2934 lines
92 KiB
C
2934 lines
92 KiB
C
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/* png.c - location for general purpose libpng functions
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*
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* Last changed in libpng 1.5.23 [July 23, 2015]
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* Copyright (c) 1998-2002,2004,2006-2015 Glenn Randers-Pehrson
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* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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*
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* This code is released under the libpng license.
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* For conditions of distribution and use, see the disclaimer
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* and license in png.h
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*/
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#include "pngpriv.h"
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/* Generate a compiler error if there is an old png.h in the search path. */
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typedef png_libpng_version_1_5_27 Your_png_h_is_not_version_1_5_27;
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/* Tells libpng that we have already handled the first "num_bytes" bytes
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* of the PNG file signature. If the PNG data is embedded into another
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* stream we can set num_bytes = 8 so that libpng will not attempt to read
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* or write any of the magic bytes before it starts on the IHDR.
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*/
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#ifdef PNG_READ_SUPPORTED
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void PNGAPI
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png_set_sig_bytes(png_structp png_ptr, int num_bytes)
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{
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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, png_size_t start, png_size_t num_to_check)
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{
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png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
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if (num_to_check > 8)
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num_to_check = 8;
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else if (num_to_check < 1)
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return (-1);
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if (start > 7)
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return (-1);
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if (start + num_to_check > 8)
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num_to_check = 8 - start;
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return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check)));
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}
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#endif /* PNG_READ_SUPPORTED */
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#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
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/* Function to allocate memory for zlib */
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PNG_FUNCTION(voidpf /* PRIVATE */,
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png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
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{
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png_voidp ptr;
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png_structp p;
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png_uint_32 save_flags;
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png_alloc_size_t num_bytes;
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if (png_ptr == NULL)
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return (NULL);
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p=(png_structp)png_ptr;
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save_flags=p->flags;
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if (items > PNG_UINT_32_MAX/size)
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{
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png_warning (p, "Potential overflow in png_zalloc()");
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return (NULL);
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}
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num_bytes = (png_alloc_size_t)items * size;
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p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
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ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
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p->flags=save_flags;
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return ((voidpf)ptr);
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}
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/* Function to free memory for zlib */
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void /* PRIVATE */
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png_zfree(voidpf png_ptr, voidpf ptr)
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{
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png_free((png_structp)png_ptr, (png_voidp)ptr);
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}
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/* Reset the CRC variable to 32 bits of 1's. Care must be taken
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* in case CRC is > 32 bits to leave the top bits 0.
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*/
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void /* PRIVATE */
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png_reset_crc(png_structp png_ptr)
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{
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/* The cast is safe because the crc is a 32 bit value. */
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png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
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}
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/* Calculate the CRC over a section of data. We can only pass as
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* much data to this routine as the largest single buffer size. We
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* also check that this data will actually be used before going to the
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* trouble of calculating it.
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*/
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void /* PRIVATE */
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png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length)
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{
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int need_crc = 1;
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if (PNG_CHUNK_ANCILLIARY(png_ptr->chunk_name))
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{
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if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
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(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
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need_crc = 0;
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}
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else /* critical */
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{
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if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
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need_crc = 0;
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}
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/* 'uLong' is defined as unsigned long, this means that on some systems it is
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* a 64 bit value. crc32, however, returns 32 bits so the following cast is
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* safe. 'uInt' may be no more than 16 bits, so it is necessary to perform a
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* loop here.
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*/
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if (need_crc && length > 0)
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{
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uLong crc = png_ptr->crc; /* Should never issue a warning */
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do
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{
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uInt safeLength = (uInt)length;
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#ifndef __COVERITY__
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if (safeLength == 0)
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safeLength = (uInt)-1; /* evil, but safe */
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#endif
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crc = crc32(crc, ptr, safeLength);
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/* The following should never issue compiler warnings, if they do the
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* target system has characteristics that will probably violate other
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* assumptions within the libpng code.
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*/
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ptr += safeLength;
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length -= safeLength;
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}
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while (length > 0);
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/* And the following is always safe because the crc is only 32 bits. */
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png_ptr->crc = (png_uint_32)crc;
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}
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}
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/* Check a user supplied version number, called from both read and write
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* functions that create a png_struct
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*/
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int
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png_user_version_check(png_structp png_ptr, png_const_charp user_png_ver)
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{
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/* 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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/* Allocate the memory for an info_struct for the application. We don't
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* really need the png_ptr, but it could potentially be useful in the
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* future. This should be used in favour of malloc(png_sizeof(png_info))
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* and png_info_init() so that applications that want to use a shared
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* libpng don't have to be recompiled if png_info changes size.
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*/
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PNG_FUNCTION(png_infop,PNGAPI
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png_create_info_struct,(png_structp png_ptr),PNG_ALLOCATED)
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{
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png_infop info_ptr;
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png_debug(1, "in png_create_info_struct");
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if (png_ptr == NULL)
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return (NULL);
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#ifdef PNG_USER_MEM_SUPPORTED
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info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO,
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png_ptr->malloc_fn, png_ptr->mem_ptr);
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#else
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info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
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#endif
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if (info_ptr != NULL)
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png_info_init_3(&info_ptr, png_sizeof(png_info));
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return (info_ptr);
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}
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/* This function frees the memory associated with a single info struct.
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* Normally, one would use either png_destroy_read_struct() or
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* png_destroy_write_struct() to free an info struct, but this may be
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* useful for some applications.
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*/
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void PNGAPI
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png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
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{
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png_infop info_ptr = NULL;
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png_debug(1, "in png_destroy_info_struct");
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if (png_ptr == NULL)
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return;
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if (info_ptr_ptr != NULL)
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info_ptr = *info_ptr_ptr;
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if (info_ptr != NULL)
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{
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png_info_destroy(png_ptr, info_ptr);
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#ifdef PNG_USER_MEM_SUPPORTED
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png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn,
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png_ptr->mem_ptr);
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#else
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png_destroy_struct((png_voidp)info_ptr);
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#endif
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*info_ptr_ptr = NULL;
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}
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}
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/* Initialize the info structure. This is now an internal function (0.89)
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* and applications using it are urged to use png_create_info_struct()
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* instead.
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*/
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void PNGAPI
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png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size)
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{
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png_infop info_ptr = *ptr_ptr;
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png_debug(1, "in png_info_init_3");
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if (info_ptr == NULL)
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return;
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if (png_sizeof(png_info) > png_info_struct_size)
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{
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png_destroy_struct(info_ptr);
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info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO);
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*ptr_ptr = info_ptr;
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if (info_ptr == NULL)
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return;
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}
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/* Set everything to 0 */
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png_memset(info_ptr, 0, png_sizeof(png_info));
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}
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void PNGAPI
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png_data_freer(png_structp png_ptr, png_infop info_ptr,
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int freer, png_uint_32 mask)
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{
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png_debug(1, "in png_data_freer");
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if (png_ptr == NULL || info_ptr == NULL)
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return;
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if (freer == PNG_DESTROY_WILL_FREE_DATA)
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info_ptr->free_me |= mask;
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else if (freer == PNG_USER_WILL_FREE_DATA)
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info_ptr->free_me &= ~mask;
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else
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png_warning(png_ptr,
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"Unknown freer parameter in png_data_freer");
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}
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void PNGAPI
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png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask,
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int num)
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{
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png_debug(1, "in png_free_data");
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if (png_ptr == NULL || info_ptr == NULL)
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return;
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#ifdef PNG_TEXT_SUPPORTED
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/* Free text item num or (if num == -1) all text items */
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if (info_ptr->text != 0 &&
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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;
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info_ptr->num_text = 0;
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}
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}
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#endif
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#ifdef PNG_tRNS_SUPPORTED
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/* Free any tRNS entry */
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if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
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{
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info_ptr->valid &= ~PNG_INFO_tRNS;
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png_free(png_ptr, info_ptr->trans_alpha);
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info_ptr->trans_alpha = NULL;
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info_ptr->num_trans = 0;
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}
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#endif
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#ifdef PNG_sCAL_SUPPORTED
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/* Free any sCAL entry */
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if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
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{
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png_free(png_ptr, info_ptr->scal_s_width);
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png_free(png_ptr, info_ptr->scal_s_height);
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info_ptr->scal_s_width = NULL;
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info_ptr->scal_s_height = NULL;
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info_ptr->valid &= ~PNG_INFO_sCAL;
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}
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#endif
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#ifdef PNG_pCAL_SUPPORTED
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/* Free any pCAL entry */
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if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
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{
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png_free(png_ptr, info_ptr->pcal_purpose);
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png_free(png_ptr, info_ptr->pcal_units);
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info_ptr->pcal_purpose = NULL;
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info_ptr->pcal_units = NULL;
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if (info_ptr->pcal_params != NULL)
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{
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int i;
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for (i = 0; i < info_ptr->pcal_nparams; i++)
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png_free(png_ptr, info_ptr->pcal_params[i]);
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png_free(png_ptr, info_ptr->pcal_params);
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info_ptr->pcal_params = NULL;
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}
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info_ptr->valid &= ~PNG_INFO_pCAL;
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}
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#endif
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#ifdef PNG_iCCP_SUPPORTED
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/* Free any profile entry */
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if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
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{
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png_free(png_ptr, info_ptr->iccp_name);
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png_free(png_ptr, info_ptr->iccp_profile);
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info_ptr->iccp_name = NULL;
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info_ptr->iccp_profile = NULL;
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info_ptr->valid &= ~PNG_INFO_iCCP;
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}
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#endif
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#ifdef PNG_sPLT_SUPPORTED
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/* Free a given sPLT entry, or (if num == -1) all sPLT entries */
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if (info_ptr->splt_palettes != 0 &&
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((mask & PNG_FREE_SPLT) & 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->splt_palettes[num].name);
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png_free(png_ptr, info_ptr->splt_palettes[num].entries);
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info_ptr->splt_palettes[num].name = NULL;
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info_ptr->splt_palettes[num].entries = NULL;
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}
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else
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{
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int i;
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for (i = 0; i < info_ptr->splt_palettes_num; i++)
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{
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png_free(png_ptr, info_ptr->splt_palettes[i].name);
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png_free(png_ptr, info_ptr->splt_palettes[i].entries);
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}
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png_free(png_ptr, info_ptr->splt_palettes);
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info_ptr->splt_palettes = NULL;
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info_ptr->splt_palettes_num = 0;
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info_ptr->valid &= ~PNG_INFO_sPLT;
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}
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}
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#endif
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#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
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if (info_ptr->unknown_chunks != 0 &&
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((mask & PNG_FREE_UNKN) & 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->unknown_chunks[num].data);
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info_ptr->unknown_chunks[num].data = 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->unknown_chunks_num; i++)
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png_free(png_ptr, info_ptr->unknown_chunks[i].data);
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png_free(png_ptr, info_ptr->unknown_chunks);
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info_ptr->unknown_chunks = NULL;
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info_ptr->unknown_chunks_num = 0;
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}
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}
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#endif
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#ifdef PNG_hIST_SUPPORTED
|
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/* Free any hIST entry */
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if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
|
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{
|
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png_free(png_ptr, info_ptr->hist);
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info_ptr->hist = NULL;
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info_ptr->valid &= ~PNG_INFO_hIST;
|
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}
|
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#endif
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|
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/* Free any PLTE entry that was internally allocated */
|
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if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
|
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{
|
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png_free(png_ptr, info_ptr->palette);
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info_ptr->palette = NULL;
|
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info_ptr->valid &= ~PNG_INFO_PLTE;
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info_ptr->num_palette = 0;
|
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}
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#ifdef PNG_INFO_IMAGE_SUPPORTED
|
|
/* Free any image bits attached to the info structure */
|
|
if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
|
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{
|
|
if (info_ptr->row_pointers != 0)
|
|
{
|
|
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;
|
|
}
|
|
|
|
/* This is an internal routine to free any memory that the info struct is
|
|
* pointing to before re-using it or freeing the struct itself. Recall
|
|
* that png_free() checks for NULL pointers for us.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_info_destroy(png_structp png_ptr, png_infop info_ptr)
|
|
{
|
|
png_debug(1, "in png_info_destroy");
|
|
|
|
png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
|
|
|
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
|
|
if (png_ptr->num_chunk_list)
|
|
{
|
|
png_free(png_ptr, png_ptr->chunk_list);
|
|
png_ptr->chunk_list = NULL;
|
|
png_ptr->num_chunk_list = 0;
|
|
}
|
|
#endif
|
|
|
|
png_info_init_3(&info_ptr, png_sizeof(png_info));
|
|
}
|
|
#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
|
|
|
/* 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_structp png_ptr)
|
|
{
|
|
if (png_ptr == NULL)
|
|
return (NULL);
|
|
|
|
return (png_ptr->io_ptr);
|
|
}
|
|
|
|
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
|
|
# ifdef PNG_STDIO_SUPPORTED
|
|
/* Initialize the default input/output functions for the PNG file. If you
|
|
* use your own read or write routines, you can call either png_set_read_fn()
|
|
* or png_set_write_fn() instead of png_init_io(). If you have defined
|
|
* PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
|
|
* function of your own because "FILE *" isn't necessarily available.
