mirror of
https://git.code.sf.net/p/libpng/code.git
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[libpng17] Made 8-bit compose and rgb_to_grayscale accuracy improvements.
These changes cause 16-bit arithmetic to be used for 8-bit data in the gamma
corrected compose and grayscale operations. The arithmetic errors have
three sources all of which are fixed in this commit:
1) 8-bit linear calculations produce massive errors for lower intensity
values.
2) The old 16-bit "16 to 8" gamma table code erroneously wrote the lowest
output value into a table entry which corresponded to multiple output
values (so where the value written should have been the closest to the
transformed input value.)
3) In a number of cases the code to access the 16-bit table did not round;
it did a simple shift, which was wrong and made the side effects of (2)
even worse.
The new gamma code does not have the 16-to-8 problem at the cost of slighly
more calculations and the algorithm used to minimize the number of
calculations has been extended to all the 16-bit tables; it has advantages
for any significant gamma correction.
This commit is contained in:
John Bowler
committed by
Glenn Randers-Pehrson
Glenn Randers-Pehrson
parent
ac3b4d9b69
commit
3e42c81193
651
pngstruct.h
651
pngstruct.h
@@ -48,10 +48,10 @@
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/* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
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* can handle at once. This type need be no larger than 16 bits (so maximum of
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* 65535), this define allows us to discover how big it is, but limited by the
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* maximuum for png_size_t. The value can be overriden in a library build
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* (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
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* lower value (e.g. 255 works). A lower value may help memory usage (slightly)
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* and may even improve performance on some systems (and degrade it on others.)
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* maximum for size_t. The value can be overriden in a library build (pngusr.h,
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* or set it in CPPFLAGS) and it works to set it to a considerably lower value
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* (e.g. 255 works). A lower value may help memory usage (slightly) and may
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* even improve performance on some systems (and degrade it on others.)
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*/
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#ifndef ZLIB_IO_MAX
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# define ZLIB_IO_MAX ((uInt)-1)
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@@ -137,313 +137,232 @@ typedef const png_colorspace * PNG_RESTRICT png_const_colorspacerp;
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#define PNG_COLORSPACE_FROM_sRGB 0x0020
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#define PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB 0x0040
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#define PNG_COLORSPACE_MATCHES_sRGB 0x0080 /* exact match on profile */
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#define PNG_COLORSPACE_RGB_TO_GRAY_SET 0x0100 /* user specified coeffs */
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#define PNG_COLORSPACE_INVALID 0x8000
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#define PNG_COLORSPACE_CANCEL(flags) (0xffff ^ (flags))
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#endif /* COLORSPACE || GAMMA */
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struct png_struct_def
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{
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#ifdef PNG_SETJMP_SUPPORTED
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jmp_buf jmp_buf_local; /* New name in 1.6.0 for jmp_buf in png_struct */
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png_longjmp_ptr longjmp_fn;/* setjmp non-local goto function. */
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jmp_buf *jmp_buf_ptr; /* passed to longjmp_fn */
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size_t jmp_buf_size; /* size of the above, if allocated */
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#endif
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png_error_ptr error_fn; /* function for printing errors and aborting */
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#ifdef PNG_WARNINGS_SUPPORTED
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png_error_ptr warning_fn; /* function for printing warnings */
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#endif
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png_voidp error_ptr; /* user supplied struct for error functions */
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png_rw_ptr write_data_fn; /* function for writing output data */
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png_rw_ptr read_data_fn; /* function for reading input data */
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png_voidp io_ptr; /* ptr to application struct for I/O functions */
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/* Rearranged in libpng 1.7 to attempt to lessen padding; in general
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* (char), (short), (int) and pointer types are kept separate, however
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* associated members under the control of the same #define are still
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* together.
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*
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* First the frequently accessed fields. Many processors perform arithmetic
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* in the address pipeline, but frequently the amount of addition or
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* subtraction is limited. By putting these fields at the head of png_struct
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* the hope is that such processors will generate code that is both smaller
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* and faster.
