Imported from libpng-0.96.tar
diff --git a/pngwrite.c b/pngwrite.c
index e455368..b571b0f 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,28 +1,32 @@
+
+/* pngwrite.c - general routines to write a PNG file
-/* pngwrite.c - general routines to write a png file
-
- libpng 1.0 beta 4 - version 0.90
+ libpng 1.0 beta 6 - version 0.96
For conditions of distribution and use, see copyright notice in png.h
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
- January 10, 1997
+ Copyright (c) 1996, 1997 Andreas Dilger
+ May 12, 1997
*/
/* get internal access to png.h */
#define PNG_INTERNAL
#include "png.h"
-/* Writes all the png information. This is the suggested way to use
- the library. If you have a new chunk to add, make a function to
- write it, and put it in the correct location here. If you want
- the chunk written after the image data, put it in png_write_end().
- I strongly encurage you to supply a PNG_INFO_ flag, and check
- info_ptr->valid before writing the chunk, as that will keep the code
- from breaking if you want to just write a plain png file.
- If you have long comments, I suggest writing them in png_write_end(),
- and compressing them. */
+/* Writes all the PNG information. This is the suggested way to use the
+ * library. If you have a new chunk to add, make a function to write it,
+ * and put it in the correct location here. If you want the chunk written
+ * after the image data, put it in png_write_end(). I strongly encurage
+ * you to supply a PNG_INFO_ flag, and check info_ptr->valid before writing
+ * the chunk, as that will keep the code from breaking if you want to just
+ * write a plain PNG file. If you have long comments, I suggest writing
+ * them in png_write_end(), and compressing them.
+ */
void
png_write_info(png_structp png_ptr, png_infop info_ptr)
{
+ int i;
+
+ png_debug(1, "in png_write_info\n");
png_write_sig(png_ptr); /* write PNG signature */
/* write IHDR information. */
png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
@@ -47,7 +51,8 @@
info_ptr->x_blue, info_ptr->y_blue);
#endif
if (info_ptr->valid & PNG_INFO_PLTE)
- png_write_PLTE(png_ptr, info_ptr->palette, info_ptr->num_palette);
+ png_write_PLTE(png_ptr, info_ptr->palette,
+ (png_uint_32)info_ptr->num_palette);
else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
png_error(png_ptr, "Valid palette required for paletted images\n");
#if defined(PNG_WRITE_tRNS_SUPPORTED)
@@ -63,16 +68,22 @@
if (info_ptr->valid & PNG_INFO_hIST)
png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
#endif
-#if defined(PNG_WRITE_pHYs_SUPPORTED)
- if (info_ptr->valid & PNG_INFO_pHYs)
- png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
- info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
-#endif
#if defined(PNG_WRITE_oFFs_SUPPORTED)
if (info_ptr->valid & PNG_INFO_oFFs)
png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
info_ptr->offset_unit_type);
#endif
+#if defined(PNG_WRITE_pCAL_SUPPORTED)
+ if (info_ptr->valid & PNG_INFO_pCAL)
+ png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
+ info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
+ info_ptr->pcal_units, info_ptr->pcal_params);
+#endif
+#if defined(PNG_WRITE_pHYs_SUPPORTED)
+ if (info_ptr->valid & PNG_INFO_pHYs)
+ png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
+ info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
+#endif
#if defined(PNG_WRITE_tIME_SUPPORTED)
if (info_ptr->valid & PNG_INFO_tIME)
{
@@ -82,15 +93,68 @@
#endif
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
/* Check to see if we need to write text chunks */
- if (info_ptr->num_text)
+ for (i = 0; i < info_ptr->num_text; i++)
{
- int i; /* local counter */
+ png_debug2(2, "Writing header text chunk %d, type %d\n", i,
+ info_ptr->text[i].compression);
+ /* If we want a compressed text chunk */
+ if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
+ {
+#if defined(PNG_WRITE_zTXt_SUPPORTED)
+ /* write compressed chunk */
+ png_write_zTXt(png_ptr, info_ptr->text[i].key,
+ info_ptr->text[i].text, info_ptr->text[i].text_length,
+ info_ptr->text[i].compression);
+#else