|
|
*/
|
|
void PNGAPI
|
|
png_init_io(png_structp png_ptr, png_FILE_p fp)
|
|
{
|
|
png_debug(1, "in png_init_io");
|
|
|
|
if (png_ptr == NULL)
|
|
return;
|
|
|
|
png_ptr->io_ptr = (png_voidp)fp;
|
|
}
|
|
# endif
|
|
|
|
# ifdef PNG_TIME_RFC1123_SUPPORTED
|
|
/* Convert the supplied time into an RFC 1123 string suitable for use in
|
|
* a "Creation Time" or other text-based time string.
|
|
*/
|
|
png_const_charp PNGAPI
|
|
png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime)
|
|
{
|
|
static PNG_CONST char short_months[12][4] =
|
|
{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
|
|
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
|
|
|
|
if (png_ptr == NULL)
|
|
return (NULL);
|
|
|
|
if (ptime->year > 9999 /* RFC1123 limitation */ ||
|
|
ptime->month == 0 || ptime->month > 12 ||
|
|
ptime->day == 0 || ptime->day > 31 ||
|
|
ptime->hour > 23 || ptime->minute > 59 ||
|
|
ptime->second > 60)
|
|
{
|
|
png_warning(png_ptr, "Ignoring invalid time value");
|
|
return (NULL);
|
|
}
|
|
|
|
{
|
|
size_t pos = 0;
|
|
char number_buf[5]; /* enough for a four-digit year */
|
|
|
|
# define APPEND_STRING(string)\
|
|
pos = png_safecat(png_ptr->time_buffer, sizeof png_ptr->time_buffer,\
|
|
pos, (string))
|
|
# define APPEND_NUMBER(format, value)\
|
|
APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
|
|
# define APPEND(ch)\
|
|
if (pos < (sizeof png_ptr->time_buffer)-1)\
|
|
png_ptr->time_buffer[pos++] = (ch)
|
|
|
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
|
|
APPEND(' ');
|
|
APPEND_STRING(short_months[(ptime->month - 1)]);
|
|
APPEND(' ');
|
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
|
|
APPEND(' ');
|
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
|
|
APPEND(':');
|
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
|
|
APPEND(':');
|
|
APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
|
|
APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
|
|
|
|
# undef APPEND
|
|
# undef APPEND_NUMBER
|
|
# undef APPEND_STRING
|
|
}
|
|
|
|
return png_ptr->time_buffer;
|
|
}
|
|
# endif /* PNG_TIME_RFC1123_SUPPORTED */
|
|
|
|
#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
|
|
|
png_const_charp PNGAPI
|
|
png_get_copyright(png_const_structp png_ptr)
|
|
{
|
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
#ifdef PNG_STRING_COPYRIGHT
|
|
return PNG_STRING_COPYRIGHT
|
|
#else
|
|
# ifdef __STDC__
|
|
return PNG_STRING_NEWLINE \
|
|
"libpng version 1.5.27 - May 26, 2016" PNG_STRING_NEWLINE \
|
|
"Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \
|
|
PNG_STRING_NEWLINE \
|
|
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
|
|
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
|
|
PNG_STRING_NEWLINE;
|
|
# else
|
|
return "libpng version 1.5.27 - May 26, 2016\
|
|
Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
|
|
Copyright (c) 1996-1997 Andreas Dilger\
|
|
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
|
|
# endif
|
|
#endif
|
|
}
|
|
|
|
/* The following return the library version as a short string in the
|
|
* format 1.0.0 through 99.99.99zz. To get the version of *.h files
|
|
* used with your application, print out PNG_LIBPNG_VER_STRING, which
|
|
* is defined in png.h.
|
|
* Note: now there is no difference between png_get_libpng_ver() and
|
|
* png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
|
|
* it is guaranteed that png.c uses the correct version of png.h.
|
|
*/
|
|
png_const_charp PNGAPI
|
|
png_get_libpng_ver(png_const_structp png_ptr)
|
|
{
|
|
/* Version of *.c files used when building libpng */
|
|
return png_get_header_ver(png_ptr);
|
|
}
|
|
|
|
png_const_charp PNGAPI
|
|
png_get_header_ver(png_const_structp png_ptr)
|
|
{
|
|
/* Version of *.h files used when building libpng */
|
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
return PNG_LIBPNG_VER_STRING;
|
|
}
|
|
|
|
png_const_charp PNGAPI
|
|
png_get_header_version(png_const_structp png_ptr)
|
|
{
|
|
/* Returns longer string containing both version and date */
|
|
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
#ifdef __STDC__
|
|
return PNG_HEADER_VERSION_STRING
|
|
# ifndef PNG_READ_SUPPORTED
|
|
" (NO READ SUPPORT)"
|
|
# endif
|
|
PNG_STRING_NEWLINE;
|
|
#else
|
|
return PNG_HEADER_VERSION_STRING;
|
|
#endif
|
|
}
|
|
|
|
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
|
|
int PNGAPI
|
|
png_handle_as_unknown(png_structp png_ptr, png_const_bytep chunk_name)
|
|
{
|
|
/* Check chunk_name and return "keep" value if it's on the list, else 0 */
|
|
png_const_bytep p, p_end;
|
|
|
|
if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list <= 0)
|
|
return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
|
|
|
p_end = png_ptr->chunk_list;
|
|
p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
|
|
|
|
/* The code is the fifth byte after each four byte string. Historically this
|
|
* code was always searched from the end of the list, so it should continue
|
|
* to do so in case there are duplicated entries.
|
|
*/
|
|
do /* num_chunk_list > 0, so at least one */
|
|
{
|
|
p -= 5;
|
|
if (!png_memcmp(chunk_name, p, 4))
|
|
return p[4];
|
|
}
|
|
while (p > p_end);
|
|
|
|
return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
|
}
|
|
|
|
int /* PRIVATE */
|
|
png_chunk_unknown_handling(png_structp png_ptr, png_uint_32 chunk_name)
|
|
{
|
|
png_byte chunk_string[5];
|
|
|
|
PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
|
|
return png_handle_as_unknown(png_ptr, chunk_string);
|
|
}
|
|
#endif
|
|
|
|
#ifdef PNG_READ_SUPPORTED
|
|
/* This function, added to libpng-1.0.6g, is untested. */
|
|
int PNGAPI
|
|
png_reset_zstream(png_structp png_ptr)
|
|
{
|
|
if (png_ptr == NULL)
|
|
return Z_STREAM_ERROR;
|
|
|
|
return (inflateReset(&png_ptr->zstream));
|
|
}
|
|
#endif /* PNG_READ_SUPPORTED */
|
|
|
|
/* This function was added to libpng-1.0.7 */
|
|
png_uint_32 PNGAPI
|
|
png_access_version_number(void)
|
|
{
|
|
/* Version of *.c files used when building libpng */
|
|
return((png_uint_32)PNG_LIBPNG_VER);
|
|
}
|
|
|
|
|
|
|
|
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
|
|
/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
|
|
* at libpng 1.5.5!
|
|
*/
|
|
|
|
/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
|
|
# ifdef PNG_CHECK_cHRM_SUPPORTED
|
|
|
|
int /* PRIVATE */
|
|
png_check_cHRM_fixed(png_structp png_ptr,
|
|
png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
|
|
png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
|
|
png_fixed_point blue_x, png_fixed_point blue_y)
|
|
{
|
|
int ret = 1;
|
|
unsigned long xy_hi,xy_lo,yx_hi,yx_lo;
|
|
|
|
png_debug(1, "in function png_check_cHRM_fixed");
|
|
|
|
if (png_ptr == NULL)
|
|
return 0;
|
|
|
|
/* (x,y,z) values are first limited to 0..100000 (PNG_FP_1), the white
|
|
* y must also be greater than 0. To test for the upper limit calculate
|
|
* (PNG_FP_1-y) - x must be <= to this for z to be >= 0 (and the expression
|
|
* cannot overflow.) At this point we know x and y are >= 0 and (x+y) is
|
|
* <= PNG_FP_1. The previous test on PNG_MAX_UINT_31 is removed because it
|
|
* pointless (and it produces compiler warnings!)
