = pcerr(dp->pm, in_depth, out_depth);
vi->maxcalc = calcerr(dp->pm, in_depth, out_depth);
vi->maxout = outerr(dp->pm, in_depth, out_depth);
vi->outquant = output_quantization_factor(dp->pm, in_depth, out_depth);
vi->maxout_total = vi->maxout + vi->outquant * .5;
vi->outlog = outlog(dp->pm, in_depth, out_depth);
if ((dp->this.colour_type & PNG_COLOR_MASK_ALPHA) != 0 ||
(dp->this.colour_type == 3 && dp->this.is_transparent))
{
vi->do_background = dp->do_background;
if (vi->do_background != 0)
{
PNG_CONST double bg_inverse = 1/dp->background_gamma;
double r, g, b;
/* Caller must at least put the gray value into the red channel */
r = dp->background_color.red; r /= outmax;
g = dp->background_color.green; g /= outmax;
b = dp->background_color.blue; b /= outmax;
# if 0
/* libpng doesn't do this optimization, if we do pngvalid will fail.
*/
if (fabs(bg_inverse-1) >= PNG_GAMMA_THRESHOLD)
# endif
{
r = pow(r, bg_inverse);
g = pow(g, bg_inverse);
b = pow(b, bg_inverse);
}
vi->background_red = r;
vi->background_green = g;
vi->background_blue = b;
}
}
else
vi->do_background = 0;
if (vi->do_background == 0)
vi->background_red = vi->background_green = vi->background_blue = 0;
vi->gamma_correction = 1/(dp->file_gamma*dp->screen_gamma);
if (fabs(vi->gamma_correction-1) < PNG_GAMMA_THRESHOLD)
vi->gamma_correction = 0;
vi->file_inverse = 1/dp->file_gamma;
if (fabs(vi->file_inverse-1) < PNG_GAMMA_THRESHOLD)
vi->file_inverse = 0;
vi->scale16 = dp->scale16;
}
/* This function handles composition of a single non-alpha component. The
* argument is the input sample value, in the range 0..1, and the alpha value.
* The result is the composed, linear, input sample. If alpha is less than zero
* this is the alpha component and the function should not be called!
*/
static double
gamma_component_compose(int do_background, double input_sample, double alpha,
double background, int *compose)
{
switch (do_background)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
case PNG_BACKGROUND_GAMMA_FILE:
case PNG_BACKGROUND_GAMMA_UNIQUE:
/* Standard PNG background processing. */
if (alpha < 1)
{
if (alpha > 0)
{
input_sample = input_sample * alpha + background * (1-alpha);
if (compose != NULL)
*compose = 1;
}
else
input_sample = background;
}
break;
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
/* The components are premultiplied in either case and the output is
* gamma encoded (to get standard Porter-Duff we expect the output
* gamma to be set to 1.0!)
*/
case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
/* The optimization is that the partial-alpha entries are linear
* while the opaque pixels are gamma encoded, but this only affects the
* output encoding.
*/
if (alpha < 1)
{
if (alpha > 0)
{
input_sample *= alpha;
if (compose != NULL)
*compose = 1;
}
else
input_sample = 0;
}
break;
#endif
default:
/* Standard cases where no compositing is done (so the component
* value is already correct.)
*/
break;
}
return input_sample;
}
/* This API returns the encoded *input* component, in the range 0..1 */
static double
gamma_component_validate(PNG_CONST char *name, PNG_CONST validate_info *vi,
PNG_CONST unsigned int id, PNG_CONST unsigned int od,
PNG_CONST double alpha /* <0 for the alpha channel itself */,
PNG_CONST double background /* component background value */)
{
PNG_CONST unsigned int isbit = id >> vi->isbit_shift;
PNG_CONST unsigned int sbit_max = vi->sbit_max;
PNG_CONST unsigned int outmax = vi->outmax;
PNG_CONST int do_background = vi->do_background;
double i;
/* First check on the 'perfect' result obtained from the digitized input
* value, id, and compare this against the actual digitized result, 'od'.
* 'i' is the input result in the range 0..1:
*/
i = isbit; i /= sbit_max;
/* Check for the fast route: if we don't do any background composition or if
* this is the alpha channel ('alpha' < 0) or if the pixel is opaque then
* just use the gamma_correction field to correct to the final output gamma.
*/
if (alpha == 1 /* opaque pixel component */ || !do_background
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
|| do_background == ALPHA_MODE_OFFSET + PNG_ALPHA_PNG
#endif
|| (alpha < 0 /* alpha channel */
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
&& do_background != ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN
#endif
))
{
/* Then get the gamma corrected version of 'i' and compare to 'od', any
* error less than .5 is insignificant - just quantization of the output
* value to the nearest digital value (nevertheless the error is still
* recorded - it's interesting ;-)
*/
double encoded_sample = i;
double encoded_error;
/* alpha less than 0 indicates the alpha channel, which is always linear
*/
if (alpha >= 0 && vi->gamma_correction > 0)
encoded_sample = pow(encoded_sample, vi->gamma_correction);
encoded_sample *= outmax;
encoded_error = fabs(od-encoded_sample);
if (encoded_error > vi->dp->maxerrout)
vi->dp->maxerrout = encoded_error;
if (encoded_error < vi->maxout_total && encoded_error < vi->outlog)
return i;
}
/* The slow route - attempt to do linear calculations. */
/* There may be an error, or background processing is required, so calculate
* the actual sample values - unencoded light intensity values. Note that in
* practice these are not completely unencoded because they include a
* 'viewing correction' to decrease or (normally) increase the perceptual
* contrast of the image. There's nothing we can do about this - we don't
* know what it is - so assume the unencoded value is perceptually linear.
*/
{
double input_sample = i; /* In range 0..1 */
double output, error, encoded_sample, encoded_error;
double es_lo, es_hi;
int compose = 0; /* Set to one if composition done */
int output_is_encoded; /* Set if encoded to screen gamma */
int log_max_error = 1; /* Check maximum error values */
png_const_charp pass = 0; /* Reason test passes (or 0 for fail) */
/* Convert to linear light (with the above caveat.) The alpha channel is
* already linear.
*/
if (alpha >= 0)
{
int tcompose;
if (vi->file_inverse > 0)
input_sample = pow(input_sample, vi->file_inverse);
/* Handle the compose processing: */
tcompose = 0;
input_sample = gamma_component_compose(do_background, input_sample,
alpha, background, &tcompose);
if (tcompose)
compose = 1;
}
/* And similarly for the output value, but we need to check the background
* handling to linearize it correctly.
*/
output = od;
output /= outmax;
output_is_encoded = vi->screen_gamma > 0;
if (alpha < 0) /* The alpha channel */
{
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
if (do_background != ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN)
#endif
{
/* In all other cases the output alpha channel is linear already,
* don't log errors here, they are much larger in linear data.
*/
output_is_encoded = 0;
log_max_error = 0;
}
}
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
else /* A component */
{
if (do_background == ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED &&
alpha < 1) /* the optimized case - linear output */
{
if (alpha > 0) log_max_error = 0;
output_is_encoded = 0;
}
}
#endif
if (output_is_encoded)
output = pow(output, vi->screen_gamma);
/* Calculate (or recalculate) the encoded_sample value and repeat the
* check above (unnecessary if we took the fast route, but harmless.)
*/
encoded_sample = input_sample;
if (output_is_encoded)
encoded_sample = pow(encoded_sample, vi->screen_inverse);
encoded_sample *= outmax;
encoded_error = fabs(od-encoded_sample);
/* Don't log errors in the alpha channel, or the 'optimized' case,
* neither are significant to the overall perception.
*/
if (log_max_error && encoded_error > vi->dp->maxerrout)
vi->dp->maxerrout = encoded_error;
if (encoded_error < vi->maxout_total)
{
if (encoded_error < vi->outlog)
return i;
/* Test passed but error is bigger than the log limit, record why the
* test passed:
*/
pass = "less than maxout:\n";
}
/* i: the original input value in the range 0..1
*
* pngvalid calculations:
* input_sample: linear result; i linearized and composed, range 0..1
* encoded_sample: encoded result; input_sample scaled to ouput bit depth
*
* libpng calculations:
* output: linear result; od scaled to 0..1 and linearized
* od: encoded result from libpng
*/
/* Now we have the numbers for real errors, both absolute values as as a
* percentage of the correct value (output):
*/
error = fabs(input_sample-output);
if (log_max_error && error > vi->dp->maxerrabs)
vi->dp->maxerrabs = error;
/* The following is an attempt to ignore the tendency of quantization to
* dominate the percentage errors for lower result values:
*/
if (log_max_error && input_sample > .5)
{
double percentage_error = error/input_sample;
if (percentage_error > vi->dp->maxerrpc)
vi->dp->maxerrpc = percentage_error;
}
/* Now calculate the digitization limits for 'encoded_sample' using the
* 'max' values. Note that maxout is in the encoded space but maxpc and
* maxabs are in linear light space.
