diff options
Diffstat (limited to 'src/3rdparty/libpng/png.c')
| -rw-r--r-- | src/3rdparty/libpng/png.c | 350 |
1 files changed, 205 insertions, 145 deletions
diff --git a/src/3rdparty/libpng/png.c b/src/3rdparty/libpng/png.c index 764f47c..eed3136 100644 --- a/src/3rdparty/libpng/png.c +++ b/src/3rdparty/libpng/png.c @@ -1,7 +1,7 @@ /* png.c - location for general purpose libpng functions * - * Last changed in libpng 1.5.1 [February 3, 2011] + * Last changed in libpng 1.5.4 [July 7, 2011] * Copyright (c) 1998-2011 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) @@ -14,7 +14,7 @@ #include "pngpriv.h" /* Generate a compiler error if there is an old png.h in the search path. */ -typedef png_libpng_version_1_5_1 Your_png_h_is_not_version_1_5_1; +typedef png_libpng_version_1_5_4 Your_png_h_is_not_version_1_5_4; /* Tells libpng that we have already handled the first "num_bytes" bytes * of the PNG file signature. If the PNG data is embedded into another @@ -137,6 +137,61 @@ png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length) png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length); } +/* Check a user supplied version number, called from both read and write + * functions that create a png_struct + */ +int +png_user_version_check(png_structp png_ptr, png_const_charp user_png_ver) +{ + if (user_png_ver) + { + int i = 0; + + do + { + if (user_png_ver[i] != png_libpng_ver[i]) + png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; + } while (png_libpng_ver[i++]); + } + + else + png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; + + if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) + { + /* 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] || + (user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) || + (user_png_ver[0] == '0' && user_png_ver[2] < '9')) + { +#ifdef PNG_WARNINGS_SUPPORTED + size_t pos = 0; + char m[128]; + + pos = png_safecat(m, sizeof m, pos, "Application built with libpng-"); + pos = png_safecat(m, sizeof m, pos, user_png_ver); + pos = png_safecat(m, sizeof m, pos, " but running with "); + pos = png_safecat(m, sizeof m, pos, png_libpng_ver); + + png_warning(png_ptr, m); +#endif + +#ifdef PNG_ERROR_NUMBERS_SUPPORTED + png_ptr->flags = 0; +#endif + + return 0; + } + } + + /* Success return. */ + return 1; +} + /* Allocate the memory for an info_struct for the application. We don't * really need the png_ptr, but it could potentially be useful in the * future. This should be used in favour of malloc(png_sizeof(png_info)) @@ -291,12 +346,10 @@ png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask, /* Free any sCAL entry */ if ((mask & PNG_FREE_SCAL) & info_ptr->free_me) { -#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED) png_free(png_ptr, info_ptr->scal_s_width); png_free(png_ptr, info_ptr->scal_s_height); info_ptr->scal_s_width = NULL; info_ptr->scal_s_height = NULL; -#endif info_ptr->valid &= ~PNG_INFO_sCAL; } #endif @@ -518,28 +571,37 @@ png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime) if (png_ptr == NULL) return (NULL); - if (png_ptr->time_buffer == NULL) { - png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29* - png_sizeof(char))); + size_t pos = 0; + char number_buf[5]; /* enough for a four digit year */ + +# define APPEND_STRING(string)\ + pos = png_safecat(png_ptr->time_buffer, sizeof png_ptr->time_buffer,\ + pos, (string)) +# define APPEND_NUMBER(format, value)\ + APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value))) +# define APPEND(ch)\ + if (pos < (sizeof png_ptr->time_buffer)-1)\ + png_ptr->time_buffer[pos++] = (ch) + + APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day % 32); + APPEND(' '); + APPEND_STRING(short_months[(ptime->month - 1) % 12]); + APPEND(' '); + APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year); + APPEND(' '); + APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour % 24); + APPEND(':'); + APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute % 60); + APPEND(':'); + APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second % 61); + APPEND_STRING(" +0000"); /* This reliably terminates the buffer */ + +# undef APPEND +# undef APPEND_NUMBER +# undef APPEND_STRING } -# ifdef USE_FAR_KEYWORD - { - char near_time_buf[29]; - png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000", - ptime->day % 32, short_months[(ptime->month - 1) % 12], - ptime->year, ptime->hour % 24, ptime->minute % 60, - ptime->second % 61); - png_memcpy(png_ptr->time_buffer, near_time_buf, - 29*png_sizeof(char)); - } -# else - png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000", - ptime->day % 32, short_months[(ptime->month - 1) % 12], - ptime->year, ptime->hour % 24, ptime->minute % 60, - ptime->second % 61); -# endif return png_ptr->time_buffer; } # endif /* PNG_TIME_RFC1123_SUPPORTED */ @@ -555,13 +617,13 @@ png_get_copyright(png_const_structp png_ptr) #else # ifdef __STDC__ return PNG_STRING_NEWLINE \ - "libpng version 1.5.1 - February 3, 2011" PNG_STRING_NEWLINE \ + "libpng version 1.5.4 - July 7, 2011" PNG_STRING_NEWLINE \ "Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \ "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \ "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \ PNG_STRING_NEWLINE; # else - return "libpng version 1.5.1 - February 3, 2011\ + return "libpng version 1.5.4 - July 7, 2011\ Copyright (c) 1998-2011 Glenn Randers-Pehrson\ Copyright (c) 1996-1997 Andreas Dilger\ Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; @@ -681,6 +743,13 @@ png_check_cHRM_fixed(png_structp png_ptr, if (png_ptr == NULL) return 0; + /* (x,y,z) values are first limited to 0..100000 (PNG_FP_1), the white + * y must also be greater than 0. To test for the upper limit calculate + * (PNG_FP_1-y) - x must be <= to this for z to be >= 0 (and the expression + * cannot overflow.) At this point we know x and y are >= 0 and (x+y) is + * <= PNG_FP_1. The previous test on PNG_MAX_UINT_31 is removed because it + * pointless (and it produces compiler warnings!) + */ if (white_x < 0 || white_y <= 0 || red_x < 0 || red_y < 0 || green_x < 0 || green_y < 0 || @@ -690,38 +759,26 @@ png_check_cHRM_fixed(png_structp png_ptr, "Ignoring attempt to set negative chromaticity value"); ret = 0; } - if (white_x > (png_fixed_point)PNG_UINT_31_MAX || - white_y > (png_fixed_point)PNG_UINT_31_MAX || - red_x > (png_fixed_point)PNG_UINT_31_MAX || - red_y > (png_fixed_point)PNG_UINT_31_MAX || - green_x > (png_fixed_point)PNG_UINT_31_MAX || - green_y > (png_fixed_point)PNG_UINT_31_MAX || - blue_x > (png_fixed_point)PNG_UINT_31_MAX || - blue_y > (png_fixed_point)PNG_UINT_31_MAX ) - { - png_warning(png_ptr, - "Ignoring attempt to set chromaticity value exceeding 21474.83"); - ret = 0; - } - if (white_x > 100000L - white_y) + /* And (x+y) must be <= PNG_FP_1 (so z is >= 0) */ + if (white_x > PNG_FP_1 - white_y) { png_warning(png_ptr, "Invalid cHRM white point"); ret = 0; } - if (red_x > 100000L - red_y) + if (red_x > PNG_FP_1 - red_y) { png_warning(png_ptr, "Invalid cHRM red point"); ret = 0; } - if (green_x > 100000L - green_y) + if (green_x > PNG_FP_1 - green_y) { png_warning(png_ptr, "Invalid cHRM green point"); ret = 0; } - if (blue_x > 100000L - blue_y) + if (blue_x > PNG_FP_1 - blue_y) { png_warning(png_ptr, "Invalid cHRM blue point"); ret = 0; @@ -763,7 +820,7 @@ png_check_IHDR(png_structp png_ptr, } # ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (width > png_ptr->user_width_max || width > PNG_USER_WIDTH_MAX) + if (width > png_ptr->user_width_max) # else if (width > PNG_USER_WIDTH_MAX) @@ -774,7 +831,7 @@ png_check_IHDR(png_structp png_ptr, } # ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (height > png_ptr->user_height_max || height > PNG_USER_HEIGHT_MAX) + if (height > png_ptr->user_height_max) # else if (height > PNG_USER_HEIGHT_MAX) # endif @@ -889,16 +946,9 @@ png_check_IHDR(png_structp png_ptr, /* Check an ASCII formated floating point value, see the more detailed * comments in pngpriv.h */ -/* The following is used internally to preserve the 'valid' flag */ +/* The following is used internally to preserve the