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4608 lines
154 KiB
C
4608 lines
154 KiB
C
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/* png.c - location for general purpose libpng functions
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*
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* Copyright (c) 2018-2019 Cosmin Truta
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* Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
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* Copyright (c) 1996-1997 Andreas Dilger
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* Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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*
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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_6_37 Your_png_h_is_not_version_1_6_37;
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#ifdef __GNUC__
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/* The version tests may need to be added to, but the problem warning has
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* consistently been fixed in GCC versions which obtain wide-spread release.
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* The problem is that many versions of GCC rearrange comparison expressions in
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* the optimizer in such a way that the results of the comparison will change
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* if signed integer overflow occurs. Such comparisons are not permitted in
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* ANSI C90, however GCC isn't clever enough to work out that that do not occur
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* below in png_ascii_from_fp and png_muldiv, so it produces a warning with
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* -Wextra. Unfortunately this is highly dependent on the optimizer and the
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* machine architecture so the warning comes and goes unpredictably and is
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* impossible to "fix", even were that a good idea.
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*/
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#if __GNUC__ == 7 && __GNUC_MINOR__ == 1
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#define GCC_STRICT_OVERFLOW 1
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#endif /* GNU 7.1.x */
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#endif /* GNU */
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#ifndef GCC_STRICT_OVERFLOW
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#define GCC_STRICT_OVERFLOW 0
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#endif
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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_structrp png_ptr, int num_bytes)
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{
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unsigned int nb = (unsigned int)num_bytes;
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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 < 0)
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nb = 0;
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if (nb > 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)nb;
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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, size_t start, 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)(memcmp(&sig[start], &png_signature[start], num_to_check)));
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}
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#endif /* READ */
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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_alloc_size_t num_bytes = size;
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if (png_ptr == NULL)
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return NULL;
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if (items >= (~(png_alloc_size_t)0)/size)
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{
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png_warning (png_voidcast(png_structrp, png_ptr),
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"Potential overflow in png_zalloc()");
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return NULL;
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}
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num_bytes *= items;
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return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
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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_voidcast(png_const_structrp,png_ptr), 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_structrp 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_structrp png_ptr, png_const_bytep ptr, size_t length)
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{
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int need_crc = 1;
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if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
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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) != 0)
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need_crc = 0;
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}
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/* 'uLong' is defined in zlib.h as unsigned long; this means that on some
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* systems it is a 64-bit value. crc32, however, returns 32 bits so the
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* following cast is safe. 'uInt' may be no more than 16 bits, so it is
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* necessary to perform a loop here.
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*/
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if (need_crc != 0 && 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 safe_length = (uInt)length;
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#ifndef __COVERITY__
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if (safe_length == 0)
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safe_length = (uInt)-1; /* evil, but safe */
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#endif
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crc = crc32(crc, ptr, safe_length);
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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 += safe_length;
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length -= safe_length;
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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_structrp png_ptr, png_const_charp user_png_ver)
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{
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/* Libpng versions 1.0.0 and later are binary compatible if the version
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* string matches through the second '.'; we must recompile any
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* applications that use any older library version.
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*/
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if (user_png_ver != NULL)
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{
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int i = -1;
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int found_dots = 0;
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do
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{
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i++;
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if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
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png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
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if (user_png_ver[i] == '.')
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found_dots++;
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} while (found_dots < 2 && user_png_ver[i] != 0 &&
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PNG_LIBPNG_VER_STRING[i] != 0);
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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) != 0)
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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,
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"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_STRING);
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PNG_UNUSED(pos)
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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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/* Success return. */
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return 1;
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}
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/* Generic function to create a png_struct for either read or write - this
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* contains the common initialization.
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*/
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PNG_FUNCTION(png_structp /* PRIVATE */,
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png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
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png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
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png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
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{
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png_struct create_struct;
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# ifdef PNG_SETJMP_SUPPORTED
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jmp_buf create_jmp_buf;
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# endif
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/* This temporary stack-allocated structure is used to provide a place to
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* build enough context to allow the user provided memory allocator (if any)
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* to be called.
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*/
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memset(&create_struct, 0, (sizeof create_struct));
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/* Added at libpng-1.2.6 */
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# ifdef PNG_USER_LIMITS_SUPPORTED
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create_struct.user_width_max = PNG_USER_WIDTH_MAX;
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create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
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# ifdef PNG_USER_CHUNK_CACHE_MAX
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/* Added at libpng-1.2.43 and 1.4.0 */
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create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
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# endif
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# ifdef PNG_USER_CHUNK_MALLOC_MAX
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/* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
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* in png_struct regardless.
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*/
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create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
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# endif
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# endif
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/* The following two API calls simply set fields in png_struct, so it is safe
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* to do them now even though error handling is not yet set up.
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*/
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# ifdef PNG_USER_MEM_SUPPORTED
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png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
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# else
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PNG_UNUSED(mem_ptr)
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PNG_UNUSED(malloc_fn)
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PNG_UNUSED(free_fn)
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# endif
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/* (*error_fn) can return control to the caller after the error_ptr is set,
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* this will result in a memory leak unless the error_fn does something
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* extremely sophisticated. The design lacks merit but is implicit in the
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* API.
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*/
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png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
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# ifdef PNG_SETJMP_SUPPORTED
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if (!setjmp(create_jmp_buf))
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# endif
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{
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# ifdef PNG_SETJMP_SUPPORTED
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/* Temporarily fake out the longjmp information until we have
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* successfully completed this function. This only works if we have
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* setjmp() support compiled in, but it is safe - this stuff should
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* never happen.
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*/
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create_struct.jmp_buf_ptr = &create_jmp_buf;
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create_struct.jmp_buf_size = 0; /*stack allocation*/
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create_struct.longjmp_fn = longjmp;
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# endif
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/* Call the general version checker (shared with read and write code):
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*/
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if (png_user_version_check(&create_struct, user_png_ver) != 0)
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{
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png_structrp png_ptr = png_voidcast(png_structrp,
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png_malloc_warn(&create_struct, (sizeof *png_ptr)));
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if (png_ptr != NULL)
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{
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/* png_ptr->zstream holds a back-pointer to the png_struct, so
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* this can only be done now:
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*/
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create_struct.zstream.zalloc = png_zalloc;
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create_struct.zstream.zfree = png_zfree;
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create_struct.zstream.opaque = png_ptr;
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# ifdef PNG_SETJMP_SUPPORTED
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/* Eliminate the local error handling: */
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create_struct.jmp_buf_ptr = NULL;
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create_struct.jmp_buf_size = 0;
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create_struct.longjmp_fn = 0;
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# endif
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*png_ptr = create_struct;
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/* This is the successful return point */
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return png_ptr;
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}
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}
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}
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/* A longjmp because of a bug in the application storage allocator or a
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* simple failure to allocate the png_struct.
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*/
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return NULL;
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}
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/* Allocate the memory for an info_struct for the application. */
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PNG_FUNCTION(png_infop,PNGAPI
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png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
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{
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png_inforp 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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/* Use the internal API that does not (or at least should not) error out, so
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* that this call always returns ok. The application typically sets up the
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* error handling *after* creating the info_struct because this is the way it
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* has always been done in 'example.c'.
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*/
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info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
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(sizeof *info_ptr)));
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if (info_ptr != NULL)
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memset(info_ptr, 0, (sizeof *info_ptr));
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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. From libpng 1.6.0 this function is also used
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* internally to implement the png_info release part of the 'struct' destroy
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* APIs. This ensures that all possible approaches free the same data (all of
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* it).
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*/
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void PNGAPI
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png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
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{
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png_inforp 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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/* Do this first in case of an error below; if the app implements its own
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* memory management this can lead to png_free calling png_error, which
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* will abort this routine and return control to the app error handler.
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* An infinite loop may result if it then tries to free the same info
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* ptr.
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*/
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*info_ptr_ptr = NULL;
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png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
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memset(info_ptr, 0, (sizeof *info_ptr));
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png_free(png_ptr, info_ptr);
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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. Use deprecated in 1.6.0, internal use removed (used internally it
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* is just a memset).
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*
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* NOTE: it is almost inconceivable that this API is used because it bypasses
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* the user-memory mechanism and the user error handling/warning mechanisms in
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* those cases where it does anything other than a memset.