*
* First find the maximum error in linear light space, range 0..1:
*/
{
double tmp = input_sample * vi->maxpc;
if (tmp < vi->maxabs) tmp = vi->maxabs;
/* If 'compose' is true the composition was done in linear space using
* integer arithmetic. This introduces an extra error of +/- 0.5 (at
* least) in the integer space used. 'maxcalc' records this, taking
* into account the possibility that even for 16 bit output 8 bit space
* may have been used.
*/
if (compose && tmp < vi->maxcalc) tmp = vi->maxcalc;
/* The 'maxout' value refers to the encoded result, to compare with
* this encode input_sample adjusted by the maximum error (tmp) above.
*/
es_lo = encoded_sample - vi->maxout;
if (es_lo > 0 && input_sample-tmp > 0)
{
double low_value = input_sample-tmp;
if (output_is_encoded)
low_value = pow(low_value, vi->screen_inverse);
low_value *= outmax;
if (low_value < es_lo) es_lo = low_value;
/* Quantize this appropriately: */
es_lo = ceil(es_lo / vi->outquant - .5) * vi->outquant;
}
else
es_lo = 0;
es_hi = encoded_sample + vi->maxout;
if (es_hi < outmax && input_sample+tmp < 1)
{
double high_value = input_sample+tmp;
if (output_is_encoded)
high_value = pow(high_value, vi->screen_inverse);
high_value *= outmax;
if (high_value > es_hi) es_hi = high_value;
es_hi = floor(es_hi / vi->outquant + .5) * vi->outquant;
}
else
es_hi = outmax;
}
/* The primary test is that the final encoded value returned by the
* library should be between the two limits (inclusive) that were
* calculated above.
*/
if (od >= es_lo && od <= es_hi)
{
/* The value passes, but we may need to log the information anyway. */
if (encoded_error < vi->outlog)
return i;
if (pass == 0)
pass = "within digitization limits:\n";
}
{
/* There has been an error in processing, or we need to log this
* value.
*/
double is_lo, is_hi;
/* pass is set at this point if either of the tests above would have
* passed. Don't do these additional tests here - just log the
* original [es_lo..es_hi] values.
*/
if (pass == 0 && vi->use_input_precision)
{
/* Ok, something is wrong - this actually happens in current libpng
* 16-to-8 processing. Assume that the input value (id, adjusted
* for sbit) can be anywhere between value-.5 and value+.5 - quite a
* large range if sbit is low.
*/
double tmp = (isbit - .5)/sbit_max;
if (tmp <= 0)
tmp = 0;
else if (alpha >= 0 && vi->file_inverse > 0 && tmp < 1)
tmp = pow(tmp, vi->file_inverse);
tmp = gamma_component_compose(do_background, tmp, alpha, background,
NULL);
if (output_is_encoded && tmp > 0 && tmp < 1)
tmp = pow(tmp, vi->screen_inverse);
is_lo = ceil(outmax * tmp - vi->maxout_total);
if (is_lo < 0)
is_lo = 0;
tmp = (isbit + .5)/sbit_max;
if (tmp <= 0)
tmp = 0;
else if (alpha >= 0 && vi->file_inverse > 0 && tmp < 1)
tmp = pow(tmp, vi->file_inverse);
tmp = gamma_component_compose(do_background, tmp, alpha, background,
NULL);
if (output_is_encoded && tmp > 0 && tmp < 1)
tmp = pow(tmp, vi->screen_inverse);
is_hi = floor(outmax * tmp + vi->maxout_total);
if (is_hi > outmax)
is_hi = outmax;
if (!(od < is_lo || od > is_hi))
{
if (encoded_error < vi->outlog)
return i;
pass = "within input precision limits:\n";
}
/* One last chance. If this is an alpha channel and the 16to8
* option has been used and 'inaccurate' scaling is used then the
* bit reduction is obtained by simply using the top 8 bits of the
* value.
*
* This is only done for older libpng versions when the 'inaccurate'
* (chop) method of scaling was used.
*/
# ifndef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
# if PNG_LIBPNG_VER < 10504
/* This may be required for other components in the future,
* but at present the presence of gamma correction effectively
* prevents the errors in the component scaling (I don't quite
* understand why, but since it's better this way I care not
* to ask, JB 20110419.)
*/
if (pass == 0 && alpha < 0 && vi->scale16 && vi->sbit > 8 &&
vi->sbit + vi->isbit_shift == 16)
{
tmp = ((id >> 8) - .5)/255;
if (tmp > 0)
{
is_lo = ceil(outmax * tmp - vi->maxout_total);
if (is_lo < 0) is_lo = 0;
}
else
is_lo = 0;
tmp = ((id >> 8) + .5)/255;
if (tmp < 1)
{
is_hi = floor(outmax * tmp + vi->maxout_total);
if (is_hi > outmax) is_hi = outmax;
}
else
is_hi = outmax;
if (!(od < is_lo || od > is_hi))
{
if (encoded_error < vi->outlog)
return i;
pass = "within 8 bit limits:\n";
}
}
# endif
# endif
}
else /* !use_input_precision */
is_lo = es_lo, is_hi = es_hi;
/* Attempt to output a meaningful error/warning message: the message
* output depends on the background/composite operation being performed
* because this changes what parameters were actually used above.
*/
{
size_t pos = 0;
/* Need either 1/255 or 1/65535 precision here; 3 or 6 decimal
* places. Just use outmax to work out which.
*/
int precision = (outmax >= 1000 ? 6 : 3);
int use_input=1, use_background=0, do_compose=0;
char msg[256];
if (pass != 0)
pos = safecat(msg, sizeof msg, pos, "\n\t");
/* Set up the various flags, the output_is_encoded flag above
* is also used below. do_compose is just a double check.
*/
switch (do_background)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
case PNG_BACKGROUND_GAMMA_FILE:
case PNG_BACKGROUND_GAMMA_UNIQUE:
use_background = (alpha >= 0 && alpha < 1);
/*FALL THROUGH*/
# ifdef PNG_READ_ALPHA_MODE_SUPPORTED
case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
# endif /* ALPHA_MODE_SUPPORTED */
do_compose = (alpha >= 0 && alpha < 1);
use_input = (alpha != 0);
break;
default:
break;
}
/* Check the 'compose' flag */
if (compose != do_compose)
png_error(vi->pp, "internal error (compose)");
/* 'name' is the component name */
pos = safecat(msg, sizeof msg, pos, name);
pos = safecat(msg, sizeof msg, pos, "(");
pos = safecatn(msg, sizeof msg, pos, id);
if (use_input || pass != 0/*logging*/)
{
if (isbit != id)
{
/* sBIT has reduced the precision of the input: */
pos = safecat(msg, sizeof msg, pos, ", sbit(");
pos = safecatn(msg, sizeof msg, pos, vi->sbit);
pos = safecat(msg, sizeof msg, pos, "): ");
pos = safecatn(msg, sizeof msg, pos, isbit);
}
pos = safecat(msg, sizeof msg, pos, "/");
/* The output is either "id/max" or "id sbit(sbit): isbit/max" */
pos = safecatn(msg, sizeof msg, pos, vi->sbit_max);
}
pos = safecat(msg, sizeof msg, pos, ")");
/* A component may have been multiplied (in linear space) by the
* alpha value, 'compose' says whether this is relevant.
*/
if (compose || pass != 0)
{
/* If any form of composition is being done report our
* calculated linear value here (the code above doesn't record
* the input value before composition is performed, so what
* gets reported is the value after composition.)
*/
if (use_input || pass != 0)
{
if (vi->file_inverse > 0)
{
pos = safecat(msg, sizeof msg, pos, "^");
pos = safecatd(msg, sizeof msg, pos, vi->file_inverse, 2);
}
else
pos = safecat(msg, sizeof msg, pos, "[linear]");
pos = safecat(msg, sizeof msg, pos, "*(alpha)");
pos = safecatd(msg, sizeof msg, pos, alpha, precision);
}
/* Now record the *linear* background value if it was used
* (this function is not passed the original, non-linear,
* value but it is contained in the test name.)
*/
if (use_background)
{
pos = safecat(msg, sizeof msg, pos, use_input ? "+" : " ");
pos = safecat(msg, sizeof msg, pos, "(background)");
pos = safecatd(msg, sizeof msg, pos, background, precision);
pos = safecat(msg, sizeof msg, pos, "*");
pos = safecatd(msg, sizeof msg, pos, 1-alpha, precision);
}
}
/* Report the calculated value (input_sample) and the linearized
* libpng value (output) unless this is just a component gamma
* correction.
*/
if (compose || alpha < 0 || pass != 0)
{
pos = safecat(msg, sizeof msg, pos,
pass != 0 ? " =\n\t" : " = ");
pos = safecatd(msg, sizeof msg, pos, input_sample, precision);
pos = safecat(msg, sizeof msg, pos, " (libpng: ");
pos = safecatd(msg, sizeof msg, pos, output, precision);
pos = safecat(msg, sizeof msg, pos, ")");
/* Finally report the output gamma encoding, if any. */
if (output_is_encoded)
{
pos = safecat(msg, sizeof msg, pos, " ^");
pos = safecatd(msg, sizeof msg, pos, vi->screen_inverse, 2);
pos = safecat(msg, sizeof msg, pos, "(to screen) =");
}
else
pos = safecat(msg, sizeof msg, pos, " [screen is linear] =");
}
if ((!compose && alpha >= 0) || pass != 0)
{
if (pass != 0) /* logging */
pos = safecat(msg, sizeof msg, pos, "\n\t[overall:");
/* This is the non-composition case, the internal linear
* values are irrelevant (though the log below will reveal
* them.) Output a much shorter warning/error message and report
* the overall gamma correction.
