blob: 43d1580c176b0b0cfff9b3fda103fd6627f0b765 [file] [log] [blame]
/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkBitmap.h"
#include "SkCodecPriv.h"
#include "SkColorPriv.h"
#include "SkColorSpace.h"
#include "SkColorTable.h"
#include "SkMath.h"
#include "SkOpts.h"
#include "SkPngCodec.h"
#include "SkSize.h"
#include "SkStream.h"
#include "SkSwizzler.h"
#include "SkTemplates.h"
#include "SkUtils.h"
///////////////////////////////////////////////////////////////////////////////
// Callback functions
///////////////////////////////////////////////////////////////////////////////
static void sk_error_fn(png_structp png_ptr, png_const_charp msg) {
SkCodecPrintf("------ png error %s\n", msg);
longjmp(png_jmpbuf(png_ptr), 1);
}
void sk_warning_fn(png_structp, png_const_charp msg) {
SkCodecPrintf("----- png warning %s\n", msg);
}
static void sk_read_fn(png_structp png_ptr, png_bytep data,
png_size_t length) {
SkStream* stream = static_cast<SkStream*>(png_get_io_ptr(png_ptr));
const size_t bytes = stream->read(data, length);
if (bytes != length) {
// FIXME: We want to report the fact that the stream was truncated.
// One way to do that might be to pass a enum to longjmp so setjmp can
// specify the failure.
png_error(png_ptr, "Read Error!");
}
}
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
static int sk_read_user_chunk(png_structp png_ptr, png_unknown_chunkp chunk) {
SkPngChunkReader* chunkReader = (SkPngChunkReader*)png_get_user_chunk_ptr(png_ptr);
// readChunk() returning true means continue decoding
return chunkReader->readChunk((const char*)chunk->name, chunk->data, chunk->size) ? 1 : -1;
}
#endif
///////////////////////////////////////////////////////////////////////////////
// Helpers
///////////////////////////////////////////////////////////////////////////////
class AutoCleanPng : public SkNoncopyable {
public:
AutoCleanPng(png_structp png_ptr)
: fPng_ptr(png_ptr)
, fInfo_ptr(nullptr) {}
~AutoCleanPng() {
// fInfo_ptr will never be non-nullptr unless fPng_ptr is.
if (fPng_ptr) {
png_infopp info_pp = fInfo_ptr ? &fInfo_ptr : nullptr;
png_destroy_read_struct(&fPng_ptr, info_pp, nullptr);
}
}
void setInfoPtr(png_infop info_ptr) {
SkASSERT(nullptr == fInfo_ptr);
fInfo_ptr = info_ptr;
}
void release() {
fPng_ptr = nullptr;
fInfo_ptr = nullptr;
}
private:
png_structp fPng_ptr;
png_infop fInfo_ptr;
};
#define AutoCleanPng(...) SK_REQUIRE_LOCAL_VAR(AutoCleanPng)
// Note: SkColorTable claims to store SkPMColors, which is not necessarily
// the case here.
// TODO: If we add support for non-native swizzles, we'll need to handle that here.
bool SkPngCodec::createColorTable(SkColorType dstColorType, bool premultiply, int* ctableCount) {
int numColors;
png_color* palette;
if (!png_get_PLTE(fPng_ptr, fInfo_ptr, &palette, &numColors)) {
return false;
}
// Note: These are not necessarily SkPMColors.
SkPMColor colorPtr[256];
png_bytep alphas;
int numColorsWithAlpha = 0;
if (png_get_tRNS(fPng_ptr, fInfo_ptr, &alphas, &numColorsWithAlpha, nullptr)) {
// Choose which function to use to create the color table. If the final destination's
// colortype is unpremultiplied, the color table will store unpremultiplied colors.
