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2874 lines
91 KiB
2874 lines
91 KiB
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/* png.c - location for general purpose libpng functions |
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* |
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* Last changed in libpng 1.5.11 [June 14, 2012] |
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* Copyright (c) 1998-2012 Glenn Randers-Pehrson |
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) |
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) |
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* |
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* This code is released under the libpng license. |
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* For conditions of distribution and use, see the disclaimer |
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* and license in png.h |
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*/ |
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#include "pngpriv.h" |
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/* Generate a compiler error if there is an old png.h in the search path. */ |
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typedef png_libpng_version_1_5_12 Your_png_h_is_not_version_1_5_12; |
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/* Tells libpng that we have already handled the first "num_bytes" bytes |
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* of the PNG file signature. If the PNG data is embedded into another |
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* stream we can set num_bytes = 8 so that libpng will not attempt to read |
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* or write any of the magic bytes before it starts on the IHDR. |
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*/ |
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#ifdef PNG_READ_SUPPORTED |
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void PNGAPI |
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png_set_sig_bytes(png_structp png_ptr, int num_bytes) |
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{ |
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png_debug(1, "in png_set_sig_bytes"); |
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if (png_ptr == NULL) |
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return; |
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if (num_bytes > 8) |
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png_error(png_ptr, "Too many bytes for PNG signature"); |
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png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes); |
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} |
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/* Checks whether the supplied bytes match the PNG signature. We allow |
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* checking less than the full 8-byte signature so that those apps that |
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* already read the first few bytes of a file to determine the file type |
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* can simply check the remaining bytes for extra assurance. Returns |
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* an integer less than, equal to, or greater than zero if sig is found, |
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* respectively, to be less than, to match, or be greater than the correct |
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* PNG signature (this is the same behavior as strcmp, memcmp, etc). |
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*/ |
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int PNGAPI |
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png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check) |
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{ |
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png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; |
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if (num_to_check > 8) |
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num_to_check = 8; |
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else if (num_to_check < 1) |
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return (-1); |
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if (start > 7) |
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return (-1); |
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if (start + num_to_check > 8) |
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num_to_check = 8 - start; |
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return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check))); |
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} |
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#endif /* PNG_READ_SUPPORTED */ |
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#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) |
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/* Function to allocate memory for zlib */ |
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PNG_FUNCTION(voidpf /* PRIVATE */, |
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png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED) |
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{ |
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png_voidp ptr; |
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png_structp p=(png_structp)png_ptr; |
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png_uint_32 save_flags=p->flags; |
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png_alloc_size_t num_bytes; |
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if (png_ptr == NULL) |
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return (NULL); |
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if (items > PNG_UINT_32_MAX/size) |
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{ |
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png_warning (p, "Potential overflow in png_zalloc()"); |
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return (NULL); |
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} |
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num_bytes = (png_alloc_size_t)items * size; |
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p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK; |
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ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes); |
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p->flags=save_flags; |
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return ((voidpf)ptr); |
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} |
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/* Function to free memory for zlib */ |
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void /* PRIVATE */ |
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png_zfree(voidpf png_ptr, voidpf ptr) |
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{ |
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png_free((png_structp)png_ptr, (png_voidp)ptr); |
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} |
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/* Reset the CRC variable to 32 bits of 1's. Care must be taken |
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* in case CRC is > 32 bits to leave the top bits 0. |
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*/ |
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void /* PRIVATE */ |
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png_reset_crc(png_structp png_ptr) |
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{ |
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/* The cast is safe because the crc is a 32 bit value. */ |
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png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0); |
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} |
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/* Calculate the CRC over a section of data. We can only pass as |
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* much data to this routine as the largest single buffer size. We |
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* also check that this data will actually be used before going to the |
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* trouble of calculating it. |
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*/ |
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void /* PRIVATE */ |
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png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length) |
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{ |
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int need_crc = 1; |
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if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name)) |
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{ |
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if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == |
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(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) |
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need_crc = 0; |
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} |
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else /* critical */ |
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{ |
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if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) |
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need_crc = 0; |
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} |
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/* 'uLong' is defined as unsigned long, this means that on some systems it is |
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* a 64 bit value. crc32, however, returns 32 bits so the following cast is |
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* safe. 'uInt' may be no more than 16 bits, so it is necessary to perform a |
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* loop here. |
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*/ |
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if (need_crc && length > 0) |
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{ |
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uLong crc = png_ptr->crc; /* Should never issue a warning */ |
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do |
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{ |
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uInt safeLength = (uInt)length; |
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if (safeLength == 0) |
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safeLength = (uInt)-1; /* evil, but safe */ |
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crc = crc32(crc, ptr, safeLength); |
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/* The following should never issue compiler warnings, if they do the |
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* target system has characteristics that will probably violate other |
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* assumptions within the libpng code. |
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*/ |
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ptr += safeLength; |
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length -= safeLength; |
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} |
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while (length > 0); |
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/* And the following is always safe because the crc is only 32 bits. */ |
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png_ptr->crc = (png_uint_32)crc; |
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} |
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} |
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/* Check a user supplied version number, called from both read and write |
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* functions that create a png_struct |
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*/ |
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int |
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png_user_version_check(png_structp png_ptr, png_const_charp user_png_ver) |
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{ |
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if (user_png_ver) |
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{ |
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int i = 0; |
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do |
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{ |
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if (user_png_ver[i] != png_libpng_ver[i]) |
