Imported from libpng-1.0.1a.tar
diff --git a/pngwutil.c b/pngwutil.c
index 492bde7..8d56232 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,12 +1,12 @@
/* pngwutil.c - utilities to write a PNG file
*
- * libpng 1.0.1
+ * libpng 1.0.1a
* For conditions of distribution and use, see copyright notice in png.h
* Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
* Copyright (c) 1996, 1997 Andreas Dilger
* Copyright (c) 1998, Glenn Randers-Pehrson
- * March 15, 1998
+ * April 21, 1998
*/
#define PNG_INTERNAL
@@ -1241,7 +1241,7 @@
if (pass < 6)
#endif
{
- /* each pixel depth is handled seperately */
+ /* each pixel depth is handled separately */
switch (row_info->pixel_depth)
{
case 1:
@@ -1251,12 +1251,13 @@
int shift;
int d;
int value;
- png_uint_32 i;
+ png_uint_32 i, istop;
dp = row;
d = 0;
shift = 7;
- for (i = png_pass_start[pass]; i < row_info->width;
+ istop = row_info->width;
+ for (i = png_pass_start[pass]; i < istop;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 3);
@@ -1284,12 +1285,13 @@
int shift;
int d;
int value;
- png_uint_32 i;
+ png_uint_32 i, istop;
dp = row;
shift = 6;
d = 0;
- for (i = png_pass_start[pass]; i < row_info->width;
+ istop = row_info->width;
+ for (i = png_pass_start[pass]; i < istop;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 2);
@@ -1316,12 +1318,13 @@
int shift;
int d;
int value;
- png_uint_32 i;
+ png_uint_32 i, istop;
dp = row;
shift = 4;
d = 0;
- for (i = png_pass_start[pass]; i < row_info->width;
+ istop = row_info->width;
+ for (i = png_pass_start[pass]; i < istop;
i += png_pass_inc[pass])
{
sp = row + (png_size_t)(i >> 1);
@@ -1345,7 +1348,7 @@
{
png_bytep sp;
png_bytep dp;
- png_uint_32 i;
+ png_uint_32 i, istop;
png_size_t pixel_bytes;
/* start at the beginning */
@@ -1354,7 +1357,8 @@
pixel_bytes = (row_info->pixel_depth >> 3);
/* loop through the row, only looking at the pixels that
matter */
- for (i = png_pass_start[pass]; i < row_info->width;
+ istop = row_info->width;
+ for (i = png_pass_start[pass]; i < istop;
i += png_pass_inc[pass])
{
/* find out where the original pixel is */
@@ -1392,6 +1396,7 @@
{
png_bytep prev_row, best_row, row_buf;
png_uint_32 mins, bpp;
+ png_byte filter_to_do = png_ptr->do_filter;
png_debug(1, "in png_write_find_filter\n");
/* find out how many bytes offset each pixel is */
@@ -1405,7 +1410,7 @@
* smallest value when summing the absolute values of the distances
* from zero using anything >= 128 as negative numbers. This is known
* as the "minimum sum of absolute differences" heuristic. Other
- * heuristics are the "weighted minumum sum of absolute differences"
+ * heuristics are the "weighted minimum sum of absolute differences"
* (experimental and can in theory improve compression), and the "zlib
* predictive" method (not implemented in libpng 0.95), which does test
* compressions of lines using different filter methods, and then chooses
@@ -1413,18 +1418,20 @@
* computationally expensive).
*/
+
/* We don't need to test the 'no filter' case if this is the only filter
* that has been chosen, as it doesn't actually do anything to the data.