*/
if (vi->gamma_correction > 0)
{
pos = safecat(msg, sizeof msg, pos, " ^");
pos = safecatd(msg, sizeof msg, pos, vi->gamma_correction, 2);
pos = safecat(msg, sizeof msg, pos, "(gamma correction) =");
}
else
pos = safecat(msg, sizeof msg, pos,
" [no gamma correction] =");
if (pass != 0)
pos = safecat(msg, sizeof msg, pos, "]");
}
/* This is our calculated encoded_sample which should (but does
* not) match od:
*/
pos = safecat(msg, sizeof msg, pos, pass != 0 ? "\n\t" : " ");
pos = safecatd(msg, sizeof msg, pos, is_lo, 1);
pos = safecat(msg, sizeof msg, pos, " < ");
pos = safecatd(msg, sizeof msg, pos, encoded_sample, 1);
pos = safecat(msg, sizeof msg, pos, " (libpng: ");
pos = safecatn(msg, sizeof msg, pos, od);
pos = safecat(msg, sizeof msg, pos, ")");
pos = safecat(msg, sizeof msg, pos, "/");
pos = safecatn(msg, sizeof msg, pos, outmax);
pos = safecat(msg, sizeof msg, pos, " < ");
pos = safecatd(msg, sizeof msg, pos, is_hi, 1);
if (pass == 0) /* The error condition */
{
# ifdef PNG_WARNINGS_SUPPORTED
png_warning(vi->pp, msg);
# else
store_warning(vi->pp, msg);
# endif
}
else /* logging this value */
store_verbose(&vi->dp->pm->this, vi->pp, pass, msg);
}
}
}
return i;
}
static void
gamma_image_validate(gamma_display *dp, png_structp pp, png_infop pi)
{
/* Get some constants derived from the input and output file formats: */
PNG_CONST png_store* PNG_CONST ps = dp->this.ps;
PNG_CONST png_byte in_ct = dp->this.colour_type;
PNG_CONST png_byte in_bd = dp->this.bit_depth;
PNG_CONST png_uint_32 w = dp->this.w;
PNG_CONST png_uint_32 h = dp->this.h;
PNG_CONST size_t cbRow = dp->this.cbRow;
PNG_CONST png_byte out_ct = png_get_color_type(pp, pi);
PNG_CONST png_byte out_bd = png_get_bit_depth(pp, pi);
/* There are three sources of error, firstly the quantization in the
* file encoding, determined by sbit and/or the file depth, secondly
* the output (screen) gamma and thirdly the output file encoding.
*
* Since this API receives the screen and file gamma in double
* precision it is possible to calculate an exact answer given an input
* pixel value. Therefore we assume that the *input* value is exact -
* sample/maxsample - calculate the corresponding gamma corrected
* output to the limits of double precision arithmetic and compare with
* what libpng returns.
*
* Since the library must quantize the output to 8 or 16 bits there is
* a fundamental limit on the accuracy of the output of +/-.5 - this
* quantization limit is included in addition to the other limits
* specified by the paramaters to the API. (Effectively, add .5
* everywhere.)
*
* The behavior of the 'sbit' paramter is defined by section 12.5
* (sample depth scaling) of the PNG spec. That section forces the
* decoder to assume that the PNG values have been scaled if sBIT is
* present:
*
* png-sample = floor( input-sample * (max-out/max-in) + .5);
*
* This means that only a subset of the possible PNG values should
* appear in the input. However, the spec allows the encoder to use a
* variety of approximations to the above and doesn't require any
* restriction of the values produced.
*
* Nevertheless the spec requires that the upper 'sBIT' bits of the
* value stored in a PNG file be the original sample bits.
* Consequently the code below simply scales the top sbit bits by
* (1<<sbit)-1 to obtain an original sample value.
*
* Because there is limited precision in the input it is arguable that
* an acceptable result is any valid result from input-.5 to input+.5.
* The basic tests below do not do this, however if 'use_input_precision'
* is set a subsequent test is performed below.
*/
PNG_CONST unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U;
int processing;
png_uint_32 y;
PNG_CONST store_palette_entry *in_palette = dp->this.palette;
PNG_CONST int in_is_transparent = dp->this.is_transparent;
int out_npalette = -1;
int out_is_transparent = 0; /* Just refers to the palette case */
store_palette out_palette;
validate_info vi;
/* Check for row overwrite errors */
store_image_check(dp->this.ps, pp, 0);
/* Supply the input and output sample depths here - 8 for an indexed image,
* otherwise the bit depth.
*/
init_validate_info(&vi, dp, pp, in_ct==3?8:in_bd, out_ct==3?8:out_bd);
processing = (vi.gamma_correction > 0 && !dp->threshold_test)
|| in_bd != out_bd || in_ct != out_ct || vi.do_background;
/* TODO: FIX THIS: MAJOR BUG! If the transformations all happen inside
* the palette there is no way of finding out, because libpng fails to
* update the palette on png_read_update_info. Indeed, libpng doesn't
* even do the required work until much later, when it doesn't have any
* info pointer. Oops. For the moment 'processing' is turned off if
* out_ct is palette.
*/
if (in_ct == 3 && out_ct == 3)
processing = 0;
if (processing && out_ct == 3)
out_is_transparent = read_palette(out_palette, &out_npalette, pp, pi);
for (y=0; y<h; ++y)
{
png_const_bytep pRow = store_image_row(ps, pp, 0, y);
png_byte std[STANDARD_ROWMAX];
transform_row(pp, std, in_ct, in_bd, y);
if (processing)
{
unsigned int x;
for (x=0; x<w; ++x)
{
double alpha = 1; /* serves as a flag value */
/* Record the palette index for index images. */
PNG_CONST unsigned int in_index =
in_ct == 3 ? sample(std, 3, in_bd, x, 0) : 256;
PNG_CONST unsigned int out_index =
out_ct == 3 ? sample(std, 3, out_bd, x, 0) : 256;
/* Handle input alpha - png_set_background will cause the output
* alpha to disappear so there is nothing to check.
*/
if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 || (in_ct == 3 &&
in_is_transparent))
{
PNG_CONST unsigned int input_alpha = in_ct == 3 ?
dp->this.palette[in_index].alpha :
sample(std, in_ct, in_bd, x, samples_per_pixel);
unsigned int output_alpha = 65536 /* as a flag value */;
if (out_ct == 3)
{
if (out_is_transparent)
output_alpha = out_palette[out_index].alpha;
}
else if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0)
output_alpha = sample(pRow, out_ct, out_bd, x,
samples_per_pixel);
if (output_alpha != 65536)
alpha = gamma_component_validate("alpha", &vi, input_alpha,
output_alpha, -1/*alpha*/, 0/*background*/);
else /* no alpha in output */
{
/* This is a copy of the calculation of 'i' above in order to
* have the alpha value to use in the background calculation.
*/
alpha = input_alpha >> vi.isbit_shift;
alpha /= vi.sbit_max;
}
}
/* Handle greyscale or RGB components. */
if ((in_ct & PNG_COLOR_MASK_COLOR) == 0) /* greyscale */
(void)gamma_component_validate("gray", &vi,
sample(std, in_ct, in_bd, x, 0),
sample(pRow, out_ct, out_bd, x, 0), alpha/*component*/,
vi.background_red);
else /* RGB or palette */
{
(void)gamma_component_validate("red", &vi,
in_ct == 3 ? in_palette[in_index].red :
sample(std, in_ct, in_bd, x, 0),
out_ct == 3 ? out_palette[out_index].red :
sample(pRow, out_ct, out_bd, x, 0),
alpha/*component*/, vi.background_red);
(void)gamma_component_validate("green", &vi,
in_ct == 3 ? in_palette[in_index].green :
sample(std, in_ct, in_bd, x, 1),
out_ct == 3 ? out_palette[out_index].green :
sample(pRow, out_ct, out_bd, x, 1),
alpha/*component*/, vi.background_green);
(void)gamma_component_validate("blue", &vi,
in_ct == 3 ? in_palette[in_index].blue :
sample(std, in_ct, in_bd, x, 2),
out_ct == 3 ? out_palette[out_index].blue :
sample(pRow, out_ct, out_bd, x, 2),
alpha/*component*/, vi.background_blue);
}
}
}
else if (memcmp(std, pRow, cbRow) != 0)
{
char msg[64];
/* No transform is expected on the threshold tests. */
sprintf(msg, "gamma: below threshold row %d changed", y);
png_error(pp, msg);
}
} /* row (y) loop */
dp->this.ps->validated = 1;
}
static void
gamma_end(png_structp pp, png_infop pi)
{
gamma_display *dp = voidcast(gamma_display*, png_get_progressive_ptr(pp));
if (!dp->this.speed)
gamma_image_validate(dp, pp, pi);
}
/* A single test run checking a gamma transformation.