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png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; |
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} while (png_libpng_ver[i++]); |
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} |
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else |
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png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH; |
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if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) |
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{ |
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/* Libpng 0.90 and later are binary incompatible with libpng 0.89, so |
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* we must recompile any applications that use any older library version. |
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* For versions after libpng 1.0, we will be compatible, so we need |
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* only check the first digit. |
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*/ |
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if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] || |
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(user_png_ver[0] == '1' && user_png_ver[2] != png_libpng_ver[2]) || |
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(user_png_ver[0] == '0' && user_png_ver[2] < '9')) |
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{ |
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#ifdef PNG_WARNINGS_SUPPORTED |
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size_t pos = 0; |
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char m[128]; |
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pos = png_safecat(m, sizeof m, pos, "Application built with libpng-"); |
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pos = png_safecat(m, sizeof m, pos, user_png_ver); |
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pos = png_safecat(m, sizeof m, pos, " but running with "); |
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pos = png_safecat(m, sizeof m, pos, png_libpng_ver); |
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png_warning(png_ptr, m); |
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#endif |
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#ifdef PNG_ERROR_NUMBERS_SUPPORTED |
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png_ptr->flags = 0; |
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#endif |
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return 0; |
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} |
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} |
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/* Success return. */ |
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return 1; |
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} |
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/* Allocate the memory for an info_struct for the application. We don't |
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* really need the png_ptr, but it could potentially be useful in the |
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* future. This should be used in favour of malloc(png_sizeof(png_info)) |
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* and png_info_init() so that applications that want to use a shared |
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* libpng don't have to be recompiled if png_info changes size. |
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*/ |
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PNG_FUNCTION(png_infop,PNGAPI |
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png_create_info_struct,(png_structp png_ptr),PNG_ALLOCATED) |
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{ |
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png_infop info_ptr; |
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png_debug(1, "in png_create_info_struct"); |
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if (png_ptr == NULL) |
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return (NULL); |
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#ifdef PNG_USER_MEM_SUPPORTED |
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info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO, |
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png_ptr->malloc_fn, png_ptr->mem_ptr); |
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#else |
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info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); |
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#endif |
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if (info_ptr != NULL) |
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png_info_init_3(&info_ptr, png_sizeof(png_info)); |
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return (info_ptr); |
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} |
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/* This function frees the memory associated with a single info struct. |
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* Normally, one would use either png_destroy_read_struct() or |
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* png_destroy_write_struct() to free an info struct, but this may be |
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* useful for some applications. |
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*/ |
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void PNGAPI |
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png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr) |
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{ |
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png_infop info_ptr = NULL; |
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png_debug(1, "in png_destroy_info_struct"); |
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if (png_ptr == NULL) |
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return; |
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if (info_ptr_ptr != NULL) |
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info_ptr = *info_ptr_ptr; |
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if (info_ptr != NULL) |
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{ |
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png_info_destroy(png_ptr, info_ptr); |
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#ifdef PNG_USER_MEM_SUPPORTED |
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png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn, |
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png_ptr->mem_ptr); |
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#else |
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png_destroy_struct((png_voidp)info_ptr); |
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#endif |
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*info_ptr_ptr = NULL; |
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} |
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} |
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/* Initialize the info structure. This is now an internal function (0.89) |
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* and applications using it are urged to use png_create_info_struct() |
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* instead. |
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*/ |
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void PNGAPI |
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png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size) |
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{ |
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png_infop info_ptr = *ptr_ptr; |
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png_debug(1, "in png_info_init_3"); |
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if (info_ptr == NULL) |
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return; |
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if (png_sizeof(png_info) > png_info_struct_size) |
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{ |
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png_destroy_struct(info_ptr); |
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info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); |
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*ptr_ptr = info_ptr; |
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} |
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/* Set everything to 0 */ |
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png_memset(info_ptr, 0, png_sizeof(png_info)); |
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} |
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void PNGAPI |
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png_data_freer(png_structp png_ptr, png_infop info_ptr, |
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int freer, png_uint_32 mask) |
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{ |
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png_debug(1, "in png_data_freer"); |
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if (png_ptr == NULL || info_ptr == NULL) |
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return; |
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if (freer == PNG_DESTROY_WILL_FREE_DATA) |
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info_ptr->free_me |= mask; |
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else if (freer == PNG_USER_WILL_FREE_DATA) |
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info_ptr->free_me &= ~mask; |
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else |
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png_warning(png_ptr, |
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"Unknown freer parameter in png_data_freer"); |
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} |
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void PNGAPI |
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png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask, |
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int num) |
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{ |
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png_debug(1, "in png_free_data"); |
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if (png_ptr == NULL || info_ptr == NULL) |
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return; |
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#ifdef PNG_TEXT_SUPPORTED |
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/* Free text item num or (if num == -1) all text items */ |
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if ((mask & PNG_FREE_TEXT) & info_ptr->free_me) |
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{ |
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if (num != -1) |
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{ |
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if (info_ptr->text && info_ptr->text[num].key) |
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{ |
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png_free(png_ptr, info_ptr->text[num].key); |
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info_ptr->text[num].key = NULL; |
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} |
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} |
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else |
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{ |
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int i; |
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for (i = 0; i < info_ptr->num_text; i++) |
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png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i); |
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png_free(png_ptr, info_ptr->text); |
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info_ptr->text = NULL; |
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info_ptr->num_text=0; |
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} |
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} |
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#endif |
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#ifdef PNG_tRNS_SUPPORTED |
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/* Free any tRNS entry */ |
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if ((mask & PNG_FREE_TRNS) & info_ptr->free_me) |
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{ |
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png_free(png_ptr, info_ptr->trans_alpha); |
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info_ptr->trans_alpha = NULL; |
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info_ptr->valid &= ~PNG_INFO_tRNS; |
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} |