+ png_warning(png_ptr, "Unable to write compressed text\n");
+#endif
+ /* Mark this chunk as written */
+ info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
+ }
+ else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
+ {
+#if defined(PNG_WRITE_tEXt_SUPPORTED)
+ /* write uncompressed chunk */
+ png_write_tEXt(png_ptr, info_ptr->text[i].key,
+ info_ptr->text[i].text, info_ptr->text[i].text_length);
+#else
+ png_warning(png_ptr, "Unable to write uncompressed text\n");
+#endif
+ /* Mark this chunk as written */
+ info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
+ }
+ }
+#endif
+}
- /* loop through the text chunks */
+/* Writes the end of the PNG file. If you don't want to write comments or
+ time information, you can pass NULL for info. If you already wrote these
+ in png_write_info(), do not write them again here. If you have long
+ comments, I suggest writing them here, and compressing them. */
+void
+png_write_end(png_structp png_ptr, png_infop info_ptr)
+{
+ png_debug(1, "in png_write_end\n");
+ if (!(png_ptr->mode & PNG_HAVE_IDAT))
+ png_error(png_ptr, "No IDATs written into file");
+
+ /* see if user wants us to write information chunks */
+ if (info_ptr != NULL)
+ {
+ int i; /* local index variable */
+#if defined(PNG_WRITE_tIME_SUPPORTED)
+ /* check to see if user has supplied a time chunk */
+ if (info_ptr->valid & PNG_INFO_tIME &&
+ !(png_ptr->flags & PNG_FLAG_WROTE_tIME))
+ png_write_tIME(png_ptr, &(info_ptr->mod_time));
+#endif
+#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
+ /* loop through comment chunks */
for (i = 0; i < info_ptr->num_text; i++)
{
- /* if chunk is compressed */
- if (info_ptr->text[i].compression >= 0)
+ png_debug2(2, "Writing trailer text chunk %d, type %d\n", i,
+ info_ptr->text[i].compression);
+ if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
{
#if defined(PNG_WRITE_zTXt_SUPPORTED)
/* write compressed chunk */
@@ -100,8 +164,10 @@
#else
png_warning(png_ptr, "Unable to write compressed text\n");
#endif
+ /* Mark this chunk as written */
+ info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
}
- else
+ else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
{
#if defined(PNG_WRITE_tEXt_SUPPORTED)
/* write uncompressed chunk */
@@ -110,60 +176,9 @@
#else
png_warning(png_ptr, "Unable to write uncompressed text\n");
#endif
- }
- }
- }
-#endif
-}
-/* writes the end of the png file. If you don't want to write comments or
- time information, you can pass NULL for info. If you already wrote these
- in png_write_info(), do not write them again here. If you have long
- comments, I suggest writing them here, and compressing them. */
-void
-png_write_end(png_structp png_ptr, png_infop info_ptr)
-{
- if (!(png_ptr->mode & PNG_HAVE_IDAT))
- png_error(png_ptr, "No IDATs written into file");
-
- /* see if user wants us to write information chunks */
- if (info_ptr)
- {
-#if defined(PNG_WRITE_tIME_SUPPORTED)
- /* check to see if user has supplied a time chunk */
- if (info_ptr->valid & PNG_INFO_tIME &&
- !(png_ptr->flags & PNG_FLAG_WROTE_tIME))
- png_write_tIME(png_ptr, &(info_ptr->mod_time));
-#endif
-#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
- /* check to see if we need to write comment chunks */
- if (info_ptr->num_text)
- {
- int i; /* local index variable */
-
- /* loop through comment chunks */
- for (i = 0; i < info_ptr->num_text; i++)
- {
-#if defined(PNG_WRITE_zTXt_SUPPORTED)
- /* check to see if comment is to be compressed */
- if (info_ptr->text[i].compression >= 0)
- {
- /* write compressed chunk */
- png_write_zTXt(png_ptr, info_ptr->text[i].key,
- info_ptr->text[i].text, info_ptr->text[i].text_length,
- info_ptr->text[i].compression);
- }
-#if defined(PNG_WRITE_tEXt_SUPPORTED)
- else
-#endif
-#endif
-#if defined(PNG_WRITE_tEXt_SUPPORTED)
- {
- /* write uncompressed chunk */
- png_write_tEXt(png_ptr, info_ptr->text[i].key,
- info_ptr->text[i].text, info_ptr->text[i].text_length);
- }
-#endif
+ /* Mark this chunk as written */
+ info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
}
}
#endif
@@ -171,7 +186,7 @@
png_ptr->mode |= PNG_AFTER_IDAT;
- /* write end of png file */
