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[libpng17] Combined sub_row, up_row, avg_row, and paeth_row buffers into a

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single try_row buffer.
This commit is contained in:
Glenn Randers-Pehrson 2015-02-10 17:02:09 -06:00
parent ba22b208ed
commit 8bc832389a
6 changed files with 177 additions and 144 deletions
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6
ANNOUNCE
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@ -1,5 +1,5 @@
Libpng 1.7.0beta49 - February 7, 2015 Libpng 1.7.0beta49 - February 10, 2015
This is not intended to be a public release. It will be replaced This is not intended to be a public release. It will be replaced
within a few weeks by a public version or by another test version. within a few weeks by a public version or by another test version.
@ -701,7 +701,9 @@ Version 1.7.0beta48 [February 7, 2015]
Work around one more Coverity-scan dead-code warning. Work around one more Coverity-scan dead-code warning.
Do not build png_product2() when it is unused. Do not build png_product2() when it is unused.
Version 1.7.0beta49 [February 7, 2015] Version 1.7.0beta49 [February 10, 2015]
Combined sub_row, up_row, avg_row, and paeth_row buffers into a
single try_row buffer.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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4
CHANGES
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@ -4990,7 +4990,9 @@ Version 1.7.0beta48 [February 7, 2015]
Work around one more Coverity-scan dead-code warning. Work around one more Coverity-scan dead-code warning.
Do not build png_product2() when it is unused. Do not build png_product2() when it is unused.
Version 1.7.0beta49 [February 7, 2015] Version 1.7.0beta49 [February 10, 2015]
Combined sub_row, up_row, avg_row, and paeth_row buffers into a
single try_row buffer.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit (subscription required; visit

12
png.h
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@ -1,7 +1,7 @@
/* png.h - header file for PNG reference library /* png.h - header file for PNG reference library
* *
* libpng version 1.7.0beta49 - February 7, 2015 * libpng version 1.7.0beta49 - February 10, 2015
* Copyright (c) 1998-2015 Glenn Randers-Pehrson * Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@ -11,7 +11,7 @@
* Authors and maintainers: * Authors and maintainers:
* libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat * libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
* libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger * libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
* libpng versions 0.97, January 1998, through 1.7.0beta49 - February 7, 2015: Glenn * libpng versions 0.97, January 1998, through 1.7.0beta49 - February 10, 2015: Glenn
* See also "Contributing Authors", below. * See also "Contributing Authors", below.
* *
* Note about libpng version numbers: * Note about libpng version numbers:
@ -200,7 +200,7 @@
* *
* This code is released under the libpng license. * This code is released under the libpng license.
* *
* libpng versions 1.2.6, August 15, 2004, through 1.7.0beta49, February 7, 2015, are * libpng versions 1.2.6, August 15, 2004, through 1.7.0beta49, February 10, 2015, are
* Copyright (c) 2004, 2006-2013 Glenn Randers-Pehrson, and are * Copyright (c) 2004, 2006-2013 Glenn Randers-Pehrson, and are
* distributed according to the same disclaimer and license as libpng-1.2.5 * distributed according to the same disclaimer and license as libpng-1.2.5
* with the following individual added to the list of Contributing Authors: * with the following individual added to the list of Contributing Authors:
@ -312,7 +312,7 @@
* Y2K compliance in libpng: * Y2K compliance in libpng:
* ========================= * =========================
* *
* February 7, 2015 * February 10, 2015
* *
* Since the PNG Development group is an ad-hoc body, we can't make * Since the PNG Development group is an ad-hoc body, we can't make
* an official declaration. * an official declaration.