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#endif |
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#ifdef PNG_sCAL_SUPPORTED |
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/* Free any sCAL entry */ |
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if ((mask & PNG_FREE_SCAL) & info_ptr->free_me) |
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{ |
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png_free(png_ptr, info_ptr->scal_s_width); |
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png_free(png_ptr, info_ptr->scal_s_height); |
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info_ptr->scal_s_width = NULL; |
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info_ptr->scal_s_height = NULL; |
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info_ptr->valid &= ~PNG_INFO_sCAL; |
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} |
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#endif |
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#ifdef PNG_pCAL_SUPPORTED |
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/* Free any pCAL entry */ |
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if ((mask & PNG_FREE_PCAL) & info_ptr->free_me) |
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{ |
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png_free(png_ptr, info_ptr->pcal_purpose); |
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png_free(png_ptr, info_ptr->pcal_units); |
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info_ptr->pcal_purpose = NULL; |
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info_ptr->pcal_units = NULL; |
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if (info_ptr->pcal_params != NULL) |
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{ |
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int i; |
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for (i = 0; i < (int)info_ptr->pcal_nparams; i++) |
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{ |
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png_free(png_ptr, info_ptr->pcal_params[i]); |
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info_ptr->pcal_params[i] = NULL; |
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} |
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png_free(png_ptr, info_ptr->pcal_params); |
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info_ptr->pcal_params = NULL; |
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} |
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info_ptr->valid &= ~PNG_INFO_pCAL; |
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} |
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#endif |
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#ifdef PNG_iCCP_SUPPORTED |
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/* Free any iCCP entry */ |
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if ((mask & PNG_FREE_ICCP) & info_ptr->free_me) |
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{ |
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png_free(png_ptr, info_ptr->iccp_name); |
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png_free(png_ptr, info_ptr->iccp_profile); |
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info_ptr->iccp_name = NULL; |
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info_ptr->iccp_profile = NULL; |
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info_ptr->valid &= ~PNG_INFO_iCCP; |
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} |
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#endif |
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#ifdef PNG_sPLT_SUPPORTED |
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/* Free a given sPLT entry, or (if num == -1) all sPLT entries */ |
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if ((mask & PNG_FREE_SPLT) & info_ptr->free_me) |
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{ |
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if (num != -1) |
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{ |
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if (info_ptr->splt_palettes) |
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{ |
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png_free(png_ptr, info_ptr->splt_palettes[num].name); |
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png_free(png_ptr, info_ptr->splt_palettes[num].entries); |
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info_ptr->splt_palettes[num].name = NULL; |
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info_ptr->splt_palettes[num].entries = NULL; |
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} |
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} |
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else |
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{ |
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if (info_ptr->splt_palettes_num) |
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{ |
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int i; |
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for (i = 0; i < (int)info_ptr->splt_palettes_num; i++) |
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png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i); |
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png_free(png_ptr, info_ptr->splt_palettes); |
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info_ptr->splt_palettes = NULL; |
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info_ptr->splt_palettes_num = 0; |
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} |
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info_ptr->valid &= ~PNG_INFO_sPLT; |
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} |
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} |
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#endif |
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#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED |
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if (png_ptr->unknown_chunk.data) |
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{ |
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png_free(png_ptr, png_ptr->unknown_chunk.data); |
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png_ptr->unknown_chunk.data = NULL; |
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} |
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|
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if ((mask & PNG_FREE_UNKN) & info_ptr->free_me) |
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{ |
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if (num != -1) |
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{ |
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if (info_ptr->unknown_chunks) |
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{ |
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png_free(png_ptr, info_ptr->unknown_chunks[num].data); |
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info_ptr->unknown_chunks[num].data = NULL; |
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} |
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} |
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|
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else |
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{ |
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int i; |
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|
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if (info_ptr->unknown_chunks_num) |
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{ |
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for (i = 0; i < info_ptr->unknown_chunks_num; i++) |
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png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i); |
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|
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png_free(png_ptr, info_ptr->unknown_chunks); |
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info_ptr->unknown_chunks = NULL; |
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info_ptr->unknown_chunks_num = 0; |
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} |
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} |
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} |
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#endif |
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|
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#ifdef PNG_hIST_SUPPORTED |
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/* Free any hIST entry */ |
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if ((mask & PNG_FREE_HIST) & info_ptr->free_me) |
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{ |
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png_free(png_ptr, info_ptr->hist); |
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info_ptr->hist = NULL; |
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info_ptr->valid &= ~PNG_INFO_hIST; |
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} |
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#endif |
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|
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/* Free any PLTE entry that was internally allocated */ |
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if ((mask & PNG_FREE_PLTE) & info_ptr->free_me) |
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{ |
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png_zfree(png_ptr, info_ptr->palette); |
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info_ptr->palette = NULL; |
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info_ptr->valid &= ~PNG_INFO_PLTE; |
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info_ptr->num_palette = 0; |
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} |
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|
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#ifdef PNG_INFO_IMAGE_SUPPORTED |
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/* Free any image bits attached to the info structure */ |
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if ((mask & PNG_FREE_ROWS) & info_ptr->free_me) |
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{ |
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if (info_ptr->row_pointers) |
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{ |
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int row; |
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for (row = 0; row < (int)info_ptr->height; row++) |
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{ |
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png_free(png_ptr, info_ptr->row_pointers[row]); |
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info_ptr->row_pointers[row] = NULL; |
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} |
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png_free(png_ptr, info_ptr->row_pointers); |
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info_ptr->row_pointers = NULL; |
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} |
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info_ptr->valid &= ~PNG_INFO_IDAT; |
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} |
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#endif |
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|
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if (num != -1) |
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mask &= ~PNG_FREE_MUL; |
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|
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info_ptr->free_me &= ~mask; |
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} |
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|
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/* This is an internal routine to free any memory that the info struct is |
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* pointing to before re-using it or freeing the struct itself. Recall |
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* that png_free() checks for NULL pointers for us. |
|
*/ |
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void /* PRIVATE */ |
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png_info_destroy(png_structp png_ptr, png_infop info_ptr) |
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{ |
|
png_debug(1, "in png_info_destroy"); |
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|
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png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1); |
|
|
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#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
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if (png_ptr->num_chunk_list) |
|
{ |
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png_free(png_ptr, png_ptr->chunk_list); |
|
png_ptr->chunk_list = NULL; |