|
|
*/
|
|
if (white_x < 0 || white_y <= 0 ||
|
|
red_x < 0 || red_y < 0 ||
|
|
green_x < 0 || green_y < 0 ||
|
|
blue_x < 0 || blue_y < 0)
|
|
{
|
|
png_warning(png_ptr,
|
|
"Ignoring attempt to set negative chromaticity value");
|
|
ret = 0;
|
|
}
|
|
/* And (x+y) must be <= PNG_FP_1 (so z is >= 0) */
|
|
if (white_x > PNG_FP_1 - white_y)
|
|
{
|
|
png_warning(png_ptr, "Invalid cHRM white point");
|
|
ret = 0;
|
|
}
|
|
|
|
if (red_x > PNG_FP_1 - red_y)
|
|
{
|
|
png_warning(png_ptr, "Invalid cHRM red point");
|
|
ret = 0;
|
|
}
|
|
|
|
if (green_x > PNG_FP_1 - green_y)
|
|
{
|
|
png_warning(png_ptr, "Invalid cHRM green point");
|
|
ret = 0;
|
|
}
|
|
|
|
if (blue_x > PNG_FP_1 - blue_y)
|
|
{
|
|
png_warning(png_ptr, "Invalid cHRM blue point");
|
|
ret = 0;
|
|
}
|
|
|
|
png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo);
|
|
png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo);
|
|
|
|
if (xy_hi == yx_hi && xy_lo == yx_lo)
|
|
{
|
|
png_warning(png_ptr,
|
|
"Ignoring attempt to set cHRM RGB triangle with zero area");
|
|
ret = 0;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
# endif /* PNG_CHECK_cHRM_SUPPORTED */
|
|
|
|
#ifdef PNG_cHRM_SUPPORTED
|
|
/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
|
|
* cHRM, as opposed to using chromaticities. These internal APIs return
|
|
* non-zero on a parameter error. The X, Y and Z values are required to be
|
|
* positive and less than 1.0.
|
|
*/
|
|
int png_xy_from_XYZ(png_xy *xy, png_XYZ XYZ)
|
|
{
|
|
png_int_32 d, dwhite, whiteX, whiteY;
|
|
|
|
d = XYZ.redX + XYZ.redY + XYZ.redZ;
|
|
if (!png_muldiv(&xy->redx, XYZ.redX, PNG_FP_1, d)) return 1;
|
|
if (!png_muldiv(&xy->redy, XYZ.redY, PNG_FP_1, d)) return 1;
|
|
dwhite = d;
|
|
whiteX = XYZ.redX;
|
|
whiteY = XYZ.redY;
|
|
|
|
d = XYZ.greenX + XYZ.greenY + XYZ.greenZ;
|
|
if (!png_muldiv(&xy->greenx, XYZ.greenX, PNG_FP_1, d)) return 1;
|
|
if (!png_muldiv(&xy->greeny, XYZ.greenY, PNG_FP_1, d)) return 1;
|
|
dwhite += d;
|
|
whiteX += XYZ.greenX;
|
|
whiteY += XYZ.greenY;
|
|
|
|
d = XYZ.blueX + XYZ.blueY + XYZ.blueZ;
|
|
if (!png_muldiv(&xy->bluex, XYZ.blueX, PNG_FP_1, d)) return 1;
|
|
if (!png_muldiv(&xy->bluey, XYZ.blueY, PNG_FP_1, d)) return 1;
|
|
dwhite += d;
|
|
whiteX += XYZ.blueX;
|
|
whiteY += XYZ.blueY;
|
|
|
|
/* The reference white is simply the same of the end-point (X,Y,Z) vectors,
|
|
* thus:
|
|
*/
|
|
if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
|
|
if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int png_XYZ_from_xy(png_XYZ *XYZ, png_xy xy)
|
|
{
|
|
png_fixed_point red_inverse, green_inverse, blue_scale;
|
|
png_fixed_point left, right, denominator;
|
|
|
|
/* Check xy and, implicitly, z. Note that wide gamut color spaces typically
|
|
* have end points with 0 tristimulus values (these are impossible end
|
|
* points, but they are used to cover the possible colors). 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 invertion of the above equations
|
|
* ------------------------------------------------------------
|
|
*
|
|
* white_scale = 1/white-y
|
|
* white-X = white-x * white-scale
|
|
* white-Y = 1.0
|
|
* white-Z = (1 - white-x - white-y) * white_scale
|
|
*
|
|
* white-C = red-C + green-C + blue-C
|
|
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
|
|
*
|
|
* This gives us three equations in (red-scale,green-scale,blue-scale) where
|
|
* all the coefficients are now known:
|
|
*
|
|
* red-x*red-scale + green-x*green-scale + blue-x*blue-scale
|
|
* = white-x/white-y
|
|
* red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
|
|
* red-z*red-scale + green-z*green-scale + blue-z*blue-scale
|
|
* = (1 - white-x - white-y)/white-y
|
|
*
|
|
* In the last equation color-z is (1 - color-x - color-y) so we can add all
|
|
* three equations together to get an alternative third:
|
|
*
|
|
* red-scale + green-scale + blue-scale = 1/white-y = white-scale
|
|
*
|
|
* So now we have a Cramer's rule solution where the determinants are just
|
|
* 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
|
|
* multiplication of three coefficients so we can't guarantee to avoid
|
|
* overflow in the libpng fixed point representation. Using Cramer's rule in
|
|
* floating point is probably a good choice here, but it's not an option for
|
|
* fixed point. Instead proceed to simplify the first two equations by
|
|
* eliminating what is likely to be the largest value, blue-scale:
|
|
*
|
|
* blue-scale = white-scale - red-scale - green-scale
|
|
*
|
|
* Hence:
|
|
*
|
|
* (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
|
|
* (white-x - blue-x)*white-scale
|
|
*
|
|
* (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
|
|
* 1 - blue-y*white-scale
|
|
*
|
|
* And now we can trivially solve for (red-scale,green-scale):
|
|
*
|
|
* green-scale =
|
|
* (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
|
|
* -----------------------------------------------------------
|
|
* green-x - blue-x
|
|
*
|
|
* red-scale =
|
|
* 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
|
|
* ---------------------------------------------------------
|
|
* red-y - blue-y
|
|
*
|
|
* Hence:
|
|
*
|
|
* red-scale =
|
|
* ( (green-x - blue-x) * (white-y - blue-y) -
|
|
* (green-y - blue-y) * (white-x - blue-x) ) / white-y
|
|
* -------------------------------------------------------------------------
|
|
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
|
|
*
|
|
* green-scale =
|
|
* ( (red-y - blue-y) * (white-x - blue-x) -
|
|
* (red-x - blue-x) * (white-y - blue-y) ) / white-y
|
|
* -------------------------------------------------------------------------
|
|
* (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
|
|
*
|
|
* Accuracy:
|
|
* The input values have 5 decimal digits of accuracy. The values are all in
|
|
* the range 0 < value < 1, so simple products are in the same range but may
|
|
* need up to 10 decimal digits to preserve the original precision and avoid
|
|
* underflow. Because we are using a 32-bit signed representation we cannot
|
|
* match this; the best is a little over 9 decimal digits, less than 10.
|
|
*
|
|
* The approach used here is to preserve the maximum precision within the
|
|
* signed representation. Because the red-scale calculation above uses the
|
|
* difference between two products of values that must be in the range -1..+1
|
|
* it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
|
|
* factor is irrelevant in the calculation because it is applied to both
|
|
* numerator and denominator.
|
|
*
|
|
* Note that the values of the differences of the products of the
|
|
* chromaticities in the above equations tend to be small, for example for
|
|
* the sRGB chromaticities they are:
|
|
*
|
|
* red numerator: -0.04751
|
|
* green numerator: -0.08788
|
|
* denominator: -0.2241 (without white-y multiplication)
|
|
*
|
|
* The resultant Y coefficients from the chromaticities of some widely used
|
|
* color space definitions are (to 15 decimal places):
|
|
*
|
|
* sRGB
|
|
* 0.212639005871510 0.715168678767756 0.072192315360734
|
|
* Kodak ProPhoto
|
|
* 0.288071128229293 0.711843217810102 0.000085653960605
|
|
* Adobe RGB
|
|
* 0.297344975250536 0.627363566255466 0.075291458493998
|
|
* Adobe Wide Gamut RGB
|
|
* 0.258728243040113 0.724682314948566 0.016589442011321
|
|
*/
|
|
/* By the argument, above overflow should be impossible here. The return
|
|
* value of 2 indicates an internal error to the caller.
|
|
*/
|
|
if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.redy - xy.bluey, 7)) return 2;
|
|
if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.redx - xy.bluex, 7)) return 2;
|
|
denominator = left - right;
|
|
|
|
/* Now find the red numerator. */
|
|
if (!png_muldiv(&left, xy.greenx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2;
|
|
if (!png_muldiv(&right, xy.greeny-xy.bluey, xy.whitex-xy.bluex, 7)) return 2;
|
|
|
|
/* Overflow is possible here and it indicates an extreme set of PNG cHRM
|
|
* chunk values. This calculation actually returns the reciprocal of the
|
|
* scale value because this allows us to delay the multiplication of white-y
|
|
* into the denominator, which tends to produce a small number.
|
|
*/
|
|
if (!png_muldiv(&red_inverse, xy.whitey, denominator, left-right) ||
|
|
red_inverse <= xy.whitey /* r+g+b scales = white scale */)
|
|
return 1;
|
|
|
|
/* Similarly for green_inverse: */
|
|
if (!png_muldiv(&left, xy.redy-xy.bluey, xy.whitex-xy.bluex, 7)) return 2;
|
|
if (!png_muldiv(&right, xy.redx-xy.bluex, xy.whitey-xy.bluey, 7)) return 2;
|
|
if (!png_muldiv(&green_inverse, xy.whitey, denominator, left-right) ||
|
|
green_inverse <= xy.whitey)
|
|
return 1;
|
|
|
|
/* And the blue scale, the checks above guarantee this can't overflow but it
|
|
* can still produce 0 for extreme cHRM values.