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*/
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png_colorp palette; /* palette from the input file */
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size_t rowbytes; /* size of row in bytes */
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size_t info_rowbytes; /* cache of updated row bytes */
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png_uint_32 width; /* width of image in pixels */
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png_uint_32 height; /* height of image in pixels */
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png_uint_32 num_rows; /* number of rows in current pass */
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png_uint_32 usr_width; /* width of row at start of write */
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png_uint_32 iwidth; /* width of current interlaced row in pixels */
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png_uint_32 row_number; /* current row in interlace pass */
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png_uint_32 chunk_name; /* PNG_CHUNK() id of current chunk */
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png_uint_32 crc; /* current chunk CRC value */
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png_uint_32 mode; /* tells us where we are in the PNG file */
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png_uint_32 flags; /* flags indicating various things to libpng */
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png_uint_32 transformations;/* which transformations to perform */
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png_uint_32 zowner; /* ID (chunk type) of zstream owner, 0 if none */
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png_uint_32 free_me; /* items libpng is responsible for freeing */
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#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
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png_user_transform_ptr read_user_transform_fn; /* user read transform */
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#endif
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#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
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png_user_transform_ptr write_user_transform_fn; /* user write transform */
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#endif
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/* These were added in libpng-1.0.2 */
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#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
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#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
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defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
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png_voidp user_transform_ptr; /* user supplied struct for user transform */
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png_byte user_transform_depth; /* bit depth of user transformed pixels */
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png_byte user_transform_channels; /* channels in user transformed pixels */
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#endif
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#endif
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png_uint_32 mode; /* tells us where we are in the PNG file */
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png_uint_32 flags; /* flags indicating various things to libpng */
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png_uint_32 transformations; /* which transformations to perform */
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png_uint_32 zowner; /* ID (chunk type) of zstream owner, 0 if none */
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z_stream zstream; /* decompression structure */
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#ifdef PNG_WRITE_SUPPORTED
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png_compression_bufferp zbuffer_list; /* Created on demand during write */
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uInt zbuffer_size; /* size of the actual buffer */
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int zlib_level; /* holds zlib compression level */
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int zlib_method; /* holds zlib compression method */
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int zlib_window_bits; /* holds zlib compression window bits */
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int zlib_mem_level; /* holds zlib compression memory level */
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int zlib_strategy; /* holds zlib compression strategy */
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#endif
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/* Added at libpng 1.5.4 */
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#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
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int zlib_text_level; /* holds zlib compression level */
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int zlib_text_method; /* holds zlib compression method */
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int zlib_text_window_bits; /* holds zlib compression window bits */
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int zlib_text_mem_level; /* holds zlib compression memory level */
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int zlib_text_strategy; /* holds zlib compression strategy */
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#endif
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/* End of material added at libpng 1.5.4 */
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/* Added at libpng 1.6.0 */
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#ifdef PNG_WRITE_SUPPORTED
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int zlib_set_level; /* Actual values set into the zstream on write */
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int zlib_set_method;
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int zlib_set_window_bits;
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int zlib_set_mem_level;
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int zlib_set_strategy;
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#endif
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png_uint_32 width; /* width of image in pixels */
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png_uint_32 height; /* height of image in pixels */
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png_uint_32 num_rows; /* number of rows in current pass */
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png_uint_32 usr_width; /* width of row at start of write */
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png_size_t rowbytes; /* size of row in bytes */
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png_uint_32 iwidth; /* width of current interlaced row in pixels */
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png_uint_32 row_number; /* current row in interlace pass */
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png_uint_32 chunk_name; /* PNG_CHUNK() id of current chunk */
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png_bytep prev_row; /* buffer to save previous (unfiltered) row.
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* This is a pointer into big_prev_row
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*/
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png_bytep row_buf; /* buffer to save current (unfiltered) row.
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* This is a pointer into big_row_buf
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*/
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#ifdef PNG_WRITE_SUPPORTED
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png_bytep sub_row; /* buffer to save "sub" row when filtering */
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png_bytep up_row; /* buffer to save "up" row when filtering */
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png_bytep avg_row; /* buffer to save "avg" row when filtering */
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png_bytep paeth_row; /* buffer to save "Paeth" row when filtering */
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#endif
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png_size_t info_rowbytes; /* Added in 1.5.4: cache of updated row bytes */
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png_uint_32 idat_size; /* current IDAT size for read */
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png_uint_32 crc; /* current chunk CRC value */
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png_colorp palette; /* palette from the input file */
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png_uint_16 num_palette; /* number of color entries in palette */
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/* Added at libpng-1.5.10 */
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int maximum_pixel_depth; /* pixel depth used for the row buffers */
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#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
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int num_palette_max; /* maximum palette index found in IDAT */
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int num_palette_max; /* maximum palette index found in IDAT */
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#endif
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png_uint_16 num_palette; /* number of color entries in palette */
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png_uint_16 num_trans; /* number of transparency values */
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png_byte compression; /* file compression type (always 0) */
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/* Single byte values, typically used either to save space or to hold 1-byte
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* values from the PNG chunk specifications.