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png_ptr->num_chunk_list = 0; |
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} |
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#endif |
|
|
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png_info_init_3(&info_ptr, png_sizeof(png_info)); |
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} |
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#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ |
|
|
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/* This function returns a pointer to the io_ptr associated with the user |
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* functions. The application should free any memory associated with this |
|
* pointer before png_write_destroy() or png_read_destroy() are called. |
|
*/ |
|
png_voidp PNGAPI |
|
png_get_io_ptr(png_structp png_ptr) |
|
{ |
|
if (png_ptr == NULL) |
|
return (NULL); |
|
|
|
return (png_ptr->io_ptr); |
|
} |
|
|
|
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) |
|
# ifdef PNG_STDIO_SUPPORTED |
|
/* Initialize the default input/output functions for the PNG file. If you |
|
* use your own read or write routines, you can call either png_set_read_fn() |
|
* or png_set_write_fn() instead of png_init_io(). If you have defined |
|
* PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a |
|
* function of your own because "FILE *" isn't necessarily available. |
|
*/ |
|
void PNGAPI |
|
png_init_io(png_structp png_ptr, png_FILE_p fp) |
|
{ |
|
png_debug(1, "in png_init_io"); |
|
|
|
if (png_ptr == NULL) |
|
return; |
|
|
|
png_ptr->io_ptr = (png_voidp)fp; |
|
} |
|
# endif |
|
|
|
# ifdef PNG_TIME_RFC1123_SUPPORTED |
|
/* Convert the supplied time into an RFC 1123 string suitable for use in |
|
* a "Creation Time" or other text-based time string. |
|
*/ |
|
png_const_charp PNGAPI |
|
png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime) |
|
{ |
|
static PNG_CONST char short_months[12][4] = |
|
{"Jan", "Feb", "Mar", "Apr", "May", "Jun", |
|
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; |
|
|
|
if (png_ptr == NULL) |
|
return (NULL); |
|
|
|
if (ptime->year > 9999 /* RFC1123 limitation */ || |
|
ptime->month == 0 || ptime->month > 12 || |
|
ptime->day == 0 || ptime->day > 31 || |
|
ptime->hour > 23 || ptime->minute > 59 || |
|
ptime->second > 60) |
|
{ |
|
png_warning(png_ptr, "Ignoring invalid time value"); |
|
return (NULL); |
|
} |
|
|
|
{ |
|
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); |
|
APPEND(' '); |
|
APPEND_STRING(short_months[(ptime->month - 1)]); |
|
APPEND(' '); |
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year); |
|
APPEND(' '); |
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour); |
|
APPEND(':'); |
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute); |
|
APPEND(':'); |
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second); |
|
APPEND_STRING(" +0000"); /* This reliably terminates the buffer */ |
|
|
|
# undef APPEND |
|
# undef APPEND_NUMBER |
|
# undef APPEND_STRING |
|
} |
|
|
|
return png_ptr->time_buffer; |
|
} |
|
# endif /* PNG_TIME_RFC1123_SUPPORTED */ |
|
|
|
#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ |
|
|
|
png_const_charp PNGAPI |
|
png_get_copyright(png_const_structp png_ptr) |
|
{ |
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ |
|
#ifdef PNG_STRING_COPYRIGHT |
|
return PNG_STRING_COPYRIGHT |
|
#else |
|
# ifdef __STDC__ |
|
return PNG_STRING_NEWLINE \ |
|
"libpng version 1.5.12 - July 11, 2012" PNG_STRING_NEWLINE \ |
|
"Copyright (c) 1998-2012 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 1.5.12 - July 11, 2012\ |
|
Copyright (c) 1998-2012 Glenn Randers-Pehrson\ |
|
Copyright (c) 1996-1997 Andreas Dilger\ |
|
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; |
|
# endif |
|
#endif |
|
} |
|
|
|
/* The following return the library version as a short string in the |
|
* format 1.0.0 through 99.99.99zz. To get the version of *.h files |
|
* used with your application, print out PNG_LIBPNG_VER_STRING, which |
|
* is defined in png.h. |
|
* Note: now there is no difference between png_get_libpng_ver() and |
|
* png_get_header_ver(). Due to the version_nn_nn_nn typedef guard, |
|
* it is guaranteed that png.c uses the correct version of png.h. |
|
*/ |
|
png_const_charp PNGAPI |
|
png_get_libpng_ver(png_const_structp png_ptr) |
|
{ |
|
/* Version of *.c files used when building libpng */ |
|
return png_get_header_ver(png_ptr); |
|
} |
|
|
|
png_const_charp PNGAPI |
|
png_get_header_ver(png_const_structp png_ptr) |
|
{ |
|
/* Version of *.h files used when building libpng */ |
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ |
|
return PNG_LIBPNG_VER_STRING; |
|
} |
|
|
|
png_const_charp PNGAPI |
|
png_get_header_version(png_const_structp png_ptr) |
|
{ |
|
/* Returns longer string containing both version and date */ |
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ |
|
#ifdef __STDC__ |
|
return PNG_HEADER_VERSION_STRING |
|
# ifndef PNG_READ_SUPPORTED |
|
" (NO READ SUPPORT)" |
|
# endif |
|
PNG_STRING_NEWLINE; |
|
#else |
|
return PNG_HEADER_VERSION_STRING; |
|
#endif |
|
} |
|
|
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED |
|
int PNGAPI |
|
png_handle_as_unknown(png_structp png_ptr, png_const_bytep chunk_name) |
|
{ |
|
/* Check chunk_name and return "keep" value if it's on the list, else 0 */ |
|
png_const_bytep p, p_end; |
|
|
|
if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list <= 0) |
|
return PNG_HANDLE_CHUNK_AS_DEFAULT; |
|
|
|
p_end = png_ptr->chunk_list; |
|
p = p_end + png_ptr->num_chunk_list*5; /* beyond end */ |
|
|
|
/* The code is the fifth byte after each four byte string. Historically this |
|
* code was always searched from the end of the list, so it should continue |
|
* to do so in case there are duplicated entries. |
|
*/ |
|
do /* num_chunk_list > 0, so at least one */ |
|
{ |
|
p -= 5; |
|
if (!png_memcmp(chunk_name, p, 4)) |
|
return p[4]; |
|
} |
|
while (p > p_end); |
|
|
|
return PNG_HANDLE_CHUNK_AS_DEFAULT; |
|
} |
|
|
|
int /* PRIVATE */ |
|
png_chunk_unknown_handling(png_structp png_ptr, png_uint_32 chunk_name) |
|
{ |
|
png_byte chunk_string[5]; |
|
|
|
PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name); |
|
return png_handle_as_unknown(png_ptr, chunk_string); |
|
} |
|
#endif |
|
|
|
#ifdef PNG_READ_SUPPORTED |
|
/* This function, added to libpng-1.0.6g, is untested. */ |
|
int PNGAPI |
|
png_reset_zstream(png_structp png_ptr) |
|
{ |
|
if (png_ptr == NULL) |
|
return Z_STREAM_ERROR; |
|
|
|
return (inflateReset(&png_ptr->zstream)); |
|
} |
|
#endif /* PNG_READ_SUPPORTED */ |
|
|
|
/* This function was added to libpng-1.0.7 */ |
|
png_uint_32 PNGAPI |
|
png_access_version_number(void) |
|
{ |
|
/* Version of *.c files used when building libpng */ |
|
return((png_uint_32)PNG_LIBPNG_VER); |
|
} |
|
|
|
|
|
|
|
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) |
|
/* png_convert_size: a PNGAPI but no longer in png.h, so deleted |
|
* at libpng 1.5.5! |
|
*/ |
|
|
|
/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */ |
|
# ifdef PNG_CHECK_cHRM_SUPPORTED |
|
|
|
int /* PRIVATE */ |
|
png_check_cHRM_fixed(png_structp png_ptr, |
|
png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x, |
|
png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y, |
|
png_fixed_point blue_x, png_fixed_point blue_y) |
|
{ |
|
int ret = 1; |
|
unsigned long xy_hi,xy_lo,yx_hi,yx_lo; |
|
|
|
png_debug(1, "in function png_check_cHRM_fixed"); |
|
|
|
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 || |
|
blue_x < 0 || blue_y < 0) |
|
{ |
|
png_warning(png_ptr, |
|
"Ignoring attempt to set negative chromaticity value"); |
|
ret = 0; |
|
} |
|
/* 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 > PNG_FP_1 - red_y) |
|
{ |
|
png_warning(png_ptr, "Invalid cHRM red point"); |
|
ret = 0; |
|
} |
|
|
|
if (green_x > PNG_FP_1 - green_y) |
|
{ |
|
png_warning(png_ptr, "Invalid cHRM green point"); |
|
ret = 0; |
|
} |
|
|
|
if (blue_x > PNG_FP_1 - blue_y) |
|
{ |
|
png_warning(png_ptr, "Invalid cHRM blue point"); |
|
ret = 0; |
|
} |
|
|
|
png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo); |
|
png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo); |
|
|
|
if (xy_hi == yx_hi && xy_lo == yx_lo) |
|
{ |
|
png_warning(png_ptr, |
|
"Ignoring attempt to set cHRM RGB triangle with zero area"); |
|
ret = 0; |
|
} |
|
|
|
return ret; |
|
} |
|
# endif /* PNG_CHECK_cHRM_SUPPORTED */ |
|
|
|
#ifdef PNG_cHRM_SUPPORTED |
|
/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for |
|
* cHRM, as opposed to using chromaticities. These internal APIs return |
|
* non-zero on a parameter error. The X, Y and Z values are required to be |
|
* positive and less than 1.0. |
|
*/ |
|
int png_xy_from_XYZ(png_xy *xy, png_XYZ XYZ) |
|
{ |
|
png_int_32 d, dwhite, whiteX, whiteY; |
|
|
|
d = XYZ.redX + XYZ.redY + XYZ.redZ; |
|
if (!png_muldiv(&xy->redx, XYZ.redX, PNG_FP_1, d)) return 1; |
|
if (!png_muldiv(&xy->redy, XYZ.redY, PNG_FP_1, d)) return 1; |
|
dwhite = d; |
|
whiteX = XYZ.redX; |
|
whiteY = XYZ.redY; |
|
|
|
d = XYZ.greenX + XYZ.greenY + XYZ.greenZ; |
|
if (!png_muldiv(&xy->greenx, XYZ.greenX, PNG_FP_1, d)) return 1; |
|
if (!png_muldiv(&xy->greeny, XYZ.greenY, PNG_FP_1, d)) return 1; |
|
dwhite += d; |
|
whiteX += XYZ.greenX; |
|
whiteY += XYZ.greenY; |
|
|
|
d = XYZ.blueX + XYZ.blueY + XYZ.blueZ; |
|
if (!png_muldiv(&xy->bluex, XYZ.blueX, PNG_FP_1, d)) return 1; |
|
if (!png_muldiv(&xy->bluey, XYZ.blueY, PNG_FP_1, d)) return 1; |
|
dwhite += d; |
|
whiteX += XYZ.blueX; |
|
whiteY += XYZ.blueY; |
|
|
|
/* The reference white is simply the same of the end-point (X,Y,Z) vectors, |
|
* thus: |
|
*/ |
|
if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1; |
|
if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1; |
|
|
|
return 0; |
|
} |
|
|
|
int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy) |
|
{ |
|
png_fixed_point red_inverse, green_inverse, blue_scale; |
|
png_fixed_point left, right, denominator; |
|
|
|
/* Check xy and, implicitly, z. Note that wide gamut color spaces typically |
|
* have end points with 0 tristimulus values (these are impossible end |
|
* points, but they are used to cover the possible colors.) |
|
*/ |
|
if (xy.redx < 0 || xy.redx > PNG_FP_1) return 1; |
|
if (xy.redy < 0 || xy.redy > PNG_FP_1-xy.redx) return 1; |
|
if (xy.greenx < 0 || xy.greenx > PNG_FP_1) return 1; |
|
if (xy.greeny < 0 || xy.greeny > PNG_FP_1-xy.greenx) return 1; |
|
if (xy.bluex < 0 || xy.bluex > PNG_FP_1) return 1; |
|
if (xy.bluey < 0 || xy.bluey > PNG_FP_1-xy.bluex) return 1; |
|
if (xy.whitex < 0 || xy.whitex > PNG_FP_1) return 1; |
|
if (xy.whitey < 0 || xy.whitey > PNG_FP_1-xy.whitex) return 1; |
|
|
|
/* The reverse calculation is more difficult because the original tristimulus |
|
* value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8 |
|
* derived values were recorded in the cHRM chunk; |
|
* (red,green,blue,white)x(x,y). This loses one degree of freedom and |
|
* therefore an arbitrary ninth value has to be introduced to undo the |
|
* original transformations. |
|
* |
|
* Think of the original end-points as points in (X,Y,Z) space. The |
|
* chromaticity values (c) have the property: |
|
* |
|
* C |
|
* c = --------- |
|
* X + Y + Z |
|
* |
|
* For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the |
|
* three chromaticity values (x,y,z) for each end-point obey the |
|
* relationship: |
|
* |
|
* x + y + z = 1 |
|
* |
|
* This describes the plane in (X,Y,Z) space that intersects each axis at the |
|
* value 1.0; call this the chromaticity plane. Thus the chromaticity |
|
* calculation has scaled each end-point so that it is on the x+y+z=1 plane |
|
* and chromaticity is the intersection of the vector from the origin to the |
|
* (X,Y,Z) value with the chromaticity plane. |
|
* |
|
* To fully invert the chromaticity calculation we would need the three |
|
* end-point scale factors, (red-scale, green-scale, blue-scale), but these |
|
* were not recorded. Instead we calculated the reference white (X,Y,Z) and |
|
* recorded the chromaticity of this. The reference white (X,Y,Z) would have |
|
* given all three of the scale factors since: |
|
* |
|
* color-C = color-c * color-scale |
|
* white-C = red-C + green-C + blue-C |
|
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale |
|
* |
|
* But cHRM records only white-x and white-y, so we have lost the white scale |
|
* factor: |
|
* |
|
* white-C = white-c*white-scale |
|
* |
|
* To handle this the inverse transformation makes an arbitrary assumption |
|
* about white-scale: |
|
* |
|
* Assume: white-Y = 1.0 |
|
* Hence: white-scale = 1/white-y |
|
* Or: red-Y + green-Y + blue-Y = 1.0 |
|
* |
|
* Notice the last statement of the assumption gives an equation in three of |
|
* the nine values we want to calculate. 8 more equations come from the |
|
* above routine as summarised at the top above (the chromaticity |
|
* calculation): |
|
* |
|
* Given: color-x = color-X / (color-X + color-Y + color-Z) |
|
* Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0 |
|
* |
|
* This is 9 simultaneous equations in the 9 variables "color-C" and can be |
|
* solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix |
|
* determinants, however this is not as bad as it seems because only 28 of |
|
* the total of 90 terms in the various matrices are non-zero. Nevertheless |
|
* Cramer's rule is notoriously numerically unstable because the determinant |
|
* calculation involves the difference of large, but similar, numbers. It is |
|
* difficult to be sure that the calculation is stable for real world values |
|
* and it is certain that it becomes unstable where the end points are close |
|
* together. |
|
* |
|
* So this code uses the perhaps slightly less optimal but more |
|
* understandable and totally obvious approach of calculating color-scale. |
|
* |
|
* This algorithm depends on the precision in white-scale and that is |
|
* (1/white-y), so we can immediately see that as white-y approaches 0 the |
|
* accuracy inherent in the cHRM chunk drops off substantially. |
|
* |
|
* libpng arithmetic: a simple invertion of the above equations |
|
* ------------------------------------------------------------ |
|
* |
|
* white_scale = 1/white-y |
|
* white-X = white-x * white-scale |
|
* white-Y = 1.0 |
|
* white-Z = (1 - white-x - white-y) * white_scale |
|
* |
|
* white-C = red-C + green-C + blue-C |
|
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale |
|
* |
|
* This gives us three equations in (red-scale,green-scale,blue-scale) where |
|
* all the coefficients are now known: |
|
* |
|
* red-x*red-scale + green-x*green-scale + blue-x*blue-scale |
|
* = white-x/white-y |
|
* red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1 |
|
* red-z*red-scale + green-z*green-scale + blue-z*blue-scale |
|
* = (1 - white-x - white-y)/white-y |
|
* |
|
* In the last equation color-z is (1 - color-x - color-y) so we can add all |
|
* three equations together to get an alternative third: |
|
* |
|
* red-scale + green-scale + blue-scale = 1/white-y = white-scale |
|
* |
|
* So now we have a Cramer's rule solution where the determinants are just |
|
* 3x3 - far more tractible. Unfortunately 3x3 determinants still involve |
|
* multiplication of three coefficients so we can't guarantee to avoid |
|
* overflow in the libpng fixed point representation. Using Cramer's rule in |
|
* floating point is probably a good choice here, but it's not an option for |
|
* fixed point. Instead proceed to simplify the first two equations by |
|
* eliminating what is likely to be the largest value, blue-scale: |
|
* |
|
* blue-scale = white-scale - red-scale - green-scale |
|
* |
|
* Hence: |
|
* |
|
* (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale = |
|
* (white-x - blue-x)*white-scale |
|
* |
|
* (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale = |
|
* 1 - blue-y*white-scale |
|
* |
|
* And now we can trivially solve for (red-scale,green-scale): |
|
* |
|
* green-scale = |
|
* (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale |
|
* ----------------------------------------------------------- |
|
* green-x - blue-x |
|
* |
|
* red-scale = |
|
* 1 - blue-y*white-scale - (green-y - blue-y) * green-scale |
|
* --------------------------------------------------------- |
|
* red-y - blue-y |
|
* |
|
* Hence: |
|
* |
|
* red-scale = |
|
* ( (green-x - blue-x) * (white-y - blue-y) - |
|
* (green-y - blue-y) * (white-x - blue-x) ) / white-y |
|
* ------------------------------------------------------------------------- |
|
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) |
|
* |
|
* green-scale = |
|
* ( (red-y - blue-y) * (white-x - blue-x) - |
|
* (red-x - blue-x) * (white-y - blue-y) ) / white-y |
|
* ------------------------------------------------------------------------- |
|
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x) |
|
* |
|
* Accuracy: |
|
* The input values have 5 decimal digits of accuracy. The values are all in |
|
* the range 0 < value < 1, so simple products are in the same range but may |
|
* need up to 10 decimal digits to preserve the original precision and avoid |
|
* underflow. Because we are using a 32-bit signed representation we cannot |
|
* match this; the best is a little over 9 decimal digits, less than 10. |
|
* |
|
* The approach used here is to preserve the maximum precision within the |
|
* signed representation. Because the red-scale calculation above uses the |
|
* difference between two products of values that must be in the range -1..+1 |
|
* it is sufficient to divide the product by 7; ceil(100,000/32767*2). The |
|
* factor is irrelevant in the calculation because it is applied to both |
|
* numerator and denominator. |
|
* |
|
* Note that the values of the differences of the products of the |
|
* chromaticities in the above equations tend to be small, for example for |
|
* the sRGB chromaticities they are: |
|
* |
|
* red numerator: -0.04751 |
|
* green numerator: -0.08788 |
|
* denominator: -0.2241 (without white-y multiplication) |
|
* |
|
* The resultant Y coefficients from the chromaticities of some widely used |
|
* color space definitions are (to 15 decimal places): |
|
* |
|
* sRGB |
|
* 0.212639005871510 0.715168678767756 0.072192315360734 |
|
* Kodak ProPhoto |
|
* 0.288071128229293 0.711843217810102 0.000085653960605 |
|
* Adobe RGB |
|
* 0.297344975250536 0.627363566255466 0.075291458493998 |
|
* Adobe Wide Gamut RGB |
|
* 0.258728243040113 0.724682314948566 0.016589442011321 |
|
*/ |
|
/* By the argument, above overflow should be impossible here. The return |
|
* value of 2 indicates an internal error to the caller. |
|
*/ |
|
if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.redy - xy.bluey, 7)) return 2; |
|
if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.redx - xy.bluex, 7)) return 2; |
|
denominator = left - right; |
|
|
|
/* Now find the red numerator. */ |
|
if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2; |
|
if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.whitex-xy.bluex, 7)) return 2; |
|
|
|
/* Overflow is possible here and it indicates an extreme set of PNG cHRM |
|
* chunk values. This calculation actually returns the reciprocal of the |
|
* scale value because this allows us to delay the multiplication of white-y |
|
* into the denominator, which tends to produce a small number. |
|
*/ |
|
if (!png_muldiv(&red_inverse, xy.whitey, denominator, left-right) || |
|
red_inverse <= xy.whitey /* r+g+b scales = white scale */) |
|
return 1; |
|
|
|
/* Similarly for green_inverse: */ |
|
if (!png_muldiv(&left, xy.redy-xy.bluey, xy.whitex-xy.bluex, 7)) return 2; |
|
if (!png_muldiv(&right, xy.redx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2; |
|
if (!png_muldiv(&green_inverse, xy.whitey, denominator, left-right) || |
|
green_inverse <= xy.whitey) |
|
return 1; |
|
|
|
/* And the blue scale, the checks above guarantee this can't overflow but it |
|
* can still produce 0 for extreme cHRM values. |
|
*/ |
|
blue_scale = png_reciprocal(xy.whitey) - png_reciprocal(red_inverse) - |
|
png_reciprocal(green_inverse); |
|
if (blue_scale <= 0) return 1; |
|
|
|
|
|
/* And fill in the png_XYZ: */ |
|
if (!png_muldiv(&XYZ->redX, xy.redx, PNG_FP_1, red_inverse)) return 1; |
|
if (!png_muldiv(&XYZ->redY, xy.redy, PNG_FP_1, red_inverse)) return 1; |
|
if (!png_muldiv(&XYZ->redZ, PNG_FP_1 - xy.redx - xy.redy, PNG_FP_1, |
|
red_inverse)) |
|
return 1; |
|
|
|
if (!png_muldiv(&XYZ->greenX, xy.greenx, PNG_FP_1, green_inverse)) return 1; |
|
if (!png_muldiv(&XYZ->greenY, xy.greeny, PNG_FP_1, green_inverse)) return 1; |
|
if (!png_muldiv(&XYZ->greenZ, PNG_FP_1 - xy.greenx - xy.greeny, PNG_FP_1, |
|
green_inverse)) |
|
return 1; |
|
|
|
if (!png_muldiv(&XYZ->blueX, xy.bluex, blue_scale, PNG_FP_1)) return 1; |
|
if (!png_muldiv(&XYZ->blueY, xy.bluey, blue_scale, PNG_FP_1)) return 1; |
|
if (!png_muldiv(&XYZ->blueZ, PNG_FP_1 - xy.bluex - xy.bluey, blue_scale, |
|
PNG_FP_1)) |
|
return 1; |
|
|
|
return 0; /*success*/ |
|
} |
|
|
|
int png_XYZ_from_xy_checked(png_structp png_ptr, png_XYZ *XYZ, png_xy xy) |
|
{ |
|
switch (png_XYZ_from_xy(XYZ, xy)) |
|
{ |
|
case 0: /* success */ |
|
return 1; |
|
|
|
case 1: |
|
/* The chunk may be technically valid, but we got png_fixed_point |
|
* overflow while trying to get XYZ values out of it. This is |
|
* entirely benign - the cHRM chunk is pretty extreme. |
|
*/ |
|
png_warning(png_ptr, |
|
"extreme cHRM chunk cannot be converted to tristimulus values"); |
|
break; |
|
|
|
default: |
|
/* libpng is broken; this should be a warning but if it happens we |
|
* want error reports so for the moment it is an error. |
|
*/ |
|
png_error(png_ptr, "internal error in png_XYZ_from_xy"); |
|
break; |
|
} |
|
|
|
/* ERROR RETURN */ |
|
return 0; |
|
} |
|
#endif |
|
|
|
void /* PRIVATE */ |
|
png_check_IHDR(png_structp png_ptr, |
|
png_uint_32 width, png_uint_32 height, int bit_depth, |
|
int color_type, int interlace_type, int compression_type, |
|
int filter_type) |
|
{ |
|
int error = 0; |
|
|
|
/* Check for width and height valid values */ |
|
if (width == 0) |
|
{ |
|
png_warning(png_ptr, "Image width is zero in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (height == 0) |
|
{ |
|
png_warning(png_ptr, "Image height is zero in IHDR"); |
|
error = 1; |
|
} |
|
|
|
# ifdef PNG_SET_USER_LIMITS_SUPPORTED |
|
if (width > png_ptr->user_width_max) |
|
|
|
# else |
|
if (width > PNG_USER_WIDTH_MAX) |
|
# endif |
|
{ |
|
png_warning(png_ptr, "Image width exceeds user limit in IHDR"); |
|
error = 1; |
|
} |
|
|
|
# ifdef PNG_SET_USER_LIMITS_SUPPORTED |
|
if (height > png_ptr->user_height_max) |
|
# else |
|
if (height > PNG_USER_HEIGHT_MAX) |
|
# endif |
|
{ |
|
png_warning(png_ptr, "Image height exceeds user limit in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (width > PNG_UINT_31_MAX) |
|
{ |
|
png_warning(png_ptr, "Invalid image width in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (height > PNG_UINT_31_MAX) |
|
{ |
|
png_warning(png_ptr, "Invalid image height in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (width > (PNG_UINT_32_MAX |
|
>> 3) /* 8-byte RGBA pixels */ |
|
- 48 /* bigrowbuf hack */ |
|
- 1 /* filter byte */ |
|
- 7*8 /* rounding of width to multiple of 8 pixels */ |
|
- 8) /* extra max_pixel_depth pad */ |
|
png_warning(png_ptr, "Width is too large for libpng to process pixels"); |
|
|
|
/* Check other values */ |
|
if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 && |
|
bit_depth != 8 && bit_depth != 16) |
|
{ |
|
png_warning(png_ptr, "Invalid bit depth in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (color_type < 0 || color_type == 1 || |
|
color_type == 5 || color_type > 6) |
|
{ |
|
png_warning(png_ptr, "Invalid color type in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) || |
|
((color_type == PNG_COLOR_TYPE_RGB || |
|
color_type == PNG_COLOR_TYPE_GRAY_ALPHA || |
|
color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8)) |
|
{ |
|
png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (interlace_type >= PNG_INTERLACE_LAST) |
|
{ |
|
png_warning(png_ptr, "Unknown interlace method in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (compression_type != PNG_COMPRESSION_TYPE_BASE) |
|
{ |
|
png_warning(png_ptr, "Unknown compression method in IHDR"); |
|
error = 1; |
|
} |
|
|
|
# ifdef PNG_MNG_FEATURES_SUPPORTED |
|
/* Accept filter_method 64 (intrapixel differencing) only if |
|
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and |
|
* 2. Libpng did not read a PNG signature (this filter_method is only |
|
* used in PNG datastreams that are embedded in MNG datastreams) and |
|
* 3. The application called png_permit_mng_features with a mask that |
|
* included PNG_FLAG_MNG_FILTER_64 and |
|
* 4. The filter_method is 64 and |
|
* 5. The color_type is RGB or RGBA |
|
*/ |
|
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) && |
|
png_ptr->mng_features_permitted) |
|
png_warning(png_ptr, "MNG features are not allowed in a PNG datastream"); |
|
|
|
if (filter_type != PNG_FILTER_TYPE_BASE) |
|
{ |
|
if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) && |
|
(filter_type == PNG_INTRAPIXEL_DIFFERENCING) && |
|
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && |
|
(color_type == PNG_COLOR_TYPE_RGB || |
|
color_type == PNG_COLOR_TYPE_RGB_ALPHA))) |
|
{ |
|
png_warning(png_ptr, "Unknown filter method in IHDR"); |
|
error = 1; |
|
} |
|
|
|
if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) |
|
{ |
|
png_warning(png_ptr, "Invalid filter method in IHDR"); |
|
error = 1; |
|
} |
|
} |
|
|
|
# else |
|
if (filter_type != PNG_FILTER_TYPE_BASE) |
|
{ |
|
png_warning(png_ptr, "Unknown filter method in IHDR"); |
|
error = 1; |
|
} |
|
# endif |
|
|
|
if (error == 1) |
|
png_error(png_ptr, "Invalid IHDR data"); |
|
} |
|
|
|
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) |
|
/* ASCII to fp functions */ |
|
/* Check an ASCII formated floating point value, see the more detailed |
|
* comments in pngpriv.h |
|
*/ |