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*/
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PNG_FUNCTION(void,PNGAPI
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png_info_init_3,(png_infopp ptr_ptr, size_t png_info_struct_size),
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PNG_DEPRECATED)
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{
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png_inforp 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 ((sizeof (png_info)) > png_info_struct_size)
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{
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*ptr_ptr = NULL;
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/* The following line is why this API should not be used: */
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free(info_ptr);
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info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
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(sizeof *info_ptr)));
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if (info_ptr == NULL)
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return;
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*ptr_ptr = info_ptr;
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}
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/* Set everything to 0 */
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memset(info_ptr, 0, (sizeof *info_ptr));
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}
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/* The following API is not called internally */
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void PNGAPI
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png_data_freer(png_const_structrp png_ptr, png_inforp 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_error(png_ptr, "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_const_structrp png_ptr, png_inforp 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 (info_ptr->text != NULL &&
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((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
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{
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if (num != -1)
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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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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(png_ptr, info_ptr->text[i].key);
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png_free(png_ptr, info_ptr->text);
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info_ptr->text = NULL;
|
|
info_ptr->num_text = 0;
|
|
info_ptr->max_text = 0;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_tRNS_SUPPORTED
|
|
/* Free any tRNS entry */
|
|
if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
|
|
{
|
|
info_ptr->valid &= ~PNG_INFO_tRNS;
|
|
png_free(png_ptr, info_ptr->trans_alpha);
|
|
info_ptr->trans_alpha = NULL;
|
|
info_ptr->num_trans = 0;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_sCAL_SUPPORTED
|
|
/* Free any sCAL entry */
|
|
if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
|
|
{
|
|
png_free(png_ptr, info_ptr->scal_s_width);
|
|
png_free(png_ptr, info_ptr->scal_s_height);
|
|
info_ptr->scal_s_width = NULL;
|
|
info_ptr->scal_s_height = NULL;
|
|
info_ptr->valid &= ~PNG_INFO_sCAL;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_pCAL_SUPPORTED
|
|
/* Free any pCAL entry */
|
|
if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
|
|
{
|
|
png_free(png_ptr, info_ptr->pcal_purpose);
|
|
png_free(png_ptr, info_ptr->pcal_units);
|
|
info_ptr->pcal_purpose = NULL;
|
|
info_ptr->pcal_units = NULL;
|
|
|
|
if (info_ptr->pcal_params != NULL)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < info_ptr->pcal_nparams; i++)
|
|
png_free(png_ptr, info_ptr->pcal_params[i]);
|
|
|
|
png_free(png_ptr, info_ptr->pcal_params);
|
|
info_ptr->pcal_params = NULL;
|
|
}
|
|
info_ptr->valid &= ~PNG_INFO_pCAL;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_iCCP_SUPPORTED
|
|
/* Free any profile entry */
|
|
if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
|
|
{
|
|
png_free(png_ptr, info_ptr->iccp_name);
|
|
png_free(png_ptr, info_ptr->iccp_profile);
|
|
info_ptr->iccp_name = NULL;
|
|
info_ptr->iccp_profile = NULL;
|
|
info_ptr->valid &= ~PNG_INFO_iCCP;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_sPLT_SUPPORTED
|
|
/* Free a given sPLT entry, or (if num == -1) all sPLT entries */
|
|
if (info_ptr->splt_palettes != NULL &&
|
|
((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
|
|
{
|
|
if (num != -1)
|
|
{
|
|
png_free(png_ptr, info_ptr->splt_palettes[num].name);
|
|
png_free(png_ptr, info_ptr->splt_palettes[num].entries);
|
|
info_ptr->splt_palettes[num].name = NULL;
|
|
info_ptr->splt_palettes[num].entries = NULL;
|
|
}
|
|
|
|
else
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < info_ptr->splt_palettes_num; i++)
|
|
{
|
|
png_free(png_ptr, info_ptr->splt_palettes[i].name);
|
|
png_free(png_ptr, info_ptr->splt_palettes[i].entries);
|
|
}
|
|
|
|
png_free(png_ptr, info_ptr->splt_palettes);
|
|
info_ptr->splt_palettes = NULL;
|
|
info_ptr->splt_palettes_num = 0;
|
|
info_ptr->valid &= ~PNG_INFO_sPLT;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
|
|
if (info_ptr->unknown_chunks != NULL &&
|
|
((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
|
|
{
|
|
if (num != -1)
|
|
{
|
|
png_free(png_ptr, info_ptr->unknown_chunks[num].data);
|
|
info_ptr->unknown_chunks[num].data = NULL;
|
|
}
|
|
|
|
else
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < info_ptr->unknown_chunks_num; i++)
|
|
png_free(png_ptr, info_ptr->unknown_chunks[i].data);
|
|
|
|
png_free(png_ptr, info_ptr->unknown_chunks);
|
|
info_ptr->unknown_chunks = NULL;
|
|
info_ptr->unknown_chunks_num = 0;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_eXIf_SUPPORTED
|
|
/* Free any eXIf entry */
|
|
if (((mask & PNG_FREE_EXIF) & info_ptr->free_me) != 0)
|
|
{
|
|
# ifdef PNG_READ_eXIf_SUPPORTED
|
|
if (info_ptr->eXIf_buf)
|
|
{
|
|
png_free(png_ptr, info_ptr->eXIf_buf);
|
|
info_ptr->eXIf_buf = NULL;
|
|
}
|
|
# endif
|
|
if (info_ptr->exif)
|
|
{
|
|
png_free(png_ptr, info_ptr->exif);
|
|
info_ptr->exif = NULL;
|
|
}
|
|
info_ptr->valid &= ~PNG_INFO_eXIf;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_hIST_SUPPORTED
|
|
/* Free any hIST entry */
|
|
if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
|
|
{
|
|
png_free(png_ptr, info_ptr->hist);
|
|
info_ptr->hist = NULL;
|
|
info_ptr->valid &= ~PNG_INFO_hIST;
|
|
}
|
|
#endif
|
|
|
|
/* Free any PLTE entry that was internally allocated */
|
|
if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
|
|
{
|
|
png_free(png_ptr, info_ptr->palette);
|
|
info_ptr->palette = NULL;
|
|
info_ptr->valid &= ~PNG_INFO_PLTE;
|
|
info_ptr->num_palette = 0;
|
|
}
|
|
|
|
#ifdef PNG_INFO_IMAGE_SUPPORTED
|
|
/* Free any image bits attached to the info structure */
|
|
if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
|
|
{
|
|
if (info_ptr->row_pointers != NULL)
|
|
{
|
|
png_uint_32 row;
|
|
for (row = 0; row < info_ptr->height; row++)
|
|
png_free(png_ptr, info_ptr->row_pointers[row]);
|
|
|
|
png_free(png_ptr, info_ptr->row_pointers);
|
|
info_ptr->row_pointers = NULL;
|
|
}
|
|
info_ptr->valid &= ~PNG_INFO_IDAT;
|
|
}
|
|
#endif
|
|
|
|
if (num != -1)
|
|
mask &= ~PNG_FREE_MUL;
|
|
|
|
info_ptr->free_me &= ~mask;
|
|
}
|
|
#endif /* READ || WRITE */
|
|
|
|
/* This function returns a pointer to the io_ptr associated with the user
|
|
* 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_const_structrp 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_structrp 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_SAVE_INT_32_SUPPORTED
|
|
/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
|
|
* defines a cast of a signed integer to an unsigned integer either to preserve
|
|
* the value, if it is positive, or to calculate:
|
|
*
|
|
* (UNSIGNED_MAX+1) + integer
|
|
*
|
|
* Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
|
|
* negative integral value is added the result will be an unsigned value
|
|
* correspnding to the 2's complement representation.
|
|
*/
|
|
void PNGAPI
|
|
png_save_int_32(png_bytep buf, png_int_32 i)
|
|
{
|
|
png_save_uint_32(buf, (png_uint_32)i);
|
|
}
|
|
# 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.
|
|
*/
|
|
int PNGAPI
|
|
png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
|
|
{
|
|
static const char short_months[12][4] =
|
|
{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
|
|
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
|
|
|
|
if (out == NULL)
|
|
return 0;
|
|
|
|
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)
|
|
return 0;
|
|
|
|
{
|
|
size_t pos = 0;
|
|
char number_buf[5]; /* enough for a four-digit year */
|
|
|
|
# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
|
|
# define APPEND_NUMBER(format, value)\
|
|
APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
|
|
# define APPEND(ch) if (pos < 28) out[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 */
|
|
PNG_UNUSED (pos)
|
|
|
|
# undef APPEND
|
|
# undef APPEND_NUMBER
|
|
# undef APPEND_STRING
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
# if PNG_LIBPNG_VER < 10700
|
|
/* To do: remove the following from libpng-1.7 */
|
|
/* Original API that uses a private buffer in png_struct.
|
|
* Deprecated because it causes png_struct to carry a spurious temporary
|
|
* buffer (png_struct::time_buffer), better to have the caller pass this in.
|
|
*/
|
|
png_const_charp PNGAPI
|
|
png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
|
|
{
|
|
if (png_ptr != NULL)
|
|
{
|
|
/* The only failure above if png_ptr != NULL is from an invalid ptime */
|
|
if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
|
|
png_warning(png_ptr, "Ignoring invalid time value");
|
|
|
|
else
|
|
return png_ptr->time_buffer;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
# endif /* LIBPNG_VER < 10700 */
|
|
# endif /* TIME_RFC1123 */
|
|
|
|
#endif /* READ || WRITE */
|
|
|
|
png_const_charp PNGAPI
|
|
png_get_copyright(png_const_structrp png_ptr)
|
|
{
|
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
#ifdef PNG_STRING_COPYRIGHT
|
|
return PNG_STRING_COPYRIGHT
|
|
#else
|
|
return PNG_STRING_NEWLINE \
|
|
"libpng version 1.6.37" PNG_STRING_NEWLINE \
|
|
"Copyright (c) 2018-2019 Cosmin Truta" PNG_STRING_NEWLINE \
|
|
"Copyright (c) 1998-2002,2004,2006-2018 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;
|
|
#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_structrp 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_structrp 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_structrp 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_BUILD_GRAYSCALE_PALETTE_SUPPORTED
|
|
/* NOTE: this routine is not used internally! */
|
|
/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
|
|
* large of png_color. This lets grayscale images be treated as
|
|
* paletted. Most useful for gamma correction and simplification
|
|
* of code. This API is not used internally.
|
|
*/
|
|
void PNGAPI
|
|
png_build_grayscale_palette(int bit_depth, png_colorp palette)
|
|
{
|
|
int num_palette;
|
|
int color_inc;
|
|
int i;
|
|
int v;
|
|
|
|
png_debug(1, "in png_do_build_grayscale_palette");
|
|
|
|
if (palette == NULL)
|
|
return;
|
|
|
|
switch (bit_depth)
|
|
{
|
|
case 1:
|
|
num_palette = 2;
|
|
color_inc = 0xff;
|
|
break;
|
|
|
|
case 2:
|
|
num_palette = 4;
|
|
color_inc = 0x55;
|
|
break;
|
|
|
|
case 4:
|
|
num_palette = 16;
|
|
color_inc = 0x11;
|
|
break;
|
|
|
|
case 8:
|
|
num_palette = 256;
|
|
color_inc = 1;
|
|
break;
|
|
|
|
default:
|
|
num_palette = 0;
|
|
color_inc = 0;
|
|
break;
|
|
}
|
|
|
|
for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
|
|
{
|
|
palette[i].red = (png_byte)(v & 0xff);
|
|
palette[i].green = (png_byte)(v & 0xff);
|
|
palette[i].blue = (png_byte)(v & 0xff);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
|
|
int PNGAPI
|
|
png_handle_as_unknown(png_const_structrp 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, this is no longer
|
|
* necessary because the 'set' routine handles duplicate entries correctly.
|
|
*/
|
|
do /* num_chunk_list > 0, so at least one */
|
|
{
|
|
p -= 5;
|
|
|
|
if (memcmp(chunk_name, p, 4) == 0)
|
|
return p[4];
|
|
}
|
|
while (p > p_end);
|
|
|
|
/* This means that known chunks should be processed and unknown chunks should
|
|
* be handled according to the value of png_ptr->unknown_default; this can be
|
|
* confusing because, as a result, there are two levels of defaulting for
|
|
* unknown chunks.
|
|
*/
|
|
return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
|
}
|
|
|
|
#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
|
|
defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
|
|
int /* PRIVATE */
|
|
png_chunk_unknown_handling(png_const_structrp 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 /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
|
|
#endif /* SET_UNKNOWN_CHUNKS */
|
|
|
|
#ifdef PNG_READ_SUPPORTED
|
|
/* This function, added to libpng-1.0.6g, is untested. */
|
|
int PNGAPI
|
|
png_reset_zstream(png_structrp png_ptr)
|
|
{
|
|
if (png_ptr == NULL)
|
|
return Z_STREAM_ERROR;
|
|
|
|
/* WARNING: this resets the window bits to the maximum! */
|
|
return (inflateReset(&png_ptr->zstream));
|
|
}
|
|
#endif /* READ */
|
|
|
|
/* 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)
|
|
/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
|
|
* If it doesn't 'ret' is used to set it to something appropriate, even in cases
|
|
* like Z_OK or Z_STREAM_END where the error code is apparently a success code.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_zstream_error(png_structrp png_ptr, int ret)
|
|
{
|
|
/* Translate 'ret' into an appropriate error string, priority is given to the
|
|
* one in zstream if set. This always returns a string, even in cases like
|
|
* Z_OK or Z_STREAM_END where the error code is a success code.
|
|
*/
|
|
if (png_ptr->zstream.msg == NULL) switch (ret)
|
|
{
|
|
default:
|
|
case Z_OK:
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
|
|
break;
|
|
|
|
case Z_STREAM_END:
|
|
/* Normal exit */
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
|
|
break;
|
|
|
|
case Z_NEED_DICT:
|
|
/* This means the deflate stream did not have a dictionary; this
|
|
* indicates a bogus PNG.