PackColorProc proc = choose_pack_color_proc(premultiply, dstColorType);
for (int i = 0; i < numColorsWithAlpha; i++) {
// We don't have a function in SkOpts that combines a set of alphas with a set
// of RGBs. We could write one, but it's hardly worth it, given that this
// is such a small fraction of the total decode time.
colorPtr[i] = proc(alphas[i], palette->red, palette->green, palette->blue);
palette++;
}
}
if (numColorsWithAlpha < numColors) {
// The optimized code depends on a 3-byte png_color struct with the colors
// in RGB order. These checks make sure it is safe to use.
static_assert(3 == sizeof(png_color), "png_color struct has changed. Opts are broken.");
#ifdef SK_DEBUG
SkASSERT(&palette->red < &palette->green);
SkASSERT(&palette->green < &palette->blue);
#endif
if (is_rgba(dstColorType)) {
SkOpts::RGB_to_RGB1(colorPtr + numColorsWithAlpha, palette,
numColors - numColorsWithAlpha);
} else {
SkOpts::RGB_to_BGR1(colorPtr + numColorsWithAlpha, palette,
numColors - numColorsWithAlpha);
}
}
// Pad the color table with the last color in the table (or black) in the case that
// invalid pixel indices exceed the number of colors in the table.
const int maxColors = 1 << fBitDepth;
if (numColors < maxColors) {
SkPMColor lastColor = numColors > 0 ? colorPtr[numColors - 1] : SK_ColorBLACK;
sk_memset32(colorPtr + numColors, lastColor, maxColors - numColors);
}
// Set the new color count.
if (ctableCount != nullptr) {
*ctableCount = maxColors;
}
fColorTable.reset(new SkColorTable(colorPtr, maxColors));
return true;
}
///////////////////////////////////////////////////////////////////////////////
// Creation
///////////////////////////////////////////////////////////////////////////////
bool SkPngCodec::IsPng(const char* buf, size_t bytesRead) {
return !png_sig_cmp((png_bytep) buf, (png_size_t)0, bytesRead);
}
static float png_fixed_point_to_float(png_fixed_point x) {
// We multiply by the same factor that libpng used to convert
// fixed point -> double. Since we want floats, we choose to
// do the conversion ourselves rather than convert
// fixed point -> double -> float.
return ((float) x) * 0.00001f;
}
static float png_inverted_fixed_point_to_float(png_fixed_point x) {
// This is necessary because the gAMA chunk actually stores 1/gamma.
return 1.0f / png_fixed_point_to_float(x);
}
// Returns a colorSpace object that represents any color space information in
// the encoded data. If the encoded data contains no color space, this will
// return NULL.
sk_sp<SkColorSpace> read_color_space(png_structp png_ptr, png_infop info_ptr) {
#if (PNG_LIBPNG_VER_MAJOR > 1) || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 6)
// First check for an ICC profile
png_bytep profile;
png_uint_32 length;
// The below variables are unused, however, we need to pass them in anyway or
// png_get_iCCP() will return nothing.
// Could knowing the |name| of the profile ever be interesting? Maybe for debugging?
png_charp name;
// The |compression| is uninteresting since:
// (1) libpng has already decompressed the profile for us.
// (2) "deflate" is the only mode of decompression that libpng supports.
int compression;
if (PNG_INFO_iCCP == png_get_iCCP(png_ptr, info_ptr, &name, &compression, &profile,
&length)) {
return SkColorSpace::NewICC(profile, length);
}
// Second, check for sRGB.
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sRGB)) {
// sRGB chunks also store a rendering intent: Absolute, Relative,
// Perceptual, and Saturation.
// FIXME (msarett): Extract this information from the sRGB chunk once
// we are able to handle this information in
// SkColorSpace.
return SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
}
// Next, check for chromaticities.
png_fixed_point XYZ[9];
float toXYZD50[9];
png_fixed_point gamma;
float gammas[3];
if (png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &XYZ[0], &XYZ[1], &XYZ[2], &XYZ[3], &XYZ[4],
&XYZ[5], &XYZ[6], &XYZ[7], &XYZ[8])) {
// FIXME (msarett): Here we are treating XYZ values as D50 even though the color
// temperature is unspecified. I suspect that this assumption
// is most often ok, but we could also calculate the color
// temperature (D value) and then convert the XYZ to D50. Maybe
// we should add a new constructor to SkColorSpace that accepts
// XYZ with D-Unkown?