|
/* 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_STICKY)) |
|
|
|
int /* PRIVATE */ |
|
png_check_fp_number(png_const_charp string, png_size_t size, int *statep, |
|
png_size_tp whereami) |
|
{ |
|
int state = *statep; |
|
png_size_t i = *whereami; |
|
|
|
while (i < size) |
|
{ |
|
int type; |
|
/* First find the type of the next character */ |
|
switch (string[i]) |
|
{ |
|
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 & PNG_FP_SAW_ANY)) |
|
{ |
|
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, type); |
|
break; |
|
|
|
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, type); |
|
|
|
else |
|
png_fp_set(state, PNG_FP_FRACTION | type); |
|
|
|
break; |
|
|
|
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, type | PNG_FP_WAS_VALID); |
|
|
|
break; |
|
|
|
case PNG_FP_INTEGER + PNG_FP_SAW_E: |
|
if ((state & PNG_FP_SAW_DIGIT) == 0) |
|
goto PNG_FP_End; |
|
|
|
png_fp_set(state, PNG_FP_EXPONENT); |
|
|
|
break; |
|
|
|
/* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN: |
|
goto PNG_FP_End; ** no sign in fraction */ |
|
|
|
/* case PNG_FP_FRACTION + PNG_FP_SAW_DOT: |
|
goto PNG_FP_End; ** Because SAW_DOT is always set */ |
|
|
|
case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT: |
|
png_fp_add(state, type | PNG_FP_WAS_VALID); |
|
break; |
|
|
|
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). |
|
*/ |
|
if ((state & PNG_FP_SAW_DIGIT) == 0) |
|
goto PNG_FP_End; |
|
|
|
png_fp_set(state, PNG_FP_EXPONENT); |
|
|
|
break; |
|
|
|
case PNG_FP_EXPONENT + 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); |
|
|
|
break; |
|
|
|
/* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT: |
|
goto PNG_FP_End; */ |
|
|
|
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_SAW_E: |
|
goto PNG_FP_End; */ |
|
|
|
default: goto PNG_FP_End; /* I.e. break 2 */ |
|
} |
|
|
|
/* The character seems ok, continue. */ |
|
++i; |
|
} |
|
|
|
PNG_FP_End: |
|
/* Here at the end, update the state and return the correct |
|
* return code. |
|
*/ |
|
*statep = state; |
|
*whereami = i; |
|
|
|
return (state & PNG_FP_SAW_DIGIT) != 0; |
|
} |
|
|
|
|
|
/* The same but for a complete string. */ |
|
int |
|
png_check_fp_string(png_const_charp string, png_size_t size) |
|
{ |
|
int state=0; |
|
png_size_t 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 */ |
|
|
|
#ifdef PNG_READ_sCAL_SUPPORTED |
|
# ifdef PNG_FLOATING_POINT_SUPPORTED |
|
/* Utility used below - a simple accurate power of ten from an integral |
|
* exponent. |
|
*/ |
|
static double |
|
png_pow10(int power) |
|
{ |
|
int recip = 0; |
|
double d = 1.0; |
|
|
|
/* Handle negative exponent with a reciprocal at the end because |
|
* 10 is exact whereas .1 is inexact in base 2 |
|
*/ |
|
if (power < 0) |
|
{ |
|
if (power < DBL_MIN_10_EXP) return 0; |
|
recip = 1, power = -power; |
|
} |
|
|
|
if (power > 0) |
|
{ |
|
/* Decompose power bitwise. */ |
|
double mult = 10.0; |
|
do |
|
{ |
|
if (power & 1) d *= mult; |
|
mult *= mult; |
|
power >>= 1; |
|
} |
|
while (power > 0); |
|
|
|
if (recip) d = 1/d; |
|
} |
|
/* else power is 0 and d is 1 */ |
|
|
|
return d; |
|
} |
|
|
|
/* Function to format a floating point value in ASCII with a given |
|
* precision. |
|
*/ |
|
void /* PRIVATE */ |
|
png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size, |
|
double fp, unsigned int precision) |
|
{ |
|
/* We use standard functions from math.h, but not printf because |
|
* that would require stdio. The caller must supply a buffer of |
|
* sufficient size or we will png_error. The tests on size and |
|
* the space in ascii[] consumed are indicated below. |
|
*/ |
|
if (precision < 1) |
|
precision = DBL_DIG; |
|
|
|
/* Enforce the limit of the implementation precision too. */ |
|
if (precision > DBL_DIG+1) |
|
precision = DBL_DIG+1; |
|
|
|
/* Basic sanity checks */ |
|
if (size >= precision+5) /* See the requirements below. */ |
|
{ |
|
if (fp < 0) |
|
{ |
|
fp = -fp; |
|
*ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */ |
|
--size; |
|
} |
|
|
|
if (fp >= DBL_MIN && fp <= DBL_MAX) |
|
{ |
|
int exp_b10; /* A base 10 exponent */ |
|
double base; /* 10^exp_b10 */ |
|
|
|
/* First extract a base 10 exponent of the number, |
|
* the calculation below rounds down when converting |
|
* from base 2 to base 10 (multiply by log10(2) - |
|
* 0.3010, but 77/256 is 0.3008, so exp_b10 needs to |
|
* be increased. Note that the arithmetic shift |
|
* performs a floor() unlike C arithmetic - using a |
|
* C multiply would break the following for negative |
|
* exponents. |
|
*/ |
|
(void)frexp(fp, &exp_b10); /* exponent to base 2 */ |
|
|
|
exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */ |
|
|
|
/* Avoid underflow here. */ |
|
base = png_pow10(exp_b10); /* May underflow */ |
|
|
|
while (base < DBL_MIN || base < fp) |
|
{ |
|
/* And this may overflow. */ |
|
double test = png_pow10(exp_b10+1); |
|
|
|
if (test <= DBL_MAX) |
|
++exp_b10, base = test; |
|
|
|
else |
|
break; |
|
} |
|
|
|
/* Normalize fp and correct exp_b10, after this fp is in the |
|
* range [.1,1) and exp_b10 is both the exponent and the digit |
|
* *before* which the decimal point should be inserted |
|
* (starting with 0 for the first digit). Note that this |
|
* works even if 10^exp_b10 is out of range because of the |
|
* test on DBL_MAX above. |
|
*/ |
|
fp /= base; |
|
while (fp >= 1) fp /= 10, ++exp_b10; |
|
|
|
/* Because of the code above fp may, at this point, be |
|
* less than .1, this is ok because the code below can |
|
* handle the leading zeros this generates, so no attempt |
|
* is made to correct that here. |
|
*/ |
|
|
|
{ |
|
int czero, clead, cdigits; |
|
char exponent[10]; |
|
|
|
/* Allow up to two leading zeros - this will not lengthen |
|
* the number compared to using E-n. |
|
*/ |
|
if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */ |
|
{ |
|
czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */ |
|
exp_b10 = 0; /* Dot added below before first output. */ |
|
} |
|
else |
|
czero = 0; /* No zeros to add */ |
|
|
|
/* Generate the digit list, stripping trailing zeros and |
|
* inserting a '.' before a digit if the exponent is 0. |
|
*/ |
|
clead = czero; /* Count of leading zeros */ |
|
cdigits = 0; /* Count of digits in list. */ |
|
|
|
do |
|
{ |
|
double d; |
|
|
|
fp *= 10.0; |
|
|
|
/* Use modf here, not floor and subtract, so that |
|
* the separation is done in one step. At the end |
|
* of the loop don't break the number into parts so |
|
* that the final digit is rounded. |
|
*/ |
|
if (cdigits+czero-clead+1 < (int)precision) |
|
fp = modf(fp, &d); |
|
|
|
else |
|
{ |
|
d = floor(fp + .5); |
|
|
|
if (d > 9.0) |
|
{ |
|
/* Rounding up to 10, handle that here. */ |
|
if (czero > 0) |
|
{ |
|
--czero, d = 1; |
|
if (cdigits == 0) --clead; |
|
} |
|
|
|
else |
|
{ |
|
while (cdigits > 0 && d > 9.0) |
|
{ |
|
int ch = *--ascii; |
|
|
|
if (exp_b10 != (-1)) |
|
++exp_b10; |
|
|
|
else if (ch == 46) |
|
{ |
|
ch = *--ascii, ++size; |
|
/* Advance exp_b10 to '1', so that the |
|
* decimal point happens after the |
|
* previous digit. |
|
*/ |
|
exp_b10 = 1; |
|
} |
|
|
|
--cdigits; |
|
d = ch - 47; /* I.e. 1+(ch-48) */ |
|
} |
|
|
|
/* Did we reach the beginning? If so adjust the |
|
* exponent but take into account the leading |
|
* decimal point. |
|
*/ |
|
if (d > 9.0) /* cdigits == 0 */ |
|
{ |
|
if (exp_b10 == (-1)) |
|
{ |
|
/* Leading decimal point (plus zeros?), if |
|
* we lose the decimal point here it must |
|
* be reentered below. |
|
*/ |
|
int ch = *--ascii; |
|
|
|
if (ch == 46) |
|
++size, exp_b10 = 1; |
|
|
|
/* Else lost a leading zero, so 'exp_b10' is |
|
* still ok at (-1) |
|
*/ |
|
} |
|
else |
|
++exp_b10; |
|
|
|
/* In all cases we output a '1' */ |
|
d = 1.0; |
|
} |
|
} |
|
} |
|
fp = 0; /* Guarantees termination below. */ |
|
} |
|
|
|
if (d == 0.0) |
|
{ |
|
++czero; |
|
if (cdigits == 0) ++clead; |
|
} |
|
|
|
else |
|
{ |
|
/* Included embedded zeros in the digit count. */ |
|
cdigits += czero - clead; |
|
clead = 0; |
|
|
|
while (czero > 0) |
|
{ |
|
/* exp_b10 == (-1) means we just output the decimal |
|
* place - after the DP don't adjust 'exp_b10' any |
|
* more! |
|
*/ |
|
if (exp_b10 != (-1)) |
|
{ |
|
if (exp_b10 == 0) *ascii++ = 46, --size; |
|
/* PLUS 1: TOTAL 4 */ |
|
--exp_b10; |
|
} |
|
*ascii++ = 48, --czero; |
|
} |
|
|
|
if (exp_b10 != (-1)) |
|
{ |
|
if (exp_b10 == 0) *ascii++ = 46, --size; /* counted |
|
above */ |
|
--exp_b10; |
|
} |
|
|
|
*ascii++ = (char)(48 + (int)d), ++cdigits; |
|
} |
|
} |
|
while (cdigits+czero-clead < (int)precision && fp > DBL_MIN); |
|
|
|
/* The total output count (max) is now 4+precision */ |
|
|
|
/* Check for an exponent, if we don't need one we are |
|
* done and just need to terminate the string. At |
|
* this point exp_b10==(-1) is effectively if flag - it got |
|
* to '-1' because of the decrement after outputing |
|
* the decimal point above (the exponent required is |
|
* *not* -1!) |
|
*/ |
|
if (exp_b10 >= (-1) && exp_b10 <= 2) |
|
{ |
|
/* The following only happens if we didn't output the |
|
* leading zeros above for negative exponent, so this |
|
* doest add to the digit requirement. Note that the |
|
* two zeros here can only be output if the two leading |
|
* zeros were *not* output, so this doesn't increase |
|
* the output count. |
|
*/ |
|
while (--exp_b10 >= 0) *ascii++ = 48; |
|
|
|
*ascii = 0; |
|
|
|
/* Total buffer requirement (including the '\0') is |
|
* 5+precision - see check at the start. |
|
*/ |
|
return; |
|
} |
|
|
|
/* Here if an exponent is required, adjust size for |
|
* the digits we output but did not count. The total |
|
* digit output here so far is at most 1+precision - no |
|
* decimal point and no leading or trailing zeros have |
|
* been output. |
|
*/ |
|
size -= cdigits; |
|
|
|
*ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */ |
|
|
|
/* The following use of an unsigned temporary avoids ambiguities in |
|
* the signed arithmetic on exp_b10 and permits GCC at least to do |
|
* better optimization. |
|
*/ |
|
{ |
|
unsigned int uexp_b10; |
|
|
|
if (exp_b10 < 0) |
|
{ |
|
*ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */ |
|
uexp_b10 = -exp_b10; |
|
} |
|
|
|
else |
|
uexp_b10 = exp_b10; |
|
|
|
cdigits = 0; |
|
|
|
while (uexp_b10 > 0) |
|
{ |
|
exponent[cdigits++] = (char)(48 + uexp_b10 % 10); |
|
uexp_b10 /= 10; |
|
} |
|
} |
|
|
|
/* Need another size check here for the exponent digits, so |
|
* this need not be considered above. |
|
*/ |
|
if ((int)size > cdigits) |
|
{ |
|
while (cdigits > 0) *ascii++ = exponent[--cdigits]; |
|
|
|
*ascii = 0; |
|
|
|
return; |
|
} |
|
} |
|
} |
|
else if (!(fp >= DBL_MIN)) |
|
{ |
|
*ascii++ = 48; /* '0' */ |
|
*ascii = 0; |
|
return; |
|
} |
|
else |
|
{ |
|
*ascii++ = 105; /* 'i' */ |
|
*ascii++ = 110; /* 'n' */ |
|
*ascii++ = 102; /* 'f' */ |
|
*ascii = 0; |
|
return; |
|
} |
|
} |
|
|
|
/* Here on buffer too small. */ |
|
png_error(png_ptr, "ASCII conversion buffer too small"); |
|
} |
|
|
|
# endif /* FLOATING_POINT */ |
|
|
|
# ifdef PNG_FIXED_POINT_SUPPORTED |
|
/* Function to format a fixed point value in ASCII. |
|
*/ |
|
void /* PRIVATE */ |
|
png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size, |
|
png_fixed_point fp) |
|
{ |
|
/* Require space for 10 decimal digits, a decimal point, a minus sign and a |
|
* trailing \0, 13 characters: |
|
*/ |
|
if (size > 12) |
|
{ |
|
png_uint_32 num; |
|
|
|
/* Avoid overflow here on the minimum integer. */ |
|
if (fp < 0) |
|
*ascii++ = 45, --size, num = -fp; |
|
else |
|
num = fp; |
|
|
|
if (num <= 0x80000000) /* else overflowed */ |
|
{ |
|
unsigned int ndigits = 0, first = 16 /* flag value */; |
|
char digits[10]; |
|
|
|
while (num) |
|
{ |
|
/* Split the low digit off num: */ |
|
unsigned int tmp = num/10; |
|
num -= tmp*10; |
|
digits[ndigits++] = (char)(48 + num); |
|
/* Record the first non-zero digit, note that this is a number |
|
* starting at 1, it's not actually the array index. |
|
*/ |
|
if (first == 16 && num > 0) |
|
first = ndigits; |
|
num = tmp; |
|
} |
|
|
|
if (ndigits > 0) |
|
{ |
|
while (ndigits > 5) *ascii++ = digits[--ndigits]; |
|
/* The remaining digits are fractional digits, ndigits is '5' or |
|
* smaller at this point. It is certainly not zero. Check for a |
|
* non-zero fractional digit: |
|
*/ |
|
if (first <= 5) |
|
{ |
|
unsigned int i; |
|
*ascii++ = 46; /* decimal point */ |
|
/* ndigits may be <5 for small numbers, output leading zeros |
|
* then ndigits digits to first: |
|
*/ |
|
i = 5; |
|
while (ndigits < i) *ascii++ = 48, --i; |
|
while (ndigits >= first) *ascii++ = digits[--ndigits]; |
|
/* Don't output the trailing zeros! */ |
|
} |
|
} |
|
else |
|
*ascii++ = 48; |
|
|
|
/* And null terminate the string: */ |
|
*ascii = 0; |
|
return; |
|
} |
|
} |
|
|
|
/* Here on buffer too small. */ |
|
png_error(png_ptr, "ASCII conversion buffer too small"); |
|
} |
|
# endif /* FIXED_POINT */ |
|
#endif /* READ_SCAL */ |
|
|
|
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \ |
|