|
|
*/
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
|
|
break;
|
|
|
|
case Z_ERRNO:
|
|
/* gz APIs only: should not happen */
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
|
|
break;
|
|
|
|
case Z_STREAM_ERROR:
|
|
/* internal libpng error */
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
|
|
break;
|
|
|
|
case Z_DATA_ERROR:
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
|
|
break;
|
|
|
|
case Z_MEM_ERROR:
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
|
|
break;
|
|
|
|
case Z_BUF_ERROR:
|
|
/* End of input or output; not a problem if the caller is doing
|
|
* incremental read or write.
|
|
*/
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
|
|
break;
|
|
|
|
case Z_VERSION_ERROR:
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
|
|
break;
|
|
|
|
case PNG_UNEXPECTED_ZLIB_RETURN:
|
|
/* Compile errors here mean that zlib now uses the value co-opted in
|
|
* pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
|
|
* and change pngpriv.h. Note that this message is "... return",
|
|
* whereas the default/Z_OK one is "... return code".
|
|
*/
|
|
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* 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_GAMMA_SUPPORTED /* always set if COLORSPACE */
|
|
static int
|
|
png_colorspace_check_gamma(png_const_structrp png_ptr,
|
|
png_colorspacerp colorspace, png_fixed_point gAMA, int from)
|
|
/* This is called to check a new gamma value against an existing one. The
|
|
* routine returns false if the new gamma value should not be written.
|
|
*
|
|
* 'from' says where the new gamma value comes from:
|
|
*
|
|
* 0: the new gamma value is the libpng estimate for an ICC profile
|
|
* 1: the new gamma value comes from a gAMA chunk
|
|
* 2: the new gamma value comes from an sRGB chunk
|
|
*/
|
|
{
|
|
png_fixed_point gtest;
|
|
|
|
if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
|
|
(png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
|
|
png_gamma_significant(gtest) != 0))
|
|
{
|
|
/* Either this is an sRGB image, in which case the calculated gamma
|
|
* approximation should match, or this is an image with a profile and the
|
|
* value libpng calculates for the gamma of the profile does not match the
|
|
* value recorded in the file. The former, sRGB, case is an error, the
|
|
* latter is just a warning.
|
|
*/
|
|
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
|
|
{
|
|
png_chunk_report(png_ptr, "gamma value does not match sRGB",
|
|
PNG_CHUNK_ERROR);
|
|
/* Do not overwrite an sRGB value */
|
|
return from == 2;
|
|
}
|
|
|
|
else /* sRGB tag not involved */
|
|
{
|
|
png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
|
|
PNG_CHUNK_WARNING);
|
|
return from == 1;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
void /* PRIVATE */
|
|
png_colorspace_set_gamma(png_const_structrp png_ptr,
|
|
png_colorspacerp colorspace, png_fixed_point gAMA)
|
|
{
|
|
/* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
|
|
* occur. Since the fixed point representation is asymmetrical it is
|
|
* possible for 1/gamma to overflow the limit of 21474 and this means the
|
|
* gamma value must be at least 5/100000 and hence at most 20000.0. For
|
|
* safety the limits here are a little narrower. The values are 0.00016 to
|
|
* 6250.0, which are truly ridiculous gamma values (and will produce
|
|
* displays that are all black or all white.)
|
|
*
|
|
* In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
|
|
* handling code, which only required the value to be >0.
|
|
*/
|
|
png_const_charp errmsg;
|
|
|
|
if (gAMA < 16 || gAMA > 625000000)
|
|
errmsg = "gamma value out of range";
|
|
|
|
# ifdef PNG_READ_gAMA_SUPPORTED
|
|
/* Allow the application to set the gamma value more than once */
|
|
else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
|
|
(colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
|
|
errmsg = "duplicate";
|
|
# endif
|
|
|
|
/* Do nothing if the colorspace is already invalid */
|
|
else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
|
return;
|
|
|
|
else
|
|
{
|
|
if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
|
|
1/*from gAMA*/) != 0)
|
|
{
|
|
/* Store this gamma value. */
|
|
colorspace->gamma = gAMA;
|
|
colorspace->flags |=
|
|
(PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
|
|
}
|
|
|
|
/* At present if the check_gamma test fails the gamma of the colorspace is
|
|
* not updated however the colorspace is not invalidated. This
|
|
* corresponds to the case where the existing gamma comes from an sRGB
|
|
* chunk or profile. An error message has already been output.
|
|
*/
|
|
return;
|
|
}
|
|
|
|
/* Error exit - errmsg has been set. */
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
|
|
}
|
|
|
|
void /* PRIVATE */
|
|
png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
|
|
{
|
|
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
|
|
{
|
|
/* Everything is invalid */
|
|
info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
|
|
PNG_INFO_iCCP);
|
|
|
|
# ifdef PNG_COLORSPACE_SUPPORTED
|
|
/* Clean up the iCCP profile now if it won't be used. */
|
|
png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
|
|
# else
|
|
PNG_UNUSED(png_ptr)
|
|
# endif
|
|
}
|
|
|
|
else
|
|
{
|
|
# ifdef PNG_COLORSPACE_SUPPORTED
|
|
/* Leave the INFO_iCCP flag set if the pngset.c code has already set
|
|
* it; this allows a PNG to contain a profile which matches sRGB and
|
|
* yet still have that profile retrievable by the application.
|
|
*/
|
|
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
|
|
info_ptr->valid |= PNG_INFO_sRGB;
|
|
|
|
else
|
|
info_ptr->valid &= ~PNG_INFO_sRGB;
|
|
|
|
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
|
info_ptr->valid |= PNG_INFO_cHRM;
|
|
|
|
else
|
|
info_ptr->valid &= ~PNG_INFO_cHRM;
|
|
# endif
|
|
|
|
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
|
|
info_ptr->valid |= PNG_INFO_gAMA;
|
|
|
|
else
|
|
info_ptr->valid &= ~PNG_INFO_gAMA;
|
|
}
|
|
}
|
|
|
|
#ifdef PNG_READ_SUPPORTED
|
|
void /* PRIVATE */
|
|
png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
|
|
{
|
|
if (info_ptr == NULL) /* reduce code size; check here not in the caller */
|
|
return;
|
|
|
|
info_ptr->colorspace = png_ptr->colorspace;
|
|
png_colorspace_sync_info(png_ptr, info_ptr);
|
|
}
|
|
#endif
|
|
#endif /* GAMMA */
|
|
|
|
#ifdef PNG_COLORSPACE_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.
|
|
*/
|
|
static int
|
|
png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
|
|
{
|
|
png_int_32 d, dwhite, whiteX, whiteY;
|
|
|
|
d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
|
|
if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
|
|
return 1;
|
|
if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
|
|
return 1;
|
|
dwhite = d;
|
|
whiteX = XYZ->red_X;
|
|
whiteY = XYZ->red_Y;
|
|
|
|
d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
|
|
if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
|
|
return 1;
|
|
if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
|
|
return 1;
|
|
dwhite += d;
|
|
whiteX += XYZ->green_X;
|
|
whiteY += XYZ->green_Y;
|
|
|
|
d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
|
|
if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
|
|
return 1;
|
|
if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
|
|
return 1;
|
|
dwhite += d;
|
|
whiteX += XYZ->blue_X;
|
|
whiteY += XYZ->blue_Y;
|
|
|
|
/* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
|
|
* thus:
|
|
*/
|
|
if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
|
|
return 1;
|
|
if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
png_XYZ_from_xy(png_XYZ *XYZ, const 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). We check
|
|
* xy->whitey against 5, not 0, to avoid a possible integer overflow.
|
|
*/
|
|
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 < 5 || 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 inversion 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) == 0)
|
|
return 2;
|
|
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
|
|
return 2;
|
|
denominator = left - right;
|
|
|
|
/* Now find the red numerator. */
|
|
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
|
|
return 2;
|
|
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
|
|
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) == 0 ||
|
|
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) == 0)
|
|
return 2;
|
|
if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
|
|
return 2;
|
|
if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
|
|
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->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
|
|
red_inverse) == 0)
|
|
return 1;
|
|
|
|
if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
|
|
green_inverse) == 0)
|
|
return 1;
|
|
|
|
if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
|
|
PNG_FP_1) == 0)
|
|
return 1;
|
|
|
|
return 0; /*success*/
|
|
}
|
|
|
|
static int
|
|
png_XYZ_normalize(png_XYZ *XYZ)
|
|
{
|
|
png_int_32 Y;
|
|
|
|
if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
|
|
XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
|
|
XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
|
|
return 1;
|
|
|
|
/* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
|
|
* IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
|
|
* relying on addition of two positive values producing a negative one is not
|
|
* safe.
|
|
*/
|
|
Y = XYZ->red_Y;
|
|
if (0x7fffffff - Y < XYZ->green_X)
|
|
return 1;
|
|
Y += XYZ->green_Y;
|
|
if (0x7fffffff - Y < XYZ->blue_X)
|
|
return 1;
|
|
Y += XYZ->blue_Y;
|
|
|
|
if (Y != PNG_FP_1)
|
|
{
|
|
if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
|
|
if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
|
|
if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
|
|
{
|
|
/* Allow an error of +/-0.01 (absolute value) on each chromaticity */
|
|
if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
|
|
PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
|
|
* chunk chromaticities. Earlier checks used to simply look for the overflow
|
|
* condition (where the determinant of the matrix to solve for XYZ ends up zero
|
|
* because the chromaticity values are not all distinct.) Despite this it is
|
|
* theoretically possible to produce chromaticities that are apparently valid
|
|
* but that rapidly degrade to invalid, potentially crashing, sets because of
|
|
* arithmetic inaccuracies when calculations are performed on them. The new
|
|
* check is to round-trip xy -> XYZ -> xy and then check that the result is
|
|
* within a small percentage of the original.
|
|
*/
|
|
static int
|
|
png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
|
|
{
|
|
int result;
|
|
png_xy xy_test;
|
|
|
|
/* As a side-effect this routine also returns the XYZ endpoints. */
|
|
result = png_XYZ_from_xy(XYZ, xy);
|
|
if (result != 0)
|
|
return result;
|
|
|
|
result = png_xy_from_XYZ(&xy_test, XYZ);
|
|
if (result != 0)
|
|
return result;
|
|
|
|
if (png_colorspace_endpoints_match(xy, &xy_test,
|
|
5/*actually, the math is pretty accurate*/) != 0)
|
|
return 0;
|
|
|
|
/* Too much slip */
|
|
return 1;
|
|
}
|
|
|
|
/* This is the check going the other way. The XYZ is modified to normalize it
|
|
* (another side-effect) and the xy chromaticities are returned.
|
|
*/
|
|
static int
|
|
png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
|
|
{
|
|
int result;
|
|
png_XYZ XYZtemp;
|
|
|
|
result = png_XYZ_normalize(XYZ);
|
|
if (result != 0)
|
|
return result;
|
|
|
|
result = png_xy_from_XYZ(xy, XYZ);
|
|
if (result != 0)
|
|
return result;
|
|
|
|
XYZtemp = *XYZ;
|
|
return png_colorspace_check_xy(&XYZtemp, xy);
|
|
}
|
|
|
|
/* Used to check for an endpoint match against sRGB */
|
|
static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
|
|
{
|
|
/* color x y */
|
|
/* red */ 64000, 33000,
|
|
/* green */ 30000, 60000,
|
|
/* blue */ 15000, 6000,
|
|
/* white */ 31270, 32900
|
|
};
|
|
|
|
static int
|
|
png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
|
|
png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
|
|
int preferred)
|
|
{
|
|
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
|
return 0;
|
|
|
|
/* The consistency check is performed on the chromaticities; this factors out
|
|
* variations because of the normalization (or not) of the end point Y
|
|
* values.