for (int i = 0; i < 9; i++) {
toXYZD50[i] = png_fixed_point_to_float(XYZ[i]);
}
if (PNG_INFO_gAMA == png_get_gAMA_fixed(png_ptr, info_ptr, &gamma)) {
float value = png_inverted_fixed_point_to_float(gamma);
gammas[0] = value;
gammas[1] = value;
gammas[2] = value;
} else {
// Default to sRGB (gamma = 2.2f) if the image has color space information,
// but does not specify gamma.
gammas[0] = 2.2f;
gammas[1] = 2.2f;
gammas[2] = 2.2f;
}
SkMatrix44 mat(SkMatrix44::kUninitialized_Constructor);
mat.set3x3ColMajorf(toXYZD50);
return SkColorSpace::NewRGB(gammas, mat);
}
// Last, check for gamma.
if (PNG_INFO_gAMA == png_get_gAMA_fixed(png_ptr, info_ptr, &gamma)) {
// Guess a default value for cHRM? Or should we just give up?
// Here we use the identity matrix as a default.
// Set the gammas.
float value = png_inverted_fixed_point_to_float(gamma);
gammas[0] = value;
gammas[1] = value;
gammas[2] = value;
return SkColorSpace::NewRGB(gammas, SkMatrix44::I());
}
#endif // LIBPNG >= 1.6
// Finally, what should we do if there is no color space information in the PNG?
// The specification says that this indicates "gamma is unknown" and that the
// "color is device dependent". I'm assuming we can represent this with NULL.
// But should we guess sRGB? Most images are sRGB, even if they don't specify.
return nullptr;
}
static int bytes_per_pixel(int bitsPerPixel) {
// Note that we will have to change this implementation if we start
// supporting outputs from libpng that are less than 8-bits per component.
return bitsPerPixel / 8;
}
// Subclass of SkPngCodec which supports scanline decoding
class SkPngScanlineDecoder : public SkPngCodec {
public:
SkPngScanlineDecoder(int width, int height, const SkEncodedInfo& info, SkStream* stream,
SkPngChunkReader* chunkReader, png_structp png_ptr, png_infop info_ptr, int bitDepth,
sk_sp<SkColorSpace> colorSpace)
: INHERITED(width, height, info, stream, chunkReader, png_ptr, info_ptr, bitDepth, 1,
colorSpace)
, fSrcRow(nullptr)
{}
Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
SkPMColor ctable[], int* ctableCount) override {
if (!conversion_possible(dstInfo, this->getInfo())) {
return kInvalidConversion;
}
const Result result = this->initializeSwizzler(dstInfo, options, ctable,
ctableCount);
if (result != kSuccess) {
return result;
}
fStorage.reset(this->getInfo().width() *
(bytes_per_pixel(this->getEncodedInfo().bitsPerPixel())));
fSrcRow = fStorage.get();
return kSuccess;
}
int onGetScanlines(void* dst, int count, size_t rowBytes) override {
// Assume that an error in libpng indicates an incomplete input.
int row = 0;
if (setjmp(png_jmpbuf(this->png_ptr()))) {
SkCodecPrintf("setjmp long jump!\n");
return row;
}
void* dstRow = dst;
for (; row < count; row++) {
png_read_row(this->png_ptr(), fSrcRow, nullptr);
this->swizzler()->swizzle(dstRow, fSrcRow);
dstRow = SkTAddOffset<void>(dstRow, rowBytes);
}
return row;
}
bool onSkipScanlines(int count) override {
// Assume that an error in libpng indicates an incomplete input.
if (setjmp(png_jmpbuf(this->png_ptr()))) {
SkCodecPrintf("setjmp long jump!\n");
return false;
}
for (int row = 0; row < count; row++) {
png_read_row(this->png_ptr(), fSrcRow, nullptr);
}
return true;
}
private:
SkAutoTMalloc<uint8_t> fStorage;
uint8_t* fSrcRow;
typedef SkPngCodec INHERITED;
};
class SkPngInterlacedScanlineDecoder : public SkPngCodec {
public:
SkPngInterlacedScanlineDecoder(int width, int height, const SkEncodedInfo& info,
SkStream* stream, SkPngChunkReader* chunkReader, png_structp png_ptr,
png_infop info_ptr, int bitDepth, int numberPasses, sk_sp<SkColorSpace> colorSpace)
: INHERITED(width, height, info, stream, chunkReader, png_ptr, info_ptr, bitDepth,
numberPasses, colorSpace)
, fHeight(-1)
, fCanSkipRewind(false)
{
SkASSERT(numberPasses != 1);
}
Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
SkPMColor ctable[], int* ctableCount) override {
if (!conversion_possible(dstInfo, this->getInfo())) {
return kInvalidConversion;
}
const Result result = this->initializeSwizzler(dstInfo, options, ctable,
ctableCount);
if (result != kSuccess) {
return result;
}
fHeight = dstInfo.height();
// FIXME: This need not be called on a second call to onStartScanlineDecode.