sticky flags */ #define png_fp_add(state, flags) ((state) |= (flags)) -#define png_fp_set(state, value)\ - ((state) = (value) | ((state) & PNG_FP_WAS_VALID)) - -/* Internal type codes: bits above the base state! */ -#define PNG_FP_SIGN 0 /* [+-] */ -#define PNG_FP_DOT 4 /* . */ -#define PNG_FP_DIGIT 8 /* [0123456789] */ -#define PNG_FP_E 12 /* [Ee] */ +#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY)) int /* PRIVATE */ png_check_fp_number(png_const_charp string, png_size_t size, int *statep, @@ -911,55 +961,55 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep, { int type; /* First find the type of the next character */ + switch (string[i]) { - char ch = string[i]; - - if (ch >= 48 && ch <= 57) - type = PNG_FP_DIGIT; - - else switch (ch) - { - case 43: case 45: type = PNG_FP_SIGN; break; - case 46: type = PNG_FP_DOT; break; - case 69: case 101: type = PNG_FP_E; break; - default: goto PNG_FP_End; - } + case 43: type = PNG_FP_SAW_SIGN; break; + case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break; + case 46: type = PNG_FP_SAW_DOT; break; + case 48: type = PNG_FP_SAW_DIGIT; break; + case 49: case 50: case 51: case 52: + case 53: case 54: case 55: case 56: + case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break; + case 69: + case 101: type = PNG_FP_SAW_E; break; + default: goto PNG_FP_End; } /* Now deal with this type according to the current * state, the type is arranged to not overlap the * bits of the PNG_FP_STATE. */ - switch ((state & PNG_FP_STATE) + type) + switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY)) { - case PNG_FP_INTEGER + PNG_FP_SIGN: + case PNG_FP_INTEGER + PNG_FP_SAW_SIGN: if (state & PNG_FP_SAW_ANY) goto PNG_FP_End; /* not a part of the number */ - png_fp_add(state, PNG_FP_SAW_SIGN); + png_fp_add(state, type); break; - case PNG_FP_INTEGER + PNG_FP_DOT: + case PNG_FP_INTEGER + PNG_FP_SAW_DOT: /* Ok as trailer, ok as lead of fraction. */ if (state & PNG_FP_SAW_DOT) /* two dots */ goto PNG_FP_End; else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */ - png_fp_add(state, PNG_FP_SAW_DOT); + png_fp_add(state, type); else - png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); + png_fp_set(state, PNG_FP_FRACTION | type); break; - case PNG_FP_INTEGER + PNG_FP_DIGIT: + case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT: if (state & PNG_FP_SAW_DOT) /* delayed fraction */ png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); - png_fp_add(state, PNG_FP_SAW_DIGIT + PNG_FP_WAS_VALID); + png_fp_add(state, type | PNG_FP_WAS_VALID); break; - case PNG_FP_INTEGER + PNG_FP_E: + + case PNG_FP_INTEGER + PNG_FP_SAW_E: if ((state & PNG_FP_SAW_DIGIT) == 0) goto PNG_FP_End; @@ -967,17 +1017,17 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep, break; - /* case PNG_FP_FRACTION + PNG_FP_SIGN: - goto PNG_FP_End; ** no sign in exponent */ + /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN: + goto PNG_FP_End; ** no sign in fraction */ - /* case PNG_FP_FRACTION + PNG_FP_DOT: + /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT: goto PNG_FP_End; ** Because SAW_DOT is always set */ - case PNG_FP_FRACTION + PNG_FP_DIGIT: - png_fp_add(state, PNG_FP_SAW_DIGIT + PNG_FP_WAS_VALID); + case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT: + png_fp_add(state, type | PNG_FP_WAS_VALID); break; - case PNG_FP_FRACTION + PNG_FP_E: + case PNG_FP_FRACTION + PNG_FP_SAW_E: /* This is correct because the trailing '.' on an * integer is handled above - so we can only get here * with the sequence ".E" (with no preceding digits). @@ -989,7 +1039,7 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep, break; - case PNG_FP_EXPONENT + PNG_FP_SIGN: + case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN: if (state & PNG_FP_SAW_ANY) goto PNG_FP_End; /* not a part of the number */ @@ -997,15 +1047,15 @@ png_check_fp_number(png_const_charp string, png_size_t size, int *statep, break; - /* case PNG_FP_EXPONENT + PNG_FP_DOT: + /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT: goto PNG_FP_End; */ - case PNG_FP_EXPONENT + PNG_FP_DIGIT: - png_fp_add(state, PNG_FP_SAW_DIGIT + PNG_FP_WAS_VALID); + case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT: + png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID); break; - /* case PNG_FP_EXPONEXT + PNG_FP_E: + /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E: goto PNG_FP_End; */ default: goto PNG_FP_End; /* I.e. break 2 */ @@ -1033,8 +1083,11 @@ png_check_fp_string(png_const_charp string, png_size_t size) int state=0; png_size_t char_index=0; - return png_check_fp_number(string, size, &state, &char_index) && - (char_index == size || string[char_index] == 0); + if (png_check_fp_number(string, size, &state, &char_index) && + (char_index == size || string[char_index] == 0)) + return state /* must be non-zero - see above */; + + return 0; /* i.e. fail */ } #endif /* pCAL or sCAL */ @@ -1102,7 +1155,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size, if (fp < 0) { fp = -fp; - *ascii++ = 45; /* '-' PLUS 1 TOTAL 1*/ + *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */ --size; } @@ -1329,7 +1382,7 @@ png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size, */ size -= cdigits; - *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision*/ + *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */ if (exp_b10 < 0) { *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */ @@ -1401,7 +1454,7 @@ png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size, if (num <= 0x80000000U) /* else overflowed */ { - unsigned int ndigits = 0, first = 16/*flag value*/; + unsigned int ndigits = 0, first = 16 /* flag value */; char digits[10]; while (num) @@ -1495,7 +1548,7 @@ png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, r /= divisor; r = floor(r+.5); - /* A png_fixed_point is a 32 bit integer. */ + /* A png_fixed_point is a 32-bit integer. */ if (r <= 2147483647. && r >= -2147483648.) { *res = (png_fixed_point)r; @@ -1540,7 +1593,7 @@ png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, if (s32 < D) /* else overflow */ { - /* s32.s00 is now the 64 bit product, do a standard + /* s32.s00 is now the 64-bit product, do a standard * division, we know that s32 < D, so the maximum * required shift is 31. */ @@ -1683,7 +1736,7 @@ png_reciprocal2(png_fixed_point a, png_fixed_point b) * 2010: moved from pngset.c) */ /* * Multiply two 32-bit numbers, V1 and V2, using 32-bit - * arithmetic, to produce a 64 bit result in the HI/LO words. + * arithmetic, to produce a 64-bit result in the HI/LO words. * * A B * x C D @@ -1727,17 +1780,17 @@ png_64bit_product (long v1, long v2, unsigned long *hi_product, /* Fixed point gamma. * * To calculate gamma this code implements fast log() and exp() calls using only - * fixed point arithmetic. This code has sufficient precision for either 8 or - * 16 bit sample values. + * fixed point arithmetic. This code has sufficient precision for either 8-bit + * or 16-bit sample values. * * The tables used here were calculated using simple 'bc' programs, but C double * precision floating point arithmetic would work fine. The programs are given * at the head of each table. * - * 8 bit log table + * 8-bit log table * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to - * 255, so it's the base 2 logarithm of a normalized 8 bit floating point - * mantissa. The numbers are 32 bit fractions. + * 255, so it's the base 2 logarithm of a normalized 8-bit floating point + * mantissa. The numbers are 32-bit fractions. */ static png_uint_32 png_8bit_l2[128] = @@ -1768,10 +1821,10 @@ png_8bit_l2[128] = 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U, 24347096U, 0U #if 0 - /* The following are the values for 16 bit tables - these work fine for the 8 - * bit conversions but produce very slightly larger errors in the 16 bit log - * (about 1.2 as opposed to 0.7 absolute error in the final value). To use - * these all the shifts below must be adjusted appropriately. + /* The following are the values for 16-bit tables - these work fine for the + * 8-bit conversions but produce very slightly larger errors in the 16-bit + * log (about 1.2 as opposed to 0.7 absolute error in the final value). To + * use these all the shifts below must be adjusted appropriately. */ 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054, 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803, @@ -1788,7 +1841,7 @@ png_8bit_l2[128] = #endif }; -static png_int_32 +PNG_STATIC png_int_32 png_log8bit(unsigned int x) { unsigned int lg2 = 0; @@ -1814,11 +1867,11 @@ png_log8bit(unsigned int x) return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16)); } -/* The above gives exact (to 16 binary places) log2 values for 8 bit images, - * for 16 bit images we use the most significant 8 bits of the 16 bit value to +/* The above gives exact (to 16 binary places) log2 values for 8-bit images, + * for 16-bit images we use the most significant 8 bits of the 16-bit value to * get an approximation then multiply the approximation by a correction factor * determined by the remaining up to 8 bits. This requires an additional step - * in the 16 bit case. + * in the 16-bit case. * * We want log2(value/65535), we have log2(v'/255), where: * @@ -1827,8 +1880,8 @@ png_log8bit(unsigned int x) * * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128 * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less - * than 258. The final factor also needs to correct for the fact that our 8 bit - * value is scaled by 255, whereas the 16 bit values must be scaled by 65535. + * than 258. The final factor also needs to correct for the fact that our 8-bit + * value is scaled by 255, whereas the 16-bit values must be scaled by 65535. * * This gives a final formula using a calculated value 'x' which is value/v' and * scaling by 65536 to match the above table: @@ -1838,13 +1891,13 @@ png_log8bit(unsigned int x) * Since these numbers are so close to '1' we can use simple linear * interpolation between the two end values 256/257 (result -368.61) and 258/257 * (result 367.179). The values used below are scaled by a further 64 to give - * 16 bit precision in the interpolation: + * 16-bit precision in the interpolation: * * Start (256): -23591 * Zero (257): 0 * End (258): 23499 */ -static png_int_32 +PNG_STATIC png_int_32 png_log16bit(png_uint_32 x) { unsigned int lg2 = 0; @@ -1865,7 +1918,7 @@ png_log16bit(png_uint_32 x) if ((x & 0x8000) == 0) lg2 += 1, x <<= 1; - /* Calculate the base logarithm from the top 8 bits as a 28 bit fractional + /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional * value. */ lg2 <<= 28; @@ -1895,18 +1948,18 @@ png_log16bit(png_uint_32 x) return (png_int_32)((lg2 + 2048) >> 12); } -/* The 'exp()' case must invert the above, taking a 20 bit fixed point - * logarithmic value and returning a 16 or 8 bit number as appropriate. In +/* The 'exp()' case must invert the above, taking a 20-bit fixed point + * logarithmic value and returning a 16 or 8-bit number as appropriate. In * each case only the low 16 bits are relevant - the fraction - since the * integer bits (the top 4) simply determine a shift. * - * The worst case is the 16 bit distinction between 65535 and 65534, this + * The worst case is the 16-bit distinction between 65535 and 65534, this * requires perhaps spurious accuracty in the decoding of the logarithm to * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance * of getting this accuracy in practice. * * To deal with this the following exp() function works out the exponent of the - * frational part of the logarithm by using an accurate 32 bit value from the + * frational part of the logarithm by using an accurate 32-bit value from the * top four fractional bits then multiplying in the remaining bits. */ static png_uint_32 @@ -1915,7 +1968,7 @@ png_32bit_exp[16] = # if PNG_DO_BC for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; } # endif - /* NOTE: the first entry is deliberately set to the maximum 32 bit value. */ + /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */ 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U, 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U, 2553802834U, 2445529972U, 