|
|
*/
|
|
if (preferred < 2 &&
|
|
(colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
|
{
|
|
/* The end points must be reasonably close to any we already have. The
|
|
* following allows an error of up to +/-.001
|
|
*/
|
|
if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
|
|
100) == 0)
|
|
{
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
png_benign_error(png_ptr, "inconsistent chromaticities");
|
|
return 0; /* failed */
|
|
}
|
|
|
|
/* Only overwrite with preferred values */
|
|
if (preferred == 0)
|
|
return 1; /* ok, but no change */
|
|
}
|
|
|
|
colorspace->end_points_xy = *xy;
|
|
colorspace->end_points_XYZ = *XYZ;
|
|
colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
|
|
|
|
/* The end points are normally quoted to two decimal digits, so allow +/-0.01
|
|
* on this test.
|
|
*/
|
|
if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
|
|
colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
|
|
|
|
else
|
|
colorspace->flags &= PNG_COLORSPACE_CANCEL(
|
|
PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
|
|
|
|
return 2; /* ok and changed */
|
|
}
|
|
|
|
int /* PRIVATE */
|
|
png_colorspace_set_chromaticities(png_const_structrp png_ptr,
|
|
png_colorspacerp colorspace, const png_xy *xy, int preferred)
|
|
{
|
|
/* We must check the end points to ensure they are reasonable - in the past
|
|
* color management systems have crashed as a result of getting bogus
|
|
* colorant values, while this isn't the fault of libpng it is the
|
|
* responsibility of libpng because PNG carries the bomb and libpng is in a
|
|
* position to protect against it.
|
|
*/
|
|
png_XYZ XYZ;
|
|
|
|
switch (png_colorspace_check_xy(&XYZ, xy))
|
|
{
|
|
case 0: /* success */
|
|
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
|
|
preferred);
|
|
|
|
case 1:
|
|
/* We can't invert the chromaticities so we can't produce value XYZ
|
|
* values. Likely as not a color management system will fail too.
|
|
*/
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
png_benign_error(png_ptr, "invalid chromaticities");
|
|
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.
|
|
*/
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
png_error(png_ptr, "internal error checking chromaticities");
|
|
}
|
|
|
|
return 0; /* failed */
|
|
}
|
|
|
|
int /* PRIVATE */
|
|
png_colorspace_set_endpoints(png_const_structrp png_ptr,
|
|
png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
|
|
{
|
|
png_XYZ XYZ = *XYZ_in;
|
|
png_xy xy;
|
|
|
|
switch (png_colorspace_check_XYZ(&xy, &XYZ))
|
|
{
|
|
case 0:
|
|
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
|
|
preferred);
|
|
|
|
case 1:
|
|
/* End points are invalid. */
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
png_benign_error(png_ptr, "invalid end points");
|
|
break;
|
|
|
|
default:
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
png_error(png_ptr, "internal error checking chromaticities");
|
|
}
|
|
|
|
return 0; /* failed */
|
|
}
|
|
|
|
#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
|
|
/* Error message generation */
|
|
static char
|
|
png_icc_tag_char(png_uint_32 byte)
|
|
{
|
|
byte &= 0xff;
|
|
if (byte >= 32 && byte <= 126)
|
|
return (char)byte;
|
|
else
|
|
return '?';
|
|
}
|
|
|
|
static void
|
|
png_icc_tag_name(char *name, png_uint_32 tag)
|
|
{
|
|
name[0] = '\'';
|
|
name[1] = png_icc_tag_char(tag >> 24);
|
|
name[2] = png_icc_tag_char(tag >> 16);
|
|
name[3] = png_icc_tag_char(tag >> 8);
|
|
name[4] = png_icc_tag_char(tag );
|
|
name[5] = '\'';
|
|
}
|
|
|
|
static int
|
|
is_ICC_signature_char(png_alloc_size_t it)
|
|
{
|
|
return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
|
|
(it >= 97 && it <= 122);
|
|
}
|
|
|
|
static int
|
|
is_ICC_signature(png_alloc_size_t it)
|
|
{
|
|
return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
|
|
is_ICC_signature_char((it >> 16) & 0xff) &&
|
|
is_ICC_signature_char((it >> 8) & 0xff) &&
|
|
is_ICC_signature_char(it & 0xff);
|
|
}
|
|
|
|
static int
|
|
png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
png_const_charp name, png_alloc_size_t value, png_const_charp reason)
|
|
{
|
|
size_t pos;
|
|
char message[196]; /* see below for calculation */
|
|
|
|
if (colorspace != NULL)
|
|
colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
|
pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
|
|
pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
|
|
pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
|
|
if (is_ICC_signature(value) != 0)
|
|
{
|
|
/* So 'value' is at most 4 bytes and the following cast is safe */
|
|
png_icc_tag_name(message+pos, (png_uint_32)value);
|
|
pos += 6; /* total +8; less than the else clause */
|
|
message[pos++] = ':';
|
|
message[pos++] = ' ';
|
|
}
|
|
# ifdef PNG_WARNINGS_SUPPORTED
|
|
else
|
|
{
|
|
char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
|
|
|
|
pos = png_safecat(message, (sizeof message), pos,
|
|
png_format_number(number, number+(sizeof number),
|
|
PNG_NUMBER_FORMAT_x, value));
|
|
pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
|
|
}
|
|
# endif
|
|
/* The 'reason' is an arbitrary message, allow +79 maximum 195 */
|
|
pos = png_safecat(message, (sizeof message), pos, reason);
|
|
PNG_UNUSED(pos)
|
|
|
|
/* This is recoverable, but make it unconditionally an app_error on write to
|
|
* avoid writing invalid ICC profiles into PNG files (i.e., we handle them
|
|
* on read, with a warning, but on write unless the app turns off
|
|
* application errors the PNG won't be written.)
|
|
*/
|
|
png_chunk_report(png_ptr, message,
|
|
(colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
|
|
|
|
return 0;
|
|
}
|
|
#endif /* sRGB || iCCP */
|
|
|
|
#ifdef PNG_sRGB_SUPPORTED
|
|
int /* PRIVATE */
|
|
png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
int intent)
|
|
{
|
|
/* sRGB sets known gamma, end points and (from the chunk) intent. */
|
|
/* IMPORTANT: these are not necessarily the values found in an ICC profile
|
|
* because ICC profiles store values adapted to a D50 environment; it is
|
|
* expected that the ICC profile mediaWhitePointTag will be D50; see the
|
|
* checks and code elsewhere to understand this better.
|
|
*
|
|
* These XYZ values, which are accurate to 5dp, produce rgb to gray
|
|
* coefficients of (6968,23435,2366), which are reduced (because they add up
|
|
* to 32769 not 32768) to (6968,23434,2366). These are the values that
|
|
* libpng has traditionally used (and are the best values given the 15bit
|
|
* algorithm used by the rgb to gray code.)
|
|
*/
|
|
static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
|
|
{
|
|
/* color X Y Z */
|
|
/* red */ 41239, 21264, 1933,
|
|
/* green */ 35758, 71517, 11919,
|
|
/* blue */ 18048, 7219, 95053
|
|
};
|
|
|
|
/* Do nothing if the colorspace is already invalidated. */
|
|
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
|
return 0;
|
|
|
|
/* Check the intent, then check for existing settings. It is valid for the
|
|
* PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
|
|
* be consistent with the correct values. If, however, this function is
|
|
* called below because an iCCP chunk matches sRGB then it is quite
|
|
* conceivable that an older app recorded incorrect gAMA and cHRM because of
|
|
* an incorrect calculation based on the values in the profile - this does
|
|
* *not* invalidate the profile (though it still produces an error, which can
|
|
* be ignored.)
|
|
*/
|
|
if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
|
|
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
|
|
(png_alloc_size_t)intent, "invalid sRGB rendering intent");
|
|
|
|
if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
|
|
colorspace->rendering_intent != intent)
|
|
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
|
|
(png_alloc_size_t)intent, "inconsistent rendering intents");
|
|
|
|
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
|
|
{
|
|
png_benign_error(png_ptr, "duplicate sRGB information ignored");
|
|
return 0;
|
|
}
|
|
|
|
/* If the standard sRGB cHRM chunk does not match the one from the PNG file
|
|
* warn but overwrite the value with the correct one.
|
|
*/
|
|
if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
|
|
!png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
|
|
100))
|
|
png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
|
|
PNG_CHUNK_ERROR);
|
|
|
|
/* This check is just done for the error reporting - the routine always
|
|
* returns true when the 'from' argument corresponds to sRGB (2).
|
|
*/
|
|
(void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
|
|
2/*from sRGB*/);
|
|
|
|
/* intent: bugs in GCC force 'int' to be used as the parameter type. */
|
|
colorspace->rendering_intent = (png_uint_16)intent;
|
|
colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
|
|
|
|
/* endpoints */
|
|
colorspace->end_points_xy = sRGB_xy;
|
|
colorspace->end_points_XYZ = sRGB_XYZ;
|
|
colorspace->flags |=
|
|
(PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
|
|
|
|
/* gamma */
|
|
colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
|
|
colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
|
|
|
|
/* Finally record that we have an sRGB profile */
|
|
colorspace->flags |=
|
|
(PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
|
|
|
|
return 1; /* set */
|
|
}
|
|
#endif /* sRGB */
|
|
|
|
#ifdef PNG_iCCP_SUPPORTED
|
|
/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
|
|
* is XYZ(0.9642,1.0,0.8249), which scales to:
|
|
*
|
|
* (63189.8112, 65536, 54060.6464)
|
|
*/
|
|
static const png_byte D50_nCIEXYZ[12] =
|
|
{ 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
|
|
|
|
static int /* bool */
|
|
icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
png_const_charp name, png_uint_32 profile_length)
|
|
{
|
|
if (profile_length < 132)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
"too short");
|
|
return 1;
|
|
}
|
|
|
|
#ifdef PNG_READ_iCCP_SUPPORTED
|
|
int /* PRIVATE */
|
|
png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
png_const_charp name, png_uint_32 profile_length)
|
|
{
|
|
if (!icc_check_length(png_ptr, colorspace, name, profile_length))
|
|
return 0;
|
|
|
|
/* This needs to be here because the 'normal' check is in
|
|
* png_decompress_chunk, yet this happens after the attempt to
|
|
* png_malloc_base the required data. We only need this on read; on write
|
|
* the caller supplies the profile buffer so libpng doesn't allocate it. See
|
|
* the call to icc_check_length below (the write case).