@ -382,7 +382,7 @@
/* Version information for png.h - this should match the version in png.c */ /* Version information for png.h - this should match the version in png.c */
#define PNG_LIBPNG_VER_STRING "1.7.0beta49" #define PNG_LIBPNG_VER_STRING "1.7.0beta49"
#define PNG_HEADER_VERSION_STRING \ #define PNG_HEADER_VERSION_STRING \
" libpng version 1.7.0beta49 - February 7, 2015\n" " libpng version 1.7.0beta49 - February 10, 2015\n"
#define PNG_LIBPNG_VER_SONUM 17 #define PNG_LIBPNG_VER_SONUM 17
#define PNG_LIBPNG_VER_DLLNUM 17 #define PNG_LIBPNG_VER_DLLNUM 17
@ -1765,7 +1765,6 @@ PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr, PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
int method)); int method));
#endif
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
/* Also set zlib parameters for compressing non-IDAT chunks */ /* Also set zlib parameters for compressing non-IDAT chunks */
@ -1787,6 +1786,7 @@ PNG_EXPORT(225, void, png_set_text_compression_window_bits,
PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr, PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
int method)); int method));
#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */ #endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
#endif /* WRITE */
/* These next functions are called for input/output, memory, and error /* These next functions are called for input/output, memory, and error
* handling. They are in the file pngrio.c, pngwio.c, and pngerror.c, * handling. They are in the file pngrio.c, pngwio.c, and pngerror.c,

7
pngstruct.h
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@ -345,13 +345,8 @@ struct png_struct_def
/* This is somewhat excessive, there is no obvious reason on write to /* This is somewhat excessive, there is no obvious reason on write to
* allocate a buffer for each possible filtered row, only for the one being * allocate a buffer for each possible filtered row, only for the one being
* tested and the current best. * tested and the current best.
*
* TODO: fix this
*/ */
png_bytep sub_row; /* buffer to save "sub" row when filtering */ png_bytep try_row; /* buffer to save trial row when filtering */
png_bytep up_row; /* buffer to save "up" row when filtering */
png_bytep avg_row; /* buffer to save "avg" row when filtering */
png_bytep paeth_row; /* buffer to save "Paeth" row when filtering */
#endif #endif
/* UNKNOWN CHUNK HANDLING */ /* UNKNOWN CHUNK HANDLING */

14
pngwrite.c
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@ -942,15 +942,9 @@ png_write_destroy(png_structrp png_ptr)
png_ptr->row_buf = NULL; png_ptr->row_buf = NULL;
#ifdef PNG_WRITE_FILTER_SUPPORTED #ifdef PNG_WRITE_FILTER_SUPPORTED
png_free(png_ptr, png_ptr->prev_row); png_free(png_ptr, png_ptr->prev_row);
png_free(png_ptr, png_ptr->sub_row); png_free(png_ptr, png_ptr->try_row);
png_free(png_ptr, png_ptr->up_row);
png_free(png_ptr, png_ptr->avg_row);
png_free(png_ptr, png_ptr->paeth_row);
png_ptr->prev_row = NULL; png_ptr->prev_row = NULL;
png_ptr->sub_row = NULL; png_ptr->try_row = NULL;
png_ptr->up_row = NULL;
png_ptr->avg_row = NULL;
png_ptr->paeth_row = NULL;
#endif #endif
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
@ -1065,8 +1059,8 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
* it is too late to start using the filters that need it, since we * 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 * will be missing the data in the previous row. If an application
* wants to start and stop using particular filters during compression, * wants to start and stop using particular filters during compression,
* it should start out with all of the filters, and then add and * it should start out with all of the filters, and then remove them
* remove them after the start of compression. * or add them back after the start of compression.
* *
* NOTE: this is a nasty constraint on the code, because it means that the * NOTE: this is a nasty constraint on the code, because it means that the
* prev_row buffer must be maintained even if there are currently no * prev_row buffer must be maintained even if there are currently no

278
pngwutil.c
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@ -1943,7 +1943,7 @@ png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
#ifdef PNG_WRITE_FILTER_SUPPORTED #ifdef PNG_WRITE_FILTER_SUPPORTED
void /* PRIVATE */ void /* PRIVATE */
png_write_alloc_filter_row_buffers(png_structrp png_ptr, int filters) png_write_alloc_filter_row_buffers(png_structrp png_ptr, int filters)
/* Allocate row buffers for any filters that need them, this is also called /* Allocate row buffers for any filters that need them. This is also called
* from png_set_filter if the filters are changed during write to ensure that * from png_set_filter if the filters are changed during write to ensure that
* the required buffers exist. png_set_filter ensures that up/avg/paeth are * the required buffers exist. png_set_filter ensures that up/avg/paeth are
* only set if png_ptr->prev_row is allocated. * only set if png_ptr->prev_row is allocated.