+ /* write end of PNG file */
png_write_IEND(png_ptr);
}
@@ -179,6 +194,7 @@
void
png_convert_from_struct_tm(png_timep ptime, struct tm FAR * ttime)
{
+ png_debug(1, "in png_convert_from_struct_tm\n");
ptime->year = (png_uint_16)(1900 + ttime->tm_year);
ptime->month = (png_byte)(ttime->tm_mon + 1);
ptime->day = (png_byte)ttime->tm_mday;
@@ -192,12 +208,13 @@
{
struct tm *tbuf;
+ png_debug(1, "in png_convert_from_time_t\n");
tbuf = gmtime(&ttime);
png_convert_from_struct_tm(ptime, tbuf);
}
#endif
-/* initialize png structure, and allocate any memory needed */
+/* Initialize png_ptr structure, and allocate any memory needed */
png_structp
png_create_write_struct(png_const_charp user_png_ver, voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn)
@@ -206,6 +223,7 @@
#ifdef USE_FAR_KEYWORD
jmp_buf jmpbuf;
#endif
+ png_debug(1, "in png_create_write_struct\n");
if ((png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG)) == NULL)
{
return (png_structp)NULL;
@@ -225,16 +243,16 @@
#endif
png_set_error_fn(png_ptr, error_ptr, error_fn, warn_fn);
- if (user_png_ver == NULL || png_strcmp(user_png_ver, png_libpng_ver))
+ /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
+ * we must recompile any applications that use any older library version.
+ * For versions after libpng 1.0, we will be compatible, so we need
+ * only check the first digit.
+ */
+ if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
+ (png_libpng_ver[0] == '0' && user_png_ver[2] < '9'))
{
- if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0])
- {
- png_error(png_ptr, "Incompatible libpng versions");
- }
- else
- {
- png_warning(png_ptr, "Different libpng versions");
- }
+ png_error(png_ptr,
+ "Incompatible libpng version in application and library");
}
/* initialize zbuf - compression buffer */
@@ -247,12 +265,13 @@
}
-/* initialize png structure, and allocate any memory needed */
+/* Initialize png_ptr structure, and allocate any memory needed */
void
png_write_init(png_structp png_ptr)
{
jmp_buf tmp_jmp; /* to save current jump buffer */
+ png_debug(1, "in png_write_init\n");
/* save jump buffer and error functions */
png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
@@ -266,6 +285,11 @@
png_ptr->zbuf_size = PNG_ZBUF_SIZE;
png_ptr->zbuf = png_malloc(png_ptr, png_ptr->zbuf_size);
png_set_write_fn(png_ptr, NULL, NULL, NULL);
+
+#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+ png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
+ 1, NULL, NULL);
+#endif
}
/* write a few rows of image data. If the image is interlaced,
@@ -279,6 +303,7 @@
png_uint_32 i; /* row counter */
png_bytepp rp; /* row pointer */
+ png_debug(1, "in png_write_rows\n");
/* loop through the rows */
for (i = 0, rp = row; i < num_rows; i++, rp++)
{
@@ -295,6 +320,7 @@
int pass, num_pass; /* pass variables */
png_bytepp rp; /* points to current row */
+ png_debug(1, "in png_write_image\n");
/* intialize interlace handling. If image is not interlaced,
this will set pass to 1 */
num_pass = png_set_interlace_handling(png_ptr);
@@ -313,6 +339,7 @@
void
png_write_row(png_structp png_ptr, png_bytep row)
{
+ png_debug(1, "in png_write_row\n");
/* initialize transformations and other stuff if first time */
if (png_ptr->row_number == 0 && png_ptr->pass == 0)
{
@@ -388,8 +415,15 @@
png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
(png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
- /* copy users row into buffer, leaving room for filter byte */
- png_memcpy(png_ptr->row_buf + 1, row, (png_size_t)png_ptr->row_info.rowbytes);
+ png_debug1(4, "row_info->color_type = %d\n", png_ptr->row_info.color_type);
+ png_debug1(4, "row_info->width = %d\n", png_ptr->row_info.width);
+ png_debug1(4, "row_info->channels = %d\n", png_ptr->row_info.channels);
+ png_debug1(4, "row_info->bit_depth = %d\n", png_ptr->row_info.bit_depth);
+ png_debug1(4, "row_info->pixel_depth = %d\n", png_ptr->row_info.pixel_depth);
+ png_debug1(4, "row_info->rowbytes = %d\n", png_ptr->row_info.rowbytes);
+
+ /* Copy user's row into buffer, leaving room for filter byte. */