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED) |
|
png_fixed_point |
|
png_fixed(png_structp png_ptr, double fp, png_const_charp text) |
|
{ |
|
double r = floor(100000 * fp + .5); |
|
|
|
if (r > 2147483647. || r < -2147483648.) |
|
png_fixed_error(png_ptr, text); |
|
|
|
return (png_fixed_point)r; |
|
} |
|
#endif |
|
|
|
#if defined(PNG_READ_GAMMA_SUPPORTED) || \ |
|
defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG__READ_pHYs_SUPPORTED) |
|
/* muldiv functions */ |
|
/* This API takes signed arguments and rounds the result to the nearest |
|
* integer (or, for a fixed point number - the standard argument - to |
|
* the nearest .00001). Overflow and divide by zero are signalled in |
|
* the result, a boolean - true on success, false on overflow. |
|
*/ |
|
int |
|
png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, |
|
png_int_32 divisor) |
|
{ |
|
/* Return a * times / divisor, rounded. */ |
|
if (divisor != 0) |
|
{ |
|
if (a == 0 || times == 0) |
|
{ |
|
*res = 0; |
|
return 1; |
|
} |
|
else |
|
{ |
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
double r = a; |
|
r *= times; |
|
r /= divisor; |
|
r = floor(r+.5); |
|
|
|
/* A png_fixed_point is a 32-bit integer. */ |
|
if (r <= 2147483647. && r >= -2147483648.) |
|
{ |
|
*res = (png_fixed_point)r; |
|
return 1; |
|
} |
|
#else |
|
int negative = 0; |
|
png_uint_32 A, T, D; |
|
png_uint_32 s16, s32, s00; |
|
|
|
if (a < 0) |
|
negative = 1, A = -a; |
|
else |
|
A = a; |
|
|
|
if (times < 0) |
|
negative = !negative, T = -times; |
|
else |
|
T = times; |
|
|
|
if (divisor < 0) |
|
negative = !negative, D = -divisor; |
|
else |
|
D = divisor; |
|
|
|
/* Following can't overflow because the arguments only |
|
* have 31 bits each, however the result may be 32 bits. |
|
*/ |
|
s16 = (A >> 16) * (T & 0xffff) + |
|
(A & 0xffff) * (T >> 16); |
|
/* Can't overflow because the a*times bit is only 30 |
|
* bits at most. |
|
*/ |
|
s32 = (A >> 16) * (T >> 16) + (s16 >> 16); |
|
s00 = (A & 0xffff) * (T & 0xffff); |
|
|
|
s16 = (s16 & 0xffff) << 16; |
|
s00 += s16; |
|
|
|
if (s00 < s16) |
|
++s32; /* carry */ |
|
|
|
if (s32 < D) /* else overflow */ |
|
{ |
|
/* s32.s00 is now the 64-bit product, do a standard |
|
* division, we know that s32 < D, so the maximum |
|
* required shift is 31. |
|
*/ |
|
int bitshift = 32; |
|
png_fixed_point result = 0; /* NOTE: signed */ |
|
|
|
while (--bitshift >= 0) |
|
{ |
|
png_uint_32 d32, d00; |
|
|
|
if (bitshift > 0) |
|
d32 = D >> (32-bitshift), d00 = D << bitshift; |
|
|
|
else |
|
d32 = 0, d00 = D; |
|
|
|
if (s32 > d32) |
|
{ |
|
if (s00 < d00) --s32; /* carry */ |
|
s32 -= d32, s00 -= d00, result += 1<<bitshift; |
|
} |
|
|
|
else |
|
if (s32 == d32 && s00 >= d00) |
|
s32 = 0, s00 -= d00, result += 1<<bitshift; |
|
} |
|
|
|
/* Handle the rounding. */ |
|
if (s00 >= (D >> 1)) |
|
++result; |
|
|
|
if (negative) |
|
result = -result; |
|
|
|
/* Check for overflow. */ |
|
if ((negative && result <= 0) || (!negative && result >= 0)) |
|
{ |
|
*res = result; |
|
return 1; |
|
} |
|
} |
|
#endif |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
#endif /* READ_GAMMA || INCH_CONVERSIONS */ |
|
|
|
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED) |
|
/* The following is for when the caller doesn't much care about the |
|
* result. |
|
*/ |
|
png_fixed_point |
|
png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times, |
|
png_int_32 divisor) |
|
{ |
|
png_fixed_point result; |
|
|
|
if (png_muldiv(&result, a, times, divisor)) |
|
return result; |
|
|
|
png_warning(png_ptr, "fixed point overflow ignored"); |
|
return 0; |
|
} |
|
#endif |
|
|
|
#ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gamma */ |
|
/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */ |
|
png_fixed_point |
|
png_reciprocal(png_fixed_point a) |
|
{ |
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
double r = floor(1E10/a+.5); |
|
|
|
if (r <= 2147483647. && r >= -2147483648.) |
|
return (png_fixed_point)r; |
|
#else |
|
png_fixed_point res; |
|
|
|
if (png_muldiv(&res, 100000, 100000, a)) |
|
return res; |
|
#endif |
|
|
|
return 0; /* error/overflow */ |
|
} |
|
|
|
/* A local convenience routine. */ |
|
static png_fixed_point |
|
png_product2(png_fixed_point a, png_fixed_point b) |
|
{ |
|
/* The required result is 1/a * 1/b; the following preserves accuracy. */ |
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
double r = a * 1E-5; |
|
r *= b; |
|
r = floor(r+.5); |
|
|
|
if (r <= 2147483647. && r >= -2147483648.) |
|
return (png_fixed_point)r; |
|
#else |
|
png_fixed_point res; |
|
|
|
if (png_muldiv(&res, a, b, 100000)) |
|
return res; |
|
#endif |
|
|
|
return 0; /* overflow */ |
|
} |
|
|
|
/* The inverse of the above. */ |
|
png_fixed_point |
|
png_reciprocal2(png_fixed_point a, png_fixed_point b) |
|
{ |
|
/* The required result is 1/a * 1/b; the following preserves accuracy. */ |
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
double r = 1E15/a; |
|
r /= b; |
|
r = floor(r+.5); |
|
|
|
if (r <= 2147483647. && r >= -2147483648.) |
|
return (png_fixed_point)r; |
|
#else |
|
/* This may overflow because the range of png_fixed_point isn't symmetric, |
|
* but this API is only used for the product of file and screen gamma so it |
|
* doesn't matter that the smallest number it can produce is 1/21474, not |
|
* 1/100000 |
|
*/ |
|
png_fixed_point res = png_product2(a, b); |
|
|
|
if (res != 0) |
|
return png_reciprocal(res); |
|
#endif |
|
|
|
return 0; /* overflow */ |
|
} |
|
#endif /* READ_GAMMA */ |
|
|
|
#ifdef PNG_CHECK_cHRM_SUPPORTED |
|
/* Added at libpng version 1.2.34 (Dec 8, 2008) and 1.4.0 (Jan 2, |
|
* 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. |
|
* |
|
* A B |
|
* x C D |
|
* ------ |
|
* AD || BD |
|
* AC || CB || 0 |
|
* |
|
* where A and B are the high and low 16-bit words of V1, |
|
* C and D are the 16-bit words of V2, AD is the product of |
|
* A and D, and X || Y is (X << 16) + Y. |
|
*/ |
|
|
|
void /* PRIVATE */ |
|
png_64bit_product (long v1, long v2, unsigned long *hi_product, |
|
unsigned long *lo_product) |
|
{ |
|
int a, b, c, d; |
|
long lo, hi, x, y; |
|
|
|
a = (v1 >> 16) & 0xffff; |
|
b = v1 & 0xffff; |
|
c = (v2 >> 16) & 0xffff; |
|
d = v2 & 0xffff; |
|
|
|
lo = b * d; /* BD */ |
|
x = a * d + c * b; /* AD + CB */ |
|
y = ((lo >> 16) & 0xffff) + x; |
|
|
|
lo = (lo & 0xffff) | ((y & 0xffff) << 16); |
|
hi = (y >> 16) & 0xffff; |
|
|
|
hi += a * c; /* AC */ |
|
|
|
*hi_product = (unsigned long)hi; |
|
*lo_product = (unsigned long)lo; |
|
} |
|
#endif /* CHECK_cHRM */ |
|
|
|
#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */ |
|
#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
/* 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-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 |
|
* 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. |
|
*/ |
|
static png_uint_32 |
|
png_8bit_l2[128] = |
|
{ |
|
# ifdef PNG_DO_BC |
|
for (i=128;i<256;++i) { .5 - l(i/255)/l(2)*65536*65536; } |
|
# else |
|
4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U, |
|
3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U, |
|
3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U, |
|
3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U, |
|
3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U, |
|
2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U, |
|
2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U, |
|
2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U, |
|
2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U, |
|
2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U, |
|
1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U, |
|
1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U, |
|
1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U, |
|
1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U, |
|
1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U, |
|
971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U, |
|
803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U, |
|
639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U, |
|
479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U, |
|
324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U, |
|
172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U, |
|
24347096U, 0U |
|
# endif |
|
|
|
#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. |
|
*/ |
|
65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054, |
|
57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803, |
|
50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068, |
|
43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782, |
|
37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887, |
|
31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339, |
|
25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098, |
|
20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132, |
|
15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415, |
|
10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523, |
|
6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495, |
|
1119, 744, 372 |
|
#endif |
|
}; |
|
|
|
PNG_STATIC png_int_32 |
|
png_log8bit(unsigned int x) |
|
{ |
|
unsigned int lg2 = 0; |
|
/* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log, |
|
* because the log is actually negate that means adding 1. The final |
|
* returned value thus has the range 0 (for 255 input) to 7.994 (for 1 |
|
* input), return 7.99998 for the overflow (log 0) case - so the result is |
|
* always at most 19 bits. |
|
*/ |
|
if ((x &= 0xff) == 0) |
|
return 0xffffffff; |
|
|
|
if ((x & 0xf0) == 0) |
|
lg2 = 4, x <<= 4; |
|
|
|
if ((x & 0xc0) == 0) |
|
lg2 += 2, x <<= 2; |
|
|
|
if ((x & 0x80) == 0) |
|
lg2 += 1, x <<= 1; |
|
|
|
/* result is at most 19 bits, so this cast is safe: */ |
|
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 |
|
* 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. |
|
* |
|
* We want log2(value/65535), we have log2(v'/255), where: |
|
* |
|
* value = v' * 256 + v'' |
|
* = v' * f |
|
* |
|
* 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. |
|
* |
|
* This gives a final formula using a calculated value 'x' which is value/v' and |
|
* scaling by 65536 to match the above table: |
|
* |
|
* log2(x/257) * 65536 |
|
* |
|
* 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: |
|
* |
|
* Start (256): -23591 |
|
* Zero (257): 0 |
|
* End (258): 23499 |
|
*/ |
|
PNG_STATIC png_int_32 |
|
png_log16bit(png_uint_32 x) |
|
{ |
|
unsigned int lg2 = 0; |
|
|
|
/* As above, but now the input has 16 bits. */ |
|
if ((x &= 0xffff) == 0) |
|
return 0xffffffff; |
|
|
|
if ((x & 0xff00) == 0) |
|
lg2 = 8, x <<= 8; |
|
|
|
if ((x & 0xf000) == 0) |
|
lg2 += 4, x <<= 4; |
|
|
|
if ((x & 0xc000) == 0) |
|
lg2 += 2, x <<= 2; |
|
|
|
if ((x & 0x8000) == 0) |
|
lg2 += 1, x <<= 1; |
|
|
|
/* Calculate the base logarithm from the top 8 bits as a 28-bit fractional |
|
* value. |
|
*/ |
|
lg2 <<= 28; |
|
lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4; |
|
|
|
/* Now we need to interpolate the factor, this requires a division by the top |
|
* 8 bits. Do this with maximum precision. |
|
*/ |
|
x = ((x << 16) + (x >> 9)) / (x >> 8); |
|
|
|
/* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24, |
|
* the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly |
|
* 16 bits to interpolate to get the low bits of the result. Round the |
|
* answer. Note that the end point values are scaled by 64 to retain overall |
|
* precision and that 'lg2' is current scaled by an extra 12 bits, so adjust |
|
* the overall scaling by 6-12. Round at every step. |
|
*/ |
|
x -= 1U << 24; |
|
|
|
if (x <= 65536U) /* <= '257' */ |
|
lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12); |
|
|
|
else |
|
lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12); |
|
|
|
/* Safe, because the result can't have more than 20 bits: */ |
|
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 |
|
* 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 |
|
* requires perhaps spurious accuracy 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 |
|
* top four fractional bits then multiplying in the remaining bits. |
|
*/ |
|
static png_uint_32 |
|
png_32bit_exp[16] = |
|
{ |
|
# ifdef PNG_DO_BC |
|
for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; } |
|
# else |
|
/* 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 |
|
# endif |
|
}; |
|
|
|
/* Adjustment table; provided to explain the numbers in the code below. */ |
|
#ifdef PNG_DO_BC |
|
for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"} |
|
11 44937.64284865548751208448 |
|
10 45180.98734845585101160448 |
|
9 45303.31936980687359311872 |
|
8 45364.65110595323018870784 |
|
7 45395.35850361789624614912 |
|
6 45410.72259715102037508096 |
|
5 45418.40724413220722311168 |
|
4 45422.25021786898173001728 |
|
3 45424.17186732298419044352 |
|
2 45425.13273269940811464704 |
|
1 45425.61317555035558641664 |
|
0 45425.85339951654943850496 |
|
#endif |
|
|
|