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*/
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png_byte compression_type; /* file compression type (always 0) */
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png_byte filter; /* file filter type (always 0) */
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png_byte interlaced; /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
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png_byte pass; /* current interlace pass (0 - 6) */
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png_byte do_filter; /* row filter flags (see PNG_FILTER_ below ) */
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png_byte color_type; /* color type of file */
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png_byte bit_depth; /* bit depth of file */
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png_byte usr_bit_depth; /* bit depth of users row: write only */
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png_byte pixel_depth; /* number of bits per pixel */
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png_byte channels; /* number of channels in file */
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#ifdef PNG_WRITE_SUPPORTED
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png_byte usr_channels; /* channels at start of write: write only */
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#endif
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png_byte sig_bytes; /* magic bytes read/written from start of file */
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png_byte maximum_pixel_depth;
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/* pixel depth used for the row buffers */
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png_byte transformed_pixel_depth;
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/* pixel depth after read/write transforms */
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#if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
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png_uint_16 filler; /* filler bytes for pixel expansion */
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/* ERROR HANDLING */
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#ifdef PNG_SETJMP_SUPPORTED
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/* jmp_buf can have very high alignment requirements on some systems, so put
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* it first.
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*/
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jmp_buf jmp_buf_local;
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jmp_buf *jmp_buf_ptr; /* passed to longjmp_fn */
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png_longjmp_ptr longjmp_fn; /* setjmp non-local goto function. */
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size_t jmp_buf_size; /* size of *jmp_buf_ptr, if allocated */
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#endif
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#if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
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defined(PNG_READ_ALPHA_MODE_SUPPORTED)
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png_byte background_gamma_type;
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png_fixed_point background_gamma;
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png_color_16 background; /* background color in screen gamma space */
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#ifdef PNG_READ_GAMMA_SUPPORTED
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png_color_16 background_1; /* background normalized to gamma 1.0 */
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/* Error/warning callbacks */
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png_error_ptr error_fn; /* print an error message and abort */
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#ifdef PNG_WARNINGS_SUPPORTED
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png_error_ptr warning_fn; /* print a warning and continue */
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#endif
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#endif /* PNG_bKGD_SUPPORTED */
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png_voidp error_ptr; /* user supplied data for the above */
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#ifdef PNG_WRITE_FLUSH_SUPPORTED
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png_flush_ptr output_flush_fn; /* Function for flushing output */
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png_uint_32 flush_dist; /* how many rows apart to flush, 0 - no flush */
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png_uint_32 flush_rows; /* number of rows written since last flush */
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#endif
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#ifdef PNG_READ_GAMMA_SUPPORTED
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int gamma_shift; /* number of "insignificant" bits in 16-bit gamma */
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png_fixed_point screen_gamma; /* screen gamma value (display_exponent) */
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png_bytep gamma_table; /* gamma table for 8-bit depth files */
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png_uint_16pp gamma_16_table; /* gamma table for 16-bit depth files */
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#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
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defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
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defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
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png_bytep gamma_from_1; /* converts from 1.0 to screen */
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png_bytep gamma_to_1; /* converts from file to 1.0 */
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png_uint_16pp gamma_16_from_1; /* converts from 1.0 to screen */
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png_uint_16pp gamma_16_to_1; /* converts from file to 1.0 */
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#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
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#endif
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#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_sBIT_SUPPORTED)
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png_color_8 sig_bit; /* significant bits in each available channel */
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#endif
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#if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
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png_color_8 shift; /* shift for significant bit tranformation */
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#endif
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#if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
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|| defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
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png_bytep trans_alpha; /* alpha values for paletted files */
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png_color_16 trans_color; /* transparent color for non-paletted files */
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#endif
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png_read_status_ptr read_row_fn; /* called after each row is decoded */
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png_write_status_ptr write_row_fn; /* called after each row is encoded */
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#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
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png_progressive_info_ptr info_fn; /* called after header data fully read */
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png_progressive_row_ptr row_fn; /* called after a prog. row is decoded */
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png_progressive_end_ptr end_fn; /* called after image is complete */
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png_bytep save_buffer_ptr; /* current location in save_buffer */
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png_bytep save_buffer; /* buffer for previously read data */
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png_bytep current_buffer_ptr; /* current location in current_buffer */
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png_bytep current_buffer; /* buffer for recently used data */
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png_uint_32 push_length; /* size of current input chunk */
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png_uint_32 skip_length; /* bytes to skip in input data */