+ png_memcpy(png_ptr->row_buf + 1, row, png_ptr->row_info.rowbytes);
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
/* handle interlacing */
@@ -411,7 +445,7 @@
if (png_ptr->transformations)
png_do_write_transformations(png_ptr);
- /* find a filter if necessary, filter the row and write it out */
+ /* Find a filter if necessary, filter the row and write it out. */
png_write_find_filter(png_ptr, &(png_ptr->row_info));
}
@@ -420,6 +454,7 @@
void
png_set_flush(png_structp png_ptr, int nrows)
{
+ png_debug(1, "in png_set_flush\n");
png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
}
@@ -429,6 +464,7 @@
{
int wrote_IDAT;
+ png_debug(1, "in png_write_flush\n");
/* We have already written out all of the data */
if (png_ptr->row_number >= png_ptr->num_rows)
return;
@@ -444,13 +480,13 @@
/* check for compression errors */
if (ret != Z_OK)
{
- if (png_ptr->zstream.msg)
+ if (png_ptr->zstream.msg != NULL)
png_error(png_ptr, png_ptr->zstream.msg);
else
png_error(png_ptr, "zlib error");
}
- if (!png_ptr->zstream.avail_out)
+ if (!(png_ptr->zstream.avail_out))
{
/* write the IDAT and reset the zlib output buffer */
png_write_IDAT(png_ptr, png_ptr->zbuf,
@@ -482,19 +518,20 @@
png_structp png_ptr = NULL;
png_infop info_ptr = NULL;
- if (png_ptr_ptr)
+ png_debug(1, "in png_destroy_write_struct\n");
+ if (png_ptr_ptr != NULL)
png_ptr = *png_ptr_ptr;
- if (info_ptr_ptr)
+ if (info_ptr_ptr != NULL)
info_ptr = *info_ptr_ptr;
- if (info_ptr)
+ if (info_ptr != NULL)
{
png_destroy_struct((png_voidp)info_ptr);
*info_ptr_ptr = (png_infop)NULL;
}
- if (png_ptr)
+ if (png_ptr != NULL)
{
png_write_destroy(png_ptr);
png_destroy_struct((png_voidp)png_ptr);
@@ -503,7 +540,7 @@
}
-/* free any memory used in png struct (old method) */
+/* Free any memory used in png_ptr struct (old method) */
void
png_write_destroy(png_structp png_ptr)
{
@@ -512,6 +549,7 @@
png_error_ptr warning_fn;
png_voidp error_ptr;
+ png_debug(1, "in png_write_destroy\n");
/* free any memory zlib uses */
deflateEnd(&png_ptr->zstream);
@@ -523,6 +561,13 @@
png_free(png_ptr, png_ptr->up_row);
png_free(png_ptr, png_ptr->avg_row);
png_free(png_ptr, png_ptr->paeth_row);
+#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+ png_free(png_ptr, png_ptr->prev_filters);
+ png_free(png_ptr, png_ptr->filter_weights);
+ png_free(png_ptr, png_ptr->inv_filter_weights);
+ png_free(png_ptr, png_ptr->filter_costs);
+ png_free(png_ptr, png_ptr->inv_filter_costs);
+#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
/* reset structure */
png_memcpy(tmp_jmp, png_ptr->jmpbuf, sizeof (jmp_buf));
@@ -540,71 +585,79 @@
png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
}
-/* Allow the application to select one or more filters to use */
+/* Allow the application to select one or more row filters to use. */
void
png_set_filter(png_structp png_ptr, int method, int filters)
{
- /* We allow 'method' only for future expansion of the base filter method */
- if (method == 0)
+ png_debug(1, "in png_set_filter\n");
+ /* We allow 'method' only for future expansion of the base filter method. */
+ if (method == PNG_FILTER_TYPE_BASE)
{
switch (filters & (PNG_ALL_FILTERS | 0x07))
{
case 5:
case 6:
- case 7: png_warning(png_ptr, "Unknown custom row filter for method 0");
- case 0: png_ptr->do_filter = PNG_FILTER_NONE; break;
- case 1: png_ptr->do_filter = PNG_FILTER_SUB; break;
- case 2: png_ptr->do_filter = PNG_FILTER_UP; break;
- case 3: png_ptr->do_filter = PNG_FILTER_AVG; break;
- case 4: png_ptr->do_filter = PNG_FILTER_PAETH; break;
+ case 7: png_warning(png_ptr, "Unknown row filter for method 0");
+ case PNG_FILTER_VALUE_NONE: png_ptr->do_filter=PNG_FILTER_NONE; break;
+ case PNG_FILTER_VALUE_SUB: png_ptr->do_filter=PNG_FILTER_SUB; break;
+ case PNG_FILTER_VALUE_UP: png_ptr->do_filter=PNG_FILTER_UP; break;
+ case PNG_FILTER_VALUE_AVG: png_ptr->do_filter=PNG_FILTER_AVG; break;
+ case PNG_FILTER_VALUE_PAETH: png_ptr->do_filter=PNG_FILTER_PAETH;break;
default: png_ptr->do_filter = (png_byte)filters; break;
}
- /* If we have allocated the row_buf, then we should have also allocated
- * all of the filter buffers that have been selected.