2341847524U, 2242560872U @@ -1938,12 +1991,12 @@ for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"} 0 45425.85339951654943850496 #endif -static png_uint_32 +PNG_STATIC png_uint_32 png_exp(png_fixed_point x) { if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */ { - /* Obtain a 4 bit approximation */ + /* Obtain a 4-bit approximation */ png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf]; /* Incorporate the low 12 bits - these decrease the returned value by @@ -1986,13 +2039,13 @@ png_exp(png_fixed_point x) return 0; } -static png_byte +PNG_STATIC png_byte png_exp8bit(png_fixed_point lg2) { - /* Get a 32 bit value: */ + /* Get a 32-bit value: */ png_uint_32 x = png_exp(lg2); - /* Convert the 32 bit value to 0..255 by multiplying by 256-1, note that the + /* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the * second, rounding, step can't overflow because of the first, subtraction, * step. */ @@ -2000,13 +2053,13 @@ png_exp8bit(png_fixed_point lg2) return (png_byte)((x + 0x7fffffU) >> 24); } -static png_uint_16 +PNG_STATIC png_uint_16 png_exp16bit(png_fixed_point lg2) { - /* Get a 32 bit value: */ + /* Get a 32-bit value: */ png_uint_32 x = png_exp(lg2); - /* Convert the 32 bit value to 0..65535 by multiplying by 65536-1: */ + /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */ x -= x >> 16; return (png_uint_16)((x + 32767U) >> 16); } @@ -2059,9 +2112,9 @@ png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val) } /* This does the right thing based on the bit_depth field of the - * png_struct, interpreting values as 8 or 16 bit. While the result - * is nominally a 16 bit value if bit depth is 8 then the result is - * 8 bit (as are the arguments.) + * png_struct, interpreting values as 8-bit or 16-bit. While the result + * is nominally a 16-bit value if bit depth is 8 then the result is + * 8-bit (as are the arguments.) */ png_uint_16 /* PRIVATE */ png_gamma_correct(png_structp png_ptr, unsigned int value, @@ -2084,7 +2137,7 @@ png_gamma_significant(png_fixed_point gamma_val) gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED; } -/* Internal function to build a single 16 bit table - the table consists of +/* Internal function to build a single 16-bit table - the table consists of * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount * to shift the input values right (or 16-number_of_signifiant_bits). * @@ -2111,7 +2164,7 @@ png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable, (png_uint_16p)png_malloc(png_ptr, 256 * png_sizeof(png_uint_16)); /* The 'threshold' test is repeated here because it can arise for one of - * the 16 bit tables even if the others don't hit it. + * the 16-bit tables even if the others don't hit it. */ if (png_gamma_significant(gamma_val)) { @@ -2173,7 +2226,7 @@ png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable, (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p)); /* 'num' is the number of tables and also the number of low bits of low - * bits of the input 16 bit value used to select a table. Each table is + * bits of the input 16-bit value used to select a table. Each table is * itself index by the high 8 bits of the value. */ for (i = 0; i < num; i++) @@ -2183,24 +2236,24 @@ png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable, /* 'gamma_val' is set to the reciprocal of the value calculated above, so * pow(out,g) is an *input* value. 'last' is the last input value set. * - * In the loop 'i' is used to find output values. Since the output is 8 - * bit there are only 256 possible values. The tables are set up to + * In the loop 'i' is used to find output values. Since the output is + * 8-bit there are only 256 possible values. The tables are set up to * select the closest possible output value for each input by finding * the input value at the boundary between each pair of output values * and filling the table up to that boundary with the lower output * value. * - * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9 bit - * values the code below uses a 16 bit value in i; the