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png_size_t save_buffer_size; /* amount of data now in save_buffer */
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png_size_t save_buffer_max; /* total size of save_buffer */
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png_size_t buffer_size; /* total amount of available input data */
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png_size_t current_buffer_size; /* amount of data now in current_buffer */
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int process_mode; /* what push library is currently doing */
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int cur_palette; /* current push library palette index */
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#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
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#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
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/* For the Borland special 64K segment handler */
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png_bytepp offset_table_ptr;
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png_bytep offset_table;
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png_uint_16 offset_table_number;
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png_uint_16 offset_table_count;
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png_uint_16 offset_table_count_free;
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#endif
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#ifdef PNG_READ_QUANTIZE_SUPPORTED
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png_bytep palette_lookup; /* lookup table for quantizing */
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png_bytep quantize_index; /* index translation for palette files */
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#endif
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#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
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png_byte heuristic_method; /* heuristic for row filter selection */
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png_byte num_prev_filters; /* number of weights for previous rows */
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png_bytep prev_filters; /* filter type(s) of previous row(s) */
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png_uint_16p filter_weights; /* weight(s) for previous line(s) */
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png_uint_16p inv_filter_weights; /* 1/weight(s) for previous line(s) */
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png_uint_16p filter_costs; /* relative filter calculation cost */
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png_uint_16p inv_filter_costs; /* 1/relative filter calculation cost */
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#endif
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#if PNG_LIBPNG_VER < 10700
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/* To do: remove this from libpng-1.7 */
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#ifdef PNG_TIME_RFC1123_SUPPORTED
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char time_buffer[29]; /* String to hold RFC 1123 time text */
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#endif
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#endif
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/* New members added in libpng-1.0.6 */
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png_uint_32 free_me; /* flags items libpng is responsible for freeing */
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#ifdef PNG_USER_CHUNKS_SUPPORTED
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png_voidp user_chunk_ptr;
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#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
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png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
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#endif
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#endif
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#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
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int unknown_default; /* As PNG_HANDLE_* */
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unsigned int num_chunk_list; /* Number of entries in the list */
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png_bytep chunk_list; /* List of png_byte[5]; the textual chunk name
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* followed by a PNG_HANDLE_* byte */
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#endif
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/* New members added in libpng-1.0.3 */
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#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
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png_byte rgb_to_gray_status;
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/* Added in libpng 1.5.5 to record setting of coefficients: */
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png_byte rgb_to_gray_coefficients_set;
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/* These were changed from png_byte in libpng-1.0.6 */
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png_uint_16 rgb_to_gray_red_coeff;
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png_uint_16 rgb_to_gray_green_coeff;
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/* deleted in 1.5.5: rgb_to_gray_blue_coeff; */
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#endif
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/* New member added in libpng-1.0.4 (renamed in 1.0.9) */
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#if defined(PNG_MNG_FEATURES_SUPPORTED)
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/* Changed from png_byte to png_uint_32 at version 1.2.0 */
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png_uint_32 mng_features_permitted;
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#endif
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/* New member added in libpng-1.0.9, ifdef'ed out in 1.0.12, enabled in 1.2.0 */
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#ifdef PNG_MNG_FEATURES_SUPPORTED
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png_byte filter_type;
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#endif
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/* New members added in libpng-1.2.0 */
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/* New members added in libpng-1.0.2 but first enabled by default in 1.2.0 */
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/* MEMORY ALLOCATION */
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#ifdef PNG_USER_MEM_SUPPORTED
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png_voidp mem_ptr; /* user supplied struct for mem functions */
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png_malloc_ptr malloc_fn; /* function for allocating memory */
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png_free_ptr free_fn; /* function for freeing memory */
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png_malloc_ptr malloc_fn; /* allocate memory */
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png_free_ptr free_fn; /* free memory */
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png_voidp mem_ptr; /* user supplied data for the above */
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#endif
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/* New member added in libpng-1.0.13 and 1.2.0 */
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png_bytep big_row_buf; /* buffer to save current (unfiltered) row */
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/* IO and BASIC READ/WRITE SUPPORT */
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png_voidp io_ptr; /* user supplied data for IO callbacks */
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#ifdef PNG_READ_QUANTIZE_SUPPORTED
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/* The following three members were added at version 1.0.14 and 1.2.4 */
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png_bytep quantize_sort; /* working sort array */
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png_bytep index_to_palette; /* where the original index currently is
|
||||
in the palette */
|
||||
png_bytep palette_to_index; /* which original index points to this
|
||||
palette color */
|
||||
#ifdef PNG_READ_SUPPORTED
|
||||
png_rw_ptr read_data_fn; /* read some bytes (must succeed) */
|
||||
png_read_status_ptr read_row_fn; /* called after each row is decoded */
|
||||
png_bytep read_buffer; /* buffer for reading chunk data */
|
||||
|
||||
/* During read the following array is set up to point to the appropriate
|
||||
* un-filter function, this allows per-image and per-processor optimization.