@ -1954,29 +1954,10 @@ png_write_alloc_filter_row_buffers(png_structrp png_ptr, int filters)
*/ */
png_alloc_size_t buf_size = png_ptr->rowbytes + 1; png_alloc_size_t buf_size = png_ptr->rowbytes + 1;
if ((filters & PNG_FILTER_SUB) != 0 && png_ptr->sub_row == NULL) if (((filters & (PNG_FILTER_SUB | PNG_FILTER_UP | PNG_FILTER_AVG |
PNG_FILTER_PAETH)) != 0) && png_ptr->try_row == NULL)
{ {
png_ptr->sub_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size)); png_ptr->try_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
}
if ((filters & PNG_FILTER_UP) != 0 && png_ptr->up_row == NULL)
{
png_ptr->up_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
}
if ((filters & PNG_FILTER_AVG) != 0 && png_ptr->avg_row == NULL)
{
png_ptr->avg_row = png_voidcast(png_bytep, png_malloc(png_ptr, buf_size));
png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
}
if ((filters & PNG_FILTER_PAETH) != 0 && png_ptr->paeth_row == NULL)
{
png_ptr->paeth_row = png_voidcast(png_bytep, png_malloc(png_ptr,
buf_size));
png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
} }
} }
#endif /* WRITE_FILTER */ #endif /* WRITE_FILTER */
@ -2352,17 +2333,117 @@ static void /* PRIVATE */
png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row, png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
png_size_t row_bytes); png_size_t row_bytes);
#ifdef PNG_WRITE_FILTER_SUPPORTED
static void /* PRIVATE */
png_setup_sub_row(png_structrp png_ptr, png_uint_32 bpp,
png_bytep row_buf, png_size_t row_bytes)
{
png_bytep rp, dp, lp;
png_size_t i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
i++, rp++, dp++)
{
*dp = *rp;
}
for (lp = row_buf + 1; i < row_bytes;
i++, rp++, lp++, dp++)
{
*dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
}
}
static void /* PRIVATE */
png_setup_up_row(png_structrp png_ptr, png_bytep row_buf, png_size_t row_bytes)
{
png_bytep rp, dp, pp;
png_size_t i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1,
pp = png_ptr->prev_row + 1; i < row_bytes;
i++, rp++, pp++, dp++)
{
*dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
}
}
static void /* PRIVATE */
png_setup_avg_row(png_structrp png_ptr,png_uint_32 bpp,
png_bytep row_buf, png_size_t row_bytes)
{
png_bytep rp, dp, pp, lp;
png_uint_32 i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1,
pp = png_ptr->prev_row + 1; i < bpp; i++)
{
*dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
}
for (lp = row_buf + 1; i < row_bytes; i++)
{
*dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
& 0xff);
}
}
static void /* PRIVATE */
png_setup_paeth_row(png_structrp png_ptr,png_uint_32 bpp,
png_bytep row_buf, png_size_t row_bytes)
{
png_bytep rp, dp, pp, cp, lp;
png_size_t i;
for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1,
pp = png_ptr->prev_row + 1; i < bpp; i++)
{
*dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
}
for (lp = row_buf + 1, cp = png_ptr->prev_row + 1; i < row_bytes; i++)
{
int a, b, c, pa, pb, pc, p;
b = *pp++;
c = *cp++;
a = *lp++;
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
#else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
#endif
p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
*dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
}
}
#define PNG_MAXSUM (((png_uint_32)(-1)) >> 1) #define PNG_MAXSUM (((png_uint_32)(-1)) >> 1)
#define PNG_HISHIFT 10 #define PNG_HISHIFT 10
#define PNG_LOMASK ((png_uint_32)0xffffL) #define PNG_LOMASK ((png_uint_32)0xffffL)
#define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT)) #define PNG_HIMASK ((png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT))
#endif /* WRITE_FILTER */
void /* PRIVATE */ void /* PRIVATE */
png_write_find_filter(png_structrp png_ptr, png_row_infop row_info) png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
{ {
png_bytep best_row; #ifndef PNG_WRITE_FILTER_SUPPORTED
#ifdef PNG_WRITE_FILTER_SUPPORTED png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
#else
png_bytep prev_row, row_buf; png_bytep prev_row, row_buf;