*
* maxabs: maximum absolute error as a fraction
* maxout: maximum output error in the output units
* maxpc: maximum percentage error (as a percentage)
*/
static void
gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn,
PNG_CONST png_byte bit_depthIn, PNG_CONST int palette_numberIn,
PNG_CONST int interlace_typeIn,
PNG_CONST double file_gammaIn, PNG_CONST double screen_gammaIn,
PNG_CONST png_byte sbitIn, PNG_CONST int threshold_testIn,
PNG_CONST char *name,
PNG_CONST int use_input_precisionIn, PNG_CONST int scale16In,
PNG_CONST int expand16In, PNG_CONST int do_backgroundIn,
PNG_CONST png_color_16 *bkgd_colorIn, double bkgd_gammaIn)
{
gamma_display d;
context(&pmIn->this, fault);
gamma_display_init(&d, pmIn, FILEID(colour_typeIn, bit_depthIn,
palette_numberIn, interlace_typeIn, 0, 0, 0),
file_gammaIn, screen_gammaIn, sbitIn,
threshold_testIn, use_input_precisionIn, scale16In,
expand16In, do_backgroundIn, bkgd_colorIn, bkgd_gammaIn);
Try
{
png_structp pp;
png_infop pi;
gama_modification gama_mod;
srgb_modification srgb_mod;
sbit_modification sbit_mod;
/* For the moment don't use the png_modifier support here. */
d.pm->encoding_counter = 0;
modifier_set_encoding(d.pm); /* Just resets everything */
d.pm->current_gamma = d.file_gamma;
/* Make an appropriate modifier to set the PNG file gamma to the
* given gamma value and the sBIT chunk to the given precision.
*/
d.pm->modifications = NULL;
gama_modification_init(&gama_mod, d.pm, d.file_gamma);
srgb_modification_init(&srgb_mod, d.pm, 127 /*delete*/);
if (d.sbit > 0)
sbit_modification_init(&sbit_mod, d.pm, d.sbit);
modification_reset(d.pm->modifications);
/* Get a png_struct for writing the image. */
pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
standard_palette_init(&d.this);
/* Introduce the correct read function. */
if (d.pm->this.progressive)
{
/* Share the row function with the standard implementation. */
png_set_progressive_read_fn(pp, &d, gamma_info, progressive_row,
gamma_end);
/* Now feed data into the reader until we reach the end: */
modifier_progressive_read(d.pm, pp, pi);
}
else
{
/* modifier_read expects a png_modifier* */
png_set_read_fn(pp, d.pm, modifier_read);
/* Check the header values: */
png_read_info(pp, pi);
/* Process the 'info' requirements. Only one image is generated */
gamma_info_imp(&d, pp, pi);
sequential_row(&d.this, pp, pi, -1, 0);
if (!d.this.speed)
gamma_image_validate(&d, pp, pi);
}
modifier_reset(d.pm);
if (d.pm->log && !d.threshold_test && !d.this.speed)
fprintf(stderr, "%d bit %s %s: max error %f (%.2g, %2g%%)\n",
d.this.bit_depth, colour_types[d.this.colour_type], name,
d.maxerrout, d.maxerrabs, 100*d.maxerrpc);
/* Log the summary values too. */
if (d.this.colour_type == 0 || d.this.colour_type == 4)
{
switch (d.this.bit_depth)
{
case 1:
break;
case 2:
if (d.maxerrout > d.pm->error_gray_2)
d.pm->error_gray_2 = d.maxerrout;
break;
case 4:
if (d.maxerrout > d.pm->error_gray_4)
d.pm->error_gray_4 = d.maxerrout;
break;
case 8:
if (d.maxerrout > d.pm->error_gray_8)
d.pm->error_gray_8 = d.maxerrout;
break;
case 16:
if (d.maxerrout > d.pm->error_gray_16)
d.pm->error_gray_16 = d.maxerrout;
break;
default:
png_error(pp, "bad bit depth (internal: 1)");
}
}
else if (d.this.colour_type == 2 || d.this.colour_type == 6)
{
switch (d.this.bit_depth)
{
case 8:
if (d.maxerrout > d.pm->error_color_8)
d.pm->error_color_8 = d.maxerrout;
break;
case 16:
if (d.maxerrout > d.pm->error_color_16)
d.pm->error_color_16 = d.maxerrout;
break;
default:
png_error(pp, "bad bit depth (internal: 2)");
}
}
else if (d.this.colour_type == 3)
{
if (d.maxerrout > d.pm->error_indexed)
d.pm->error_indexed = d.maxerrout;
}
}
Catch(fault)
modifier_reset((png_modifier*)fault);
}
static void gamma_threshold_test(png_modifier *pm, png_byte colour_type,
png_byte bit_depth, int interlace_type, double file_gamma,
double screen_gamma)
{
size_t pos = 0;
char name[64];
pos = safecat(name, sizeof name, pos, "threshold ");
pos = safecatd(name, sizeof name, pos, file_gamma, 3);
pos = safecat(name, sizeof name, pos, "/");
pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
(void)gamma_test(pm, colour_type, bit_depth, 0/*palette*/, interlace_type,
file_gamma, screen_gamma, 0/*sBIT*/, 1/*threshold test*/, name,
0 /*no input precision*/,
0 /*no scale16*/, 0 /*no expand16*/, 0 /*no background*/, 0 /*hence*/,
0 /*no background gamma*/);
}
static void
perform_gamma_threshold_tests(png_modifier *pm)
{
png_byte colour_type = 0;
png_byte bit_depth = 0;
int palette_number = 0;
/* Don't test more than one instance of each palette - it's pointless, in
* fact this test is somewhat excessive since libpng doesn't make this
* decision based on colour type or bit depth!
*/
while (next_format(&colour_type, &bit_depth, &palette_number))
if (palette_number == 0)
{
double test_gamma = 1.0;
while (test_gamma >= .4)
{
/* There's little point testing the interlacing vs non-interlacing,
* but this can be set from the command line.
*/
gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type,
test_gamma, 1/test_gamma);
test_gamma *= .95;
}
/* And a special test for sRGB */
gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type,
.45455, 2.2);
if (fail(pm))
return;
}
}
static void gamma_transform_test(png_modifier *pm,
PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth,
PNG_CONST int palette_number,
PNG_CONST int interlace_type, PNG_CONST double file_gamma,
PNG_CONST double screen_gamma, PNG_CONST png_byte sbit,
PNG_CONST int use_input_precision, PNG_CONST int scale16)
{
size_t pos = 0;
char name[64];
if (sbit != bit_depth && sbit != 0)
{
pos = safecat(name, sizeof name, pos, "sbit(");
pos = safecatn(name, sizeof name, pos, sbit);
pos = safecat(name, sizeof name, pos, ") ");
}
else
pos = safecat(name, sizeof name, pos, "gamma ");
if (scale16)
pos = safecat(name, sizeof name, pos, "16to8 ");
pos = safecatd(name, sizeof name, pos, file_gamma, 3);
pos = safecat(name, sizeof name, pos, "->");
pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
gamma_test(pm, colour_type, bit_depth, palette_number, interlace_type,
file_gamma, screen_gamma, sbit, 0, name, use_input_precision,
scale16, pm->test_gamma_expand16, 0 , 0, 0);
}
static void perform_gamma_transform_tests(png_modifier *pm)
{
png_byte colour_type = 0;
png_byte bit_depth = 0;
int palette_number = 0;
while (next_format(&colour_type, &bit_depth, &palette_number))
{
unsigned int i, j;
for (i=0; i<pm->ngamma_tests; ++i) for (j=0; j<pm->ngamma_tests; ++j)
if (i != j)
{
gamma_transform_test(pm, colour_type, bit_depth, palette_number,
pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], 0/*sBIT*/,
pm->use_input_precision, 0 /*do not scale16*/);
if (fail(pm))
return;
}
}
}
static void perform_gamma_sbit_tests(png_modifier *pm)
{
png_byte sbit;
/* The only interesting cases are colour and grayscale, alpha is ignored here
* for overall speed. Only bit depths where sbit is less than the bit depth
* are tested.
*/
for (sbit=pm->sbitlow; sbit<(1<<READ_BDHI); ++sbit)
{
png_byte colour_type, bit_depth;
int npalette;
colour_type = bit_depth = 0;
npalette = 0;
while (next_format(&colour_type, &bit_depth, &npalette))
if ((colour_type & PNG_COLOR_MASK_ALPHA) == 0 &&
((colour_type == 3 && sbit < 8) ||
(colour_type != 3 && sbit < bit_depth)))
{
unsigned int i;
for (i=0; i<pm->ngamma_tests; ++i)
{
unsigned int j;
for (j=0; j<pm->ngamma_tests; ++j) if (i != j)
{
gamma_transform_test(pm, colour_type, bit_depth, npalette,
pm->interlace_type, 1/pm->gammas[i], pm->gammas[j],
sbit, pm->use_input_precision_sbit, 0 /*scale16*/);
if (fail(pm))
return;
}
}
}
}
}
/* Note that this requires a 16 bit source image but produces 8 bit output, so
* we only need the 16bit write support, but the 16 bit images are only
* generated if DO_16BIT is defined.