|
||||
*/
|
||||
void (*read_filter[PNG_FILTER_VALUE_LAST-1])(png_row_infop row_info,
|
||||
png_bytep row, png_const_bytep prev_row);
|
||||
|
||||
#if (defined PNG_COLORSPACE_SUPPORTED || defined PNG_GAMMA_SUPPORTED)
|
||||
/* The png_struct colorspace structure is only required on read - on write it
|
||||
* is in (just) the info_struct.
|
||||
*/
|
||||
png_colorspace colorspace;
|
||||
#endif
|
||||
|
||||
/* New members added in libpng-1.0.16 and 1.2.6 */
|
||||
png_byte compression_type;
|
||||
#endif /* PNG_READ_SUPPORTED */
|
||||
|
||||
#ifdef PNG_USER_LIMITS_SUPPORTED
|
||||
png_uint_32 user_width_max;
|
||||
png_uint_32 user_height_max;
|
||||
|
||||
/* Added in libpng-1.4.0: Total number of sPLT, text, and unknown
|
||||
* chunks that can be stored (0 means unlimited).
|
||||
*/
|
||||
png_uint_32 user_chunk_cache_max;
|
||||
|
||||
/* The limits only affect read from libpng 1.7 */
|
||||
/* Total memory that a zTXt, sPLT, iTXt, iCCP, or unknown chunk
|
||||
* can occupy when decompressed. 0 means unlimited.
|
||||
*/
|
||||
png_alloc_size_t user_chunk_malloc_max;
|
||||
/* limit on total *number* of sPLT, text and unknown chunks that can be
|
||||
* stored. 0 means unlimited.
|
||||
*/
|
||||
png_uint_32 user_chunk_cache_max;
|
||||
png_uint_32 user_width_max;
|
||||
png_uint_32 user_height_max;
|
||||
#endif
|
||||
|
||||
/* New member added in libpng-1.0.25 and 1.2.17 */
|
||||
/* The progressive reader gets passed data and calls application handling
|
||||
* functions when appropriate.
|
||||
*/
|
||||
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
|
||||
png_progressive_info_ptr info_fn; /* called after header data fully read */
|
||||
png_progressive_row_ptr row_fn; /* called after a row is decoded */
|
||||
png_progressive_end_ptr end_fn; /* called after image is complete */
|
||||
|
||||
/* Progressive read control data */
|
||||
png_bytep save_buffer_ptr; /* current location in save_buffer */
|
||||
png_bytep save_buffer; /* buffer for previously read data */
|
||||
png_bytep current_buffer_ptr; /* current location in current_buffer */
|
||||
png_bytep current_buffer; /* buffer for recently used data */
|
||||
|
||||
size_t save_buffer_size; /* amount of data now in save_buffer */
|
||||
size_t save_buffer_max; /* total size of save_buffer */
|
||||
size_t buffer_size; /* total amount of available input data */
|
||||
size_t current_buffer_size; /* amount of data now in current_buffer */
|
||||
|
||||
png_uint_32 push_length; /* size of current input chunk */
|
||||
png_uint_32 skip_length; /* bytes to skip in input data */
|
||||
|
||||
int process_mode; /* what push library is currently doing */
|
||||
int cur_palette; /* current push library palette index */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_SUPPORTED
|
||||
png_rw_ptr write_data_fn;/* write some bytes (must succeed) */
|
||||
png_write_status_ptr write_row_fn; /* called after each row is encoded */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_FLUSH_SUPPORTED
|
||||
png_flush_ptr output_flush_fn; /* Function for flushing output */
|
||||
png_uint_32 flush_dist; /* how many rows apart to flush, 0 - no flush */
|
||||
png_uint_32 flush_rows; /* number of rows written since last flush */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
|
||||
png_bytep prev_filters; /* filter type(s) of previous row(s) */
|
||||
png_uint_16p filter_weights; /* weight(s) for previous line(s) */
|
||||
png_uint_16p inv_filter_weights; /* 1/weight(s) for previous line(s) */
|
||||
png_uint_16p filter_costs; /* relative filter calculation cost */
|
||||
png_uint_16p inv_filter_costs; /* 1/relative filter calculation cost */
|
||||
png_byte heuristic_method; /* heuristic for row filter selection */
|
||||
png_byte num_prev_filters; /* number of weights for previous rows */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_SUPPORTED
|
||||
png_byte usr_bit_depth; /* bit depth of users row */
|
||||
png_byte usr_channels; /* channels at start of write */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_IO_STATE_SUPPORTED
|
||||
png_uint_32 io_state; /* tells the app read/write progress */
|
||||
#endif
|
||||
|
||||
/* ROW BUFFERS
|
||||
*
|
||||
* Members that hold pointers to the decompressed image rows.