fSrcRowBytes = this->getInfo().width() *
(bytes_per_pixel(this->getEncodedInfo().bitsPerPixel()));
fGarbageRow.reset(fSrcRowBytes);
fGarbageRowPtr = static_cast<uint8_t*>(fGarbageRow.get());
fCanSkipRewind = true;
return SkCodec::kSuccess;
}
int onGetScanlines(void* dst, int count, size_t dstRowBytes) override {
// rewind stream if have previously called onGetScanlines,
// since we need entire progressive image to get scanlines
if (fCanSkipRewind) {
// We already rewound in onStartScanlineDecode, so there is no reason to rewind.
// Next time onGetScanlines is called, we will need to rewind.
fCanSkipRewind = false;
} else {
// rewindIfNeeded resets fCurrScanline, since it assumes that start
// needs to be called again before scanline decoding. PNG scanline
// decoding is the exception, since it needs to rewind between
// calls to getScanlines. Keep track of fCurrScanline, to undo the
// reset.
const int currScanline = this->nextScanline();
// This method would never be called if currScanline is -1
SkASSERT(currScanline != -1);
if (!this->rewindIfNeeded()) {
return kCouldNotRewind;
}
this->updateCurrScanline(currScanline);
}
if (setjmp(png_jmpbuf(this->png_ptr()))) {
SkCodecPrintf("setjmp long jump!\n");
// FIXME (msarett): Returning 0 is pessimistic. If we can complete a single pass,
// we may be able to report that all of the memory has been initialized. Even if we
// fail on the first pass, we can still report than some scanlines are initialized.
return 0;
}
SkAutoTMalloc<uint8_t> storage(count * fSrcRowBytes);
uint8_t* storagePtr = storage.get();
uint8_t* srcRow;
const int startRow = this->nextScanline();
for (int i = 0; i < this->numberPasses(); i++) {
// read rows we planned to skip into garbage row
for (int y = 0; y < startRow; y++){
png_read_row(this->png_ptr(), fGarbageRowPtr, nullptr);
}
// read rows we care about into buffer
srcRow = storagePtr;
for (int y = 0; y < count; y++) {
png_read_row(this->png_ptr(), srcRow, nullptr);
srcRow += fSrcRowBytes;
}
// read rows we don't want into garbage buffer
for (int y = 0; y < fHeight - startRow - count; y++) {
png_read_row(this->png_ptr(), fGarbageRowPtr, nullptr);
}
}
//swizzle the rows we care about
srcRow = storagePtr;
void* dstRow = dst;
for (int y = 0; y < count; y++) {
this->swizzler()->swizzle(dstRow, srcRow);
dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
srcRow += fSrcRowBytes;
}
return count;
}
bool onSkipScanlines(int count) override {
// The non-virtual version will update fCurrScanline.
return true;
}
SkScanlineOrder onGetScanlineOrder() const override {
return kNone_SkScanlineOrder;
}
private:
int fHeight;
size_t fSrcRowBytes;
SkAutoMalloc fGarbageRow;
uint8_t* fGarbageRowPtr;
// FIXME: This imitates behavior in SkCodec::rewindIfNeeded. That function
// is called whenever some action is taken that reads the stream and
// therefore the next call will require a rewind. So it modifies a boolean
// to note that the *next* time it is called a rewind is needed.
// SkPngInterlacedScanlineDecoder has an extra wrinkle - calling
// onStartScanlineDecode followed by onGetScanlines does *not* require a
// rewind. Since rewindIfNeeded does not have this flexibility, we need to
// add another layer.
bool fCanSkipRewind;
typedef SkPngCodec INHERITED;
};
// Reads the header and initializes the output fields, if not NULL.