|
|
*/
|
|
blue_scale = png_reciprocal(xy.whitey) - png_reciprocal(red_inverse) -
|
|
png_reciprocal(green_inverse);
|
|
if (blue_scale <= 0) return 1;
|
|
|
|
|
|
/* And fill in the png_XYZ: */
|
|
if (!png_muldiv(&XYZ->redX, xy.redx, PNG_FP_1, red_inverse)) return 1;
|
|
if (!png_muldiv(&XYZ->redY, xy.redy, PNG_FP_1, red_inverse)) return 1;
|
|
if (!png_muldiv(&XYZ->redZ, PNG_FP_1 - xy.redx - xy.redy, PNG_FP_1,
|
|
red_inverse))
|
|
return 1;
|
|
|
|
if (!png_muldiv(&XYZ->greenX, xy.greenx, PNG_FP_1, green_inverse)) return 1;
|
|
if (!png_muldiv(&XYZ->greenY, xy.greeny, PNG_FP_1, green_inverse)) return 1;
|
|
if (!png_muldiv(&XYZ->greenZ, PNG_FP_1 - xy.greenx - xy.greeny, PNG_FP_1,
|
|
green_inverse))
|
|
return 1;
|
|
|
|
if (!png_muldiv(&XYZ->blueX, xy.bluex, blue_scale, PNG_FP_1)) return 1;
|
|
if (!png_muldiv(&XYZ->blueY, xy.bluey, blue_scale, PNG_FP_1)) return 1;
|
|
if (!png_muldiv(&XYZ->blueZ, PNG_FP_1 - xy.bluex - xy.bluey, blue_scale,
|
|
PNG_FP_1))
|
|
return 1;
|
|
|
|
return 0; /*success*/
|
|
}
|
|
|
|
int png_XYZ_from_xy_checked(png_structp png_ptr, png_XYZ *XYZ, png_xy xy)
|
|
{
|
|
switch (png_XYZ_from_xy(XYZ, xy))
|
|
{
|
|
case 0: /* success */
|
|
return 1;
|
|
|
|
case 1:
|
|
/* The chunk may be technically valid, but we got png_fixed_point
|
|
* overflow while trying to get XYZ values out of it. This is
|
|
* entirely benign - the cHRM chunk is pretty extreme.
|
|
*/
|
|
png_warning(png_ptr,
|
|
"extreme cHRM chunk cannot be converted to tristimulus values");
|
|
break;
|
|
|
|
default:
|
|
/* libpng is broken; this should be a warning but if it happens we
|
|
* want error reports so for the moment it is an error.
|
|
*/
|
|
png_error(png_ptr, "internal error in png_XYZ_from_xy");
|
|
break;
|
|
}
|
|
|
|
/* ERROR RETURN */
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#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_structp png_ptr,
|
|
png_uint_32 width, png_uint_32 height, int bit_depth,
|
|
int color_type, int interlace_type, int compression_type,
|
|
int filter_type)
|
|
{
|
|
int error = 0;
|
|
|
|
/* Check for width and height valid values */
|
|
if (width == 0)
|
|
{
|
|
png_warning(png_ptr, "Image width is zero in IHDR");
|
|
error = 1;
|
|
}
|
|
else if (width > PNG_UINT_31_MAX)
|
|
{
|
|
png_warning(png_ptr, "Invalid image width in IHDR");
|
|
error = 1;
|
|
}
|
|
|
|
else if (png_gt(width,
|
|
(PNG_SIZE_MAX >> 3) /* 8-byte RGBA pixels */
|
|
- 48 /* big_row_buf hack */
|
|
- 1 /* filter byte */
|
|
- 7*8 /* rounding width to multiple of 8 pix */
|
|
- 8)) /* 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;
|
|
}
|
|
else
|
|
{
|
|
# 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;
|
|
}
|
|
else if (height > PNG_UINT_31_MAX)
|
|
{
|
|
png_warning(png_ptr, "Invalid image height in IHDR");
|
|
error = 1;
|
|
}
|
|
else
|
|
{
|
|
# 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) &&
|
|
png_ptr->mng_features_permitted)
|
|
png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
|
|
|
|
if (filter_type != PNG_FILTER_TYPE_BASE)
|
|
{
|
|
if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
|
|
(filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
|
|
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
|
|
(color_type == PNG_COLOR_TYPE_RGB ||
|
|
color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
|
|
{
|
|
png_warning(png_ptr, "Unknown filter method in IHDR");
|
|
error = 1;
|
|
}
|
|
|
|
if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
|
|
{
|
|
png_warning(png_ptr, "Invalid filter method in IHDR");
|
|
error = 1;
|
|
}
|
|
}
|
|
|
|
# else
|
|
if (filter_type != PNG_FILTER_TYPE_BASE)
|
|
{
|
|
png_warning(png_ptr, "Unknown filter method in IHDR");
|
|
error = 1;
|
|
}
|
|
# endif
|
|
|
|
if (error == 1)
|
|
png_error(png_ptr, "Invalid IHDR data");
|
|
}
|
|
|
|
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
|
|
/* ASCII to fp functions */
|
|
/* Check an ASCII formated floating point value, see the more detailed
|
|
* comments in pngpriv.h
|
|
*/
|
|
/* The following is used internally to preserve the sticky flags */
|
|
#define png_fp_add(state, flags) ((state) |= (flags))
|
|
#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
|
|
|
|
int /* PRIVATE */
|
|
png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
|
|
png_size_tp whereami)
|
|
{
|
|
int state = *statep;
|
|
png_size_t i = *whereami;
|
|
|
|
while (i < size)
|
|
{
|
|
int type;
|
|
/* First find the type of the next character */
|
|
switch (string[i])
|
|
{
|
|
case 43: type = PNG_FP_SAW_SIGN; break;
|
|
case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
|
|
case 46: type = PNG_FP_SAW_DOT; break;
|
|
case 48: type = PNG_FP_SAW_DIGIT; break;
|
|
case 49: case 50: case 51: case 52:
|
|
case 53: case 54: case 55: case 56:
|
|
case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
|
|
case 69:
|
|
case 101: type = PNG_FP_SAW_E; break;
|
|
default: goto PNG_FP_End;
|
|
}
|
|
|
|
/* Now deal with this type according to the current
|
|
* state, the type is arranged to not overlap the
|
|
* bits of the PNG_FP_STATE.
|
|
*/
|
|
switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
|
|
{
|
|
case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
|
|
if (state & PNG_FP_SAW_ANY)
|
|
goto PNG_FP_End; /* not a part of the number */
|
|
|
|
png_fp_add(state, type);
|
|
break;
|
|
|
|
case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
|
|
/* Ok as trailer, ok as lead of fraction. */
|
|
if (state & PNG_FP_SAW_DOT) /* two dots */
|
|
goto PNG_FP_End;
|
|
|
|
else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */
|
|
png_fp_add(state, type);
|
|
|
|
else
|
|
png_fp_set(state, PNG_FP_FRACTION | type);
|
|
|
|
break;
|
|
|
|
case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
|
|
if (state & PNG_FP_SAW_DOT) /* delayed fraction */
|
|
png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
|
|
|
|
png_fp_add(state, type | PNG_FP_WAS_VALID);
|
|
|
|
break;
|
|
|
|
case PNG_FP_INTEGER + PNG_FP_SAW_E:
|
|
if ((state & PNG_FP_SAW_DIGIT) == 0)
|
|
goto PNG_FP_End;
|
|
|
|
png_fp_set(state, PNG_FP_EXPONENT);
|
|
|
|
break;
|
|
|
|
/* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
|
|
goto PNG_FP_End; ** no sign in fraction */
|
|
|
|
/* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
|
|
goto PNG_FP_End; ** Because SAW_DOT is always set */
|
|
|
|
case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
|
|
png_fp_add(state, type | PNG_FP_WAS_VALID);
|
|
break;
|
|
|
|
case PNG_FP_FRACTION + PNG_FP_SAW_E:
|
|
/* This is correct because the trailing '.' on an
|
|
* integer is handled above - so we can only get here
|
|
* with the sequence ".E" (with no preceding digits).
|
|
*/
|
|
if ((state & PNG_FP_SAW_DIGIT) == 0)
|
|
goto PNG_FP_End;
|
|
|
|
png_fp_set(state, PNG_FP_EXPONENT);
|
|
|
|
break;
|
|
|
|
case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
|
|
if (state & PNG_FP_SAW_ANY)
|
|
goto PNG_FP_End; /* not a part of the number */
|
|
|
|
png_fp_add(state, PNG_FP_SAW_SIGN);
|
|
|
|
break;
|
|
|
|
/* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
|
|
goto PNG_FP_End; */
|
|
|
|
case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
|
|
png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
|
|
|
|
break;
|
|
|
|
/* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
|
|
goto PNG_FP_End; */
|
|
|
|
default: goto PNG_FP_End; /* I.e. break 2 */
|
|
}
|
|
|
|
/* The character seems ok, continue. */
|
|
++i;
|
|
}
|
|
|
|
PNG_FP_End:
|
|
/* Here at the end, update the state and return the correct
|
|
* return code.
|
|
*/
|
|
*statep = state;
|
|
*whereami = i;
|
|
|
|
return (state & PNG_FP_SAW_DIGIT) != 0;
|
|
}
|
|
|
|
|
|
/* The same but for a complete string. */
|
|
int
|
|
png_check_fp_string(png_const_charp string, png_size_t size)
|
|
{
|
|
int state=0;
|
|
png_size_t char_index=0;
|
|
|
|
if (png_check_fp_number(string, size, &state, &char_index) &&
|
|
(char_index == size || string[char_index] == 0))
|
|
return state /* must be non-zero - see above */;
|
|
|
|
return 0; /* i.e. fail */
|
|
}
|
|
#endif /* pCAL or sCAL */
|
|
|
|
#ifdef PNG_sCAL_SUPPORTED
|
|
# ifdef PNG_FLOATING_POINT_SUPPORTED
|
|
/* Utility used below - a simple accurate power of ten from an integral
|
|
* exponent.
|
|
*/
|
|
static double
|
|
png_pow10(int power)
|
|
{
|
|
int recip = 0;
|
|
double d = 1.0;
|
|
|
|
/* Handle negative exponent with a reciprocal at the end because
|
|
* 10 is exact whereas .1 is inexact in base 2
|
|
*/
|
|
if (power < 0)
|
|
{
|
|
if (power < DBL_MIN_10_EXP) return 0;
|
|
recip = 1, power = -power;
|
|
}
|
|
|
|
if (power > 0)
|
|
{
|
|
/* Decompose power bitwise. */
|
|
double mult = 10.0;
|
|
do
|
|
{
|
|
if (power & 1) d *= mult;
|
|
mult *= mult;
|
|
power >>= 1;
|
|
}
|
|
while (power > 0);
|
|
|
|
if (recip != 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.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size,
|
|
double fp, unsigned int precision)
|
|
{
|
|
/* We use standard functions from math.h, but not printf because
|
|
* that would require stdio. The caller must supply a buffer of
|
|
* sufficient size or we will png_error. The tests on size and
|
|
* the space in ascii[] consumed are indicated below.