|
||||
*/
|
||||
png_bytep row_buf; /* buffer for the current (unfiltered) row */
|
||||
#if (defined PNG_WRITE_FILTER_SUPPORTED) || (defined PNG_READ_SUPPORTED)
|
||||
png_bytep prev_row; /* buffer to save the previous (unfiltered) row */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_READ_SUPPORTED
|
||||
/* The row_buf and prev_row pointers are misaligned so that the start of the
|
||||
* row - after the filter byte - is aligned, the 'big_' pointers record the
|
||||
* original allocated pointer.
|
||||
*/
|
||||
png_bytep big_row_buf;
|
||||
png_bytep big_prev_row;
|
||||
size_t big_row_buf_size; /* Actual size of both */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_SUPPORTED
|
||||
/* This is somewhat excessive, there is no obvious reason on write to
|
||||
* allocate a buffer for each possible filtered row, only for the one being
|
||||
* tested and the current best.
|
||||
*
|
||||
* TODO: fix this
|
||||
*/
|
||||
png_bytep sub_row; /* buffer to save "sub" row when filtering */
|
||||
png_bytep up_row; /* buffer to save "up" row when filtering */
|
||||
png_bytep avg_row; /* buffer to save "avg" row when filtering */
|
||||
png_bytep paeth_row; /* buffer to save "Paeth" row when filtering */
|
||||
#endif
|
||||
|
||||
/* UNKNOWN CHUNK HANDLING */
|
||||
/* TODO: this is excessively complicated, there are multiple ways of doing
|
||||
* the same thing. It should be cleaned up, possibly by finding out which
|
||||
* APIs applications really use.
|
||||
*/
|
||||
#ifdef PNG_USER_CHUNKS_SUPPORTED
|
||||
/* General purpose pointer for all user/unknown chunk handling; points to
|
||||
* application supplied data for use in the read_user_chunk_fn callback
|
||||
* (currently there is no write side support - the write side must use the
|
||||
* set_unknown_chunks interface.)
|
||||
*/
|
||||
png_voidp user_chunk_ptr;
|
||||
#endif
|
||||
|
||||
#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
|
||||
/* This is called back from the unknown chunk handling */
|
||||
png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
|
||||
#endif
|
||||
#ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
|
||||
/* Temporary storage for unknown chunk that the library doesn't recognize,
|
||||
* used while reading the chunk.
|
||||
@@ -451,33 +370,175 @@ struct png_struct_def
|
||||
png_unknown_chunk unknown_chunk;
|
||||
#endif
|
||||
|
||||
/* New member added in libpng-1.2.26 */
|
||||
png_size_t old_big_row_buf_size;
|
||||
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
|
||||
png_bytep chunk_list; /* List of png_byte[5]; the textual chunk name
|
||||
* followed by a PNG_HANDLE_* byte */
|
||||
int unknown_default; /* As PNG_HANDLE_* */
|
||||
unsigned int num_chunk_list; /* Number of entries in the list */
|
||||
#endif
|
||||
|
||||
/* USER TRANSFORM SUPPORT */
|
||||
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
|
||||
png_user_transform_ptr read_user_transform_fn; /* user read transform */
|
||||
#endif
|
||||
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
|
||||
png_user_transform_ptr write_user_transform_fn; /* user write transform */
|
||||
#endif
|
||||
#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
|
||||
png_voidp user_transform_ptr; /* user supplied data for the above */
|
||||
png_byte user_transform_depth; /* bit depth of user transformed pixels */
|
||||
png_byte user_transform_channels; /* channels in user transformed pixels */
|
||||
#endif
|
||||
|
||||
/* READ TRANSFORM SUPPORT
|
||||
*
|
||||
* Quite a lot of things can be done to the original image data on read, and
|
||||
* most of these are configurable. The data required by the configurable
|
||||
* read transforms should be stored here. The png_color_16 and png_color_8
|
||||
* structures have low alignment requirements and odd sizes, so may cause
|
||||
* misalignment when present. Member alignment is as follows:
|
||||
*
|
||||
* png_color_16 png_uint_16
|
||||
* png_color_8 png_byte
|
||||
*/
|
||||
/* GAMMA/BACKGROUND/ALPHA-MODE/RGB-TO-GRAY/tRNS/sBIT
|
||||
*
|
||||
* These things are all interrelated because they need some or all of the
|
||||
* gamma tables. Some attempt has been made below to order these members by
|
||||
* size, so that as little padding as possible is required.
