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[libpng15] Simplified read/write API initial version; basic read/write tested
on a variety of images, limited documentation (in the header file.)
This commit is contained in:
John Bowler
committed by
Glenn Randers-Pehrson
Glenn Randers-Pehrson
parent
92a1d46c8d
commit
7875d534cb
418
png.c
418
png.c
@@ -645,13 +645,13 @@ png_get_copyright(png_const_structp png_ptr)
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#else
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# ifdef __STDC__
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return PNG_STRING_NEWLINE \
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"libpng version 1.5.7beta02 - November 4, 2011" PNG_STRING_NEWLINE \
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"libpng version 1.5.7beta02 - November 8, 2011" PNG_STRING_NEWLINE \
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"Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
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"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
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"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
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PNG_STRING_NEWLINE;
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# else
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return "libpng version 1.5.7beta02 - November 4, 2011\
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return "libpng version 1.5.7beta02 - November 8, 2011\
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Copyright (c) 1998-2011 Glenn Randers-Pehrson\
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Copyright (c) 1996-1997 Andreas Dilger\
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Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
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@@ -2854,4 +2854,418 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth)
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}
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}
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#endif /* READ_GAMMA */
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/* sRGB support */
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#if defined PNG_SIMPLIFIED_READ_SUPPORTED ||\
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defined PNG_SIMPLIFIED_WRITE_SUPPORTED
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/* sRGB conversion tables; these are machine generated with the following code.
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*/
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#ifdef PNG_INCLUDE_SELF_GENERATING_AND_SELF_DOCUMENTING_CODE
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#define _C99_SOURCE 1
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#include <stdio.h>
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#include <math.h>
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#include <stdlib.h>
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static unsigned int max_input = 255*65535;
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double sRGB(unsigned int i)
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{
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double l = i;
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l /= max_input;
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if (l <= 0.0031308)
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l *= 12.92;
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else
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l = 1.055 * pow(l, 1/2.4) - 0.055;
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return l;
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}
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unsigned int invsRGB(unsigned int i)
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{
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double l = i/255.;
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if (l <= 0.04045)
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l /= 12.92;
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else
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l = pow((l+0.055)/1.055, 2.4);
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l *= 65535;
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return nearbyint(l);
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}
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int main(void)
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{
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unsigned int i, i16;
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unsigned short base[512];
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unsigned char delta[512];
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double max_error = 0;
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double max_error16 = 0;
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unsigned int error_count = 0;
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unsigned int error_count16 = 0;
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for (i=0; i<=511; ++i)
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{
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double lo = 255 * sRGB(i << 15);
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double hi = 255 * sRGB((i+1) << 15);
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unsigned int calc;
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calc = nearbyint((lo+.5) * 256);
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if (calc > 65535)
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{
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fprintf(stderr, "table[%d][0]: overflow %08x (%d)\n", i, calc, calc);
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exit(1);
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}
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base[i] = calc;
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calc = nearbyint((hi-lo) * 32);
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if (calc > 255)
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{
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fprintf(stderr, "table[%d][1]: overflow %08x (%d)\n", i, calc, calc);
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exit(1);
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}
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delta[i] = calc;
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}
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for (i=0; i <= max_input; ++i)
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{
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unsigned int iexact = nearbyint(255*sRGB(i));
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unsigned int icalc = base[i>>15] + (((i&0x7fff)*delta[i>>15])>>12);
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icalc >>= 8;
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if (icalc != iexact)
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{
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double err = fabs(255*sRGB(i) - icalc);
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++error_count;
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if (err > .646)
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{
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printf(
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"/* 0x%08x: exact: %3d, got: %3d [tables: %08x, %08x] (%f) */\n",
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i, iexact, icalc, base[i>>15], delta[i>>15], err);
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if (err > max_error)
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max_error = err;
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}
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}
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}
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for (i16=0; i16 <= 65535; ++i16)
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{
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unsigned int i = 255*i16;
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unsigned int iexact = nearbyint(255*sRGB(i));
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unsigned int icalc = base[i>>15] + (((i&0x7fff)*delta[i>>15])>>12);