|
|
*/
|
|
if (precision < 1)
|
|
precision = DBL_DIG;
|
|
|
|
/* Enforce the limit of the implementation precision too. */
|
|
if (precision > DBL_DIG+1)
|
|
precision = DBL_DIG+1;
|
|
|
|
/* Basic sanity checks */
|
|
if (size >= precision+5) /* See the requirements below. */
|
|
{
|
|
if (fp < 0)
|
|
{
|
|
fp = -fp;
|
|
*ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
|
|
--size;
|
|
}
|
|
|
|
if (fp >= DBL_MIN && fp <= DBL_MAX)
|
|
{
|
|
int exp_b10; /* A base 10 exponent */
|
|
double base; /* 10^exp_b10 */
|
|
|
|
/* First extract a base 10 exponent of the number,
|
|
* the calculation below rounds down when converting
|
|
* from base 2 to base 10 (multiply by log10(2) -
|
|
* 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
|
|
* be increased. Note that the arithmetic shift
|
|
* performs a floor() unlike C arithmetic - using a
|
|
* C multiply would break the following for negative
|
|
* exponents.
|
|
*/
|
|
(void)frexp(fp, &exp_b10); /* exponent to base 2 */
|
|
|
|
exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
|
|
|
|
/* Avoid underflow here. */
|
|
base = png_pow10(exp_b10); /* May underflow */
|
|
|
|
while (base < DBL_MIN || base < fp)
|
|
{
|
|
/* And this may overflow. */
|
|
double test = png_pow10(exp_b10+1);
|
|
|
|
if (test <= DBL_MAX)
|
|
++exp_b10, base = test;
|
|
|
|
else
|
|
break;
|
|
}
|
|
|
|
/* Normalize fp and correct exp_b10, after this fp is in the
|
|
* range [.1,1) and exp_b10 is both the exponent and the digit
|
|
* *before* which the decimal point should be inserted
|
|
* (starting with 0 for the first digit). Note that this
|
|
* works even if 10^exp_b10 is out of range because of the
|
|
* test on DBL_MAX above.
|
|
*/
|
|
fp /= base;
|
|
while (fp >= 1) fp /= 10, ++exp_b10;
|
|
|
|
/* Because of the code above fp may, at this point, be
|
|
* less than .1, this is ok because the code below can
|
|
* handle the leading zeros this generates, so no attempt
|
|
* is made to correct that here.
|
|
*/
|
|
|
|
{
|
|
int czero, clead, cdigits;
|
|
char exponent[10];
|
|
|
|
/* Allow up to two leading zeros - this will not lengthen
|
|
* the number compared to using E-n.
|
|
*/
|
|
if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
|
|
{
|
|
czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
|
|
exp_b10 = 0; /* Dot added below before first output. */
|
|
}
|
|
else
|
|
czero = 0; /* No zeros to add */
|
|
|
|
/* Generate the digit list, stripping trailing zeros and
|
|
* inserting a '.' before a digit if the exponent is 0.
|
|
*/
|
|
clead = czero; /* Count of leading zeros */
|
|
cdigits = 0; /* Count of digits in list. */
|
|
|
|
do
|
|
{
|
|
double d;
|
|
|
|
fp *= 10.0;
|
|
|
|
/* Use modf here, not floor and subtract, so that
|
|
* the separation is done in one step. At the end
|
|
* of the loop don't break the number into parts so
|
|
* that the final digit is rounded.
|
|
*/
|
|
if (cdigits+czero-clead+1 < (int)precision)
|
|
fp = modf(fp, &d);
|
|
|
|
else
|
|
{
|
|
d = floor(fp + .5);
|
|
|
|
if (d > 9.0)
|
|
{
|
|
/* Rounding up to 10, handle that here. */
|
|
if (czero > 0)
|
|
{
|
|
--czero, d = 1;
|
|
if (cdigits == 0) --clead;
|
|
}
|
|
|
|
else
|
|
{
|
|
while (cdigits > 0 && d > 9.0)
|
|
{
|
|
int ch = *--ascii;
|
|
|
|
if (exp_b10 != (-1))
|
|
++exp_b10;
|
|
|
|
else if (ch == 46)
|
|
{
|
|
ch = *--ascii, ++size;
|
|
/* Advance exp_b10 to '1', so that the
|
|
* decimal point happens after the
|
|
* previous digit.
|
|
*/
|
|
exp_b10 = 1;
|
|
}
|
|
|
|
--cdigits;
|
|
d = ch - 47; /* I.e. 1+(ch-48) */
|
|
}
|
|
|
|
/* Did we reach the beginning? If so adjust the
|
|
* exponent but take into account the leading
|
|
* decimal point.
|
|
*/
|
|
if (d > 9.0) /* cdigits == 0 */
|
|
{
|
|
if (exp_b10 == (-1))
|
|
{
|
|
/* Leading decimal point (plus zeros?), if
|
|
* we lose the decimal point here it must
|
|
* be reentered below.
|
|
*/
|
|
int ch = *--ascii;
|
|
|
|
if (ch == 46)
|
|
++size, exp_b10 = 1;
|
|
|
|
/* Else lost a leading zero, so 'exp_b10' is
|
|
* still ok at (-1)
|
|
*/
|
|
}
|
|
else
|
|
++exp_b10;
|
|
|
|
/* In all cases we output a '1' */
|
|
d = 1.0;
|
|
}
|
|
}
|
|
}
|
|
fp = 0; /* Guarantees termination below. */
|
|
}
|
|
|
|
if (d == 0.0)
|
|
{
|
|
++czero;
|
|
if (cdigits == 0) ++clead;
|
|
}
|
|
|
|
else
|
|
{
|
|
/* Included embedded zeros in the digit count. */
|
|
cdigits += czero - clead;
|
|
clead = 0;
|
|
|
|
while (czero > 0)
|
|
{
|
|
/* exp_b10 == (-1) means we just output the decimal
|
|
* place - after the DP don't adjust 'exp_b10' any
|
|
* more!
|
|
*/
|
|
if (exp_b10 != (-1))
|
|
{
|
|
if (exp_b10 == 0) *ascii++ = 46, --size;
|
|
/* PLUS 1: TOTAL 4 */
|
|
--exp_b10;
|
|
}
|
|
*ascii++ = 48, --czero;
|
|
}
|
|
|
|
if (exp_b10 != (-1))
|
|
{
|
|
if (exp_b10 == 0) *ascii++ = 46, --size; /* counted
|
|
above */
|
|
--exp_b10;
|
|
}
|
|
|
|
*ascii++ = (char)(48 + (int)d), ++cdigits;
|
|
}
|
|
}
|
|
while (cdigits+czero-clead < (int)precision && fp > DBL_MIN);
|
|
|
|
/* The total output count (max) is now 4+precision */
|
|
|
|
/* Check for an exponent, if we don't need one we are
|
|
* done and just need to terminate the string. At
|
|
* this point exp_b10==(-1) is effectively if flag - it got
|
|
* to '-1' because of the decrement after 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 = -exp_b10;
|
|
}
|
|
|
|
else
|
|
uexp_b10 = exp_b10;
|
|
|
|
cdigits = 0;
|
|
|
|
while (uexp_b10 > 0)
|
|
{
|
|
exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
|
|
uexp_b10 /= 10;
|
|
}
|
|
}
|
|
|
|
/* Need another size check here for the exponent digits, so
|
|
* this need not be considered above.
|
|
*/
|
|
if ((int)size > cdigits)
|
|
{
|
|
while (cdigits > 0) *ascii++ = exponent[--cdigits];
|
|
|
|
*ascii = 0;
|
|
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
else if (!(fp >= DBL_MIN))
|
|
{
|
|
*ascii++ = 48; /* '0' */
|
|
*ascii = 0;
|
|
return;
|
|
}
|
|
else
|
|
{
|
|
*ascii++ = 105; /* 'i' */
|
|
*ascii++ = 110; /* 'n' */
|
|
*ascii++ = 102; /* 'f' */
|
|
*ascii = 0;
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Here on buffer too small. */
|
|
png_error(png_ptr, "ASCII conversion buffer too small");
|
|
}
|
|
|
|
# endif /* FLOATING_POINT */
|
|
|
|
# ifdef PNG_FIXED_POINT_SUPPORTED
|
|
/* Function to format a fixed point value in ASCII.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size,
|
|
png_fixed_point fp)
|
|
{
|
|
/* Require space for 10 decimal digits, a decimal point, a minus sign and a
|
|
* trailing \0, 13 characters:
|
|
*/
|
|
if (size > 12)
|
|
{
|
|
png_uint_32 num;
|
|
|
|
/* Avoid overflow here on the minimum integer. */
|
|
if (fp < 0)
|
|
*ascii++ = 45, --size, num = -fp;
|
|
else
|
|
num = fp;
|
|
|
|
if (num <= 0x80000000) /* else overflowed */
|
|
{
|
|
unsigned int ndigits = 0, first = 16 /* flag value */;
|
|
char digits[10];
|
|
|
|
while (num)
|
|
{
|
|
/* Split the low digit off num: */
|
|
unsigned int tmp = num/10;
|
|
num -= tmp*10;
|
|
digits[ndigits++] = (char)(48 + num);
|
|
/* Record the first non-zero digit, note that this is a number
|
|
* starting at 1, it's not actually the array index.
|
|
*/
|
|
if (first == 16 && num > 0)
|
|
first = ndigits;
|
|
num = tmp;
|
|
}
|
|
|
|
if (ndigits > 0)
|
|
{
|
|
while (ndigits > 5) *ascii++ = digits[--ndigits];
|
|
/* The remaining digits are fractional digits, ndigits is '5' or
|
|
* smaller at this point. It is certainly not zero. Check for a
|
|
* non-zero fractional digit:
|
|
*/
|
|
if (first <= 5)
|
|
{
|
|
unsigned int i;
|
|
*ascii++ = 46; /* decimal point */
|
|
/* ndigits may be <5 for small numbers, output leading zeros
|
|
* then ndigits digits to first:
|
|
*/
|
|
i = 5;
|
|
while (ndigits < i) *ascii++ = 48, --i;
|
|
while (ndigits >= first) *ascii++ = digits[--ndigits];
|
|
/* Don't output the trailing zeros! */
|
|
}
|
|
}
|
|
else
|
|
*ascii++ = 48;
|
|
|
|
/* And null terminate the string: */
|
|
*ascii = 0;
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Here on buffer too small. */
|
|
png_error(png_ptr, "ASCII conversion buffer too small");
|
|
}
|
|
# endif /* FIXED_POINT */
|
|
#endif /* READ_SCAL */
|
|
|
|
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
|
|
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED)
|
|
png_fixed_point
|
|
png_fixed(png_structp png_ptr, double fp, png_const_charp text)
|
|
{
|
|
double r = floor(100000 * fp + .5);
|
|
|
|
if (r > 2147483647. || r < -2147483648.)