|
||||
*/
|
||||
#ifdef PNG_READ_GAMMA_SUPPORTED
|
||||
png_bytep gamma_table; /* gamma table for 8-bit depth files */
|
||||
png_uint_16p gamma_16_table; /* gamma table for 16-bit depth files */
|
||||
|
||||
#if defined PNG_READ_BACKGROUND_SUPPORTED ||\
|
||||
defined PNG_READ_ALPHA_MODE_SUPPORTED ||\
|
||||
defined PNG_READ_RGB_TO_GRAY_SUPPORTED
|
||||
png_bytep gamma_from_1; /* converts from 1.0 to screen */
|
||||
png_uint_16p gamma_to_1; /* converts from file to 1.0 */
|
||||
png_uint_16p gamma_16_from_1; /* converts from 1.0 to screen */
|
||||
png_uint_16p gamma_16_to_1; /* converts from file to 1.0 */
|
||||
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
||||
#endif /* PNG_READ_GAMMA_SUPPORTED */
|
||||
|
||||
#if defined PNG_READ_tRNS_SUPPORTED || defined PNG_READ_BACKGROUND_SUPPORTED ||\
|
||||
defined PNG_READ_EXPAND_SUPPORTED
|
||||
png_bytep trans_alpha; /* alpha values for paletted files */
|
||||
#endif
|
||||
|
||||
/* Integer values */
|
||||
#if defined PNG_READ_BACKGROUND_SUPPORTED ||\
|
||||
defined PNG_READ_ALPHA_MODE_SUPPORTED
|
||||
png_fixed_point background_gamma;
|
||||
#endif
|
||||
#ifdef PNG_READ_GAMMA_SUPPORTED
|
||||
png_fixed_point screen_gamma; /* screen gamma value (display_exponent) */
|
||||
int gamma_shift; /* number of "insignificant" bits in 16-bit gamma */
|
||||
#endif
|
||||
|
||||
/* png_color_16 */
|
||||
#if defined PNG_READ_BACKGROUND_SUPPORTED ||\
|
||||
defined PNG_READ_ALPHA_MODE_SUPPORTED
|
||||
png_color_16 background; /* background color in screen gamma space */
|
||||
png_color_16 background_1; /* background normalized to gamma 1.0 */
|
||||
#endif
|
||||
#if defined PNG_READ_tRNS_SUPPORTED || defined PNG_READ_BACKGROUND_SUPPORTED ||\
|
||||
defined PNG_READ_EXPAND_SUPPORTED
|
||||
png_color_16 trans_color; /* transparent color for non-paletted files */
|
||||
#endif
|
||||
|
||||
/* png_uint_16 */
|
||||
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
|
||||
png_uint_16 rgb_to_gray_red_coeff;
|
||||
png_uint_16 rgb_to_gray_green_coeff;
|
||||
/* The blue coefficient is calculated from the above */
|
||||
#endif
|
||||
|
||||
/* png_color_8 */
|
||||
#if defined PNG_READ_GAMMA_SUPPORTED || defined PNG_READ_sBIT_SUPPORTED
|
||||
png_color_8 sig_bit; /* significant bits in each available channel */
|
||||
#endif
|
||||
|
||||
/* png_byte */
|
||||
#if defined PNG_READ_BACKGROUND_SUPPORTED ||\
|
||||
defined PNG_READ_ALPHA_MODE_SUPPORTED
|
||||
png_byte background_gamma_type;
|
||||
#endif
|
||||
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
|
||||
png_byte rgb_to_gray_status;
|
||||
#endif
|
||||
|
||||
/* SHIFT - both READ_SHIFT and WRITE_SHIFT */
|
||||
#if defined PNG_READ_SHIFT_SUPPORTED || defined PNG_WRITE_SHIFT_SUPPORTED
|
||||
png_color_8 shift; /* shift for significant bit tranformation */
|
||||
#endif
|
||||
|
||||
/* FILLER SUPPORT (pixel expansion or read, contraction on write) */
|
||||
#if defined PNG_READ_FILLER_SUPPORTED || defined PNG_WRITE_FILLER_SUPPORTED
|
||||
png_uint_16 filler; /* filler bytes for pixel expansion */
|
||||
#endif
|
||||
|
||||
/* QUANTIZE (convert to color-mapped) */
|
||||
#ifdef PNG_READ_QUANTIZE_SUPPORTED
|
||||
png_bytep palette_lookup; /* lookup table for quantizing */
|