*/
#ifdef DO_16BIT
static void perform_gamma_scale16_tests(png_modifier *pm)
{
# ifndef PNG_MAX_GAMMA_8
# define PNG_MAX_GAMMA_8 11
# endif
/* Include the alpha cases here. Note that sbit matches the internal value
* used by the library - otherwise we will get spurious errors from the
* internal sbit style approximation.
*
* The threshold test is here because otherwise the 16 to 8 conversion will
* proceed *without* gamma correction, and the tests above will fail (but not
* by much) - this could be fixed, it only appears with the -g option.
*/
unsigned int i, j;
for (i=0; i<pm->ngamma_tests; ++i)
{
for (j=0; j<pm->ngamma_tests; ++j)
{
if (i != j &&
fabs(pm->gammas[j]/pm->gammas[i]-1) >= PNG_GAMMA_THRESHOLD)
{
gamma_transform_test(pm, 0, 16, 0, pm->interlace_type,
1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8,
pm->use_input_precision_16to8, 1 /*scale16*/);
if (fail(pm))
return;
gamma_transform_test(pm, 2, 16, 0, pm->interlace_type,
1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8,
pm->use_input_precision_16to8, 1 /*scale16*/);
if (fail(pm))
return;
gamma_transform_test(pm, 4, 16, 0, pm->interlace_type,
1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8,
pm->use_input_precision_16to8, 1 /*scale16*/);
if (fail(pm))
return;
gamma_transform_test(pm, 6, 16, 0, pm->interlace_type,
1/pm->gammas[i], pm->gammas[j], PNG_MAX_GAMMA_8,
pm->use_input_precision_16to8, 1 /*scale16*/);
if (fail(pm))
return;
}
}
}
}
#endif /* 16 to 8 bit conversion */
#if defined PNG_READ_BACKGROUND_SUPPORTED ||\
defined PNG_READ_ALPHA_MODE_SUPPORTED
static void gamma_composition_test(png_modifier *pm,
PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth,
PNG_CONST int palette_number,
PNG_CONST int interlace_type, PNG_CONST double file_gamma,
PNG_CONST double screen_gamma,
PNG_CONST int use_input_precision, PNG_CONST int do_background,
PNG_CONST int expand_16)
{
size_t pos = 0;
png_const_charp base;
double bg;
char name[128];
png_color_16 background;
/* Make up a name and get an appropriate background gamma value. */
switch (do_background)
{
default:
base = "";
bg = 4; /* should not be used */
break;
case PNG_BACKGROUND_GAMMA_SCREEN:
base = " bckg(Screen):";
bg = 1/screen_gamma;
break;
case PNG_BACKGROUND_GAMMA_FILE:
base = " bckg(File):";
bg = file_gamma;
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
base = " bckg(Unique):";
/* This tests the handling of a unique value, the math is such that the
* value tends to be <1, but is neither screen nor file (even if they
* match!)
*/
bg = (file_gamma + screen_gamma) / 3;
break;
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
case ALPHA_MODE_OFFSET + PNG_ALPHA_PNG:
base = " alpha(PNG)";
bg = 4; /* should not be used */
break;
case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
base = " alpha(Porter-Duff)";
bg = 4; /* should not be used */
break;
case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
base = " alpha(Optimized)";
bg = 4; /* should not be used */
break;
case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
base = " alpha(Broken)";
bg = 4; /* should not be used */
break;
#endif
}
/* Use random background values - the background is always presented in the
* output space (8 or 16 bit components).
*/
if (expand_16 || bit_depth == 16)
{
png_uint_32 r = random_32();
background.red = (png_uint_16)r;
background.green = (png_uint_16)(r >> 16);
r = random_32();
background.blue = (png_uint_16)r;
background.gray = (png_uint_16)(r >> 16);
}
else /* 8 bit colors */
{
png_uint_32 r = random_32();
background.red = (png_byte)r;
background.green = (png_byte)(r >> 8);
background.blue = (png_byte)(r >> 16);
background.gray = (png_byte)(r >> 24);
}
background.index = 193; /* rgb(193,193,193) to detect errors */
if (!(colour_type & PNG_COLOR_MASK_COLOR))
{
/* Grayscale input, we do not convert to RGB (TBD), so we must set the
* background to gray - else libpng seems to fail.
*/
background.red = background.green = background.blue = background.gray;
}
pos = safecat(name, sizeof name, pos, "gamma ");
pos = safecatd(name, sizeof name, pos, file_gamma, 3);
pos = safecat(name, sizeof name, pos, "->");
pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
pos = safecat(name, sizeof name, pos, base);
if (do_background < ALPHA_MODE_OFFSET)
{
/* Include the background color and gamma in the name: */
pos = safecat(name, sizeof name, pos, "(");
/* This assumes no expand gray->rgb - the current code won't handle that!
*/
if (colour_type & PNG_COLOR_MASK_COLOR)
{
pos = safecatn(name, sizeof name, pos, background.red);
pos = safecat(name, sizeof name, pos, ",");
pos = safecatn(name, sizeof name, pos, background.green);
pos = safecat(name, sizeof name, pos, ",");
pos = safecatn(name, sizeof name, pos, background.blue);
}
else
pos = safecatn(name, sizeof name, pos, background.gray);
pos = safecat(name, sizeof name, pos, ")^");
pos = safecatd(name, sizeof name, pos, bg, 3);
}
gamma_test(pm, colour_type, bit_depth, palette_number, interlace_type,
file_gamma, screen_gamma, 0/*sBIT*/, 0, name, use_input_precision,
0/*strip 16*/, expand_16, do_background, &background, bg);
}
static void
perform_gamma_composition_tests(png_modifier *pm, int do_background,
int expand_16)
{
png_byte colour_type = 0;
png_byte bit_depth = 0;
int palette_number = 0;
/* Skip the non-alpha cases - there is no setting of a transparency colour at
* present.
*/
while (next_format(&colour_type, &bit_depth, &palette_number))
if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0)
{
unsigned int i, j;
/* Don't skip the i==j case here - it's relevant. */
for (i=0; i<pm->ngamma_tests; ++i) for (j=0; j<pm->ngamma_tests; ++j)
{
gamma_composition_test(pm, colour_type, bit_depth, palette_number,
pm->interlace_type, 1/pm->gammas[i], pm->gammas[j],
pm->use_input_precision, do_background, expand_16);
if (fail(pm))
return;
}
}
}
#endif /* READ_BACKGROUND || READ_ALPHA_MODE */
static void
init_gamma_errors(png_modifier *pm)
{
pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = 0;
pm->error_color_8 = 0;
pm->error_indexed = 0;
pm->error_gray_16 = pm->error_color_16 = 0;
}
static void
summarize_gamma_errors(png_modifier *pm, png_const_charp who, int low_bit_depth)
{
if (who)
printf("Gamma correction with %s:\n", who);
if (low_bit_depth)
{
printf(" 2 bit gray: %.5f\n", pm->error_gray_2);
printf(" 4 bit gray: %.5f\n", pm->error_gray_4);
printf(" 8 bit gray: %.5f\n", pm->error_gray_8);
printf(" 8 bit color: %.5f\n", pm->error_color_8);
printf(" indexed: %.5f\n", pm->error_indexed);
}
#ifdef DO_16BIT
printf(" 16 bit gray: %.5f\n", pm->error_gray_16);
printf(" 16 bit color: %.5f\n", pm->error_color_16);
#endif
}
static void
perform_gamma_test(png_modifier *pm, int summary)
{
/*TODO: remove this*/
/* Save certain values for the temporary overrides below. */
unsigned int calculations_use_input_precision =
pm->calculations_use_input_precision;
double maxout8 = pm->maxout8;
/* First some arbitrary no-transform tests: */
if (!pm->this.speed && pm->test_gamma_threshold)
{
perform_gamma_threshold_tests(pm);
if (fail(pm))
return;
}
/* Now some real transforms. */
if (pm->test_gamma_transform)
{
init_gamma_errors(pm);
/*TODO: remove this. Necessary because the current libpng
* implementation works in 8 bits:
*/
if (pm->test_gamma_expand16)
pm->calculations_use_input_precision = 1;
perform_gamma_transform_tests(pm);
if (!calculations_use_input_precision)
pm->calculations_use_input_precision = 0;
if (summary)
{
printf("Gamma correction error summary\n\n");
printf("The printed value is the maximum error in the pixel values\n");
printf("calculated by the libpng gamma correction code. The error\n");
printf("is calculated as the difference between the output pixel\n");
printf("value (always an integer) and the ideal value from the\n");
printf("libpng specification (typically not an integer).\n\n");
printf("Expect this value to be less than .5 for 8 bit formats,\n");
printf("less than 1 for formats with fewer than 8 bits and a small\n");
printf("number (typically less than 5) for the 16 bit formats.\n");
printf("For performance reasons the value for 16 bit formats\n");
printf("increases when the image file includes an sBIT chunk.\n\n");
summarize_gamma_errors(pm, 0/*who*/, 1);
}
}
/* The sbit tests produce much larger errors: */
if (pm->test_gamma_sbit)
{
init_gamma_errors(pm);
perform_gamma_sbit_tests(pm);
if (summary)
summarize_gamma_errors(pm, "sBIT", pm->sbitlow < 8U);
}
#ifdef DO_16BIT /* Should be READ_16BIT_SUPPORTED */
if (pm->test_gamma_scale16)
{
/* The 16 to 8 bit strip operations: */
init_gamma_errors(pm);
perform_gamma_scale16_tests(pm);
if (summary)
{
printf("Gamma correction with 16 to 8 bit reduction:\n");
printf(" 16 bit gray: %.5f\n", pm->error_gray_16);
printf(" 16 bit color: %.5f\n", pm->error_color_16);
}
}
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
if (pm->test_gamma_background)
{
init_gamma_errors(pm);
/*TODO: remove this. Necessary because the current libpng
* implementation works in 8 bits:
*/
if (pm->test_gamma_expand16)
{
pm->calculations_use_input_precision = 1;
pm->maxout8 = .499; /* because the 16 bit background is smashed */
}
perform_gamma_composition_tests(pm, PNG_BACKGROUND_GAMMA_UNIQUE,
pm->test_gamma_expand16);
if (!calculations_use_input_precision)
pm->calculations_use_input_precision = 0;
pm->maxout8 = maxout8;
if (summary)
summarize_gamma_errors(pm, "background", 1);
}
#endif
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
if (pm->test_gamma_alpha_mode)
{
int do_background;
init_gamma_errors(pm);
/*TODO: remove this. Necessary because the current libpng
* implementation works in 8 bits:
*/
if (pm->test_gamma_expand16)
pm->calculations_use_input_precision = 1;
for (do_background = ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD;
do_background <= ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN && !fail(pm);
++do_background)
perform_gamma_composition_tests(pm, do_background,
pm->test_gamma_expand16);
if (!calculations_use_input_precision)
pm->calculations_use_input_precision = 0;
if (summary)
summarize_gamma_errors(pm, "alpha mode", 1);
}
#endif
}
#endif /* PNG_READ_GAMMA_SUPPORTED */
/* INTERLACE MACRO VALIDATION */
/* This is copied verbatim from the specification, it is simply the pass
* number in which each pixel in each 8x8 tile appears. The array must
* be indexed adam7[y][x] and notice that the pass numbers are based at
* 1, not 0 - the base libpng uses.