|
|
*/
|
|
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
|
|
else if (png_ptr->user_chunk_malloc_max > 0 &&
|
|
png_ptr->user_chunk_malloc_max < profile_length)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
"exceeds application limits");
|
|
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
|
|
else if (PNG_USER_CHUNK_MALLOC_MAX < profile_length)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
"exceeds libpng limits");
|
|
# else /* !SET_USER_LIMITS */
|
|
/* This will get compiled out on all 32-bit and better systems. */
|
|
else if (PNG_SIZE_MAX < profile_length)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
"exceeds system limits");
|
|
# endif /* !SET_USER_LIMITS */
|
|
|
|
return 1;
|
|
}
|
|
#endif /* READ_iCCP */
|
|
|
|
int /* PRIVATE */
|
|
png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
png_const_charp name, png_uint_32 profile_length,
|
|
png_const_bytep profile/* first 132 bytes only */, int color_type)
|
|
{
|
|
png_uint_32 temp;
|
|
|
|
/* Length check; this cannot be ignored in this code because profile_length
|
|
* is used later to check the tag table, so even if the profile seems over
|
|
* long profile_length from the caller must be correct. The caller can fix
|
|
* this up on read or write by just passing in the profile header length.
|
|
*/
|
|
temp = png_get_uint_32(profile);
|
|
if (temp != profile_length)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"length does not match profile");
|
|
|
|
temp = (png_uint_32) (*(profile+8));
|
|
if (temp > 3 && (profile_length & 3))
|
|
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
"invalid length");
|
|
|
|
temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
|
|
if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
|
|
profile_length < 132+12*temp) /* truncated tag table */
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"tag count too large");
|
|
|
|
/* The 'intent' must be valid or we can't store it, ICC limits the intent to
|
|
* 16 bits.
|
|
*/
|
|
temp = png_get_uint_32(profile+64);
|
|
if (temp >= 0xffff) /* The ICC limit */
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"invalid rendering intent");
|
|
|
|
/* This is just a warning because the profile may be valid in future
|
|
* versions.
|
|
*/
|
|
if (temp >= PNG_sRGB_INTENT_LAST)
|
|
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
|
"intent outside defined range");
|
|
|
|
/* At this point the tag table can't be checked because it hasn't necessarily
|
|
* been loaded; however, various header fields can be checked. These checks
|
|
* are for values permitted by the PNG spec in an ICC profile; the PNG spec
|
|
* restricts the profiles that can be passed in an iCCP chunk (they must be
|
|
* appropriate to processing PNG data!)
|
|
*/
|
|
|
|
/* Data checks (could be skipped). These checks must be independent of the
|
|
* version number; however, the version number doesn't accommodate changes in
|
|
* the header fields (just the known tags and the interpretation of the
|
|
* data.)
|
|
*/
|
|
temp = png_get_uint_32(profile+36); /* signature 'ascp' */
|
|
if (temp != 0x61637370)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"invalid signature");
|
|
|
|
/* Currently the PCS illuminant/adopted white point (the computational
|
|
* white point) are required to be D50,
|
|
* however the profile contains a record of the illuminant so perhaps ICC
|
|
* expects to be able to change this in the future (despite the rationale in
|
|
* the introduction for using a fixed PCS adopted white.) Consequently the
|
|
* following is just a warning.
|
|
*/
|
|
if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
|
|
(void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
|
|
"PCS illuminant is not D50");
|
|
|
|
/* The PNG spec requires this:
|
|
* "If the iCCP chunk is present, the image samples conform to the colour
|
|
* space represented by the embedded ICC profile as defined by the
|
|
* International Color Consortium [ICC]. The colour space of the ICC profile
|
|
* shall be an RGB colour space for colour images (PNG colour types 2, 3, and
|
|
* 6), or a greyscale colour space for greyscale images (PNG colour types 0
|
|
* and 4)."
|
|
*
|
|
* This checking code ensures the embedded profile (on either read or write)
|
|
* conforms to the specification requirements. Notice that an ICC 'gray'
|
|
* color-space profile contains the information to transform the monochrome
|
|
* data to XYZ or L*a*b (according to which PCS the profile uses) and this
|
|
* should be used in preference to the standard libpng K channel replication
|
|
* into R, G and B channels.
|
|
*
|
|
* Previously it was suggested that an RGB profile on grayscale data could be
|
|
* handled. However it it is clear that using an RGB profile in this context
|
|
* must be an error - there is no specification of what it means. Thus it is
|
|
* almost certainly more correct to ignore the profile.
|
|
*/
|
|
temp = png_get_uint_32(profile+16); /* data colour space field */
|
|
switch (temp)
|
|
{
|
|
case 0x52474220: /* 'RGB ' */
|
|
if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"RGB color space not permitted on grayscale PNG");
|
|
break;
|
|
|
|
case 0x47524159: /* 'GRAY' */
|
|
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"Gray color space not permitted on RGB PNG");
|
|
break;
|
|
|
|
default:
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"invalid ICC profile color space");
|
|
}
|
|
|
|
/* It is up to the application to check that the profile class matches the
|
|
* application requirements; the spec provides no guidance, but it's pretty
|
|
* weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
|
|
* ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
|
|
* cases. Issue an error for device link or abstract profiles - these don't
|
|
* contain the records necessary to transform the color-space to anything
|
|
* other than the target device (and not even that for an abstract profile).
|
|
* Profiles of these classes may not be embedded in images.
|
|
*/
|
|
temp = png_get_uint_32(profile+12); /* profile/device class */
|
|
switch (temp)
|
|
{
|
|
case 0x73636e72: /* 'scnr' */
|
|
case 0x6d6e7472: /* 'mntr' */
|
|
case 0x70727472: /* 'prtr' */
|
|
case 0x73706163: /* 'spac' */
|
|
/* All supported */
|
|
break;
|
|
|
|
case 0x61627374: /* 'abst' */
|
|
/* May not be embedded in an image */
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"invalid embedded Abstract ICC profile");
|
|
|
|
case 0x6c696e6b: /* 'link' */
|
|
/* DeviceLink profiles cannot be interpreted in a non-device specific
|
|
* fashion, if an app uses the AToB0Tag in the profile the results are
|
|
* undefined unless the result is sent to the intended device,
|
|
* therefore a DeviceLink profile should not be found embedded in a
|
|
* PNG.
|
|
*/
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"unexpected DeviceLink ICC profile class");
|
|
|
|
case 0x6e6d636c: /* 'nmcl' */
|
|
/* A NamedColor profile is also device specific, however it doesn't
|
|
* contain an AToB0 tag that is open to misinterpretation. Almost
|
|
* certainly it will fail the tests below.
|
|
*/
|
|
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
|
"unexpected NamedColor ICC profile class");
|
|
break;
|
|
|
|
default:
|
|
/* To allow for future enhancements to the profile accept unrecognized
|
|
* profile classes with a warning, these then hit the test below on the
|
|
* tag content to ensure they are backward compatible with one of the
|
|
* understood profiles.
|
|
*/
|
|
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
|
"unrecognized ICC profile class");
|
|
break;
|
|
}
|
|
|
|
/* For any profile other than a device link one the PCS must be encoded
|
|
* either in XYZ or Lab.
|
|
*/
|
|
temp = png_get_uint_32(profile+20);
|
|
switch (temp)
|
|
{
|
|
case 0x58595a20: /* 'XYZ ' */
|
|
case 0x4c616220: /* 'Lab ' */
|
|
break;
|
|
|
|
default:
|
|
return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
"unexpected ICC PCS encoding");
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
int /* PRIVATE */
|
|
png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
png_const_charp name, png_uint_32 profile_length,
|
|
png_const_bytep profile /* header plus whole tag table */)
|
|
{
|
|
png_uint_32 tag_count = png_get_uint_32(profile+128);
|
|
png_uint_32 itag;
|
|
png_const_bytep tag = profile+132; /* The first tag */
|
|
|
|
/* First scan all the tags in the table and add bits to the icc_info value
|
|
* (temporarily in 'tags').
|
|
*/
|
|
for (itag=0; itag < tag_count; ++itag, tag += 12)
|
|
{
|
|
png_uint_32 tag_id = png_get_uint_32(tag+0);
|
|
png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
|
|
png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
|
|
|
|
/* The ICC specification does not exclude zero length tags, therefore the
|
|
* start might actually be anywhere if there is no data, but this would be
|
|
* a clear abuse of the intent of the standard so the start is checked for
|
|
* being in range. All defined tag types have an 8 byte header - a 4 byte
|
|
* type signature then 0.
|
|
*/
|
|
|
|
/* This is a hard error; potentially it can cause read outside the
|
|
* profile.
|
|
*/
|
|
if (tag_start > profile_length || tag_length > profile_length - tag_start)
|
|
return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
|
|
"ICC profile tag outside profile");
|
|
|
|
if ((tag_start & 3) != 0)
|
|
{
|
|
/* CNHP730S.icc shipped with Microsoft Windows 64 violates this; it is
|
|
* only a warning here because libpng does not care about the
|
|
* alignment.
|
|
*/
|
|
(void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
|
|
"ICC profile tag start not a multiple of 4");
|
|
}
|
|
}
|
|
|
|
return 1; /* success, maybe with warnings */
|
|
}
|
|
|
|
#ifdef PNG_sRGB_SUPPORTED
|
|
#if PNG_sRGB_PROFILE_CHECKS >= 0
|
|
/* Information about the known ICC sRGB profiles */
|
|
static const struct
|
|
{
|
|
png_uint_32 adler, crc, length;
|
|
png_uint_32 md5[4];
|
|
png_byte have_md5;
|
|
png_byte is_broken;
|
|
png_uint_16 intent;
|
|
|
|
# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
|
|
# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
|
|
{ adler, crc, length, md5, broke, intent },
|
|
|
|
} png_sRGB_checks[] =
|
|
{
|
|
/* This data comes from contrib/tools/checksum-icc run on downloads of
|
|
* all four ICC sRGB profiles from www.color.org.
|
|
*/
|
|
/* adler32, crc32, MD5[4], intent, date, length, file-name */
|
|
PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
|
|
PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
|
|
"2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
|
|
|
|
/* ICC sRGB v2 perceptual no black-compensation: */
|
|
PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
|
|
PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
|
|
"2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
|
|
|
|
PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
|
|
PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
|
|
"2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
|
|
|
|
/* ICC sRGB v4 perceptual */
|
|
PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
|
|
PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
|
|
"2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
|
|
|
|
/* The following profiles have no known MD5 checksum. If there is a match
|
|
* on the (empty) MD5 the other fields are used to attempt a match and
|
|
* a warning is produced. The first two of these profiles have a 'cprt' tag
|
|
* which suggests that they were also made by Hewlett Packard.
|
|
*/
|
|
PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
|
|
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
|
|
"2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
|
|
|
|
/* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
|
|
* match the D50 PCS illuminant in the header (it is in fact the D65 values,
|
|
* so the white point is recorded as the un-adapted value.) The profiles
|
|
* below only differ in one byte - the intent - and are basically the same as
|
|
* the previous profile except for the mediaWhitePointTag error and a missing
|
|
* chromaticAdaptationTag.
|
|
*/
|
|
PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
|
|
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
|
|
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
|
|
|
|
PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
|
|
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
|
|
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
|
|
};
|
|
|
|
static int
|
|
png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
|
|
png_const_bytep profile, uLong adler)
|
|
{
|
|
/* The quick check is to verify just the MD5 signature and trust the
|
|
* rest of the data. Because the profile has already been verified for
|
|
* correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
|
|
* field too, so if the profile has been edited with an intent not defined
|
|
* by sRGB (but maybe defined by a later ICC specification) the read of
|
|
* the profile will fail at that point.