||||
png_bytep quantize_index; /* index translation for palette files */
|
||||
png_bytep quantize_sort; /* working sort array */
|
||||
png_bytep index_to_palette; /* where the original index currently is in the
|
||||
* palette
|
||||
*/
|
||||
png_bytep palette_to_index; /* which original index points to this palette
|
||||
* color
|
||||
*/
|
||||
#endif
|
||||
|
||||
/* MNG SUPPORT */
|
||||
#ifdef PNG_MNG_FEATURES_SUPPORTED
|
||||
png_uint_32 mng_features_permitted;
|
||||
png_byte filter_type;
|
||||
#endif
|
||||
|
||||
/* COMPRESSION AND DECOMPRESSION SUPPORT.
|
||||
*
|
||||
* zlib expects a 'zstream' as the fundamental control structure, it allows
|
||||
* all the parameters to be passed as one pointer.
|
||||
*/
|
||||
z_stream zstream; /* decompression structure */
|
||||
|
||||
#ifdef PNG_READ_SUPPORTED
|
||||
/* New member added in libpng-1.2.30 */
|
||||
png_bytep read_buffer; /* buffer for reading chunk data */
|
||||
png_alloc_size_t read_buffer_size; /* current size of the buffer */
|
||||
/* These, and IDAT_read_size below, control how much input and output (at
|
||||
* most) is available to zlib.
|
||||
*/
|
||||
png_uint_32 idat_size; /* current IDAT size for read */
|
||||
png_alloc_size_t read_buffer_size; /* current size of the buffer */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
|
||||
int zlib_text_level; /* holds zlib compression level */
|
||||
int zlib_text_method; /* holds zlib compression method */
|
||||
int zlib_text_window_bits; /* holds zlib compression window bits */
|
||||
int zlib_text_mem_level; /* holds zlib compression memory level */
|
||||
int zlib_text_strategy; /* holds zlib compression strategy */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_WRITE_SUPPORTED
|
||||
int zlib_level; /* holds zlib compression level */
|
||||
int zlib_method; /* holds zlib compression method */
|
||||
int zlib_window_bits; /* holds zlib compression window bits */
|
||||
int zlib_mem_level; /* holds zlib compression memory level */
|
||||
int zlib_strategy; /* holds zlib compression strategy */
|
||||
|
||||
int zlib_set_level; /* Actual values set into the zstream on write */
|
||||
int zlib_set_method;
|
||||
int zlib_set_window_bits;
|
||||
int zlib_set_mem_level;
|
||||
int zlib_set_strategy;
|
||||
|
||||
png_compression_bufferp zbuffer_list; /* Created on demand during write */
|
||||
uInt zbuffer_size; /* size of the actual zlib buffer */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
|
||||
uInt IDAT_read_size; /* limit on read buffer size for IDAT */
|
||||
#endif
|
||||
|
||||
#ifdef PNG_IO_STATE_SUPPORTED
|
||||
/* New member added in libpng-1.4.0 */
|
||||
png_uint_32 io_state;
|
||||
#endif
|
||||
|
||||
/* New member added in libpng-1.5.6 */
|
||||
png_bytep big_prev_row;
|
||||
|
||||
void (*read_filter[PNG_FILTER_VALUE_LAST-1])(png_row_infop row_info,
|
||||
png_bytep row, png_const_bytep prev_row);
|
||||
|
||||
#ifdef PNG_READ_SUPPORTED
|
||||
#if defined PNG_COLORSPACE_SUPPORTED || defined PNG_GAMMA_SUPPORTED
|
||||
png_colorspace colorspace;
|
||||
#endif
|
||||
uInt IDAT_read_size; /* limit on read buffer size for IDAT */
|
||||
#endif
|
||||
};
|
||||
#endif /* PNGSTRUCT_H */
|
||||
|
||||
Reference in New Issue
Block a user