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icalc >>= 8;
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if (icalc != iexact)
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{
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double err = fabs(255*sRGB(i) - icalc);
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++error_count16;
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if (err > max_error16)
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max_error16 = err;
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if (abs(icalc - iexact) > 1)
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printf(
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"/* 0x%04x: exact: %3d, got: %3d [tables: %08x, %08x] (%f) */\n",
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i16, iexact, icalc, base[i>>15], delta[i>>15], err);
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}
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}
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printf("/* maximum error: %g, %g%% of readings */\n", max_error,
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(100.*error_count)/max_input);
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printf("/* maximum 16-bit error: %g, %g%% of readings */\n", max_error16,
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(100.*error_count16)/65535);
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printf("PNG_CONST png_uint_16 png_sRGB_table[256] =\n{\n ");
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for (i=0; i<255; )
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{
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do
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{
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printf("%d,", invsRGB(i++));
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}
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while ((i & 0x7) != 0 && i<255);
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if (i<255) printf("\n ");
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}
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printf("%d\n};\n\n", invsRGB(i));
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printf("PNG_CONST png_uint_16 png_sRGB_base[512] =\n{\n ");
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for (i=0; i<511; )
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{
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do
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{
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printf("%d,", base[i++]);
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}
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while ((i & 0x7) != 0 && i<511);
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if (i<511) printf("\n ");
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}
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printf("%d\n};\n\n", base[i]);
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printf("PNG_CONST png_byte png_sRGB_delta[512] =\n{\n ");
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for (i=0; i<511; )
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{
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do
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{
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printf("%d,", delta[i++]);
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}
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while ((i & 0xf) != 0 && i<511);
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if (i<511) printf("\n ");
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}
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printf("%d\n};\n\n", delta[i]);
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return 0;
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}
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#endif /* self documenting code */
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/* The result is a set of tables with the following errors: */
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/* 0x000148c1: exact: 16, got: 15 [tables: 00000d36, 0000009d] (0.646071) */
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/* 0x000148c2: exact: 16, got: 15 [tables: 00000d36, 0000009d] (0.646218) */
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/* 0x000148c3: exact: 16, got: 15 [tables: 00000d36, 0000009d] (0.646365) */
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/* maximum error: 0.646365, 0.494416% of readings */
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/* maximum 16-bit error: 0.644455, 0.5066% of readings */
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#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
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/* The convert-to-sRGB table is only currently required for read. */
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PNG_CONST png_uint_16 png_sRGB_table[256] =
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{
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0,20,40,60,80,99,119,139,
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159,179,199,219,241,264,288,313,
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340,367,396,427,458,491,526,562,
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599,637,677,718,761,805,851,898,
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947,997,1048,1101,1156,1212,1270,1330,
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1391,1453,1517,1583,1651,1720,1790,1863,
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1937,2013,2090,2170,2250,2333,2418,2504,
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2592,2681,2773,2866,2961,3058,3157,3258,
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3360,3464,3570,3678,3788,3900,4014,4129,
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4247,4366,4488,4611,4736,4864,4993,5124,
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5257,5392,5530,5669,5810,5953,6099,6246,
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6395,6547,6700,6856,7014,7174,7335,7500,
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7666,7834,8004,8177,8352,8528,8708,8889,
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9072,9258,9445,9635,9828,10022,10219,10417,
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10619,10822,11028,11235,11446,11658,11873,12090,
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12309,12530,12754,12980,13209,13440,13673,13909,
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14146,14387,14629,14874,15122,15371,15623,15878,
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16135,16394,16656,16920,17187,17456,17727,18001,
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18277,18556,18837,19121,19407,19696,19987,20281,
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20577,20876,21177,21481,21787,22096,22407,22721,
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23038,23357,23678,24002,24329,24658,24990,25325,
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25662,26001,26344,26688,27036,27386,27739,28094,
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28452,28813,29176,29542,29911,30282,30656,31033,
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31412,31794,32179,32567,32957,33350,33745,34143,
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34544,34948,35355,35764,36176,36591,37008,37429,
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37852,38278,38706,39138,39572,40009,40449,40891,
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41337,41785,42236,42690,43147,43606,44069,44534,
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45002,45473,45947,46423,46903,47385,47871,48359,
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48850,49344,49841,50341,50844,51349,51858,52369,
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52884,53401,53921,54445,54971,55500,56032,56567,
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57105,57646,58190,58737,59287,59840,60396,60955,
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61517,62082,62650,63221,63795,64372,64952,65535
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};
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#endif /* simplified read only */
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/* The base/delta tables are required for both read and write (but currently
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* only the simplified versions.)