*/
- if (png_ptr->do_filter & PNG_FILTER_NONE &&
- png_ptr->do_filter != PNG_FILTER_NONE)
+ if (filter_to_do & PNG_FILTER_NONE &&
+ filter_to_do != PNG_FILTER_NONE)
{
png_bytep rp;
png_uint_32 sum = 0;
- png_uint_32 i;
+ png_uint_32 i,istop;
int v;
- for (i = 0, rp = row_buf + 1; i < row_info->rowbytes; i++, rp++)
+ istop = row_info->rowbytes;
+ for (i = 0, rp = row_buf + 1; i < istop; i++, rp++)
{
v = *rp;
sum += (v < 128) ? v : 256 - v;
@@ -1438,9 +1445,10 @@
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; /* Gives us some footroom */
/* Reduce the sum if we match any of the previous rows */
- for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
+ istop = (png_uint_32)png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
- if (png_ptr->prev_filters[i] == PNG_FILTER_NONE)
+ if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_NONE)
{
sumlo = (sumlo * png_ptr->filter_weights[i]) >>
PNG_WEIGHT_SHIFT;
@@ -1468,15 +1476,34 @@
}
/* sub filter */
- if (png_ptr->do_filter & PNG_FILTER_SUB)
+ if (filter_to_do == PNG_FILTER_SUB)
+ /* it's the only filter so no testing is needed */
+ {
+ png_bytep rp, lp, dp;
+ png_uint_32 i,istop;
+ for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_row + 1; i < bpp;
+ i++, rp++, dp++)
+ {
+ *dp = *rp;
+ }
+ istop = row_info->rowbytes;
+ for (lp = row_buf + 1; i < istop;
+ 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)
{
png_bytep rp, dp, lp;
png_uint_32 sum = 0, lmins = mins;
- png_uint_32 i;
+ png_uint_32 i, istop;
int v;
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
- /* We temporarily increase the "minumum sum" by the factor we
+ /* We temporarily increase the "minimum sum" by the factor we
* would reduce the sum of this filter, so that we can do the
* early exit comparison without scaling the sum each time.
*/
@@ -1486,7 +1513,8 @@
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
+ istop = (png_uint_32)png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB)
{
@@ -1534,7 +1562,8 @@
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
+ istop = (png_uint_32)png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB)
{
@@ -1565,13 +1594,29 @@
}
/* up filter */
- if (png_ptr->do_filter & PNG_FILTER_UP)
+ if (filter_to_do == PNG_FILTER_UP)
+ {
+ png_bytep rp, dp, pp;
+ png_uint_32 i, istop;
+
+ istop = row_info->rowbytes;
+ for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
+ pp = prev_row + 1; i < istop;
+ 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)
{
png_bytep rp, dp, pp;
png_uint_32 sum = 0, lmins = mins;
- png_uint_32 i;
+ png_uint_32 i, istop;
int v;
+
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
{
@@ -1579,7 +1624,8 @@
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
+ istop = (png_uint_32)png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_UP)
{
@@ -1602,8 +1648,9 @@
}
#endif
+ istop = row_info->rowbytes;
for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1,
- pp = prev_row + 1; i < row_info->rowbytes;
+ pp = prev_row + 1; i < istop;
i++, rp++, pp++, dp++)
{
v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
@@ -1621,9 +1668,10 @@
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
+ istop = (png_uint_32)png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
- if (png_ptr->prev_filters[i] == PNG_FILTER_UP)
+ if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_UP)
{
sumlo = (sumlo * png_ptr->filter_weights[i]) >>
PNG_WEIGHT_SHIFT;
@@ -1652,11 +1700,28 @@
}
/* avg filter */
- if (png_ptr->do_filter & PNG_FILTER_AVG)
+ if (filter_to_do == PNG_FILTER_AVG)
+ {
+ png_bytep rp, dp, pp, lp;
+ png_uint_32 i,istop;
+ for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1,
+ pp = prev_row + 1; i < bpp; i++, rp++, pp++, dp++)
+ {
+ *dp = (png_byte)(((int)*rp - ((int)*pp / 2)) & 0xff);
+ }
+ istop = row_info->rowbytes;
+ for (lp = row_buf + 1; i < istop; i++, rp++, pp++, lp++, dp++)
+ {
+ *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)
{
png_bytep rp, dp, pp, lp;
png_uint_32 sum = 0, lmins = mins;
- png_uint_32 i;
+ png_uint_32 i,istop;
int v;