|
|
png_fixed_error(png_ptr, text);
|
|
|
|
return (png_fixed_point)r;
|
|
}
|
|
#endif
|
|
|
|
#if defined(PNG_READ_GAMMA_SUPPORTED) || \
|
|
defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
|
|
/* muldiv functions */
|
|
/* This API takes signed arguments and rounds the result to the nearest
|
|
* integer (or, for a fixed point number - the standard argument - to
|
|
* the nearest .00001). Overflow and divide by zero are signalled in
|
|
* the result, a boolean - true on success, false on overflow.
|
|
*/
|
|
int
|
|
png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
|
|
png_int_32 divisor)
|
|
{
|
|
/* Return a * times / divisor, rounded. */
|
|
if (divisor != 0)
|
|
{
|
|
if (a == 0 || times == 0)
|
|
{
|
|
*res = 0;
|
|
return 1;
|
|
}
|
|
else
|
|
{
|
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
double r = a;
|
|
r *= times;
|
|
r /= divisor;
|
|
r = floor(r+.5);
|
|
|
|
/* A png_fixed_point is a 32-bit integer. */
|
|
if (r <= 2147483647. && r >= -2147483648.)
|
|
{
|
|
*res = (png_fixed_point)r;
|
|
return 1;
|
|
}
|
|
#else
|
|
int negative = 0;
|
|
png_uint_32 A, T, D;
|
|
png_uint_32 s16, s32, s00;
|
|
|
|
if (a < 0)
|
|
negative = 1, A = -a;
|
|
else
|
|
A = a;
|
|
|
|
if (times < 0)
|
|
negative = !negative, T = -times;
|
|
else
|
|
T = times;
|
|
|
|
if (divisor < 0)
|
|
negative = !negative, D = -divisor;
|
|
else
|
|
D = divisor;
|
|
|
|
/* Following can't overflow because the arguments only
|
|
* have 31 bits each, however the result may be 32 bits.
|
|
*/
|
|
s16 = (A >> 16) * (T & 0xffff) +
|
|
(A & 0xffff) * (T >> 16);
|
|
/* Can't overflow because the a*times bit is only 30
|
|
* bits at most.
|
|
*/
|
|
s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
|
|
s00 = (A & 0xffff) * (T & 0xffff);
|
|
|
|
s16 = (s16 & 0xffff) << 16;
|
|
s00 += s16;
|
|
|
|
if (s00 < s16)
|
|
++s32; /* carry */
|
|
|
|
if (s32 < D) /* else overflow */
|
|
{
|
|
/* s32.s00 is now the 64-bit product, do a standard
|
|
* division, we know that s32 < D, so the maximum
|
|
* required shift is 31.
|
|
*/
|
|
int bitshift = 32;
|
|
png_fixed_point result = 0; /* NOTE: signed */
|
|
|
|
while (--bitshift >= 0)
|
|
{
|
|
png_uint_32 d32, d00;
|
|
|
|
if (bitshift > 0)
|
|
d32 = D >> (32-bitshift), d00 = D << bitshift;
|
|
|
|
else
|
|
d32 = 0, d00 = D;
|
|
|
|
if (s32 > d32)
|
|
{
|
|
if (s00 < d00) --s32; /* carry */
|
|
s32 -= d32, s00 -= d00, result += 1<<bitshift;
|
|
}
|
|
|
|
else
|
|
if (s32 == d32 && s00 >= d00)
|
|
s32 = 0, s00 -= d00, result += 1<<bitshift;
|
|
}
|
|
|
|
/* Handle the rounding. */
|
|
if (s00 >= (D >> 1))
|
|
++result;
|
|
|
|
if (negative != 0)
|
|
result = -result;
|
|
|
|
/* Check for overflow. */
|
|
if ((negative && result <= 0) || (!negative && result >= 0))
|
|
{
|
|
*res = result;
|
|
return 1;
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif /* READ_GAMMA || INCH_CONVERSIONS */
|
|
|
|
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
|
|
/* The following is for when the caller doesn't much care about the
|
|
* result.
|
|
*/
|
|
png_fixed_point
|
|
png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times,
|
|
png_int_32 divisor)
|
|
{
|
|
png_fixed_point result;
|
|
|
|
if (png_muldiv(&result, a, times, divisor))
|
|
return result;
|
|
|
|
png_warning(png_ptr, "fixed point overflow ignored");
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED)
|
|
/* more fixed point functions for gamma and cHRM (xy/XYZ) suport. */
|
|
/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
|
|
png_fixed_point
|
|
png_reciprocal(png_fixed_point a)
|
|
{
|
|
if (a != 0)
|
|
{
|
|
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
double r = floor(1E10/a+.5);
|
|
|
|
if (r <= 2147483647. && r >= -2147483648.)
|
|
return (png_fixed_point)r;
|
|
#else
|
|
png_fixed_point res;
|
|
|
|
if (png_muldiv(&res, 100000, 100000, a))
|
|
return res;
|
|
#endif
|
|
}
|
|
|
|
return 0; /* error/overflow */
|
|
}
|
|
|
|
#ifdef PNG_READ_GAMMA_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))
|
|
return res;
|
|
#endif
|
|
|
|
return 0; /* overflow */
|
|
}
|
|
#endif /* READ_GAMMA */
|
|
|
|
/* 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 || cHRM */
|
|
|
|
#ifdef PNG_CHECK_cHRM_SUPPORTED
|
|
/* Added at libpng version 1.2.34 (Dec 8, 2008) and 1.4.0 (Jan 2,
|
|
* 2010: moved from pngset.c) */
|
|
/*
|
|
* Multiply two 32-bit numbers, V1 and V2, using 32-bit
|
|
* arithmetic, to produce a 64-bit result in the HI/LO words.
|
|
*
|
|
* A B
|
|
* x C D
|
|
* ------
|
|
* AD || BD
|
|
* AC || CB || 0
|
|
*
|
|
* where A and B are the high and low 16-bit words of V1,
|
|
* C and D are the 16-bit words of V2, AD is the product of
|
|
* A and D, and X || Y is (X << 16) + Y.
|
|
*/
|
|
|
|
void /* PRIVATE */
|
|
png_64bit_product (long v1, long v2, unsigned long *hi_product,
|
|
unsigned long *lo_product)
|
|
{
|
|
int a, b, c, d;
|
|
long lo, hi, x, y;
|
|
|
|
a = (v1 >> 16) & 0xffff;
|
|
b = v1 & 0xffff;
|
|
c = (v2 >> 16) & 0xffff;
|
|
d = v2 & 0xffff;
|
|
|
|
lo = b * d; /* BD */
|
|
x = a * d + c * b; /* AD + CB */
|
|
y = ((lo >> 16) & 0xffff) + x;
|
|
|
|
lo = (lo & 0xffff) | ((y & 0xffff) << 16);
|
|
hi = (y >> 16) & 0xffff;
|
|
|
|
hi += a * c; /* AC */
|
|
|
|
*hi_product = (unsigned long)hi;
|
|
*lo_product = (unsigned long)lo;
|
|
}
|
|
#endif /* CHECK_cHRM */
|
|
|
|
#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
|
|
#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
/* Fixed point gamma.
|
|
*
|
|
* To calculate gamma this code implements fast log() and exp() calls using only
|
|
* fixed point arithmetic. This code has sufficient precision for either 8-bit
|
|
* or 16-bit sample values.
|
|
*
|
|
* The tables used here were calculated using simple 'bc' programs, but C double
|
|
* precision floating point arithmetic would work fine. The programs are given
|
|
* at the head of each table.
|
|
*
|
|
* 8-bit log table
|
|
* This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
|
|
* 255, so it's the base 2 logarithm of a normalized 8-bit floating point
|
|
* mantissa. The numbers are 32-bit fractions.
|
|
*/
|
|
static png_uint_32
|
|
png_8bit_l2[128] =
|
|
{
|
|
# ifdef PNG_DO_BC
|
|
for (i=128;i<256;++i) { .5 - l(i/255)/l(2)*65536*65536; }
|
|
# else
|
|
4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
|
|
3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
|
|
3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
|
|
3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
|
|
3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
|
|
2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
|
|
2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
|
|
2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
|
|
2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
|
|
2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
|
|
1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
|
|
1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
|
|
1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
|
|
1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
|
|
1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
|
|
971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
|
|
803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
|
|
639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
|
|
479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
|
|
324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
|
|
172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
|
|
24347096U, 0U
|
|
# endif
|
|
|
|
#if 0
|
|
/* The following are the values for 16-bit tables - these work fine for the
|
|
* 8-bit conversions but produce very slightly larger errors in the 16-bit
|
|
* log (about 1.2 as opposed to 0.7 absolute error in the final value). To
|
|
* use these all the shifts below must be adjusted appropriately.
|
|
*/
|
|
65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
|
|
57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
|
|
50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
|
|
43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
|
|
37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
|
|
31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
|
|
25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
|
|
20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
|
|
15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
|
|
10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
|
|
6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
|
|
1119, 744, 372
|
|
#endif
|
|
};
|
|
|
|
PNG_STATIC png_int_32
|
|
png_log8bit(unsigned int x)
|
|
{
|
|
unsigned int lg2 = 0;
|
|
/* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
|
|
* because the log is actually negate that means adding 1. The final
|
|
* returned value thus has the range 0 (for 255 input) to 7.994 (for 1
|
|
* input), return 7.99998 for the overflow (log 0) case - so the result is
|
|
* always at most 19 bits.