*/
static PNG_CONST
png_byte adam7[8][8] =
{
{ 1,6,4,6,2,6,4,6 },
{ 7,7,7,7,7,7,7,7 },
{ 5,6,5,6,5,6,5,6 },
{ 7,7,7,7,7,7,7,7 },
{ 3,6,4,6,3,6,4,6 },
{ 7,7,7,7,7,7,7,7 },
{ 5,6,5,6,5,6,5,6 },
{ 7,7,7,7,7,7,7,7 }
};
/* This routine validates all the interlace support macros in png.h for
* a variety of valid PNG widths and heights. It uses a number of similarly
* named internal routines that feed off the above array.
*/
static png_uint_32
png_pass_start_row(int pass)
{
int x, y;
++pass;
for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
return y;
return 0xf;
}
static png_uint_32
png_pass_start_col(int pass)
{
int x, y;
++pass;
for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
return x;
return 0xf;
}
static int
png_pass_row_shift(int pass)
{
int x, y, base=(-1), inc=8;
++pass;
for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
{
if (base == (-1))
base = y;
else if (base == y)
{}
else if (inc == y-base)
base=y;
else if (inc == 8)
inc = y-base, base=y;
else if (inc != y-base)
return 0xff; /* error - more than one 'inc' value! */
}
if (base == (-1)) return 0xfe; /* error - no row in pass! */
/* The shift is always 1, 2 or 3 - no pass has all the rows! */
switch (inc)
{
case 2: return 1;
case 4: return 2;
case 8: return 3;
default: break;
}
/* error - unrecognized 'inc' */
return (inc << 8) + 0xfd;
}
static int
png_pass_col_shift(int pass)
{
int x, y, base=(-1), inc=8;
++pass;
for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
{
if (base == (-1))
base = x;
else if (base == x)
{}
else if (inc == x-base)
base=x;
else if (inc == 8)
inc = x-base, base=x;
else if (inc != x-base)
return 0xff; /* error - more than one 'inc' value! */
}
if (base == (-1)) return 0xfe; /* error - no row in pass! */
/* The shift is always 1, 2 or 3 - no pass has all the rows! */
switch (inc)
{
case 1: return 0; /* pass 7 has all the columns */
case 2: return 1;
case 4: return 2;
case 8: return 3;
default: break;
}
/* error - unrecognized 'inc' */
return (inc << 8) + 0xfd;
}
static png_uint_32
png_row_from_pass_row(png_uint_32 yIn, int pass)
{
/* By examination of the array: */
switch (pass)
{
case 0: return yIn * 8;
case 1: return yIn * 8;
case 2: return yIn * 8 + 4;
case 3: return yIn * 4;
case 4: return yIn * 4 + 2;
case 5: return yIn * 2;
case 6: return yIn * 2 + 1;
default: break;
}
return 0xff; /* bad pass number */
}
static png_uint_32
png_col_from_pass_col(png_uint_32 xIn, int pass)
{
/* By examination of the array: */
switch (pass)
{
case 0: return xIn * 8;
case 1: return xIn * 8 + 4;
case 2: return xIn * 4;
case 3: return xIn * 4 + 2;
case 4: return xIn * 2;
case 5: return xIn * 2 + 1;
case 6: return xIn;
default: break;
}
return 0xff; /* bad pass number */
}
static int
png_row_in_interlace_pass(png_uint_32 y, int pass)
{
/* Is row 'y' in pass 'pass'? */
int x;
y &= 7;
++pass;
for (x=0; x<8; ++x) if (adam7[y][x] == pass)
return 1;
return 0;
}
static int
png_col_in_interlace_pass(png_uint_32 x, int pass)
{
/* Is column 'x' in pass 'pass'? */
int y;
x &= 7;
++pass;
for (y=0; y<8; ++y) if (adam7[y][x] == pass)
return 1;
return 0;
}
static png_uint_32
png_pass_rows(png_uint_32 height, int pass)
{
png_uint_32 tiles = height>>3;
png_uint_32 rows = 0;
unsigned int x, y;
height &= 7;
++pass;
for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
{
rows += tiles;
if (y < height) ++rows;
break; /* i.e. break the 'x', column, loop. */
}
return rows;
}
static png_uint_32
png_pass_cols(png_uint_32 width, int pass)
{
png_uint_32 tiles = width>>3;
png_uint_32 cols = 0;
unsigned int x, y;
width &= 7;
++pass;
for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
{
cols += tiles;
if (x < width) ++cols;
break; /* i.e. break the 'y', row, loop. */
}
return cols;
}
static void
perform_interlace_macro_validation(void)
{
/* The macros to validate, first those that depend only on pass:
*
* PNG_PASS_START_ROW(pass)
* PNG_PASS_START_COL(pass)
* PNG_PASS_ROW_SHIFT(pass)
* PNG_PASS_COL_SHIFT(pass)
*/
int pass;
for (pass=0; pass<7; ++pass)
{
png_uint_32 m, f, v;
m = PNG_PASS_START_ROW(pass);
f = png_pass_start_row(pass);
if (m != f)
{
fprintf(stderr, "PNG_PASS_START_ROW(%d) = %u != %x\n", pass, m, f);
exit(1);
}
m = PNG_PASS_START_COL(pass);
f = png_pass_start_col(pass);
if (m != f)
{
fprintf(stderr, "PNG_PASS_START_COL(%d) = %u != %x\n", pass, m, f);
exit(1);
}
m = PNG_PASS_ROW_SHIFT(pass);
f = png_pass_row_shift(pass);
if (m != f)
{
fprintf(stderr, "PNG_PASS_ROW_SHIFT(%d) = %u != %x\n", pass, m, f);
exit(1);
}
m = PNG_PASS_COL_SHIFT(pass);
f = png_pass_col_shift(pass);
if (m != f)
{
fprintf(stderr, "PNG_PASS_COL_SHIFT(%d) = %u != %x\n", pass, m, f);
exit(1);
}
/* Macros that depend on the image or sub-image height too:
*
* PNG_PASS_ROWS(height, pass)
* PNG_PASS_COLS(width, pass)
* PNG_ROW_FROM_PASS_ROW(yIn, pass)
* PNG_COL_FROM_PASS_COL(xIn, pass)
* PNG_ROW_IN_INTERLACE_PASS(y, pass)
* PNG_COL_IN_INTERLACE_PASS(x, pass)
*/
for (v=0;;)
{
/* First the base 0 stuff: */
m = PNG_ROW_FROM_PASS_ROW(v, pass);
f = png_row_from_pass_row(v, pass);
if (m != f)
{
fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
v, pass, m, f);
exit(1);
}
m = PNG_COL_FROM_PASS_COL(v, pass);
f = png_col_from_pass_col(v, pass);
if (m != f)
{
fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
v, pass, m, f);
exit(1);
}
m = PNG_ROW_IN_INTERLACE_PASS(v, pass);
f = png_row_in_interlace_pass(v, pass);
if (m != f)
{
fprintf(stderr, "PNG_ROW_IN_INTERLACE_PASS(%u, %d) = %u != %x\n",
v, pass, m, f);
exit(1);
}
m = PNG_COL_IN_INTERLACE_PASS(v, pass);
f = png_col_in_interlace_pass(v, pass);
if (m != f)
{
fprintf(stderr, "PNG_COL_IN_INTERLACE_PASS(%u, %d) = %u != %x\n",
v, pass, m, f);
exit(1);
}
/* Then the base 1 stuff: */
++v;
m = PNG_PASS_ROWS(v, pass);
f = png_pass_rows(v, pass);
if (m != f)
{
fprintf(stderr, "PNG_PASS_ROWS(%u, %d) = %u != %x\n",
v, pass, m, f);
exit(1);
}
m = PNG_PASS_COLS(v, pass);
f = png_pass_cols(v, pass);
if (m != f)
{
fprintf(stderr, "PNG_PASS_COLS(%u, %d) = %u != %x\n",
v, pass, m, f);
exit(1);
}
/* Move to the next v - the stepping algorithm starts skipping
* values above 1024.