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 */ |
|
png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf]; |
|
|
|
/* Incorporate the low 12 bits - these decrease the returned value by |
|
* multiplying by a number less than 1 if the bit is set. The multiplier |
|
* is determined by the above table and the shift. Notice that the values |
|
* converge on 45426 and this is used to allow linear interpolation of the |
|
* low bits. |
|
*/ |
|
if (x & 0x800) |
|
e -= (((e >> 16) * 44938U) + 16U) >> 5; |
|
|
|
if (x & 0x400) |
|
e -= (((e >> 16) * 45181U) + 32U) >> 6; |
|
|
|
if (x & 0x200) |
|
e -= (((e >> 16) * 45303U) + 64U) >> 7; |
|
|
|
if (x & 0x100) |
|
e -= (((e >> 16) * 45365U) + 128U) >> 8; |
|
|
|
if (x & 0x080) |
|
e -= (((e >> 16) * 45395U) + 256U) >> 9; |
|
|
|
if (x & 0x040) |
|
e -= (((e >> 16) * 45410U) + 512U) >> 10; |
|
|
|
/* And handle the low 6 bits in a single block. */ |
|
e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9; |
|
|
|
/* Handle the upper bits of x. */ |
|
e >>= x >> 16; |
|
return e; |
|
} |
|
|
|
/* Check for overflow */ |
|
if (x <= 0) |
|
return png_32bit_exp[0]; |
|
|
|
/* Else underflow */ |
|
return 0; |
|
} |
|
|
|
PNG_STATIC png_byte |
|
png_exp8bit(png_fixed_point lg2) |
|
{ |
|
/* 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 |
|
* second, rounding, step can't overflow because of the first, subtraction, |
|
* step. |
|
*/ |
|
x -= x >> 8; |
|
return (png_byte)((x + 0x7fffffU) >> 24); |
|
} |
|
|
|
PNG_STATIC png_uint_16 |
|
png_exp16bit(png_fixed_point lg2) |
|
{ |
|
/* 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: */ |
|
x -= x >> 16; |
|
return (png_uint_16)((x + 32767U) >> 16); |
|
} |
|
#endif /* FLOATING_ARITHMETIC */ |
|
|
|
png_byte |
|
png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val) |
|
{ |
|
if (value > 0 && value < 255) |
|
{ |
|
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
double r = floor(255*pow(value/255.,gamma_val*.00001)+.5); |
|
return (png_byte)r; |
|
# else |
|
png_int_32 lg2 = png_log8bit(value); |
|
png_fixed_point res; |
|
|
|
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1)) |
|
return png_exp8bit(res); |
|
|
|
/* Overflow. */ |
|
value = 0; |
|
# endif |
|
} |
|
|
|
return (png_byte)value; |
|
} |
|
|
|
png_uint_16 |
|
png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val) |
|
{ |
|
if (value > 0 && value < 65535) |
|
{ |
|
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5); |
|
return (png_uint_16)r; |
|
# else |
|
png_int_32 lg2 = png_log16bit(value); |
|
png_fixed_point res; |
|
|
|
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1)) |
|
return png_exp16bit(res); |
|
|
|
/* Overflow. */ |
|
value = 0; |
|
# endif |
|
} |
|
|
|
return (png_uint_16)value; |
|
} |
|
|
|
/* This does the right thing based on the bit_depth field of the |
|
* 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, |
|
png_fixed_point gamma_val) |
|
{ |
|
if (png_ptr->bit_depth == 8) |
|
return png_gamma_8bit_correct(value, gamma_val); |
|
|
|
else |
|
return png_gamma_16bit_correct(value, gamma_val); |
|
} |
|
|
|
/* This is the shared test on whether a gamma value is 'significant' - whether |
|
* it is worth doing gamma correction. |
|
*/ |
|
int /* PRIVATE */ |
|
png_gamma_significant(png_fixed_point gamma_val) |
|
{ |
|
return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED || |
|
gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED; |
|
} |
|
|
|
/* 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). |
|
* |
|
* The caller is responsible for ensuring that the table gets cleaned up on |
|
* png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument |
|
* should be somewhere that will be cleaned. |
|
*/ |
|
static void |
|
png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable, |
|
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) |
|
{ |
|
/* Various values derived from 'shift': */ |
|
PNG_CONST unsigned int num = 1U << (8U - shift); |
|
PNG_CONST unsigned int max = (1U << (16U - shift))-1U; |
|
PNG_CONST unsigned int max_by_2 = 1U << (15U-shift); |
|
unsigned int i; |
|
|
|
png_uint_16pp table = *ptable = |
|
(png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p)); |
|
|
|
for (i = 0; i < num; i++) |
|
{ |
|
png_uint_16p sub_table = table[i] = |
|
(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. |
|
*/ |
|
if (png_gamma_significant(gamma_val)) |
|
{ |
|
/* The old code would overflow at the end and this would cause the |
|
* 'pow' function to return a result >1, resulting in an |
|
* arithmetic error. This code follows the spec exactly; ig is |
|
* the recovered input sample, it always has 8-16 bits. |
|
* |
|
* We want input * 65535/max, rounded, the arithmetic fits in 32 |
|
* bits (unsigned) so long as max <= 32767. |
|
*/ |
|
unsigned int j; |
|
for (j = 0; j < 256; j++) |
|
{ |
|
png_uint_32 ig = (j << (8-shift)) + i; |
|
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED |
|
/* Inline the 'max' scaling operation: */ |
|
double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5); |
|
sub_table[j] = (png_uint_16)d; |
|
# else |
|
if (shift) |
|
ig = (ig * 65535U + max_by_2)/max; |
|
|
|
sub_table[j] = png_gamma_16bit_correct(ig, gamma_val); |
|
# endif |
|
} |
|
} |
|
else |
|
{ |
|
/* We must still build a table, but do it the fast way. */ |
|
unsigned int j; |
|
|
|
for (j = 0; j < 256; j++) |
|
{ |
|
png_uint_32 ig = (j << (8-shift)) + i; |
|
|
|
if (shift) |
|
ig = (ig * 65535U + max_by_2)/max; |
|
|
|
sub_table[j] = (png_uint_16)ig; |
|
} |
|
} |
|
} |
|
} |
|
|
|
/* NOTE: this function expects the *inverse* of the overall gamma transformation |
|
* required. |
|
*/ |
|
static void |
|
png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable, |
|
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) |
|
{ |
|
PNG_CONST unsigned int num = 1U << (8U - shift); |
|
PNG_CONST unsigned int max = (1U << (16U - shift))-1U; |
|
unsigned int i; |
|
png_uint_32 last; |
|
|
|
png_uint_16pp table = *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 the |
|
* input 16-bit value used to select a table. Each table is itself indexed |
|
* by the high 8 bits of the value. |
|
*/ |
|
for (i = 0; i < num; i++) |
|
table[i] = (png_uint_16p)png_malloc(png_ptr, |
|
256 * png_sizeof(png_uint_16)); |
|
|
|
/* '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 |
|
* 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 |
|
* 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 */ |
|
{ |
|
/* Find the corresponding maximum input 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); |
|
|
|
/* Adjust (round) to (16-shift) bits: */ |
|
bound = (bound * max + 32768U)/65535U + 1U; |
|
|
|
while (last < bound) |
|
{ |
|
table[last & (0xffU >> shift)][last >> (8U - shift)] = out; |
|
last++; |
|
} |
|
} |
|
|
|
/* And fill in the final entries. */ |
|
while (last < (num << 8)) |
|
{ |
|
table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U; |
|
last++; |
|
} |
|
} |
|
|
|
/* 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. |
|
*/ |
|
static void |
|
png_build_8bit_table(png_structp png_ptr, png_bytepp ptable, |
|
PNG_CONST png_fixed_point gamma_val) |
|
{ |
|
unsigned int i; |
|
png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256); |
|
|
|
if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++) |
|
table[i] = png_gamma_8bit_correct(i, gamma_val); |
|
|
|
else for (i=0; i<256; ++i) |
|
table[i] = (png_byte)i; |
|
} |
|
|
|
/* Used from png_read_destroy and below to release the memory used by the gamma |
|
* tables. |
|
*/ |
|
void /* PRIVATE */ |
|
png_destroy_gamma_table(png_structp png_ptr) |
|
{ |
|
png_free(png_ptr, png_ptr->gamma_table); |
|
png_ptr->gamma_table = NULL; |
|
|
|
if (png_ptr->gamma_16_table != NULL) |
|
{ |
|
int i; |
|
int istop = (1 << (8 - png_ptr->gamma_shift)); |
|
for (i = 0; i < istop; i++) |
|
{ |
|
png_free(png_ptr, png_ptr->gamma_16_table[i]); |
|
} |
|
png_free(png_ptr, png_ptr->gamma_16_table); |
|
png_ptr->gamma_16_table = NULL; |
|
} |
|
|
|
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ |
|
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \ |
|
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) |
|
png_free(png_ptr, png_ptr->gamma_from_1); |
|
png_ptr->gamma_from_1 = NULL; |
|
png_free(png_ptr, png_ptr->gamma_to_1); |
|
png_ptr->gamma_to_1 = NULL; |
|
|
|
if (png_ptr->gamma_16_from_1 != NULL) |
|
{ |
|
int i; |
|
int istop = (1 << (8 - png_ptr->gamma_shift)); |
|
for (i = 0; i < istop; i++) |
|
{ |
|
png_free(png_ptr, png_ptr->gamma_16_from_1[i]); |
|
} |
|
png_free(png_ptr, png_ptr->gamma_16_from_1); |
|
png_ptr->gamma_16_from_1 = NULL; |
|
} |
|
if (png_ptr->gamma_16_to_1 != NULL) |
|
{ |
|
int i; |
|
int istop = (1 << (8 - png_ptr->gamma_shift)); |
|
for (i = 0; i < istop; i++) |
|
{ |
|
png_free(png_ptr, png_ptr->gamma_16_to_1[i]); |
|
} |
|
png_free(png_ptr, png_ptr->gamma_16_to_1); |
|
png_ptr->gamma_16_to_1 = NULL; |
|
} |
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ |
|
} |
|
|
|
/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit |
|
* tables, we don't make a full table if we are reducing to 8-bit in |
|
* the future. Note also how the gamma_16 tables are segmented so that |
|
* we don't need to allocate > 64K chunks for a full 16-bit table. |
|
*/ |
|
void /* PRIVATE */ |
|
png_build_gamma_table(png_structp png_ptr, int bit_depth) |
|
{ |
|
png_debug(1, "in png_build_gamma_table"); |
|
|
|
/* Remove any existing table; this copes with multiple calls to |
|
* png_read_update_info. The warning is because building the gamma tables |
|
* multiple times is a performance hit - it's harmless but the ability to call |
|
* png_read_update_info() multiple times is new in 1.5.6 so it seems sensible |
|
* to warn if the app introduces such a hit. |
|
*/ |
|
if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL) |
|
{ |
|
png_warning(png_ptr, "gamma table being rebuilt"); |
|
png_destroy_gamma_table(png_ptr); |
|
} |
|
|
|
if (bit_depth <= 8) |
|
{ |
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_table, |
|
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma, |
|
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_COMPOSE | PNG_RGB_TO_GRAY)) |
|
{ |
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1, |
|
png_reciprocal(png_ptr->gamma)); |
|
|
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1, |
|
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : |
|
png_ptr->gamma/* Probably doing rgb_to_gray */); |
|
} |
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ |
|
} |
|
else |
|
{ |
|
png_byte shift, sig_bit; |
|
|
|
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) |
|
{ |
|
sig_bit = png_ptr->sig_bit.red; |
|
|
|
if (png_ptr->sig_bit.green > sig_bit) |
|
sig_bit = png_ptr->sig_bit.green; |
|
|
|
if (png_ptr->sig_bit.blue > sig_bit) |
|
sig_bit = png_ptr->sig_bit.blue; |
|
} |
|
else |
|
sig_bit = png_ptr->sig_bit.gray; |
|
|
|
/* 16-bit gamma code uses this equation: |
|
* |
|
* ov = table[(iv & 0xff) >> gamma_shift][iv >> 8] |
|
* |
|
* Where 'iv' is the input color value and 'ov' is the output value - |
|
* pow(iv, gamma). |
|
* |
|
* Thus the gamma table consists of up to 256 256-entry tables. The table |
|
* is selected by the (8-gamma_shift) most significant of the low 8 bits of |
|
* the color value then indexed by the upper 8 bits: |
|
* |
|
* table[low bits][high 8 bits] |
|
* |
|
* So the table 'n' corresponds to all those 'iv' of: |
|
* |
|
* <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> |
|
* |
|
*/ |
|
if (sig_bit > 0 && sig_bit < 16U) |
|
shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */ |
|
|
|
else |
|
shift = 0; /* keep all 16 bits */ |
|
|
|
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 |
|
* eventually be 8 bits. By default it is 11. |
|
*/ |
|
if (shift < (16U - PNG_MAX_GAMMA_8)) |
|
shift = (16U - PNG_MAX_GAMMA_8); |
|
} |
|
|
|
if (shift > 8U) |
|
shift = 8U; /* Guarantees at least one table! */ |
|
|
|
png_ptr->gamma_shift = shift; |
|
|
|
#ifdef PNG_16BIT_SUPPORTED |
|
/* 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, |
|
png_ptr->screen_gamma) : PNG_FP_1); |
|
|
|
#ifdef PNG_16BIT_SUPPORTED |
|
else |
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift, |
|
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma, |
|
png_ptr->screen_gamma) : PNG_FP_1); |
|
#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_COMPOSE | PNG_RGB_TO_GRAY)) |
|
{ |
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift, |
|
png_reciprocal(png_ptr->gamma)); |
|
|
|
/* Notice that the '16 from 1' table should be full precision, however |
|
* the lookup on this table still uses gamma_shift, so it can't be. |
|
* TODO: fix this. |
|
*/ |
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift, |
|
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : |
|
png_ptr->gamma/* Probably doing rgb_to_gray */); |
|
} |
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */ |
|
} |
|
} |
|
#endif /* READ_GAMMA */ |
|
#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
|
|