//
// @param stream Input data. Will be read to get enough information to properly
// setup the codec.
// @param chunkReader SkPngChunkReader, for reading unknown chunks. May be NULL.
// If not NULL, png_ptr will hold an *unowned* pointer to it. The caller is
// expected to continue to own it for the lifetime of the png_ptr.
// @param outCodec Optional output variable. If non-NULL, will be set to a new
// SkPngCodec on success.
// @param png_ptrp Optional output variable. If non-NULL, will be set to a new
// png_structp on success.
// @param info_ptrp Optional output variable. If non-NULL, will be set to a new
// png_infop on success;
// @return true on success, in which case the caller is responsible for calling
// png_destroy_read_struct(png_ptrp, info_ptrp).
// If it returns false, the passed in fields (except stream) are unchanged.
static bool read_header(SkStream* stream, SkPngChunkReader* chunkReader, SkCodec** outCodec,
png_structp* png_ptrp, png_infop* info_ptrp) {
// The image is known to be a PNG. Decode enough to know the SkImageInfo.
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr,
sk_error_fn, sk_warning_fn);
if (!png_ptr) {
return false;
}
AutoCleanPng autoClean(png_ptr);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == nullptr) {
return false;
}
autoClean.setInfoPtr(info_ptr);
// FIXME: Could we use the return value of setjmp to specify the type of
// error?
if (setjmp(png_jmpbuf(png_ptr))) {
return false;
}
png_set_read_fn(png_ptr, static_cast<void*>(stream), sk_read_fn);
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
// Hookup our chunkReader so we can see any user-chunks the caller may be interested in.
// This needs to be installed before we read the png header. Android may store ninepatch
// chunks in the header.
if (chunkReader) {
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, (png_byte*)"", 0);
png_set_read_user_chunk_fn(png_ptr, (png_voidp) chunkReader, sk_read_user_chunk);
}
#endif
// The call to png_read_info() gives us all of the information from the
// PNG file before the first IDAT (image data chunk).
png_read_info(png_ptr, info_ptr);
png_uint_32 origWidth, origHeight;
int bitDepth, encodedColorType;
png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bitDepth,
&encodedColorType, nullptr, nullptr, nullptr);
// Tell libpng to strip 16 bit/color files down to 8 bits/color.
// TODO: Should we handle this in SkSwizzler? Could this also benefit
// RAW decodes?
if (bitDepth == 16) {
SkASSERT(PNG_COLOR_TYPE_PALETTE != encodedColorType);
png_set_strip_16(png_ptr);
}
// Now determine the default colorType and alphaType and set the required transforms.
// Often, we depend on SkSwizzler to perform any transforms that we need. However, we
// still depend on libpng for many of the rare and PNG-specific cases.
SkEncodedInfo::Color color;
SkEncodedInfo::Alpha alpha;
switch (encodedColorType) {
case PNG_COLOR_TYPE_PALETTE:
// Extract multiple pixels with bit depths of 1, 2, and 4 from a single
// byte into separate bytes (useful for paletted and grayscale images).
if (bitDepth < 8) {
// TODO: Should we use SkSwizzler here?
png_set_packing(png_ptr);
}
color = SkEncodedInfo::kPalette_Color;
// Set the alpha depending on if a transparency chunk exists.
alpha = png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ?
SkEncodedInfo::kUnpremul_Alpha : SkEncodedInfo::kOpaque_Alpha;
break;
case PNG_COLOR_TYPE_RGB:
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
// Convert to RGBA if transparency chunk exists.
png_set_tRNS_to_alpha(png_ptr);
color = SkEncodedInfo::kRGBA_Color;
alpha = SkEncodedInfo::kBinary_Alpha;
} else {
color = SkEncodedInfo::kRGB_Color;
alpha = SkEncodedInfo::kOpaque_Alpha;
}
break;
case PNG_COLOR_TYPE_GRAY:
// Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel.
if (bitDepth < 8) {
// TODO: Should we use SkSwizzler here?
png_set_expand_gray_1_2_4_to_8(png_ptr);
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
png_set_tRNS_to_alpha(png_ptr);
color = SkEncodedInfo::kGrayAlpha_Color;
alpha = SkEncodedInfo::kBinary_Alpha;
} else {
color = SkEncodedInfo::kGray_Color;
alpha = SkEncodedInfo::kOpaque_Alpha;
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
color = SkEncodedInfo::kGrayAlpha_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
break;
case PNG_COLOR_TYPE_RGBA:
color = SkEncodedInfo::kRGBA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
break;
default:
// All the color types have been covered above.