*/
if (v > 1024)
{
if (v == PNG_UINT_31_MAX)
break;
v = (v << 1) ^ v;
if (v >= PNG_UINT_31_MAX)
v = PNG_UINT_31_MAX-1;
}
}
}
}
/* Test color encodings. These values are back-calculated from the published
* chromaticities. The values are accurate to about 14 decimal places; 15 are
* given. These values are much more accurate than the ones given in the spec,
* which typically don't exceed 4 decimal places. This allows testing of the
* libpng code to its theoretical accuracy of 4 decimal places. (If pngvalid
* used the published errors the 'slack' permitted would have to be +/-.5E-4 or
* more.)
*
* The png_modifier code assumes that encodings[0] is sRGB and treats it
* specially: do not change the first entry in this list!
*/
static PNG_CONST color_encoding test_encodings[] =
{
/* sRGB: must be first in this list! */
/*gamma:*/ { 1/2.2,
/*red: */ { 0.412390799265959, 0.212639005871510, 0.019330818715592 },
/*green:*/ { 0.357584339383878, 0.715168678767756, 0.119194779794626 },
/*blue: */ { 0.180480788401834, 0.072192315360734, 0.950532152249660} },
/* Kodak ProPhoto (wide gamut) */
/*gamma:*/ { 1/1.6 /*approximate: uses 1.8 power law compared to sRGB 2.4*/,
/*red: */ { 0.797760489672303, 0.288071128229293, 0.000000000000000 },
/*green:*/ { 0.135185837175740, 0.711843217810102, 0.000000000000000 },
/*blue: */ { 0.031349349581525, 0.000085653960605, 0.825104602510460} },
/* Adobe RGB (1998) */
/*gamma:*/ { 1/(2+51./256),
/*red: */ { 0.576669042910131, 0.297344975250536, 0.027031361386412 },
/*green:*/ { 0.185558237906546, 0.627363566255466, 0.070688852535827 },
/*blue: */ { 0.188228646234995, 0.075291458493998, 0.991337536837639} },
/* Adobe Wide Gamut RGB */
/*gamma:*/ { 1/(2+51./256),
/*red: */ { 0.716500716779386, 0.258728243040113, 0.000000000000000 },
/*green:*/ { 0.101020574397477, 0.724682314948566, 0.051211818965388 },
/*blue: */ { 0.146774385252705, 0.016589442011321, 0.773892783545073} },
};
/* main program */
int main(int argc, PNG_CONST char **argv)
{
volatile int summary = 1; /* Print the error summary at the end */
volatile int memstats = 0; /* Print memory statistics at the end */
/* Create the given output file on success: */
PNG_CONST char *volatile touch = NULL;
/* This is an array of standard gamma values (believe it or not I've seen
* every one of these mentioned somewhere.)
*
* In the following list the most useful values are first!
*/
static double
gammas[]={2.2, 1.0, 2.2/1.45, 1.8, 1.5, 2.4, 2.5, 2.62, 2.9};
/* This records the command and arguments: */
size_t cp = 0;
char command[1024];
png_modifier pm;
context(&pm.this, fault);
modifier_init(&pm);
/* Preallocate the image buffer, because we know how big it needs to be,
* note that, for testing purposes, it is deliberately mis-aligned by tag
* bytes either side. All rows have an additional five bytes of padding for
* overwrite checking.
*/
store_ensure_image(&pm.this, NULL, 2, TRANSFORM_ROWMAX, TRANSFORM_HEIGHTMAX);
/* Don't give argv[0], it's normally some horrible libtool string: */
cp = safecat(command, sizeof command, cp, "pngvalid");
/* Default to error on warning: */
pm.this.treat_warnings_as_errors = 1;
/* Store the test gammas */
pm.gammas = gammas;
pm.ngammas = (sizeof gammas) / (sizeof gammas[0]);
pm.ngamma_tests = 0; /* default to off */
/* And the test encodings */
pm.encodings = test_encodings;
pm.nencodings = (sizeof test_encodings) / (sizeof test_encodings[0]);
pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */
/* The following allows results to pass if they correspond to anything in the
* transformed range [input-.5,input+.5]; this is is required because of the
* way libpng treates the 16_TO_8 flag when building the gamma tables.
*
* TODO: review this
*/
pm.use_input_precision_16to8 = 1U;
/* Some default values (set the behavior for 'make check' here).
* These values simply control the maximum error permitted in the gamma
* transformations. The practial limits for human perception are described
* below (the setting for maxpc16), however for 8 bit encodings it isn't
* possible to meet the accepted capabilities of human vision - i.e. 8 bit
* images can never be good enough, regardless of encoding.
*/
pm.maxout8 = .1; /* Arithmetic error in *encoded* value */
pm.maxabs8 = .00005; /* 1/20000 */
pm.maxcalc8 = .004; /* +/-1 in 8 bits for compose errors */
pm.maxpc8 = .499; /* I.e., .499% fractional error */
pm.maxout16 = .499; /* Error in *encoded* value */
pm.maxabs16 = .00005;/* 1/20000 */
pm.maxcalc16 =.000015;/* +/-1 in 16 bits for compose errors */
/* NOTE: this is a reasonable perceptual limit. We assume that humans can
* perceive light level differences of 1% over a 100:1 range, so we need to
* maintain 1 in 10000 accuracy (in linear light space), which is what the
* following guarantees. It also allows significantly higher errors at
* higher 16 bit values, which is important for performance. The actual
* maximum 16 bit error is about +/-1.9 in the fixed point implementation but
* this is only allowed for values >38149 by the following:
*/
pm.maxpc16 = .005; /* I.e., 1/200% - 1/20000 */
/* Now parse the command line options. */
while (--argc >= 1)
{
int catmore = 0; /* Set if the argument has an argument. */
/* Record each argument for posterity: */
cp = safecat(command, sizeof command, cp, " ");
cp = safecat(command, sizeof command, cp, *++argv);
if (strcmp(*argv, "-v") == 0)
pm.this.verbose = 1;
else if (strcmp(*argv, "-l") == 0)
pm.log = 1;
else if (strcmp(*argv, "-q") == 0)
summary = pm.this.verbose = pm.log = 0;
else if (strcmp(*argv, "-w") == 0)
pm.this.treat_warnings_as_errors = 0;
else if (strcmp(*argv, "--speed") == 0)
pm.this.speed = 1, pm.ngamma_tests = pm.ngammas, pm.test_standard = 0,
summary = 0;
else if (strcmp(*argv, "--memory") == 0)
memstats = 1;
else if (strcmp(*argv, "--size") == 0)
pm.test_size = 1;
else if (strcmp(*argv, "--nosize") == 0)
pm.test_size = 0;
else if (strcmp(*argv, "--standard") == 0)
pm.test_standard = 1;
else if (strcmp(*argv, "--nostandard") == 0)
pm.test_standard = 0;
else if (strcmp(*argv, "--transform") == 0)
pm.test_transform = 1;
else if (strcmp(*argv, "--notransform") == 0)
pm.test_transform = 0;
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
else if (strncmp(*argv, "--transform-disable=",
sizeof "--transform-disable") == 0)
{
pm.test_transform = 1;
transform_disable(*argv + sizeof "--transform-disable");
}
else if (strncmp(*argv, "--transform-enable=",
sizeof "--transform-enable") == 0)
{
pm.test_transform = 1;
transform_enable(*argv + sizeof "--transform-enable");
}
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
else if (strcmp(*argv, "--gamma") == 0)
{
/* Just do two gamma tests here (2.2 and linear) for speed: */
pm.ngamma_tests = 2U;
pm.test_gamma_threshold = 1;
pm.test_gamma_transform = 1;
pm.test_gamma_sbit = 1;
pm.test_gamma_scale16 = 1;
pm.test_gamma_background = 1;
pm.test_gamma_alpha_mode = 1;
}
else if (strcmp(*argv, "--nogamma") == 0)
pm.ngamma_tests = 0;
else if (strcmp(*argv, "--gamma-threshold") == 0)