png_uint_32 mins, bpp; png_uint_32 mins, bpp;
png_byte best_filter_value = PNG_FILTER_VALUE_NONE;
png_byte last_tested_row_value = PNG_FILTER_VALUE_NONE;
png_byte filter_to_do = png_ptr->do_filter; png_byte filter_to_do = png_ptr->do_filter;
png_size_t row_bytes = row_info->rowbytes; png_size_t row_bytes = row_info->rowbytes;
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
@ -2383,10 +2464,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
bpp = (row_info->pixel_depth + 7) >> 3; bpp = (row_info->pixel_depth + 7) >> 3;
prev_row = png_ptr->prev_row; prev_row = png_ptr->prev_row;
#endif row_buf = png_ptr->row_buf;
best_row = png_ptr->row_buf;
#ifdef PNG_WRITE_FILTER_SUPPORTED
row_buf = best_row;
mins = PNG_MAXSUM; mins = PNG_MAXSUM;
/* The prediction method we use is to find which method provides the /* The prediction method we use is to find which method provides the
@ -2475,22 +2553,10 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
if (filter_to_do == PNG_FILTER_SUB) if (filter_to_do == PNG_FILTER_SUB)
/* It's the only filter so no testing is needed */ /* It's the only filter so no testing is needed */
{ {
png_bytep rp, lp, dp; png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
png_size_t i; last_tested_row_value = PNG_FILTER_VALUE_SUB;
png_setup_sub_row(png_ptr, bpp, row_buf, row_bytes);
for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp; best_filter_value = PNG_FILTER_VALUE_SUB;
i++, rp++, dp++)
{
*dp = *rp;
}
for (lp = row_buf + 1; i < row_bytes;
i++, rp++, lp++, dp++)
{
*dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
}
best_row = png_ptr->sub_row;
} }
else if ((filter_to_do & PNG_FILTER_SUB) != 0) else if ((filter_to_do & PNG_FILTER_SUB) != 0)
@ -2538,7 +2604,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
} }
#endif #endif
for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp; for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1; i < bpp;
i++, rp++, dp++) i++, rp++, dp++)
{ {
v = *dp = *rp; v = *dp = *rp;
@ -2594,24 +2660,17 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
if (sum < mins) if (sum < mins)
{ {
mins = sum; mins = sum;
best_row = png_ptr->sub_row; best_filter_value = PNG_FILTER_VALUE_SUB;
} }
} }
/* Up filter */ /* Up filter */
if (filter_to_do == PNG_FILTER_UP) if (filter_to_do == PNG_FILTER_UP)
{ {
png_bytep rp, dp, pp; last_tested_row_value = PNG_FILTER_VALUE_UP;
png_size_t i; png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
png_setup_up_row(png_ptr, row_buf, row_bytes);
for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, best_filter_value = PNG_FILTER_VALUE_UP;
pp = prev_row + 1; i < row_bytes;
i++, rp++, pp++, dp++)
{
*dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
}
best_row = png_ptr->up_row;
} }
else if ((filter_to_do & PNG_FILTER_UP) != 0) else if ((filter_to_do & PNG_FILTER_UP) != 0)
@ -2656,7 +2715,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
} }
#endif #endif
for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1,
pp = prev_row + 1; i < row_bytes; i++) pp = prev_row + 1; i < row_bytes; i++)
{ {
v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
@ -2704,28 +2763,17 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
if (sum < mins) if (sum < mins)
{ {
mins = sum; mins = sum;
best_row = png_ptr->up_row; best_filter_value = PNG_FILTER_VALUE_UP;
} }
} }
/* Avg filter */ /* Avg filter */
if (filter_to_do == PNG_FILTER_AVG) if (filter_to_do == PNG_FILTER_AVG)
{ {
png_bytep rp, dp, pp, lp; last_tested_row_value = PNG_FILTER_VALUE_AVG;
png_uint_32 i; png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
png_setup_avg_row(png_ptr, bpp, row_buf, row_bytes);
for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, best_filter_value = PNG_FILTER_VALUE_AVG;
pp = prev_row + 1; i < bpp; i++)
{
*dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
}
for (lp = row_buf + 1; i < row_bytes; i++)
{
*dp++ = (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2))
& 0xff);
}