SkASSERT(false);
color = SkEncodedInfo::kRGBA_Color;
alpha = SkEncodedInfo::kUnpremul_Alpha;
}
int numberPasses = png_set_interlace_handling(png_ptr);
autoClean.release();
if (png_ptrp) {
*png_ptrp = png_ptr;
}
if (info_ptrp) {
*info_ptrp = info_ptr;
}
if (outCodec) {
sk_sp<SkColorSpace> colorSpace = read_color_space(png_ptr, info_ptr);
if (!colorSpace) {
// Treat unmarked pngs as sRGB.
colorSpace = SkColorSpace::NewNamed(SkColorSpace::kSRGB_Named);
}
SkEncodedInfo info = SkEncodedInfo::Make(color, alpha, 8);
if (1 == numberPasses) {
*outCodec = new SkPngScanlineDecoder(origWidth, origHeight, info, stream,
chunkReader, png_ptr, info_ptr, bitDepth, colorSpace);
} else {
*outCodec = new SkPngInterlacedScanlineDecoder(origWidth, origHeight, info, stream,
chunkReader, png_ptr, info_ptr, bitDepth, numberPasses, colorSpace);
}
}
return true;
}
SkPngCodec::SkPngCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
SkPngChunkReader* chunkReader, png_structp png_ptr, png_infop info_ptr,
int bitDepth, int numberPasses, sk_sp<SkColorSpace> colorSpace)
: INHERITED(width, height, info, stream, colorSpace)
, fPngChunkReader(SkSafeRef(chunkReader))
, fPng_ptr(png_ptr)
, fInfo_ptr(info_ptr)
, fNumberPasses(numberPasses)
, fBitDepth(bitDepth)
{}
SkPngCodec::~SkPngCodec() {
this->destroyReadStruct();
}
void SkPngCodec::destroyReadStruct() {
if (fPng_ptr) {
// We will never have a nullptr fInfo_ptr with a non-nullptr fPng_ptr
SkASSERT(fInfo_ptr);
png_destroy_read_struct(&fPng_ptr, &fInfo_ptr, nullptr);
fPng_ptr = nullptr;
fInfo_ptr = nullptr;
}
}
///////////////////////////////////////////////////////////////////////////////
// Getting the pixels
///////////////////////////////////////////////////////////////////////////////
SkCodec::Result SkPngCodec::initializeSwizzler(const SkImageInfo& requestedInfo,
const Options& options,
SkPMColor ctable[],
int* ctableCount) {
// FIXME: Could we use the return value of setjmp to specify the type of
// error?
if (setjmp(png_jmpbuf(fPng_ptr))) {
SkCodecPrintf("setjmp long jump!\n");
return kInvalidInput;
}
png_read_update_info(fPng_ptr, fInfo_ptr);
if (SkEncodedInfo::kPalette_Color == this->getEncodedInfo().color()) {
if (!this->createColorTable(requestedInfo.colorType(),
kPremul_SkAlphaType == requestedInfo.alphaType(), ctableCount)) {
return kInvalidInput;
}
}
// Copy the color table to the client if they request kIndex8 mode
copy_color_table(requestedInfo, fColorTable, ctable, ctableCount);
// Create the swizzler. SkPngCodec retains ownership of the color table.
const SkPMColor* colors = get_color_ptr(fColorTable.get());
fSwizzler.reset(SkSwizzler::CreateSwizzler(this->getEncodedInfo(), colors, requestedInfo,
options));
SkASSERT(fSwizzler);
return kSuccess;
}
bool SkPngCodec::onRewind() {
// This sets fPng_ptr and fInfo_ptr to nullptr. If read_header
// succeeds, they will be repopulated, and if it fails, they will
// remain nullptr. Any future accesses to fPng_ptr and fInfo_ptr will
// come through this function which will rewind and again attempt
// to reinitialize them.