|
|
*/
|
|
|
|
png_uint_32 length = 0;
|
|
png_uint_32 intent = 0x10000; /* invalid */
|
|
#if PNG_sRGB_PROFILE_CHECKS > 1
|
|
uLong crc = 0; /* the value for 0 length data */
|
|
#endif
|
|
unsigned int i;
|
|
|
|
#ifdef PNG_SET_OPTION_SUPPORTED
|
|
/* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
|
|
if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
|
|
PNG_OPTION_ON)
|
|
return 0;
|
|
#endif
|
|
|
|
for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
|
|
{
|
|
if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
|
|
png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
|
|
png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
|
|
png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
|
|
{
|
|
/* This may be one of the old HP profiles without an MD5, in that
|
|
* case we can only use the length and Adler32 (note that these
|
|
* are not used by default if there is an MD5!)
|
|
*/
|
|
# if PNG_sRGB_PROFILE_CHECKS == 0
|
|
if (png_sRGB_checks[i].have_md5 != 0)
|
|
return 1+png_sRGB_checks[i].is_broken;
|
|
# endif
|
|
|
|
/* Profile is unsigned or more checks have been configured in. */
|
|
if (length == 0)
|
|
{
|
|
length = png_get_uint_32(profile);
|
|
intent = png_get_uint_32(profile+64);
|
|
}
|
|
|
|
/* Length *and* intent must match */
|
|
if (length == (png_uint_32) png_sRGB_checks[i].length &&
|
|
intent == (png_uint_32) png_sRGB_checks[i].intent)
|
|
{
|
|
/* Now calculate the adler32 if not done already. */
|
|
if (adler == 0)
|
|
{
|
|
adler = adler32(0, NULL, 0);
|
|
adler = adler32(adler, profile, length);
|
|
}
|
|
|
|
if (adler == png_sRGB_checks[i].adler)
|
|
{
|
|
/* These basic checks suggest that the data has not been
|
|
* modified, but if the check level is more than 1 perform
|
|
* our own crc32 checksum on the data.
|
|
*/
|
|
# if PNG_sRGB_PROFILE_CHECKS > 1
|
|
if (crc == 0)
|
|
{
|
|
crc = crc32(0, NULL, 0);
|
|
crc = crc32(crc, profile, length);
|
|
}
|
|
|
|
/* So this check must pass for the 'return' below to happen.
|
|
*/
|
|
if (crc == png_sRGB_checks[i].crc)
|
|
# endif
|
|
{
|
|
if (png_sRGB_checks[i].is_broken != 0)
|
|
{
|
|
/* These profiles are known to have bad data that may cause
|
|
* problems if they are used, therefore attempt to
|
|
* discourage their use, skip the 'have_md5' warning below,
|
|
* which is made irrelevant by this error.
|
|
*/
|
|
png_chunk_report(png_ptr, "known incorrect sRGB profile",
|
|
PNG_CHUNK_ERROR);
|
|
}
|
|
|
|
/* Warn that this being done; this isn't even an error since
|
|
* the profile is perfectly valid, but it would be nice if
|
|
* people used the up-to-date ones.
|
|
*/
|
|
else if (png_sRGB_checks[i].have_md5 == 0)
|
|
{
|
|
png_chunk_report(png_ptr,
|
|
"out-of-date sRGB profile with no signature",
|
|
PNG_CHUNK_WARNING);
|
|
}
|
|
|
|
return 1+png_sRGB_checks[i].is_broken;
|
|
}
|
|
}
|
|
|
|
# if PNG_sRGB_PROFILE_CHECKS > 0
|
|
/* The signature matched, but the profile had been changed in some
|
|
* way. This probably indicates a data error or uninformed hacking.
|
|
* Fall through to "no match".
|
|
*/
|
|
png_chunk_report(png_ptr,
|
|
"Not recognizing known sRGB profile that has been edited",
|
|
PNG_CHUNK_WARNING);
|
|
break;
|
|
# endif
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0; /* no match */
|
|
}
|
|
|
|
void /* PRIVATE */
|
|
png_icc_set_sRGB(png_const_structrp png_ptr,
|
|
png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
|
|
{
|
|
/* Is this profile one of the known ICC sRGB profiles? If it is, just set
|
|
* the sRGB information.
|
|
*/
|
|
if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
|
|
(void)png_colorspace_set_sRGB(png_ptr, colorspace,
|
|
(int)/*already checked*/png_get_uint_32(profile+64));
|
|
}
|
|
#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
|
|
#endif /* sRGB */
|
|
|
|
int /* PRIVATE */
|
|
png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
|
|
int color_type)
|
|
{
|
|
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
|
|
return 0;
|
|
|
|
if (icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
|
|
png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
|
|
color_type) != 0 &&
|
|
png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
|
|
profile) != 0)
|
|
{
|
|
# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
|
|
/* If no sRGB support, don't try storing sRGB information */
|
|
png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
|
|
# endif
|
|
return 1;
|
|
}
|
|
|
|
/* Failure case */
|
|
return 0;
|
|
}
|
|
#endif /* iCCP */
|
|
|
|
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
|
|
void /* PRIVATE */
|
|
png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
|
|
{
|
|
/* Set the rgb_to_gray coefficients from the colorspace. */
|
|
if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
|
|
(png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
|
{
|
|
/* png_set_background has not been called, get the coefficients from the Y
|
|
* values of the colorspace colorants.
|
|
*/
|
|
png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
|
|
png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
|
|
png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
|
|
png_fixed_point total = r+g+b;
|
|
|
|
if (total > 0 &&
|
|
r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
|
|
g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
|
|
b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
|
|
r+g+b <= 32769)
|
|
{
|
|
/* We allow 0 coefficients here. r+g+b may be 32769 if two or
|
|
* all of the coefficients were rounded up. Handle this by
|
|
* reducing the *largest* coefficient by 1; this matches the
|
|
* approach used for the default coefficients in pngrtran.c
|
|
*/
|
|
int add = 0;
|
|
|
|
if (r+g+b > 32768)
|
|
add = -1;
|
|
else if (r+g+b < 32768)
|
|
add = 1;
|
|
|
|
if (add != 0)
|
|
{
|
|
if (g >= r && g >= b)
|
|
g += add;
|
|
else if (r >= g && r >= b)
|
|
r += add;
|
|
else
|
|
b += add;
|
|
}
|
|
|
|
/* Check for an internal error. */
|
|
if (r+g+b != 32768)
|
|
png_error(png_ptr,
|
|
"internal error handling cHRM coefficients");
|
|
|
|
else
|
|
{
|
|
png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
|
|
png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
|
|
}
|
|
}
|
|
|
|
/* This is a png_error at present even though it could be ignored -
|
|
* it should never happen, but it is important that if it does, the
|
|
* bug is fixed.
|
|
*/
|
|
else
|
|
png_error(png_ptr, "internal error handling cHRM->XYZ");
|
|
}
|
|
}
|
|
#endif /* READ_RGB_TO_GRAY */
|
|
|
|
#endif /* COLORSPACE */
|
|
|
|
#ifdef __GNUC__
|
|
/* This exists solely to work round a warning from GNU C. */
|
|
static int /* PRIVATE */
|
|
png_gt(size_t a, size_t b)
|
|
{
|
|
return a > b;
|
|
}
|
|
#else
|
|
# define png_gt(a,b) ((a) > (b))
|
|
#endif
|
|
|
|
void /* PRIVATE */
|
|
png_check_IHDR(png_const_structrp 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 (width > PNG_UINT_31_MAX)
|
|
{
|
|
png_warning(png_ptr, "Invalid image width in IHDR");
|
|
error = 1;
|
|
}
|
|
|
|
if (png_gt(((width + 7) & (~7U)),
|
|
((PNG_SIZE_MAX
|
|
- 48 /* big_row_buf hack */
|
|
- 1) /* filter byte */
|
|
/ 8) /* 8-byte RGBA pixels */
|
|
- 1)) /* extra max_pixel_depth pad */
|
|
{
|
|
/* The size of the row must be within the limits of this architecture.
|
|
* Because the read code can perform arbitrary transformations the
|
|
* maximum size is checked here. Because the code in png_read_start_row
|
|
* adds extra space "for safety's sake" in several places a conservative
|
|
* limit is used here.
|
|
*
|
|
* NOTE: it would be far better to check the size that is actually used,
|
|
* but the effect in the real world is minor and the changes are more
|
|
* extensive, therefore much more dangerous and much more difficult to
|
|
* write in a way that avoids compiler warnings.
|
|
*/
|
|
png_warning(png_ptr, "Image width is too large for this architecture");
|
|
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;
|
|
}
|
|
|
|
if (height == 0)
|
|
{
|
|
png_warning(png_ptr, "Image height is zero in IHDR");
|
|
error = 1;
|
|
}
|
|
|
|
if (height > PNG_UINT_31_MAX)
|
|
{
|
|
png_warning(png_ptr, "Invalid image height 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;
|
|
}
|
|
|
|
/* 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) != 0 &&
|
|
png_ptr->mng_features_permitted != 0)
|
|
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) != 0 &&
|
|
(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) != 0)
|
|
{
|
|
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 formatted 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, size_t size, int *statep,
|
|
png_size_tp whereami)
|
|
{
|
|
int state = *statep;
|
|
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) != 0)
|
|
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) != 0) /* two dots */
|
|
goto PNG_FP_End;
|
|
|
|
else if ((state & PNG_FP_SAW_DIGIT) != 0) /* 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) != 0) /* 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) != 0)
|
|
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, size_t size)
|
|
{
|
|
int state=0;
|
|
size_t char_index=0;
|
|
|
|
if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
|
|
(char_index == size || string[char_index] == 0))
|
|
return state /* must be non-zero - see above */;
|
|
|
|
return 0; /* i.e. fail */
|
|
}
|
|
#endif /* pCAL || sCAL */
|
|
|
|
#ifdef PNG_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;
|
|
|
|
/* 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;
|
|
do
|
|
{
|
|
if (power & 1) d *= mult;
|
|
mult *= mult;
|
|
power >>= 1;
|
|
}
|
|
while (power > 0);
|
|
|
|
if (recip != 0) 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.
|
|
*/
|
|
#if GCC_STRICT_OVERFLOW
|
|
#pragma GCC diagnostic push
|
|
/* The problem arises below with exp_b10, which can never overflow because it
|
|
* comes, originally, from frexp and is therefore limited to a range which is
|
|
* typically +/-710 (log2(DBL_MAX)/log2(DBL_MIN)).
|
|
*/
|
|
#pragma GCC diagnostic warning "-Wstrict-overflow=2"
|
|
#endif /* GCC_STRICT_OVERFLOW */
|
|
void /* PRIVATE */
|
|
png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, 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.