best_row = png_ptr->avg_row;
} }
else if ((filter_to_do & PNG_FILTER_AVG) != 0) else if ((filter_to_do & PNG_FILTER_AVG) != 0)
@ -2769,7 +2817,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
} }
#endif #endif
for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1,
pp = prev_row + 1; i < bpp; i++) pp = prev_row + 1; i < bpp; i++)
{ {
v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff); v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
@ -2825,48 +2873,17 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
if (sum < mins) if (sum < mins)
{ {
mins = sum; mins = sum;
best_row = png_ptr->avg_row; best_filter_value = PNG_FILTER_VALUE_AVG;
} }
} }
/* Paeth filter */ /* Paeth filter */
if ((filter_to_do == PNG_FILTER_PAETH) != 0) if ((filter_to_do == PNG_FILTER_PAETH) != 0)
{ {
png_bytep rp, dp, pp, cp, lp; last_tested_row_value = PNG_FILTER_VALUE_PAETH;
png_size_t i; png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
png_setup_paeth_row(png_ptr, bpp, row_buf, row_bytes);
for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1, best_filter_value = PNG_FILTER_VALUE_PAETH;
pp = prev_row + 1; i < bpp; i++)
{
*dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
}
for (lp = row_buf + 1, cp = prev_row + 1; i < row_bytes; i++)
{
int a, b, c, pa, pb, pc, p;
b = *pp++;
c = *cp++;
a = *lp++;
p = b - c;
pc = a - c;
#ifdef PNG_USE_ABS
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
#else
pa = p < 0 ? -p : p;
pb = pc < 0 ? -pc : pc;
pc = (p + pc) < 0 ? -(p + pc) : p + pc;
#endif
p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
*dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
}
best_row = png_ptr->paeth_row;
} }
else if ((filter_to_do & PNG_FILTER_PAETH) != 0) else if ((filter_to_do & PNG_FILTER_PAETH) != 0)
@ -2910,7 +2927,7 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
} }
#endif #endif
for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1, for (i = 0, rp = row_buf + 1, dp = png_ptr->try_row + 1,
pp = prev_row + 1; i < bpp; i++) pp = prev_row + 1; i < bpp; i++)
{ {
v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff); v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
@ -2999,15 +3016,38 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
if (sum < mins) if (sum < mins)
{ {
best_row = png_ptr->paeth_row; best_filter_value = PNG_FILTER_VALUE_PAETH;
} }
} }
#endif /* WRITE_FILTER */
/* Do the actual writing of the filtered row data from the chosen filter. */ /* Do the actual writing of the filtered row data from the chosen filter. */
png_write_filtered_row(png_ptr, best_row, row_info->rowbytes+1); if (best_filter_value == PNG_FILTER_VALUE_NONE)
png_write_filtered_row(png_ptr, png_ptr->row_buf, row_info->rowbytes+1);
else
{
png_ptr->try_row[0] = best_filter_value;
if (best_filter_value != last_tested_row_value)
{
/* TO DO: make this redundant code into functions? */
if (best_filter_value == PNG_FILTER_VALUE_SUB)
png_setup_sub_row(png_ptr, bpp, row_buf, row_bytes);
if (best_filter_value == PNG_FILTER_VALUE_UP)
png_setup_up_row(png_ptr, row_buf, row_bytes);
if (best_filter_value == PNG_FILTER_VALUE_AVG)
png_setup_avg_row(png_ptr, bpp, row_buf, row_bytes);
if (best_filter_value == PNG_FILTER_VALUE_PAETH)
png_setup_paeth_row(png_ptr, bpp, row_buf, row_bytes);
}
png_write_filtered_row(png_ptr, png_ptr->try_row, row_info->rowbytes+1);
}
#ifdef PNG_WRITE_FILTER_SUPPORTED
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
/* Save the type of filter we picked this time for future calculations */ /* Save the type of filter we picked this time for future calculations */
if (png_ptr->num_prev_filters > 0) if (png_ptr->num_prev_filters > 0)
@ -3019,9 +3059,9 @@ png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1]; png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1];
} }
png_ptr->prev_filters[j] = best_row[0]; png_ptr->prev_filters[j] = best_filter_value;
} }
#endif #endif /* WRITE_WEIGHTED_FILTER */
#endif /* WRITE_FILTER */ #endif /* WRITE_FILTER */
} }