this->destroyReadStruct();
png_structp png_ptr;
png_infop info_ptr;
if (!read_header(this->stream(), fPngChunkReader.get(), nullptr, &png_ptr, &info_ptr)) {
return false;
}
fPng_ptr = png_ptr;
fInfo_ptr = info_ptr;
return true;
}
SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst,
size_t dstRowBytes, const Options& options,
SkPMColor ctable[], int* ctableCount,
int* rowsDecoded) {
if (!conversion_possible(requestedInfo, this->getInfo())) {
return kInvalidConversion;
}
if (options.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
// Note that ctable and ctableCount may be modified if there is a color table
const Result result = this->initializeSwizzler(requestedInfo, options, ctable, ctableCount);
if (result != kSuccess) {
return result;
}
const int width = requestedInfo.width();
const int height = requestedInfo.height();
const int bpp = bytes_per_pixel(this->getEncodedInfo().bitsPerPixel());
const size_t srcRowBytes = width * bpp;
// FIXME: Could we use the return value of setjmp to specify the type of
// error?
int row = 0;
// This must be declared above the call to setjmp to avoid memory leaks on incomplete images.
SkAutoTMalloc<uint8_t> storage;
if (setjmp(png_jmpbuf(fPng_ptr))) {
// Assume that any error that occurs while reading rows is caused by an incomplete input.
if (fNumberPasses > 1) {
// FIXME (msarett): Handle incomplete interlaced pngs.
return (row == height) ? kSuccess : kInvalidInput;
}
// FIXME: We do a poor job on incomplete pngs compared to other decoders (ex: Chromium,
// Ubuntu Image Viewer). This is because we use the default buffer size in libpng (8192
// bytes), and if we can't fill the buffer, we immediately fail.
// For example, if we try to read 8192 bytes, and the image (incorrectly) only contains
// half that, which may have been enough to contain a non-zero number of lines, we fail
// when we could have decoded a few more lines and then failed.
// The read function that we provide for libpng has no way of indicating that we have
// made a partial read.
// Making our buffer size smaller improves our incomplete decodes, but what impact does
// it have on regular decode performance? Should we investigate using a different API
// instead of png_read_row? Chromium uses png_process_data.
*rowsDecoded = row;
return (row == height) ? kSuccess : kIncompleteInput;
}
// FIXME: We could split these out based on subclass.
void* dstRow = dst;
if (fNumberPasses > 1) {
storage.reset(height * srcRowBytes);
uint8_t* const base = storage.get();
for (int i = 0; i < fNumberPasses; i++) {
uint8_t* srcRow = base;
for (int y = 0; y < height; y++) {
png_read_row(fPng_ptr, srcRow, nullptr);
srcRow += srcRowBytes;
}
}
// Now swizzle it.
uint8_t* srcRow = base;
for (; row < height; row++) {
fSwizzler->swizzle(dstRow, srcRow);
dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
srcRow += srcRowBytes;
}
} else {
storage.reset(srcRowBytes);
uint8_t* srcRow = storage.get();
for (; row < height; row++) {
png_read_row(fPng_ptr, srcRow, nullptr);
fSwizzler->swizzle(dstRow, srcRow);
dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
}
}
// read rest of file, and get additional comment and time chunks in info_ptr
png_read_end(fPng_ptr, fInfo_ptr);
return kSuccess;
}
uint32_t SkPngCodec::onGetFillValue(SkColorType colorType) const {
const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
if (colorPtr) {
return get_color_table_fill_value(colorType, colorPtr, 0);
}
return INHERITED::onGetFillValue(colorType);
}
SkCodec* SkPngCodec::NewFromStream(SkStream* stream, SkPngChunkReader* chunkReader) {
SkAutoTDelete<SkStream> streamDeleter(stream);
SkCodec* outCodec;
if (read_header(stream, chunkReader, &outCodec, nullptr, nullptr)) {
// Codec has taken ownership of the stream.
SkASSERT(outCodec);
streamDeleter.release();
return outCodec;
}
return nullptr;
}