diff options
Diffstat (limited to 'pngwutil.c')
| -rw-r--r-- | pngwutil.c | 54 |
1 files changed, 13 insertions, 41 deletions
diff --git a/pngwutil.c b/pngwutil.c index 5f2464000..63d19f1b9 100644 --- a/pngwutil.c +++ b/pngwutil.c @@ -1,7 +1,7 @@ /* pngwutil.c - utilities to write a PNG file * - * libpng version 1.2.6 - August 15, 2004 + * libpng version 1.2.7beta1 - August 26, 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) @@ -515,7 +515,18 @@ 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)) - png_ptr->zlib_window_bits = 15; + { + 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; + } if (!(png_ptr->flags & PNG_FLAG_ZLIB_CUSTOM_METHOD)) png_ptr->zlib_method = 8; deflateInit2(&png_ptr->zstream, png_ptr->zlib_level, @@ -602,45 +613,6 @@ 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_ROWBYTES(png_ptr->channels*png_ptr->bit_depth, - 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; } |