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*/
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PNG_CONST png_uint_16 png_sRGB_base[512] =
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{
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128,1782,3382,4641,5673,6563,7355,8072,
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8732,9346,9920,10463,10977,11466,11935,12384,
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12815,13232,13634,14024,14402,14768,15125,15473,
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15811,16142,16465,16781,17090,17393,17689,17980,
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18266,18546,18822,19093,19359,19621,19879,20133,
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20383,20630,20873,21113,21349,21583,21813,22040,
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22265,22487,22706,22923,23138,23350,23559,23767,
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23972,24175,24376,24575,24772,24967,25160,25352,
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25541,25729,25916,26100,26283,26465,26645,26823,
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27000,27176,27350,27523,27694,27865,28033,28201,
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28368,28533,28697,28860,29021,29182,29341,29500,
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29657,29813,29969,30123,30276,30428,30580,30730,
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30880,31028,31176,31323,31469,31614,31758,31902,
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32044,32186,32327,32468,32607,32746,32884,33021,
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33158,33294,33429,33563,33697,33830,33963,34095,
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34226,34356,34486,34616,34744,34872,35000,35127,
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35253,35379,35504,35629,35753,35876,35999,36122,
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36244,36365,36486,36606,36726,36845,36964,37083,
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37201,37318,37435,37551,37667,37783,37898,38013,
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38127,38241,38354,38467,38580,38692,38803,38915,
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39025,39136,39246,39356,39465,39574,39682,39790,
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39898,40005,40112,40219,40325,40431,40537,40642,
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40747,40851,40955,41059,41163,41266,41369,41471,
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41573,41675,41776,41878,41978,42079,42179,42279,
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42379,42478,42577,42676,42774,42873,42970,43068,
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43165,43262,43359,43455,43552,43647,43743,43838,
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43934,44028,44123,44217,44311,44405,44498,44592,
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44685,44777,44870,44962,45054,45146,45238,45329,
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45420,45511,45601,45692,45782,45872,45961,46051,
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46140,46229,46318,46406,46494,46582,46670,46758,
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46845,46933,47020,47107,47193,47280,47366,47452,
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47538,47623,47708,47794,47879,47963,48048,48132,
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48217,48301,48384,48468,48552,48635,48718,48801,
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48884,48966,49048,49131,49213,49294,49376,49457,
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49539,49620,49701,49781,49862,49942,50023,50103,
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50183,50262,50342,50421,50501,50580,50659,50738,
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50816,50895,50973,51051,51129,51207,51284,51362,
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51439,51517,51594,51670,51747,51824,51900,51977,
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52053,52129,52205,52280,52356,52431,52507,52582,
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52657,52732,52807,52881,52956,53030,53104,53178,
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53252,53326,53399,53473,53546,53620,53693,53766,
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53839,53911,53984,54056,54129,54201,54273,54345,
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54417,54489,54560,54632,54703,54774,54845,54916,
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54987,55058,55128,55199,55269,55340,55410,55480,
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55550,55619,55689,55759,55828,55897,55967,56036,
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56105,56174,56242,56311,56380,56448,56516,56585,
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56653,56721,56789,56857,56924,56992,57059,57127,
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57194,57261,57328,57395,57462,57529,57595,57662,
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57728,57795,57861,57927,57993,58059,58125,58191,
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58256,58322,58387,58453,58518,58583,58648,58713,
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58778,58843,58908,58972,59037,59101,59165,59230,
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59294,59358,59422,59486,59549,59613,59677,59740,
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59804,59867,59930,59993,60056,60119,60182,60245,
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60308,60370,60433,60495,60558,60620,60682,60744,
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60806,60868,60930,60992,61054,61115,61177,61238,
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61300,61361,61422,61483,61544,61605,61666,61727,
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61788,61848,61909,61969,62030,62090,62150,62210,
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62271,62331,62391,62450,62510,62570,62630,62689,
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62749,62808,62867,62927,62986,63045,63104,63163,
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63222,63281,63339,63398,63457,63515,63574,63632,
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63691,63749,63807,63865,63923,63981,64039,64097,
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64155,64212,64270,64328,64385,64442,64500,64557,
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64614,64671,64729,64786,64843,64899,64956,65013,
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65070,65126,65183,65239,65296,65352,65408,65465
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};
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PNG_CONST png_byte png_sRGB_delta[512] =
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{
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207,200,157,129,111,99,90,82,77,72,68,64,61,59,56,54,
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52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
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35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
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28,27,27,27,26,26,26,26,25,25,25,25,24,24,24,24,
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23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
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21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
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19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
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17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
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16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
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15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
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14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
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13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
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12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
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12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
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11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
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11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
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11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
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10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
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10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
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10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
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9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
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9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
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9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
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9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
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8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
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7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
|
||||
};
|
||||
|
||||
/* Hence the define in pngpriv.h to calculate the sRGB value of a linear value
|
||||
* expressed as a fixed point integer scaled by 255*65535 (note that the tables
|
||||
* include the +.5 to do rounding correctly.)