pm.ngamma_tests = 2U, pm.test_gamma_threshold = 1;
else if (strcmp(*argv, "--nogamma-threshold") == 0)
pm.test_gamma_threshold = 0;
else if (strcmp(*argv, "--gamma-transform") == 0)
pm.ngamma_tests = 2U, pm.test_gamma_transform = 1;
else if (strcmp(*argv, "--nogamma-transform") == 0)
pm.test_gamma_transform = 0;
else if (strcmp(*argv, "--gamma-sbit") == 0)
pm.ngamma_tests = 2U, pm.test_gamma_sbit = 1;
else if (strcmp(*argv, "--nogamma-sbit") == 0)
pm.test_gamma_sbit = 0;
else if (strcmp(*argv, "--gamma-16-to-8") == 0)
pm.ngamma_tests = 2U, pm.test_gamma_scale16 = 1;
else if (strcmp(*argv, "--nogamma-16-to-8") == 0)
pm.test_gamma_scale16 = 0;
else if (strcmp(*argv, "--gamma-background") == 0)
pm.ngamma_tests = 2U, pm.test_gamma_background = 1;
else if (strcmp(*argv, "--nogamma-background") == 0)
pm.test_gamma_background = 0;
else if (strcmp(*argv, "--gamma-alpha-mode") == 0)
pm.ngamma_tests = 2U, pm.test_gamma_alpha_mode = 1;
else if (strcmp(*argv, "--nogamma-alpha-mode") == 0)
pm.test_gamma_alpha_mode = 0;
else if (strcmp(*argv, "--expand16") == 0)
pm.test_gamma_expand16 = 1;
else if (strcmp(*argv, "--noexpand16") == 0)
pm.test_gamma_expand16 = 0;
else if (strcmp(*argv, "--more-gammas") == 0)
pm.ngamma_tests = 3U;
else if (strcmp(*argv, "--all-gammas") == 0)
pm.ngamma_tests = pm.ngammas;
else if (strcmp(*argv, "--progressive-read") == 0)
pm.this.progressive = 1;
else if (strcmp(*argv, "--interlace") == 0)
pm.interlace_type = PNG_INTERLACE_ADAM7;
else if (strcmp(*argv, "--use-input-precision") == 0)
pm.use_input_precision = 1;
else if (strcmp(*argv, "--calculations-use-input-precision") == 0)
pm.calculations_use_input_precision = 1;
else if (strcmp(*argv, "--assume-16-bit-calculations") == 0)
pm.assume_16_bit_calculations = 1;
else if (strcmp(*argv, "--calculations-follow-bit-depth") == 0)
pm.calculations_use_input_precision =
pm.assume_16_bit_calculations = 0;
else if (strcmp(*argv, "--exhaustive") == 0)
pm.test_exhaustive = 1;
else if (argc > 1 && strcmp(*argv, "--sbitlow") == 0)
--argc, pm.sbitlow = (png_byte)atoi(*++argv), catmore = 1;
else if (argc > 1 && strcmp(*argv, "--touch") == 0)
--argc, touch = *++argv, catmore = 1;
else if (argc > 1 && strncmp(*argv, "--max", 5) == 0)
{
--argc;
if (strcmp(5+*argv, "abs8") == 0)
pm.maxabs8 = atof(*++argv);
else if (strcmp(5+*argv, "abs16") == 0)
pm.maxabs16 = atof(*++argv);
else if (strcmp(5+*argv, "calc8") == 0)
pm.maxcalc8 = atof(*++argv);
else if (strcmp(5+*argv, "calc16") == 0)
pm.maxcalc16 = atof(*++argv);
else if (strcmp(5+*argv, "out8") == 0)
pm.maxout8 = atof(*++argv);
else if (strcmp(5+*argv, "out16") == 0)
pm.maxout16 = atof(*++argv);
else if (strcmp(5+*argv, "pc8") == 0)
pm.maxpc8 = atof(*++argv);
else if (strcmp(5+*argv, "pc16") == 0)
pm.maxpc16 = atof(*++argv);
else
{
fprintf(stderr, "pngvalid: %s: unknown 'max' option\n", *argv);
exit(1);
}
catmore = 1;
}
else if (strcmp(*argv, "--log8") == 0)
--argc, pm.log8 = atof(*++argv), catmore = 1;
else if (strcmp(*argv, "--log16") == 0)
--argc, pm.log16 = atof(*++argv), catmore = 1;
else
{
fprintf(stderr, "pngvalid: %s: unknown argument\n", *argv);
exit(1);
}
if (catmore) /* consumed an extra *argv */
{
cp = safecat(command, sizeof command, cp, " ");
cp = safecat(command, sizeof command, cp, *argv);
}
}
/* If pngvalid is run with no arguments default to a reasonable set of the
* tests.
*/
if (pm.test_standard == 0 && pm.test_size == 0 && pm.test_transform == 0 &&
pm.ngamma_tests == 0)
{
/* Make this do all the tests done in the test shell scripts with the same
* parameters, where possible. The limitation is that all the progressive
* read and interlace stuff has to be done in separate runs, so only the
* basic 'standard' and 'size' tests are done.
*/
pm.test_standard = 1;
pm.test_size = 1;
pm.test_transform = 1;
pm.ngamma_tests = 2U;
}
if (pm.ngamma_tests > 0 &&
pm.test_gamma_threshold == 0 && pm.test_gamma_transform == 0 &&
pm.test_gamma_sbit == 0 && pm.test_gamma_scale16 == 0 &&
pm.test_gamma_background == 0 && pm.test_gamma_alpha_mode == 0)
{
pm.test_gamma_threshold = 1;
pm.test_gamma_transform = 1;
pm.test_gamma_sbit = 1;
pm.test_gamma_scale16 = 1;
pm.test_gamma_background = 1;
pm.test_gamma_alpha_mode = 1;
}
else if (pm.ngamma_tests == 0)
{
/* Nothing to test so turn everything off: */
pm.test_gamma_threshold = 0;
pm.test_gamma_transform = 0;
pm.test_gamma_sbit = 0;
pm.test_gamma_scale16 = 0;
pm.test_gamma_background = 0;
pm.test_gamma_alpha_mode = 0;
}
Try
{
/* Make useful base images */
make_transform_images(&pm.this);
/* Perform the standard and gamma tests. */
if (pm.test_standard)
{
perform_interlace_macro_validation();
perform_formatting_test(&pm.this);
perform_standard_test(&pm);
perform_error_test(&pm);
}
/* Various oddly sized images: */
if (pm.test_size)
{
make_size_images(&pm.this);
perform_size_test(&pm);
}
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
/* Combinatorial transforms: */
if (pm.test_transform)
perform_transform_test(&pm);
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
#ifdef PNG_READ_GAMMA_SUPPORTED
if (pm.ngamma_tests > 0)
perform_gamma_test(&pm, summary);
#endif
}
Catch(fault)
{
fprintf(stderr, "pngvalid: test aborted (probably failed in cleanup)\n");
if (!pm.this.verbose)
{
if (pm.this.error[0] != 0)
fprintf(stderr, "pngvalid: first error: %s\n", pm.this.error);
fprintf(stderr, "pngvalid: run with -v to see what happened\n");
}
exit(1);
}
if (summary)
{
printf("%s: %s (%s point arithmetic)\n",
(pm.this.nerrors || (pm.this.treat_warnings_as_errors &&
pm.this.nwarnings)) ? "FAIL" : "PASS",
command,
#if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || PNG_LIBPNG_VER < 10500
"floating"
#else
"fixed"
#endif
);
}
if (memstats)
{
printf("Allocated memory statistics (in bytes):\n"
"\tread %lu maximum single, %lu peak, %lu total\n"
"\twrite %lu maximum single, %lu peak, %lu total\n",
(unsigned long)pm.this.read_memory_pool.max_max,
(unsigned long)pm.this.read_memory_pool.max_limit,
(unsigned long)pm.this.read_memory_pool.max_total,
(unsigned long)pm.this.write_memory_pool.max_max,
(unsigned long)pm.this.write_memory_pool.max_limit,
(unsigned long)pm.this.write_memory_pool.max_total);
}
/* Do this here to provoke memory corruption errors in memory not directly
* allocated by libpng - not a complete test, but better than nothing.
*/
store_delete(&pm.this);
/* Error exit if there are any errors, and maybe if there are any
* warnings.
*/
if (pm.this.nerrors || (pm.this.treat_warnings_as_errors &&
pm.this.nwarnings))
{
if (!pm.this.verbose)
fprintf(stderr, "pngvalid: %s\n", pm.this.error);
fprintf(stderr, "pngvalid: %d errors, %d warnings\n", pm.this.nerrors,
pm.this.nwarnings);
exit(1);
}
/* Success case. */
if (touch != NULL)
{
FILE *fsuccess = fopen(touch, "wt");
if (fsuccess != NULL)
{
int error = 0;
fprintf(fsuccess, "PNG validation succeeded\n");
fflush(fsuccess);
error = ferror(fsuccess);
if (fclose(fsuccess) || error)
{
fprintf(stderr, "%s: write failed\n", touch);
exit(1);
}
}
}
return 0;
}