|
|
*/
|
|
|
|
{
|
|
unsigned 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 = 0U-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;
|
|
/* 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+1 < precision+clead)
|
|
fp = modf(fp, &d);
|
|
|
|
else
|
|
{
|
|
d = floor(fp + .5);
|
|
|
|
if (d > 9)
|
|
{
|
|
/* Rounding up to 10, handle that here. */
|
|
if (czero > 0)
|
|
{
|
|
--czero; d = 1;
|
|
if (cdigits == 0) --clead;
|
|
}
|
|
else
|
|
{
|
|
while (cdigits > 0 && d > 9)
|
|
{
|
|
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) /* 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;
|
|
}
|
|
}
|
|
}
|
|
fp = 0; /* Guarantees termination below. */
|
|
}
|
|
|
|
if (d == 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 < precision+clead && 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 a flag: it got
|
|
* to '-1' because of the decrement, after outputting
|
|
* 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
|
|
* doesn't 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 = 0U-exp_b10;
|
|
}
|
|
|
|
else
|
|
uexp_b10 = 0U+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 (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");
|
|
}
|
|
#if GCC_STRICT_OVERFLOW
|
|
#pragma GCC diagnostic pop
|
|
#endif /* GCC_STRICT_OVERFLOW */
|
|
|
|
# endif /* FLOATING_POINT */
|
|
|
|
# ifdef PNG_FIXED_POINT_SUPPORTED
|
|
/* Function to format a fixed point value in ASCII.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
|
|
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; num = (png_uint_32)(-fp);
|
|
}
|
|
else
|
|
num = (png_uint_32)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 /* SCAL */
|
|
|
|
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
|
|
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
|
|
(defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
|
|
defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
|
|
(defined(PNG_sCAL_SUPPORTED) && \
|
|
defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
|
|
png_fixed_point
|
|
png_fixed(png_const_structrp 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);
|
|
|
|
# ifndef PNG_ERROR_TEXT_SUPPORTED
|
|
PNG_UNUSED(text)
|
|
# endif
|
|
|
|
return (png_fixed_point)r;
|
|
}
|
|
#endif
|
|
|
|
#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_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.
|
|
*/
|
|
#if GCC_STRICT_OVERFLOW /* from above */
|
|
/* It is not obvious which comparison below gets optimized in such a way that
|
|
* signed overflow would change the result; looking through the code does not
|
|
* reveal any tests which have the form GCC complains about, so presumably the
|
|
* optimizer is moving an add or subtract into the 'if' somewhere.
|
|
*/
|
|
#pragma GCC diagnostic push
|
|
#pragma GCC diagnostic warning "-Wstrict-overflow=2"
|
|
#endif /* GCC_STRICT_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 != 0)
|
|
result = -result;
|
|
|
|
/* Check for overflow. */
|
|
if ((negative != 0 && result <= 0) ||
|
|
(negative == 0 && result >= 0))
|
|
{
|
|
*res = result;
|
|
return 1;
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#if GCC_STRICT_OVERFLOW
|
|
#pragma GCC diagnostic pop
|
|
#endif /* GCC_STRICT_OVERFLOW */
|
|
#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_const_structrp 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) != 0)
|
|
return result;
|
|
|
|
png_warning(png_ptr, "fixed point overflow ignored");
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_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) != 0)
|
|
return res;
|
|
#endif
|
|
|
|
return 0; /* error/overflow */
|
|
}
|
|
|
|
/* 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;
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_READ_GAMMA_SUPPORTED
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
/* 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) != 0)
|
|
return res;
|
|
#endif
|
|
|
|
return 0; /* overflow */
|
|
}
|
|
#endif /* 16BIT */
|
|
|
|
/* 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
|
|
if (a != 0 && b != 0)
|
|
{
|
|
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_READ_GAMMA_SUPPORTED /* gamma table code */
|
|
#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
/* Fixed point gamma.
|
|
*
|
|
* The code to calculate the tables used below can be found in the shell script
|
|
* contrib/tools/intgamma.sh
|
|
*
|
|
* 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.
|
|
*
|
|
* 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 const png_uint_32
|
|
png_8bit_l2[128] =
|
|
{
|
|
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
|
|
|
|
#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
|
|
};
|
|
|
|
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 -1 for the overflow (log 0) case, - so the result is
|
|
* always at most 19 bits.
|
|
*/
|
|
if ((x &= 0xff) == 0)
|
|
return -1;
|
|
|
|
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
|
|
*/
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
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 -1;
|
|
|
|
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);
|
|
}
|
|
#endif /* 16BIT */
|
|
|
|
/* 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
|
|
* fractional part of the logarithm by using an accurate 32-bit value from the
|
|
* top four fractional bits then multiplying in the remaining bits.
|
|
*/
|
|
static const png_uint_32
|
|
png_32bit_exp[16] =
|
|
{
|
|
/* 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
|
|
};
|
|
|
|
/* Adjustment table; provided to explain the numbers in the code below. */
|
|
#if 0
|
|
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
|
|
|
|
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) & 0x0f];
|
|
|
|
/* 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;
|
|
}
|
|
|
|
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) & 0xff);
|
|
}
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
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 /* 16BIT */
|
|
#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
|
|
/* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
|
|
* convert this to a floating point value. This includes values that
|
|
* would overflow if 'value' were to be converted to 'int'.
|
|
*
|
|
* Apparently GCC, however, does an intermediate conversion to (int)
|
|
* on some (ARM) but not all (x86) platforms, possibly because of
|
|
* hardware FP limitations. (E.g. if the hardware conversion always
|
|
* assumes the integer register contains a signed value.) This results
|
|
* in ANSI-C undefined behavior for large values.
|
|
*
|
|
* Other implementations on the same machine might actually be ANSI-C90
|
|
* conformant and therefore compile spurious extra code for the large
|
|
* values.
|
|
*
|
|
* We can be reasonably sure that an unsigned to float conversion
|
|
* won't be faster than an int to float one. Therefore this code
|
|
* assumes responsibility for the undefined behavior, which it knows
|
|
* can't happen because of the check above.
|
|
*
|
|
* Note the argument to this routine is an (unsigned int) because, on
|
|
* 16-bit platforms, it is assigned a value which might be out of
|
|
* range for an (int); that would result in undefined behavior in the
|
|
* caller if the *argument* ('value') were to be declared (int).
|
|
*/
|
|
double r = floor(255*pow((int)/*SAFE*/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) != 0)
|
|
return png_exp8bit(res);
|
|
|
|
/* Overflow. */
|
|
value = 0;
|
|
# endif
|
|
}
|
|
|
|
return (png_byte)(value & 0xff);
|
|
}
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
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
|
|
/* The same (unsigned int)->(double) constraints apply here as above,
|
|
* however in this case the (unsigned int) to (int) conversion can
|
|
* overflow on an ANSI-C90 compliant system so the cast needs to ensure
|
|
* that this is not possible.
|
|
*/
|
|
double r = floor(65535*pow((png_int_32)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) != 0)
|
|
return png_exp16bit(res);
|
|
|
|
/* Overflow. */
|
|
value = 0;
|
|
# endif
|
|
}
|
|
|
|
return (png_uint_16)value;
|
|
}
|
|
#endif /* 16BIT */
|
|
|
|
/* 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_structrp png_ptr, unsigned int value,
|
|
png_fixed_point gamma_val)
|
|
{
|
|
if (png_ptr->bit_depth == 8)
|
|
return png_gamma_8bit_correct(value, gamma_val);
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
else
|
|
return png_gamma_16bit_correct(value, gamma_val);
|
|
#else
|
|
/* should not reach this */
|
|
return 0;
|
|
#endif /* 16BIT */
|
|
}
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
/* 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_structrp png_ptr, png_uint_16pp *ptable,
|
|
unsigned int shift, png_fixed_point gamma_val)
|
|
{
|
|
/* Various values derived from 'shift': */
|
|
unsigned int num = 1U << (8U - shift);
|
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
/* CSE the division and work round wacky GCC warnings (see the comments
|
|
* in png_gamma_8bit_correct for where these come from.)
|
|
*/
|
|
double fmax = 1.0 / (((png_int_32)1 << (16U - shift)) - 1);
|
|
#endif
|
|
unsigned int max = (1U << (16U - shift)) - 1U;
|
|
unsigned int max_by_2 = 1U << (15U - shift);
|
|
unsigned int i;
|
|
|
|
png_uint_16pp table = *ptable =
|
|
(png_uint_16pp)png_calloc(png_ptr, num * (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 * (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) != 0)
|
|
{
|
|
/* 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: */
|
|
/* See png_gamma_8bit_correct for why the cast to (int) is
|
|
* required here.
|
|
*/
|
|
double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
|
|
sub_table[j] = (png_uint_16)d;
|
|
# else
|
|
if (shift != 0)
|
|
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 != 0)
|
|
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_structrp png_ptr, png_uint_16pp *ptable,
|
|
unsigned int shift, png_fixed_point gamma_val)
|
|
{
|
|
unsigned int num = 1U << (8U - shift);
|
|
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 * (sizeof (png_uint_16p)));
|
|
|
|
/* 'num' is the number of tables and also the number of low bits of low
|
|
* bits of the input 16-bit value used to select a table. Each table is
|
|
* 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 * (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++;
|
|
}
|
|
}
|
|
#endif /* 16BIT */
|
|
|
|
/* 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_structrp png_ptr, png_bytepp ptable,
|
|
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) != 0)
|
|
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 & 0xff);
|
|
}
|
|
|
|
/* Used from png_read_destroy and below to release the memory used by the gamma
|
|
* tables.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_destroy_gamma_table(png_structrp png_ptr)
|
|
{
|
|
png_free(png_ptr, png_ptr->gamma_table);
|
|
png_ptr->gamma_table = NULL;
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
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;
|
|
}
|
|
#endif /* 16BIT */
|
|
|
|
#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;
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
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 /* 16BIT */
|
|
#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_structrp 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->colorspace.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)) != 0)
|
|
{
|
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
|
|
png_reciprocal(png_ptr->colorspace.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->colorspace.gamma/* Probably doing rgb_to_gray */);
|
|
}
|
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
}
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
else
|
|
{
|
|
png_byte shift, sig_bit;
|
|
|
|
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
|
|
{
|
|
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 == insignificant bits */
|
|
shift = (png_byte)((16U - sig_bit) & 0xff);
|
|
|
|
else
|
|
shift = 0; /* keep all 16 bits */
|
|
|
|
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
|
|
{
|
|
/* 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;
|
|
|
|
/* 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)) != 0)
|
|
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
|
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
|
|
png_ptr->screen_gamma) : PNG_FP_1);
|
|
|
|
else
|
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
|
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.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)) != 0)
|
|
{
|
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
|
|
png_reciprocal(png_ptr->colorspace.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->colorspace.gamma/* Probably doing rgb_to_gray */);
|
|
}
|
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
}
|
|
#endif /* 16BIT */
|
|
}
|
|
#endif /* READ_GAMMA */
|
|
|
|
/* HARDWARE OR SOFTWARE OPTION SUPPORT */
|
|
#ifdef PNG_SET_OPTION_SUPPORTED
|
|
int PNGAPI
|
|
png_set_option(png_structrp png_ptr, int option, int onoff)
|
|
{
|
|
if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
|
|
(option & 1) == 0)
|
|
{
|
|
png_uint_32 mask = 3U << option;
|
|
png_uint_32 setting = (2U + (onoff != 0)) << option;
|
|
png_uint_32 current = png_ptr->options;
|
|
|
|
png_ptr->options = (png_uint_32)((current & ~mask) | setting);
|
|
|
|
return (int)(current & mask) >> option;
|
|
}
|
|
|
|
return PNG_OPTION_INVALID;
|
|
}
|
|
#endif
|
|
|
|
/* sRGB support */
|
|
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
|
|
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
|
|
/* sRGB conversion tables; these are machine generated with the code in
|
|
* contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
|
|
* specification (see the article at https://en.wikipedia.org/wiki/SRGB)
|
|
* is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
|
|
* The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
|
|
* The inverse (linear to sRGB) table has accuracies as follows:
|
|
*
|
|
* For all possible (255*65535+1) input values:
|
|
*
|
|
* error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
|
|
*
|
|
* For the input values corresponding to the 65536 16-bit values:
|
|
*
|
|
* error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
|
|
*
|
|
* In all cases the inexact readings are only off by one.
