X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/c801d85f158c4cba50b588807daabdcbd0ed3853..f79fd1e54b4533507c6de798eecfdde765a3fc4e:/src/png/pngwutil.c diff --git a/src/png/pngwutil.c b/src/png/pngwutil.c index 492bde7bb0..4736361d2e 100644 --- a/src/png/pngwutil.c +++ b/src/png/pngwutil.c @@ -1,12 +1,11 @@ /* pngwutil.c - utilities to write a PNG file * - * libpng 1.0.1 + * libpng 1.0.3 - January 14, 1999 * 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 + * Copyright (c) 1998, 1999 Glenn Randers-Pehrson */ #define PNG_INTERNAL @@ -274,7 +273,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height, } /* write the palette. We are careful not to trust png_color to be in the - * correct order for PNG, so people can redefine it to any convient + * correct order for PNG, so people can redefine it to any convenient * structure. */ void @@ -377,9 +376,9 @@ png_write_sBIT(png_structp png_ptr, png_color_8p sbit, int color_type) { png_byte maxbits; - maxbits = color_type==PNG_COLOR_TYPE_PALETTE ? 8:png_ptr->usr_bit_depth; - if (sbit->red == 0 || sbit->red > maxbits || - sbit->green == 0 || sbit->green > maxbits || + maxbits = color_type==PNG_COLOR_TYPE_PALETTE ? 8 : png_ptr->usr_bit_depth; + if (sbit->red == 0 || sbit->red > maxbits || + sbit->green == 0 || sbit->green > maxbits || sbit->blue == 0 || sbit->blue > maxbits) { png_warning(png_ptr, "Invalid sBIT depth specified"); @@ -575,7 +574,8 @@ png_write_hIST(png_structp png_ptr, png_uint_16p hist, int num_hist) } #endif -#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED) +#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED) || \ + defined(PNG_WRITE_pCAL_SUPPORTED) /* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification, * and if invalid, correct the keyword rather than discarding the entire * chunk. The PNG 1.0 specification requires keywords 1-79 characters in @@ -766,7 +766,7 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text, } /* We can't write the chunk until we find out how much data we have, - * which means we need to run the compressor first, and save the + * which means we need to run the compressor first and save the * output. This shouldn't be a problem, as the vast majority of * comments should be reasonable, but we will set up an array of * malloc'd pointers to be sure. @@ -835,7 +835,7 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text, png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size; png_ptr->zstream.next_out = png_ptr->zbuf; } - /* continue until we don't have anymore to compress */ + /* continue until we don't have any more to compress */ } while (png_ptr->zstream.avail_in); /* finish the compression */ @@ -952,7 +952,7 @@ void png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams, png_charp units, png_charpp params) { - png_size_t purpose_len, units_len, total_len; + png_size_t purpose_len, units_len, total_len; png_uint_32p params_len; png_byte buf[10]; png_charp new_purpose; @@ -1180,7 +1180,7 @@ png_write_finish_row(png_structp png_ptr) if (png_ptr->pass < 7) { if (png_ptr->prev_row != NULL) - png_memset(png_ptr->prev_row, 0, + png_memset(png_ptr->prev_row, 0, (png_size_t) (((png_uint_32)png_ptr->usr_channels * (png_uint_32)png_ptr->usr_bit_depth * png_ptr->width + 7) >> 3) + 1); @@ -1241,7 +1241,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) if (pass < 6) #endif { - /* each pixel depth is handled seperately */ + /* each pixel depth is handled separately */ switch (row_info->pixel_depth) { case 1: @@ -1252,11 +1252,12 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) int d; int value; png_uint_32 i; + png_uint_32 row_width = row_info->width; dp = row; d = 0; shift = 7; - for (i = png_pass_start[pass]; i < row_info->width; + for (i = png_pass_start[pass]; i < row_width; i += png_pass_inc[pass]) { sp = row + (png_size_t)(i >> 3); @@ -1285,11 +1286,12 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) int d; int value; png_uint_32 i; + png_uint_32 row_width = row_info->width; dp = row; shift = 6; d = 0; - for (i = png_pass_start[pass]; i < row_info->width; + for (i = png_pass_start[pass]; i < row_width; i += png_pass_inc[pass]) { sp = row + (png_size_t)(i >> 2); @@ -1317,11 +1319,12 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) int d; int value; png_uint_32 i; + png_uint_32 row_width = row_info->width; dp = row; shift = 4; d = 0; - for (i = png_pass_start[pass]; i < row_info->width; + for (i = png_pass_start[pass]; i < row_width; i += png_pass_inc[pass]) { sp = row + (png_size_t)(i >> 1); @@ -1346,6 +1349,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) png_bytep sp; png_bytep dp; png_uint_32 i; + png_uint_32 row_width = row_info->width; png_size_t pixel_bytes; /* start at the beginning */ @@ -1354,7 +1358,7 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass) 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; + for (i = png_pass_start[pass]; i < row_width; i += png_pass_inc[pass]) { /* find out where the original pixel is */ @@ -1392,6 +1396,11 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) { png_bytep prev_row, best_row, row_buf; png_uint_32 mins, bpp; + png_byte filter_to_do = png_ptr->do_filter; + png_uint_32 row_bytes = row_info->rowbytes; +#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) + int num_p_filters = (int)png_ptr->num_prev_filters; +#endif png_debug(1, "in png_write_find_filter\n"); /* find out how many bytes offset each pixel is */ @@ -1403,28 +1412,38 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) /* The prediction method we use is to find which method provides the * smallest value when summing the absolute values of the distances - * from zero using anything >= 128 as negative numbers. This is known + * 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 - * the (series of) filter(s) which give minimum compressed data size (VERY + * predictive" method (not implemented yet), which does test compressions + * of lines using different filter methods, and then chooses the + * (series of) filter(s) that give minimum compressed data size (VERY * computationally expensive). + * + * GRR 980525: consider also + * (1) minimum sum of absolute differences from running average (i.e., + * keep running sum of non-absolute differences & count of bytes) + * [track dispersion, too? restart average if dispersion too large?] + * (1b) minimum sum of absolute differences from sliding average, probably + * with window size <= deflate window (usually 32K) + * (2) minimum sum of squared differences from zero or running average + * (i.e., ~ root-mean-square approach) */ + /* 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; int v; - for (i = 0, rp = row_buf + 1; i < row_info->rowbytes; i++, rp++) + for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++) { v = *rp; sum += (v < 128) ? v : 256 - v; @@ -1434,17 +1453,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { png_uint_32 sumhi, sumlo; + int j; sumlo = sum & PNG_LOMASK; 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++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_NONE) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE) { - sumlo = (sumlo * png_ptr->filter_weights[i]) >> + sumlo = (sumlo * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; - sumhi = (sumhi * png_ptr->filter_weights[i]) >> + sumhi = (sumhi * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1468,7 +1488,25 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) } /* 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; + for (i = 0, rp = row_buf + 1, dp = png_ptr->sub_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); + } + 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; @@ -1476,23 +1514,24 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) 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. */ if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 lmhi, lmlo; lmlo = lmins & PNG_LOMASK; lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB) { - lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> + lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; - lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> + lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1530,17 +1569,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 sumhi, sumlo; sumlo = sum & PNG_LOMASK; sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_SUB) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_SUB) { - sumlo = (sumlo * png_ptr->inv_filter_weights[i]) >> + sumlo = (sumlo * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; - sumhi = (sumhi * png_ptr->inv_filter_weights[i]) >> + sumhi = (sumhi * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1565,27 +1605,43 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) } /* 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; + + for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, + 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) { png_bytep rp, dp, pp; png_uint_32 sum = 0, lmins = mins; png_uint_32 i; int v; + #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 lmhi, lmlo; lmlo = lmins & PNG_LOMASK; lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_UP) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP) { - lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> + lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; - lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> + lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1603,10 +1659,9 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #endif for (i = 0, rp = row_buf + 1, dp = png_ptr->up_row + 1, - pp = prev_row + 1; i < row_info->rowbytes; - i++, rp++, pp++, dp++) + 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); sum += (v < 128) ? v : 256 - v; @@ -1617,17 +1672,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 sumhi, sumlo; sumlo = sum & PNG_LOMASK; sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_UP) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_UP) { - sumlo = (sumlo * png_ptr->filter_weights[i]) >> + sumlo = (sumlo * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; - sumhi = (sumhi * png_ptr->filter_weights[i]) >> + sumhi = (sumhi * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1652,7 +1708,24 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) } /* 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; + for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, + 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) { png_bytep rp, dp, pp, lp; png_uint_32 sum = 0, lmins = mins; @@ -1662,17 +1735,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 lmhi, lmlo; lmlo = lmins & PNG_LOMASK; lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < (png_uint_32)png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_AVG) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_AVG) { - lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> + lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; - lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> + lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1690,16 +1764,16 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #endif for (i = 0, rp = row_buf + 1, dp = png_ptr->avg_row + 1, - pp = prev_row + 1; i < bpp; i++, rp++, pp++, dp++) + 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); sum += (v < 128) ? v : 256 - v; } - for (lp = row_buf + 1; i < row_info->rowbytes; - i++, rp++, pp++, lp++, dp++) + for (lp = row_buf + 1; i < row_bytes; i++) { - v = *dp = (png_byte)(((int)*rp - (((int)*pp + (int)*lp) / 2)) & 0xff); + v = *dp++ = + (png_byte)(((int)*rp++ - (((int)*pp++ + (int)*lp++) / 2)) & 0xff); sum += (v < 128) ? v : 256 - v; @@ -1710,17 +1784,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 sumhi, sumlo; sumlo = sum & PNG_LOMASK; sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_NONE) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_NONE) { - sumlo = (sumlo * png_ptr->filter_weights[i]) >> + sumlo = (sumlo * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; - sumhi = (sumhi * png_ptr->filter_weights[i]) >> + sumhi = (sumhi * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1745,7 +1820,45 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) } /* 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; + for (i = 0, rp = row_buf + 1, dp = png_ptr->paeth_row + 1, + 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) { png_bytep rp, dp, pp, cp, lp; png_uint_32 sum = 0, lmins = mins; @@ -1755,17 +1868,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 lmhi, lmlo; lmlo = lmins & PNG_LOMASK; lmhi = (lmins >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_VALUE_PAETH) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH) { - lmlo = (lmlo * png_ptr->inv_filter_weights[i]) >> + lmlo = (lmlo * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; - lmhi = (lmhi * png_ptr->inv_filter_weights[i]) >> + lmhi = (lmhi * png_ptr->inv_filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1783,34 +1897,48 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #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++) { - v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff); + 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; - i++, rp++, pp++, lp++, dp++, cp++) + + 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; - + b = *pp++; + c = *cp++; + a = *lp++; + +#ifndef PNG_SLOW_PAETH + 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; +#else /* PNG_SLOW_PAETH */ p = a + b - c; 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); + v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff); sum += (v < 128) ? v : 256 - v; @@ -1821,17 +1949,18 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) if (png_ptr->heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED) { + int j; png_uint_32 sumhi, sumlo; sumlo = sum & PNG_LOMASK; sumhi = (sum >> PNG_HISHIFT) & PNG_HIMASK; - for (i = 0; i < png_ptr->num_prev_filters; i++) + for (j = 0; j < num_p_filters; j++) { - if (png_ptr->prev_filters[i] == PNG_FILTER_PAETH) + if (png_ptr->prev_filters[j] == PNG_FILTER_VALUE_PAETH) { - sumlo = (sumlo * png_ptr->filter_weights[i]) >> + sumlo = (sumlo * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; - sumhi = (sumhi * png_ptr->filter_weights[i]) >> + sumhi = (sumhi * png_ptr->filter_weights[j]) >> PNG_WEIGHT_SHIFT; } } @@ -1855,19 +1984,19 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info) } /* 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; - - for (i = 1; i < (int)png_ptr->num_prev_filters; i++) + int j; + for (j = 1; j < num_p_filters; j++) { - png_ptr->prev_filters[i] = png_ptr->prev_filters[i - 1]; + png_ptr->prev_filters[j] = png_ptr->prev_filters[j - 1]; } - png_ptr->prev_filters[i] = best_row[0]; + png_ptr->prev_filters[j] = best_row[0]; } #endif }