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
@@ -1666,7 +1731,8 @@
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++)
+ istop = (png_uint_32)png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_AVG)
{
@@ -1696,8 +1762,8 @@
sum += (v < 128) ? v : 256 - v;
}
- for (lp = row_buf + 1; i < row_info->rowbytes;
- i++, rp++, pp++, lp++, dp++)
+ istop = row_info->rowbytes;
+ for (lp = row_buf + 1; i < istop; i++, rp++, pp++, lp++, dp++)
{
v = *dp = (png_byte)(((int)*rp - (((int)*pp + (int)*lp) / 2)) & 0xff);
@@ -1714,9 +1780,10 @@
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < png_ptr->num_prev_filters; i++)
+ istop = png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
- if (png_ptr->prev_filters[i] == PNG_FILTER_NONE)
+ if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_NONE)
{
sumlo = (sumlo * png_ptr->filter_weights[i]) >>
PNG_WEIGHT_SHIFT;
@@ -1745,11 +1812,50 @@
}
/* Paeth filter */
- if (png_ptr->do_filter & PNG_FILTER_PAETH)
+ if (filter_to_do == PNG_FILTER_PAETH)
+ {
+ png_bytep rp, dp, pp, cp, lp;
+ png_uint_32 i, istop;
+ for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
+ pp = prev_row + 1; i < bpp; i++, rp++, pp++, dp++)
+ {
+ *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
+ }
+
+ istop = row_info->rowbytes;
+ for (lp = row_buf + 1, cp = prev_row + 1; i < istop;
+ i++, rp++, pp++, lp++, dp++, cp++)
+ {
+ int a, b, c, pa, pb, pc, p;
+
+ b = *pp;
+ c = *cp;
+ a = *lp;
+
+ p = a + b - c;
+
+#ifdef PNG_USE_ABS
+ pa = abs(p - a);
+ pb = abs(p - b);
+ pc = abs(p - c);
+#else
+ pa = p > a ? p - a : a - p;
+ pb = p > b ? p - b : b - p;
+ pc = p > c ? p - c : c - p;
+#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)
{
png_bytep rp, dp, pp, cp, lp;
png_uint_32 sum = 0, lmins = mins;
- png_uint_32 i;
+ png_uint_32 i, istop;
int v;
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
@@ -1759,7 +1865,8 @@
lmlo = lmins & PNG_LOMASK;
lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < png_ptr->num_prev_filters; i++)
+ istop = png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_PAETH)
{
@@ -1783,13 +1890,15 @@
#endif
for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1,
- pp = prev_row + 1; (unsigned)i < bpp; i++, rp++, pp++, dp++)
+ pp = prev_row + 1; i < bpp; i++, rp++, pp++, dp++)
{
v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
sum += (v < 128) ? v : 256 - v;
}
- for (lp = row_buf + 1, cp = prev_row + 1; i < row_info->rowbytes;
+
+ istop = row_info->rowbytes;
+ for (lp = row_buf + 1, cp = prev_row + 1; i < istop;
i++, rp++, pp++, lp++, dp++, cp++)
{
int a, b, c, pa, pb, pc, p;
@@ -1799,16 +1908,30 @@
a = *lp;
p = a + b - c;
+
+#ifndef PNG_SLOW_PAETH
+#ifdef PNG_USE_ABS
pa = abs(p - a);
pb = abs(p - b);
pc = abs(p - c);
+#else
+ pa = p > a ? p - a : a - p;
+ pb = p > b ? p - b : b - p;
+ pc = p > c ? p - c : c - p;
+#endif
+ p = (pa <= pb && pa <=pc) ? a : (pb <= pc) ? b : c;
+#else /* PNG_SLOW_PAETH */
+ pa = abs(p - a);
+ pb = abs(p - b);
+ pc = abs(p - c);
if (pa <= pb && pa <= pc)
p = a;
else if (pb <= pc)
p = b;
else
p = c;
+#endif /* PNG_SLOW_PAETH */
v = *dp = (png_byte)(((int)*rp - p) & 0xff);
@@ -1825,9 +1948,10 @@
sumlo = sum & PNG_LOMASK;
sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK;
- for (i = 0; i < png_ptr->num_prev_filters; i++)
+ istop = png_ptr->num_prev_filters;
+ for (i = 0; i < istop; i++)
{
- if (png_ptr->prev_filters[i] == PNG_FILTER_PAETH)
+ if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_PAETH)
{
sumlo = (sumlo * png_ptr->filter_weights[i]) >>
PNG_WEIGHT_SHIFT;
@@ -1855,15 +1979,17 @@
}
/* Do the actual writing of the filtered row data from the chosen filter. */
+
png_write_filtered_row(png_ptr, best_row);
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
/* Save the type of filter we picked this time for future calculations */
if (png_ptr->num_prev_filters > 0)
{
- int i;
+ int i, istop;
- for (i = 1; i < (int)png_ptr->num_prev_filters; i++)
+ istop = (int)png_ptr->num_prev_filters;
+ for (i = 1; i < istop; i++)
{
png_ptr->prev_filters[i] = png_ptr->prev_filters[i - 1];
}