|
|
*/
|
|
|
|
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
|
/* The convert-to-sRGB table is only currently required for read. */
|
|
const png_uint_16 png_sRGB_table[256] =
|
|
{
|
|
0,20,40,60,80,99,119,139,
|
|
159,179,199,219,241,264,288,313,
|
|
340,367,396,427,458,491,526,562,
|
|
599,637,677,718,761,805,851,898,
|
|
947,997,1048,1101,1156,1212,1270,1330,
|
|
1391,1453,1517,1583,1651,1720,1790,1863,
|
|
1937,2013,2090,2170,2250,2333,2418,2504,
|
|
2592,2681,2773,2866,2961,3058,3157,3258,
|
|
3360,3464,3570,3678,3788,3900,4014,4129,
|
|
4247,4366,4488,4611,4736,4864,4993,5124,
|
|
5257,5392,5530,5669,5810,5953,6099,6246,
|
|
6395,6547,6700,6856,7014,7174,7335,7500,
|
|
7666,7834,8004,8177,8352,8528,8708,8889,
|
|
9072,9258,9445,9635,9828,10022,10219,10417,
|
|
10619,10822,11028,11235,11446,11658,11873,12090,
|
|
12309,12530,12754,12980,13209,13440,13673,13909,
|
|
14146,14387,14629,14874,15122,15371,15623,15878,
|
|
16135,16394,16656,16920,17187,17456,17727,18001,
|
|
18277,18556,18837,19121,19407,19696,19987,20281,
|
|
20577,20876,21177,21481,21787,22096,22407,22721,
|
|
23038,23357,23678,24002,24329,24658,24990,25325,
|
|
25662,26001,26344,26688,27036,27386,27739,28094,
|
|
28452,28813,29176,29542,29911,30282,30656,31033,
|
|
31412,31794,32179,32567,32957,33350,33745,34143,
|
|
34544,34948,35355,35764,36176,36591,37008,37429,
|
|
37852,38278,38706,39138,39572,40009,40449,40891,
|
|
41337,41785,42236,42690,43147,43606,44069,44534,
|
|
45002,45473,45947,46423,46903,47385,47871,48359,
|
|
48850,49344,49841,50341,50844,51349,51858,52369,
|
|
52884,53401,53921,54445,54971,55500,56032,56567,
|
|
57105,57646,58190,58737,59287,59840,60396,60955,
|
|
61517,62082,62650,63221,63795,64372,64952,65535
|
|
};
|
|
#endif /* SIMPLIFIED_READ */
|
|
|
|
/* The base/delta tables are required for both read and write (but currently
|
|
* only the simplified versions.)
|
|
*/
|
|
const png_uint_16 png_sRGB_base[512] =
|
|
{
|
|
128,1782,3383,4644,5675,6564,7357,8074,
|
|
8732,9346,9921,10463,10977,11466,11935,12384,
|
|
12816,13233,13634,14024,14402,14769,15125,15473,
|
|
15812,16142,16466,16781,17090,17393,17690,17981,
|
|
18266,18546,18822,19093,19359,19621,19879,20133,
|
|
20383,20630,20873,21113,21349,21583,21813,22041,
|
|
22265,22487,22707,22923,23138,23350,23559,23767,
|
|
23972,24175,24376,24575,24772,24967,25160,25352,
|
|
25542,25730,25916,26101,26284,26465,26645,26823,
|
|
27000,27176,27350,27523,27695,27865,28034,28201,
|
|
28368,28533,28697,28860,29021,29182,29341,29500,
|
|
29657,29813,29969,30123,30276,30429,30580,30730,
|
|
30880,31028,31176,31323,31469,31614,31758,31902,
|
|
32045,32186,32327,32468,32607,32746,32884,33021,
|
|
33158,33294,33429,33564,33697,33831,33963,34095,
|
|
34226,34357,34486,34616,34744,34873,35000,35127,
|
|
35253,35379,35504,35629,35753,35876,35999,36122,
|
|
36244,36365,36486,36606,36726,36845,36964,37083,
|
|
37201,37318,37435,37551,37668,37783,37898,38013,
|
|
38127,38241,38354,38467,38580,38692,38803,38915,
|
|
39026,39136,39246,39356,39465,39574,39682,39790,
|
|
39898,40005,40112,40219,40325,40431,40537,40642,
|
|
40747,40851,40955,41059,41163,41266,41369,41471,
|
|
41573,41675,41777,41878,41979,42079,42179,42279,
|
|
42379,42478,42577,42676,42775,42873,42971,43068,
|
|
43165,43262,43359,43456,43552,43648,43743,43839,
|
|
43934,44028,44123,44217,44311,44405,44499,44592,
|
|
44685,44778,44870,44962,45054,45146,45238,45329,
|
|
45420,45511,45601,45692,45782,45872,45961,46051,
|
|
46140,46229,46318,46406,46494,46583,46670,46758,
|
|
46846,46933,47020,47107,47193,47280,47366,47452,
|
|
47538,47623,47709,47794,47879,47964,48048,48133,
|
|
48217,48301,48385,48468,48552,48635,48718,48801,
|
|
48884,48966,49048,49131,49213,49294,49376,49458,
|
|
49539,49620,49701,49782,49862,49943,50023,50103,
|
|
50183,50263,50342,50422,50501,50580,50659,50738,
|
|
50816,50895,50973,51051,51129,51207,51285,51362,
|
|
51439,51517,51594,51671,51747,51824,51900,51977,
|
|
52053,52129,52205,52280,52356,52432,52507,52582,
|
|
52657,52732,52807,52881,52956,53030,53104,53178,
|
|
53252,53326,53400,53473,53546,53620,53693,53766,
|
|
53839,53911,53984,54056,54129,54201,54273,54345,
|
|
54417,54489,54560,54632,54703,54774,54845,54916,
|
|
54987,55058,55129,55199,55269,55340,55410,55480,
|
|
55550,55620,55689,55759,55828,55898,55967,56036,
|
|
56105,56174,56243,56311,56380,56448,56517,56585,
|
|
56653,56721,56789,56857,56924,56992,57059,57127,
|
|
57194,57261,57328,57395,57462,57529,57595,57662,
|
|
57728,57795,57861,57927,57993,58059,58125,58191,
|
|
58256,58322,58387,58453,58518,58583,58648,58713,
|
|
58778,58843,58908,58972,59037,59101,59165,59230,
|
|
59294,59358,59422,59486,59549,59613,59677,59740,
|
|
59804,59867,59930,59993,60056,60119,60182,60245,
|
|
60308,60370,60433,60495,60558,60620,60682,60744,
|
|
60806,60868,60930,60992,61054,61115,61177,61238,
|
|
61300,61361,61422,61483,61544,61605,61666,61727,
|
|
61788,61848,61909,61969,62030,62090,62150,62211,
|
|
62271,62331,62391,62450,62510,62570,62630,62689,
|
|
62749,62808,62867,62927,62986,63045,63104,63163,
|
|
63222,63281,63340,63398,63457,63515,63574,63632,
|
|
63691,63749,63807,63865,63923,63981,64039,64097,
|
|
64155,64212,64270,64328,64385,64443,64500,64557,
|
|
64614,64672,64729,64786,64843,64900,64956,65013,
|
|
65070,65126,65183,65239,65296,65352,65409,65465
|
|
};
|
|
|
|
const png_byte png_sRGB_delta[512] =
|
|
{
|
|
207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
|
|
52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
|
|
35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
|
|
28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
|
|
23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
|
|
21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
|
|
19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
|
|
17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
|
|
16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
|
|
15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
|
|
14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
|
|
13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
|
|
12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
|
|
12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
|
|
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
|
|
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
|
|
11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
|
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
|
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
|
10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
|
|
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
|
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
|
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
|
|
};
|
|
#endif /* SIMPLIFIED READ/WRITE sRGB support */
|
|
|
|
/* SIMPLIFIED READ/WRITE SUPPORT */
|
|
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
|
|
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
|
|
static int
|
|
png_image_free_function(png_voidp argument)
|
|
{
|
|
png_imagep image = png_voidcast(png_imagep, argument);
|
|
png_controlp cp = image->opaque;
|
|
png_control c;
|
|
|
|
/* Double check that we have a png_ptr - it should be impossible to get here
|
|
* without one.
|
|
*/
|
|
if (cp->png_ptr == NULL)
|
|
return 0;
|
|
|
|
/* First free any data held in the control structure. */
|
|
# ifdef PNG_STDIO_SUPPORTED
|
|
if (cp->owned_file != 0)
|
|
{
|
|
FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
|
|
cp->owned_file = 0;
|
|
|
|
/* Ignore errors here. */
|
|
if (fp != NULL)
|
|
{
|
|
cp->png_ptr->io_ptr = NULL;
|
|
(void)fclose(fp);
|
|
}
|
|
}
|
|
# endif
|
|
|
|
/* Copy the control structure so that the original, allocated, version can be
|
|
* safely freed. Notice that a png_error here stops the remainder of the
|
|
* cleanup, but this is probably fine because that would indicate bad memory
|
|
* problems anyway.
|
|
*/
|
|
c = *cp;
|
|
image->opaque = &c;
|
|
png_free(c.png_ptr, cp);
|
|
|
|
/* Then the structures, calling the correct API. */
|
|
if (c.for_write != 0)
|
|
{
|
|
# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
|
|
png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
|
|
# else
|
|
png_error(c.png_ptr, "simplified write not supported");
|
|
# endif
|
|
}
|
|
else
|
|
{
|
|
# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
|
png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
|
|
# else
|
|
png_error(c.png_ptr, "simplified read not supported");
|
|
# endif
|
|
}
|
|
|
|
/* Success. */
|
|
return 1;
|
|
}
|
|
|
|
void PNGAPI
|
|
png_image_free(png_imagep image)
|
|
{
|
|
/* Safely call the real function, but only if doing so is safe at this point
|
|
* (if not inside an error handling context). Otherwise assume
|
|
* png_safe_execute will call this API after the return.
|
|
*/
|
|
if (image != NULL && image->opaque != NULL &&
|
|
image->opaque->error_buf == NULL)
|
|
{
|
|
png_image_free_function(image);
|
|
image->opaque = NULL;
|
|
}
|
|
}
|
|
|
|
int /* PRIVATE */
|
|
png_image_error(png_imagep image, png_const_charp error_message)
|
|
{
|
|
/* Utility to log an error. */
|
|
png_safecat(image->message, (sizeof image->message), 0, error_message);
|
|
image->warning_or_error |= PNG_IMAGE_ERROR;
|
|
png_image_free(image);
|
|
return 0;
|
|
}
|
|
|
|
#endif /* SIMPLIFIED READ/WRITE */
|
|
#endif /* READ || WRITE */
|