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Imported from libpng-1.2.7rc1.tar

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This commit is contained in:
Glenn Randers-Pehrson
2004-09-04 13:25:08 -05:00
parent 67864af957
commit 5b77916ecd
55 changed files with 183 additions and 135 deletions
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54
pngwutil.c
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@@ -1,7 +1,7 @@
/* pngwutil.c - utilities to write a PNG file
*
* libpng version 1.2.7beta2 - August 29, 2004
* libpng version 1.2.7rc1 - September 4, 2004
* For conditions of distribution and use, see copyright notice in png.h
* Copyright (c) 1998-2004 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -515,18 +515,7 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL))
png_ptr->zlib_mem_level = 8;
if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS))
{
if (png_ptr->rowbytes <= 16384 && png_ptr->height <= 16384)
{
png_uint_32 imagebytes = (png_ptr->rowbytes+1) * png_ptr->height;
png_uint_32 windowsize = 14; /* try for a smaller window */
while ((1U << windowsize) >= imagebytes && windowsize > 7)
--windowsize;
png_ptr->zlib_window_bits = windowsize + 1;
}
else
png_ptr->zlib_window_bits = 15;
}
png_ptr->zlib_window_bits = 15;
if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD))
png_ptr->zlib_method = 8;
deflateInit2(&png_ptr->zstream, png_ptr->zlib_level,
@@ -613,6 +602,45 @@ png_write_IDAT(png_structp png_ptr, png_bytep data, png_size_t length)
#endif
png_debug(1, "in png_write_IDAT\n");
/* Optimize the CMF field in the zlib stream. */
/* This hack of the zlib stream is compliant to the stream specification. */
if (!(png_ptr->mode & PNG_HAVE_IDAT) &&
png_ptr->compression_type == PNG_COMPRESSION_TYPE_BASE)
{
unsigned int z_cmf = data[0]; /* zlib compression method and flags */
if ((z_cmf & 0x0f) == 8 && (z_cmf & 0xf0) <= 0x70)
{
/* Avoid memory underflows and multiplication overflows. */
/* The conditions below are practically always satisfied;
however, they still must be checked. */
if (length >= 2 &&
png_ptr->height < 16384 && png_ptr->width < 16384)
{
png_uint_32 uncompressed_idat_size = png_ptr->height *
((png_ptr->width *
png_ptr->channels * png_ptr->bit_depth + 15) >> 3);
unsigned int z_cinfo = z_cmf >> 4;
unsigned int half_z_window_size = 1 << (z_cinfo + 7);
while (uncompressed_idat_size <= half_z_window_size &&
half_z_window_size >= 256)
{
z_cinfo--;
half_z_window_size >>= 1;
}
z_cmf = (z_cmf & 0x0f) | (z_cinfo << 4);
if (data[0] != (png_byte)z_cmf)
{
data[0] = (png_byte)z_cmf;
data[1] &= 0xe0;
data[1] += (png_byte)(0x1f - ((z_cmf << 8) + data[1]) % 0x1f);
}
}
}
else
png_error(png_ptr,
"Invalid zlib compression method or flags in IDAT");
}
png_write_chunk(png_ptr, (png_bytep)png_IDAT, data, length);
png_ptr->mode |= PNG_HAVE_IDAT;
}