|
||||
*/
|
||||
#endif /* SIMPLIFIED READ/WRITE sRGB support */
|
||||
|
||||
/* SIMPLIFIED READ/WRITE SUPPORT */
|
||||
#if defined PNG_SIMPLIFIED_READ_SUPPORTED ||\
|
||||
defined PNG_SIMPLIFIED_WRITE_SUPPORTED
|
||||
static int
|
||||
png_image_free_function(png_voidp argument)
|
||||
{
|
||||
png_imagep image = argument;
|
||||
png_controlp cp = image->opaque;
|
||||
png_control c;
|
||||
|
||||
/* Double check that we have a png_ptr - it should be impossible to get here
|
||||
* without one.
|
||||
*/
|
||||
if (cp->png_ptr == NULL)
|
||||
return 0;
|
||||
|
||||
/* First free any data held in the control structure. */
|
||||
# ifdef PNG_STDIO_SUPPORTED
|
||||
if (cp->owned_file)
|
||||
{
|
||||
FILE *fp = cp->png_ptr->io_ptr;
|
||||
cp->owned_file = 0;
|
||||
|
||||
/* Ignore errors here. */
|
||||
if (fp != NULL)
|
||||
{
|
||||
cp->png_ptr->io_ptr = NULL;
|
||||
(void)fclose(fp);
|
||||
}
|
||||
}
|
||||
# endif
|
||||
|
||||
/* Copy the control structure so that the original, allocated, version can be
|
||||
* safely freed. Notice that a png_error here stops the remainder of the
|
||||
* cleanup, but this is probably fine because that would indicate bad memory
|
||||
* problems anyway.
|
||||
*/
|
||||
c = *cp;
|
||||
image->opaque = &c;
|
||||
png_free(c.png_ptr, cp);
|
||||
|
||||
/* Then the structures, calling the correct API. */
|
||||
if (c.for_write)
|
||||
{
|
||||
# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
|
||||
png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
|
||||
# else
|
||||
png_error(c.png_ptr, "simplified write not supported");
|
||||
# endif
|
||||
}
|
||||
else
|
||||
{
|
||||
# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
||||
png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
|
||||
# else
|
||||
png_error(c.png_ptr, "simplified read not supported");
|
||||
# endif
|
||||
}
|
||||
|
||||
/* Success. */
|
||||
return 1;
|
||||
}
|
||||
|
||||
void PNGAPI
|
||||
png_image_free(png_imagep image)
|
||||
{
|
||||
/* Safely call the real function, but only if doing so is safe at this point
|
||||
* (if not inside an error handling context). Otherwise assume
|
||||
* png_safe_execute will call this API after the return.
|
||||
*/
|
||||
if (image != NULL && image->opaque != NULL &&
|
||||
image->opaque->error_buf == NULL)
|
||||
{
|
||||
/* Ignore errors here: */
|
||||
(void)png_safe_execute(image, png_image_free_function, image);
|
||||
image->opaque = NULL;
|
||||
}
|
||||
}
|
||||
|
||||
int /* PRIVATE */
|
||||
png_image_error(png_imagep image, png_const_charp error_message)
|
||||
{
|
||||
/* Utility to log an error. */
|
||||
png_safecat(image->message, sizeof image->message, 0, error_message);
|
||||
image->warning_or_error = 1;
|
||||
png_image_free(image);
|
||||
return 0;
|
||||
}
|
||||
|
||||
#endif /* SIMPLIFIED READ/WRITE */
|
||||
#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
||||
|
||||
Reference in New Issue
Block a user