+ /* If we have allocated the row_buf, this means we have already started
+ * with the image and we should have allocated all of the filter buffers
+ * that have been selected. If prev_row isn't already allocated, then
+ * it is too late to start using the filters that need it, since we
+ * will be missing the data in the previous row. If an application
+ * wants to start and stop using particular filters during compression,
+ * it should start out with all of the filters, and then add and
+ * remove them after the start of compression.
*/
- if (png_ptr->row_buf)
+ if (png_ptr->row_buf != NULL)
{
- if (png_ptr->do_filter & PNG_FILTER_SUB && !(png_ptr->sub_row))
+ if (png_ptr->do_filter & PNG_FILTER_SUB && png_ptr->sub_row == NULL)
{
- png_ptr->sub_row = (png_bytep )png_malloc(png_ptr,
+ png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
png_ptr->rowbytes + 1);
- png_ptr->sub_row[0] = 1; /* Set the row filter type */
+ png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
}
- if (png_ptr->do_filter & PNG_FILTER_UP && !(png_ptr->up_row))
+ if (png_ptr->do_filter & PNG_FILTER_UP && png_ptr->up_row == NULL)
{
- if (!(png_ptr->prev_row))
+ if (png_ptr->prev_row == NULL)
{
- png_warning(png_ptr, "Can't to add up filter after starting");
+ png_warning(png_ptr, "Can't add Up filter after starting");
png_ptr->do_filter &= ~PNG_FILTER_UP;
}
else
{
- png_ptr->up_row = (png_bytep )png_malloc(png_ptr,
+ png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
png_ptr->rowbytes + 1);
- png_ptr->up_row[0] = 2; /* Set the row filter type */
+ png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
}
}
- if (png_ptr->do_filter & PNG_FILTER_AVG && !(png_ptr->avg_row))
+ if (png_ptr->do_filter & PNG_FILTER_AVG && png_ptr->avg_row == NULL)
{
- if (!(png_ptr->prev_row))
+ if (png_ptr->prev_row == NULL)
{
- png_warning(png_ptr, "Can't add average filter after starting");
+ png_warning(png_ptr, "Can't add Average filter after starting");
png_ptr->do_filter &= ~PNG_FILTER_AVG;
}
else
{
- png_ptr->up_row = (png_bytep )png_malloc(png_ptr,
+ png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
png_ptr->rowbytes + 1);
- png_ptr->up_row[0] = 3; /* Set the row filter type */
+ png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
}
}
- if (png_ptr->do_filter & PNG_FILTER_PAETH && !(png_ptr->paeth_row))
+ if (png_ptr->do_filter & PNG_FILTER_PAETH &&
+ png_ptr->paeth_row == NULL)
{
- if (!(png_ptr->prev_row))
+ if (png_ptr->prev_row == NULL)
{
png_warning(png_ptr, "Can't add Paeth filter after starting");
png_ptr->do_filter &= ~PNG_FILTER_PAETH;
@@ -613,7 +666,7 @@
{
png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr,
png_ptr->rowbytes + 1);
- png_ptr->paeth_row[0] = 4; /* Set the row filter type */
+ png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
}
}
@@ -622,12 +675,137 @@
}
}
else
- png_error(png_ptr, "Unknown custom filter method");
+ png_error(png_ptr, "Unknown custom filter method");
}
+/* This allows us to influence the way in which libpng chooses the "best"
+ * filter for the current scanline. While the "minimum-sum-of-absolute-
+ * differences metric is relatively fast and effective, there is some
+ * question as to whether it can be improved upon by trying to keep the
+ * filtered data going to zlib more consistent, hopefully resulting in
+ * better compression. */
+#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) /* GRR 970116 */
+void
+png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
+ int num_weights, png_doublep filter_weights,
+ png_doublep filter_costs)
+{
+ int i;
+
+ png_debug(1, "in png_set_filter_heuristics\n");
+ if (heuristic_method >= PNG_FILTER_HEURISTIC_LAST)
+ {
+ png_warning(png_ptr, "Unknown filter heuristic method");
+ return;
+ }
+
+ if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT)
+ {
+ heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
+ }
+
+ if (num_weights < 0 || filter_weights == NULL ||
+ heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
+ {
+ num_weights = 0;
+ }
+
+ png_ptr->num_prev_filters = num_weights;
+ png_ptr->heuristic_method = heuristic_method;
+
+ if (num_weights > 0)
+ {
+ if (png_ptr->prev_filters == NULL)
+ {
+ png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
+ sizeof(png_byte) * num_weights);
+
+ /* To make sure that the weighting starts out fairly */
+ for (i = 0; i < num_weights; i++)
+ {
+ png_ptr->prev_filters[i] = 255;
+ }
+ }
+
+ if (png_ptr->filter_weights == NULL)
+ {
+ png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
+ sizeof(png_uint_16) * num_weights);
+
+ png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
+ sizeof(png_uint_16) * num_weights);
+
+ for (i = 0; i < num_weights; i++)
+ {
+ png_ptr->inv_filter_weights[i] =
+ png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
+ }
+ }
+
+ for (i = 0; i < num_weights; i++)
+ {
+ if (filter_weights[i] < 0.0)
+ {
+ png_ptr->inv_filter_weights[i] =
+ png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
+ }
+ else
+ {
+ png_ptr->inv_filter_weights[i] =
+ (png_uint_16)((double)PNG_WEIGHT_FACTOR*filter_weights[i]+0.5);
+ png_ptr->filter_weights[i] =
+ (png_uint_16)((double)PNG_WEIGHT_FACTOR/filter_weights[i]+0.5);
+ }
+ }
+ }
+
+ /* If, in the future, there are other filter methods, this would
+ * need to be based on png_ptr->filter.
+ */
+ if (png_ptr->filter_costs == NULL)
+ {
+ png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
+ sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST);
+
+ png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
+ sizeof(png_uint_16) * PNG_FILTER_VALUE_LAST);
+
+ for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
+ {
+ png_ptr->inv_filter_costs[i] =
+ png_ptr->filter_costs[i] = PNG_COST_FACTOR;
+ }
+ }
+
+ /* Here is where we set the relative costs of the different filters. We
+ * should take the desired compression level into account when setting
+ * the costs, so that Paeth, for instance, has a high relative cost at low
+ * compression levels, while it has a lower relative cost at higher
+ * compression settings. The filter types are in order of increasing
+ * relative cost, so it would be possible to do this with an algorithm.
+ */
+ for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
+ {
+ if (filter_costs == NULL || filter_costs[i] < 0.0)
+ {
+ png_ptr->inv_filter_costs[i] =
+ png_ptr->filter_costs[i] = PNG_COST_FACTOR;
+ }
+ else if (filter_costs[i] >= 1.0)
+ {
+ png_ptr->inv_filter_costs[i] =
+ (png_uint_16)((double)PNG_COST_FACTOR / filter_costs[i] + 0.5);
+ png_ptr->filter_costs[i] =
+ (png_uint_16)((double)PNG_COST_FACTOR * filter_costs[i] + 0.5);
+ }
+ }
+}
+#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
+
void
png_set_compression_level(png_structp png_ptr, int level)
{
+ png_debug(1, "in png_set_compression_level\n");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_LEVEL;
png_ptr->zlib_level = level;
}
@@ -635,6 +813,7 @@
void
png_set_compression_mem_level(png_structp png_ptr, int mem_level)
{
+ png_debug(1, "in png_set_compression_mem_level\n");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL;
png_ptr->zlib_mem_level = mem_level;
}
@@ -642,6 +821,7 @@
void
png_set_compression_strategy(png_structp png_ptr, int strategy)
{
+ png_debug(1, "in png_set_compression_strategy\n");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
png_ptr->zlib_strategy = strategy;
}
@@ -658,6 +838,7 @@
void
png_set_compression_method(png_structp png_ptr, int method)
{
+ png_debug(1, "in png_set_compression_method\n");
if (method != 8)
png_warning(png_ptr, "Only compression method 8 is supported by PNG");
png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_METHOD;