|
|
*/
|
|
if ((x &= 0xff) == 0)
|
|
return 0xffffffff;
|
|
|
|
if ((x & 0xf0) == 0)
|
|
lg2 = 4, x <<= 4;
|
|
|
|
if ((x & 0xc0) == 0)
|
|
lg2 += 2, x <<= 2;
|
|
|
|
if ((x & 0x80) == 0)
|
|
lg2 += 1, x <<= 1;
|
|
|
|
/* result is at most 19 bits, so this cast is safe: */
|
|
return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
|
|
}
|
|
|
|
/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
|
|
* for 16-bit images we use the most significant 8 bits of the 16-bit value to
|
|
* get an approximation then multiply the approximation by a correction factor
|
|
* determined by the remaining up to 8 bits. This requires an additional step
|
|
* in the 16-bit case.
|
|
*
|
|
* We want log2(value/65535), we have log2(v'/255), where:
|
|
*
|
|
* value = v' * 256 + v''
|
|
* = v' * f
|
|
*
|
|
* So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
|
|
* to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
|
|
* than 258. The final factor also needs to correct for the fact that our 8-bit
|
|
* value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
|
|
*
|
|
* This gives a final formula using a calculated value 'x' which is value/v' and
|
|
* scaling by 65536 to match the above table:
|
|
*
|
|
* log2(x/257) * 65536
|
|
*
|
|
* Since these numbers are so close to '1' we can use simple linear
|
|
* interpolation between the two end values 256/257 (result -368.61) and 258/257
|
|
* (result 367.179). The values used below are scaled by a further 64 to give
|
|
* 16-bit precision in the interpolation:
|
|
*
|
|
* Start (256): -23591
|
|
* Zero (257): 0
|
|
* End (258): 23499
|
|
*/
|
|
PNG_STATIC png_int_32
|
|
png_log16bit(png_uint_32 x)
|
|
{
|
|
unsigned int lg2 = 0;
|
|
|
|
/* As above, but now the input has 16 bits. */
|
|
if ((x &= 0xffff) == 0)
|
|
return 0xffffffff;
|
|
|
|
if ((x & 0xff00) == 0)
|
|
lg2 = 8, x <<= 8;
|
|
|
|
if ((x & 0xf000) == 0)
|
|
lg2 += 4, x <<= 4;
|
|
|
|
if ((x & 0xc000) == 0)
|
|
lg2 += 2, x <<= 2;
|
|
|
|
if ((x & 0x8000) == 0)
|
|
lg2 += 1, x <<= 1;
|
|
|
|
/* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
|
|
* value.
|
|
*/
|
|
lg2 <<= 28;
|
|
lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
|
|
|
|
/* Now we need to interpolate the factor, this requires a division by the top
|
|
* 8 bits. Do this with maximum precision.
|
|
*/
|
|
x = ((x << 16) + (x >> 9)) / (x >> 8);
|
|
|
|
/* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
|
|
* the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
|
|
* 16 bits to interpolate to get the low bits of the result. Round the
|
|
* answer. Note that the end point values are scaled by 64 to retain overall
|
|
* precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
|
|
* the overall scaling by 6-12. Round at every step.
|
|
*/
|
|
x -= 1U << 24;
|
|
|
|
if (x <= 65536U) /* <= '257' */
|
|
lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
|
|
|
|
else
|
|
lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
|
|
|
|
/* Safe, because the result can't have more than 20 bits: */
|
|
return (png_int_32)((lg2 + 2048) >> 12);
|
|
}
|
|
|
|
/* The 'exp()' case must invert the above, taking a 20-bit fixed point
|
|
* logarithmic value and returning a 16 or 8-bit number as appropriate. In
|
|
* each case only the low 16 bits are relevant - the fraction - since the
|
|
* integer bits (the top 4) simply determine a shift.
|
|
*
|
|
* The worst case is the 16-bit distinction between 65535 and 65534, this
|
|
* requires perhaps spurious accuracy in the decoding of the logarithm to
|
|
* distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
|
|
* of getting this accuracy in practice.
|
|
*
|
|
* To deal with this the following exp() function works out the exponent of the
|
|
* frational part of the logarithm by using an accurate 32-bit value from the
|
|
* top four fractional bits then multiplying in the remaining bits.
|
|
*/
|
|
static png_uint_32
|
|
png_32bit_exp[16] =
|
|
{
|
|
# ifdef PNG_DO_BC
|
|
for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; }
|
|
# else
|
|
/* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
|
|
4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
|
|
3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
|
|
2553802834U, 2445529972U, 2341847524U, 2242560872U
|
|
# endif
|
|
};
|
|
|
|
/* Adjustment table; provided to explain the numbers in the code below. */
|
|
#ifdef PNG_DO_BC
|
|
for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
|
|
11 44937.64284865548751208448
|
|
10 45180.98734845585101160448
|
|
9 45303.31936980687359311872
|
|
8 45364.65110595323018870784
|
|
7 45395.35850361789624614912
|
|
6 45410.72259715102037508096
|
|
5 45418.40724413220722311168
|
|
4 45422.25021786898173001728
|
|
3 45424.17186732298419044352
|
|
2 45425.13273269940811464704
|
|
1 45425.61317555035558641664
|
|
0 45425.85339951654943850496
|
|
#endif
|
|
|
|
PNG_STATIC png_uint_32
|
|
png_exp(png_fixed_point x)
|
|
{
|
|
if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
|
|
{
|
|
/* Obtain a 4-bit approximation */
|
|
png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf];
|
|
|
|
/* Incorporate the low 12 bits - these decrease the returned value by
|
|
* multiplying by a number less than 1 if the bit is set. The multiplier
|
|
* is determined by the above table and the shift. Notice that the values
|
|
* converge on 45426 and this is used to allow linear interpolation of the
|
|
* low bits.
|
|
*/
|
|
if (x & 0x800)
|
|
e -= (((e >> 16) * 44938U) + 16U) >> 5;
|
|
|
|
if (x & 0x400)
|
|
e -= (((e >> 16) * 45181U) + 32U) >> 6;
|
|
|
|
if (x & 0x200)
|
|
e -= (((e >> 16) * 45303U) + 64U) >> 7;
|
|
|
|
if (x & 0x100)
|
|
e -= (((e >> 16) * 45365U) + 128U) >> 8;
|
|
|
|
if (x & 0x080)
|
|
e -= (((e >> 16) * 45395U) + 256U) >> 9;
|
|
|
|
if (x & 0x040)
|
|
e -= (((e >> 16) * 45410U) + 512U) >> 10;
|
|
|
|
/* And handle the low 6 bits in a single block. */
|
|
e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
|
|
|
|
/* Handle the upper bits of x. */
|
|
e >>= x >> 16;
|
|
return e;
|
|
}
|
|
|
|
/* Check for overflow */
|
|
if (x <= 0)
|
|
return png_32bit_exp[0];
|
|
|
|
/* Else underflow */
|
|
return 0;
|
|
}
|
|
|
|
PNG_STATIC png_byte
|
|
png_exp8bit(png_fixed_point lg2)
|
|
{
|
|
/* Get a 32-bit value: */
|
|
png_uint_32 x = png_exp(lg2);
|
|
|
|
/* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the
|
|
* second, rounding, step can't overflow because of the first, subtraction,
|
|
* step.
|
|
*/
|
|
x -= x >> 8;
|
|
return (png_byte)((x + 0x7fffffU) >> 24);
|
|
}
|
|
|
|
PNG_STATIC png_uint_16
|
|
png_exp16bit(png_fixed_point lg2)
|
|
{
|
|
/* Get a 32-bit value: */
|
|
png_uint_32 x = png_exp(lg2);
|
|
|
|
/* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
|
|
x -= x >> 16;
|
|
return (png_uint_16)((x + 32767U) >> 16);
|
|
}
|
|
#endif /* FLOATING_ARITHMETIC */
|
|
|
|
png_byte
|
|
png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
|
|
{
|
|
if (value > 0 && value < 255)
|
|
{
|
|
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
double r = floor(255*pow(value/255.,gamma_val*.00001)+.5);
|
|
return (png_byte)r;
|
|
# else
|
|
png_int_32 lg2 = png_log8bit(value);
|
|
png_fixed_point res;
|
|
|
|
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
|
|
return png_exp8bit(res);
|
|
|
|
/* Overflow. */
|
|
value = 0;
|
|
# endif
|
|
}
|
|
|
|
return (png_byte)value;
|
|
}
|
|
|
|
png_uint_16
|
|
png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
|
|
{
|
|
if (value > 0 && value < 65535)
|
|
{
|
|
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5);
|
|
return (png_uint_16)r;
|
|
# else
|
|
png_int_32 lg2 = png_log16bit(value);
|
|
png_fixed_point res;
|
|
|
|
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
|
|
return png_exp16bit(res);
|
|
|
|
/* Overflow. */
|
|
value = 0;
|
|
# endif
|
|
}
|
|
|
|
return (png_uint_16)value;
|
|
}
|
|
|
|
/* This does the right thing based on the bit_depth field of the
|
|
* png_struct, interpreting values as 8-bit or 16-bit. While the result
|
|
* is nominally a 16-bit value if bit depth is 8 then the result is
|
|
* 8-bit (as are the arguments.)
|
|
*/
|
|
png_uint_16 /* PRIVATE */
|
|
png_gamma_correct(png_structp png_ptr, unsigned int value,
|
|
png_fixed_point gamma_val)
|
|
{
|
|
if (png_ptr->bit_depth == 8)
|
|
return png_gamma_8bit_correct(value, gamma_val);
|
|
|
|
else
|
|
return png_gamma_16bit_correct(value, gamma_val);
|
|
}
|
|
|
|
/* This is the shared test on whether a gamma value is 'significant' - whether
|
|
* it is worth doing gamma correction.
|
|
*/
|
|
int /* PRIVATE */
|
|
png_gamma_significant(png_fixed_point gamma_val)
|
|
{
|
|
return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
|
|
gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
|
|
}
|
|
|
|
#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_structp png_ptr, png_uint_16pp *ptable,
|
|
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
|
|
{
|
|
/* Various values derived from 'shift': */
|
|
PNG_CONST unsigned int num = 1U << (8U - shift);
|
|
PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
|
|
PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
|
|
unsigned int i;
|
|
|
|
png_uint_16pp table = *ptable =
|
|
(png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p));
|
|
|
|
for (i = 0; i < num; i++)
|
|
{
|
|
png_uint_16p sub_table = table[i] =
|
|
(png_uint_16p)png_malloc(png_ptr, 256 * png_sizeof(png_uint_16));
|
|
|
|
/* The 'threshold' test is repeated here because it can arise for one of
|
|
* the 16-bit tables even if the others don't hit it.
|
|
*/
|
|
if (png_gamma_significant(gamma_val))
|
|
{
|
|
/* The old code would overflow at the end and this would cause the
|
|
* 'pow' function to return a result >1, resulting in an
|
|
* arithmetic error. This code follows the spec exactly; ig is
|
|
* the recovered input sample, it always has 8-16 bits.