values start at + * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit + * values the code below uses a 16-bit value in i; the values start at * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last * entries are filled with 255). Start i at 128 and fill all 'last' * table entries <= 'max' */ last = 0; - for (i = 0; i < 255; ++i) /* 8 bit output value */ + for (i = 0; i < 255; ++i) /* 8-bit output value */ { /* Find the corresponding maximum input value */ - png_uint_16 out = (png_uint_16)(i * 257U); /* 16 bit output value */ + png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */ /* Find the boundary value in 16 bits: */ png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val); @@ -2223,7 +2276,7 @@ png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable, } } -/* Build a single 8 bit table: same as the 16 bit case but much simpler (and +/* Build a single 8-bit table: same as the 16-bit case but much simpler (and * typically much faster). Note that libpng currently does no sBIT processing * (apparently contrary to the spec) so a 256 entry table is always generated. */ @@ -2258,8 +2311,9 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) png_ptr->screen_gamma) : PNG_FP_1); #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ + defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - if (png_ptr->transformations & ((PNG_BACKGROUND) | PNG_RGB_TO_GRAY)) + if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) { png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1, png_reciprocal(png_ptr->gamma)); @@ -2268,7 +2322,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : png_ptr->gamma/* Probably doing rgb_to_gray */); } -#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */ +#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ } else { @@ -2287,7 +2341,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) else sig_bit = png_ptr->sig_bit.gray; - /* 16 bit gamma code uses this equation: + /* 16-bit gamma code uses this equation: * * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8] * @@ -2302,7 +2356,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) * * So the table 'n' corresponds to all those 'iv' of: * - * <all high 8 bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> + * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> * */ if (sig_bit > 0 && sig_bit < 16U) @@ -2311,7 +2365,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) else shift = 0; /* keep all 16 bits */ - if (png_ptr->transformations & PNG_16_TO_8) + if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) { /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively * the significant bits in the *input* when the output will @@ -2327,7 +2381,12 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) png_ptr->gamma_shift = shift; #ifdef PNG_16BIT_SUPPORTED - if (png_ptr->transformations & (PNG_16_TO_8 | PNG_BACKGROUND)) + /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now + * PNG_COMPOSE). This effectively smashed the background calculation for + * 16-bit output because the 8-bit table assumes the result will be reduced + * to 8 bits. + */ + if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) #endif png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift, png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma, @@ -2341,8 +2400,9 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) #endif #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ + defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - if (png_ptr->transformations & (PNG_BACKGROUND | PNG_RGB_TO_GRAY)) + if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) { png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift, png_reciprocal(png_ptr->gamma)); @@ -2355,7 +2415,7 @@ png_build_gamma_table(png_structp png_ptr, int bit_depth) png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : png_ptr->gamma/* Probably doing rgb_to_gray */); } -#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */ +#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ } } #endif /* READ_GAMMA */ |