|
|
*
|
|
* We want input * 65535/max, rounded, the arithmetic fits in 32
|
|
* bits (unsigned) so long as max <= 32767.
|
|
*/
|
|
unsigned int j;
|
|
for (j = 0; j < 256; j++)
|
|
{
|
|
png_uint_32 ig = (j << (8-shift)) + i;
|
|
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
/* Inline the 'max' scaling operation: */
|
|
double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5);
|
|
sub_table[j] = (png_uint_16)d;
|
|
# else
|
|
if (shift != 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;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/* NOTE: this function expects the *inverse* of the overall gamma transformation
|
|
* required.
|
|
*/
|
|
static void
|
|
png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable,
|
|
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
|
|
{
|
|
PNG_CONST unsigned int num = 1U << (8U - shift);
|
|
PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
|
|
unsigned int i;
|
|
png_uint_32 last;
|
|
|
|
png_uint_16pp table = *ptable =
|
|
(png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p));
|
|
|
|
/* 'num' is the number of tables and also the number of low bits of the
|
|
* input 16-bit value used to select a table. Each table is itself indexed
|
|
* by the high 8 bits of the value.
|
|
*/
|
|
for (i = 0; i < num; i++)
|
|
table[i] = (png_uint_16p)png_malloc(png_ptr,
|
|
256 * png_sizeof(png_uint_16));
|
|
|
|
/* 'gamma_val' is set to the reciprocal of the value calculated above, so
|
|
* pow(out,g) is an *input* value. 'last' is the last input value set.
|
|
*
|
|
* In the loop 'i' is used to find output values. Since the output is
|
|
* 8-bit there are only 256 possible values. The tables are set up to
|
|
* select the closest possible output value for each input by finding
|
|
* the input value at the boundary between each pair of output values
|
|
* and filling the table up to that boundary with the lower output
|
|
* value.
|
|
*
|
|
* The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
|
|
* values the code below uses a 16-bit value in i; the values start at
|
|
* 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
|
|
* entries are filled with 255). Start i at 128 and fill all 'last'
|
|
* table entries <= 'max'
|
|
*/
|
|
last = 0;
|
|
for (i = 0; i < 255; ++i) /* 8-bit output value */
|
|
{
|
|
/* Find the corresponding maximum input value */
|
|
png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
|
|
|
|
/* Find the boundary value in 16 bits: */
|
|
png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
|
|
|
|
/* Adjust (round) to (16-shift) bits: */
|
|
bound = (bound * max + 32768U)/65535U + 1U;
|
|
|
|
while (last < bound)
|
|
{
|
|
table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
|
|
last++;
|
|
}
|
|
}
|
|
|
|
/* And fill in the final entries. */
|
|
while (last < (num << 8))
|
|
{
|
|
table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
|
|
last++;
|
|
}
|
|
}
|
|
|
|
/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
|
|
* typically much faster). Note that libpng currently does no sBIT processing
|
|
* (apparently contrary to the spec) so a 256-entry table is always generated.
|
|
*/
|
|
static void
|
|
png_build_8bit_table(png_structp png_ptr, png_bytepp ptable,
|
|
PNG_CONST png_fixed_point gamma_val)
|
|
{
|
|
unsigned int i;
|
|
png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
|
|
|
|
if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++)
|
|
table[i] = png_gamma_8bit_correct(i, gamma_val);
|
|
|
|
else for (i=0; i<256; ++i)
|
|
table[i] = (png_byte)i;
|
|
}
|
|
|
|
/* Used from png_read_destroy and below to release the memory used by the gamma
|
|
* tables.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_destroy_gamma_table(png_structp png_ptr)
|
|
{
|
|
png_free(png_ptr, png_ptr->gamma_table);
|
|
png_ptr->gamma_table = NULL;
|
|
|
|
if (png_ptr->gamma_16_table != NULL)
|
|
{
|
|
int i;
|
|
int istop = (1 << (8 - png_ptr->gamma_shift));
|
|
for (i = 0; i < istop; i++)
|
|
{
|
|
png_free(png_ptr, png_ptr->gamma_16_table[i]);
|
|
}
|
|
png_free(png_ptr, png_ptr->gamma_16_table);
|
|
png_ptr->gamma_16_table = NULL;
|
|
}
|
|
|
|
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
|
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
|
png_free(png_ptr, png_ptr->gamma_from_1);
|
|
png_ptr->gamma_from_1 = NULL;
|
|
png_free(png_ptr, png_ptr->gamma_to_1);
|
|
png_ptr->gamma_to_1 = NULL;
|
|
|
|
if (png_ptr->gamma_16_from_1 != NULL)
|
|
{
|
|
int i;
|
|
int istop = (1 << (8 - png_ptr->gamma_shift));
|
|
for (i = 0; i < istop; i++)
|
|
{
|
|
png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
|
|
}
|
|
png_free(png_ptr, png_ptr->gamma_16_from_1);
|
|
png_ptr->gamma_16_from_1 = NULL;
|
|
}
|
|
if (png_ptr->gamma_16_to_1 != NULL)
|
|
{
|
|
int i;
|
|
int istop = (1 << (8 - png_ptr->gamma_shift));
|
|
for (i = 0; i < istop; i++)
|
|
{
|
|
png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
|
|
}
|
|
png_free(png_ptr, png_ptr->gamma_16_to_1);
|
|
png_ptr->gamma_16_to_1 = NULL;
|
|
}
|
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
}
|
|
|
|
/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
|
|
* tables, we don't make a full table if we are reducing to 8-bit in
|
|
* the future. Note also how the gamma_16 tables are segmented so that
|
|
* we don't need to allocate > 64K chunks for a full 16-bit table.
|
|
*/
|
|
void /* PRIVATE */
|
|
png_build_gamma_table(png_structp png_ptr, int bit_depth)
|
|
{
|
|
png_debug(1, "in png_build_gamma_table");
|
|
|
|
/* Remove any existing table; this copes with multiple calls to
|
|
* png_read_update_info. The warning is because building the gamma tables
|
|
* multiple times is a performance hit - it's harmless but the ability to call
|
|
* png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
|
|
* to warn if the app introduces such a hit.
|
|
*/
|
|
if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
|
|
{
|
|
png_warning(png_ptr, "gamma table being rebuilt");
|
|
png_destroy_gamma_table(png_ptr);
|
|
}
|
|
|
|
if (bit_depth <= 8)
|
|
{
|
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
|
|
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma,
|
|
png_ptr->screen_gamma) : PNG_FP_1);
|
|
|
|
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
|
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
|
if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
|
|
{
|
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
|
|
png_reciprocal(png_ptr->gamma));
|
|
|
|
png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
|
|
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
|
|
png_ptr->gamma/* Probably doing rgb_to_gray */);
|
|
}
|
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
}
|
|
else
|
|
{
|
|
png_byte shift, sig_bit;
|
|
|
|
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
|
|
{
|
|
sig_bit = png_ptr->sig_bit.red;
|
|
|
|
if (png_ptr->sig_bit.green > sig_bit)
|
|
sig_bit = png_ptr->sig_bit.green;
|
|
|
|
if (png_ptr->sig_bit.blue > sig_bit)
|
|
sig_bit = png_ptr->sig_bit.blue;
|
|
}
|
|
else
|
|
sig_bit = png_ptr->sig_bit.gray;
|
|
|
|
/* 16-bit gamma code uses this equation:
|
|
*
|
|
* ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
|
|
*
|
|
* Where 'iv' is the input color value and 'ov' is the output value -
|
|
* pow(iv, gamma).
|
|
*
|
|
* Thus the gamma table consists of up to 256 256-entry tables. The table
|
|
* is selected by the (8-gamma_shift) most significant of the low 8 bits of
|
|
* the color value then indexed by the upper 8 bits:
|
|
*
|
|
* table[low bits][high 8 bits]
|
|
*
|
|
* So the table 'n' corresponds to all those 'iv' of:
|
|
*
|
|
* <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
|
|
*
|
|
*/
|
|
if (sig_bit > 0 && sig_bit < 16U)
|
|
shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */
|
|
|
|
else
|
|
shift = 0; /* keep all 16 bits */
|
|
|
|
if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
|
|
{
|
|
/* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
|
|
* the significant bits in the *input* when the output will
|
|
* eventually be 8 bits. By default it is 11.
|
|
*/
|
|
if (shift < (16U - PNG_MAX_GAMMA_8))
|
|
shift = (16U - PNG_MAX_GAMMA_8);
|
|
}
|
|
|
|
if (shift > 8U)
|
|
shift = 8U; /* Guarantees at least one table! */
|
|
|
|
png_ptr->gamma_shift = shift;
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
/* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
|
|
* PNG_COMPOSE). This effectively smashed the background calculation for
|
|
* 16-bit output because the 8-bit table assumes the result will be reduced
|
|
* to 8 bits.
|
|
*/
|
|
if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
|
|
#endif
|
|
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
|
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma,
|
|
png_ptr->screen_gamma) : PNG_FP_1);
|
|
|
|
#ifdef PNG_16BIT_SUPPORTED
|
|
else
|
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
|
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma,
|
|
png_ptr->screen_gamma) : PNG_FP_1);
|
|
#endif
|
|
|
|
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
|
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
|
if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
|
|
{
|
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
|
|
png_reciprocal(png_ptr->gamma));
|
|
|
|
/* Notice that the '16 from 1' table should be full precision, however
|
|
* the lookup on this table still uses gamma_shift, so it can't be.
|
|
* TODO: fix this.
|
|
*/
|
|
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
|
|
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
|
|
png_ptr->gamma/* Probably doing rgb_to_gray */);
|
|
}
|
|
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
}
|
|
}
|
|
#endif /* READ_GAMMA */
|
|
#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
|
|
|
/* HARDWARE OPTION SUPPORT */
|
|
#ifdef PNG_SET_OPTION_SUPPORTED
|
|
int PNGAPI
|
|
png_set_option(png_structp png_ptr, int option, int onoff)
|
|
{
|
|
if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
|
|
(option & 1) == 0)
|
|
{
|
|
int mask = 3 << option;
|
|
int setting = (2 + (onoff != 0)) << option;
|
|
int current = png_ptr->options;
|
|
|
|
png_ptr->options = (png_byte)((current & ~mask) | setting);
|
|
|
|
return (current & mask) >> option;
|
|
}
|
|
|
|
return PNG_OPTION_INVALID;
|
|
}
|
|
#endif
|