png.h

hl2 source code. Do not use it illegal.

#define PNG_FILTER_VALUE_NONE  0
#define PNG_FILTER_VALUE_SUB   1
#define PNG_FILTER_VALUE_UP    2
#define PNG_FILTER_VALUE_AVG   3
#define PNG_FILTER_VALUE_PAETH 4
#define PNG_FILTER_VALUE_LAST  5

#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) /* EXPERIMENTAL */
/* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
 * defines, either the default (minimum-sum-of-absolute-differences), or
 * the experimental method (weighted-minimum-sum-of-absolute-differences).
 *
 * Weights are factors >= 1.0, indicating how important it is to keep the
 * filter type consistent between rows.  Larger numbers mean the current
 * filter is that many times as likely to be the same as the "num_weights"
 * previous filters.  This is cumulative for each previous row with a weight.
 * There needs to be "num_weights" values in "filter_weights", or it can be
 * NULL if the weights aren't being specified.  Weights have no influence on
 * the selection of the first row filter.  Well chosen weights can (in theory)
 * improve the compression for a given image.
 *
 * Costs are factors >= 1.0 indicating the relative decoding costs of a
 * filter type.  Higher costs indicate more decoding expense, and are
 * therefore less likely to be selected over a filter with lower computational
 * costs.  There needs to be a value in "filter_costs" for each valid filter
 * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
 * setting the costs.  Costs try to improve the speed of decompression without
 * unduly increasing the compressed image size.
 *
 * A negative weight or cost indicates the default value is to be used, and
 * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
 * The default values for both weights and costs are currently 1.0, but may
 * change if good general weighting/cost heuristics can be found.  If both
 * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
 * to the UNWEIGHTED method, but with added encoding time/computation.
 */
extern PNG_EXPORT(void,png_set_filter_heuristics) PNGARG((png_structp png_ptr,
   int heuristic_method, int num_weights, png_doublep filter_weights,
   png_doublep filter_costs));
#endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */

/* Heuristic used for row filter selection.  These defines should NOT be
 * changed.
 */
#define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
#define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
#define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
#define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */

/* Set the library compression level.  Currently, valid values range from
 * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
 * (0 - no compression, 9 - "maximal" compression).  Note that tests have
 * shown that zlib compression levels 3-6 usually perform as well as level 9
 * for PNG images, and do considerably fewer caclulations.  In the future,
 * these values may not correspond directly to the zlib compression levels.
 */
extern PNG_EXPORT(void,png_set_compression_level) PNGARG((png_structp png_ptr,
   int level));

extern PNG_EXPORT(void,png_set_compression_mem_level)
   PNGARG((png_structp png_ptr, int mem_level));

extern PNG_EXPORT(void,png_set_compression_strategy)
   PNGARG((png_structp png_ptr, int strategy));

extern PNG_EXPORT(void,png_set_compression_window_bits)
   PNGARG((png_structp png_ptr, int window_bits));

extern PNG_EXPORT(void,png_set_compression_method) PNGARG((png_structp png_ptr,
   int method));

/* These next functions are called for input/output, memory, and error
 * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
 * and call standard C I/O routines such as fread(), fwrite(), and
 * fprintf().  These functions can be made to use other I/O routines
 * at run time for those applications that need to handle I/O in a
 * different manner by calling png_set_???_fn().  See libpng.txt for
 * more information.
 */

#if !defined(PNG_NO_STDIO)
/* Initialize the input/output for the PNG file to the default functions. */
extern PNG_EXPORT(void,png_init_io) PNGARG((png_structp png_ptr, FILE *fp));
#endif

/* Replace the (error and abort), and warning functions with user
 * supplied functions.  If no messages are to be printed you must still
 * write and use replacement functions. The replacement error_fn should
 * still do a longjmp to the last setjmp location if you are using this
 * method of error handling.  If error_fn or warning_fn is NULL, the
 * default function will be used.
 */

extern PNG_EXPORT(void,png_set_error_fn) PNGARG((png_structp png_ptr,
   png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));

/* Return the user pointer associated with the error functions */
extern PNG_EXPORT(png_voidp,png_get_error_ptr) PNGARG((png_structp png_ptr));

/* Replace the default data output functions with a user supplied one(s).
 * If buffered output is not used, then output_flush_fn can be set to NULL.
 * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
 * output_flush_fn will be ignored (and thus can be NULL).
 */
extern PNG_EXPORT(void,png_set_write_fn) PNGARG((png_structp png_ptr,
   png_voidp io_ptr, png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));

/* Replace the default data input function with a user supplied one. */
extern PNG_EXPORT(void,png_set_read_fn) PNGARG((png_structp png_ptr,
   png_voidp io_ptr, png_rw_ptr read_data_fn));

/* Return the user pointer associated with the I/O functions */
extern PNG_EXPORT(png_voidp,png_get_io_ptr) PNGARG((png_structp png_ptr));

extern PNG_EXPORT(void,png_set_read_status_fn) PNGARG((png_structp png_ptr,
   png_read_status_ptr read_row_fn));

extern PNG_EXPORT(void,png_set_write_status_fn) PNGARG((png_structp png_ptr,
   png_write_status_ptr write_row_fn));

#ifdef PNG_USER_MEM_SUPPORTED
/* Replace the default memory allocation functions with user supplied one(s). */
extern PNG_EXPORT(void,png_set_mem_fn) PNGARG((png_structp png_ptr,
   png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn));

/* Return the user pointer associated with the memory functions */
extern PNG_EXPORT(png_voidp,png_get_mem_ptr) PNGARG((png_structp png_ptr));
#endif /* PNG_USER_MEM_SUPPORTED */

#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
extern PNG_EXPORT(void,png_set_read_user_transform_fn) PNGARG((png_structp
   png_ptr, png_user_transform_ptr read_user_transform_fn));
#endif

#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
extern PNG_EXPORT(void,png_set_write_user_transform_fn) PNGARG((png_structp
   png_ptr, png_user_transform_ptr write_user_transform_fn));
#endif

#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
/* Sets the function callbacks for the push reader, and a pointer to a
 * user-defined structure available to the callback functions.
 */
extern PNG_EXPORT(void,png_set_progressive_read_fn) PNGARG((png_structp png_ptr,
   png_voidp progressive_ptr,
   png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
   png_progressive_end_ptr end_fn));

/* returns the user pointer associated with the push read functions */
extern PNG_EXPORT(png_voidp,png_get_progressive_ptr)
   PNGARG((png_structp png_ptr));

/* function to be called when data becomes available */
extern PNG_EXPORT(void,png_process_data) PNGARG((png_structp png_ptr,
   png_infop info_ptr, png_bytep buffer, png_size_t buffer_size));

/* function that combines rows.  Not very much different than the
 * png_combine_row() call.  Is this even used?????
 */
extern PNG_EXPORT(void,png_progressive_combine_row) PNGARG((png_structp png_ptr,
   png_bytep old_row, png_bytep new_row));
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */

extern PNG_EXPORT(png_voidp,png_malloc) PNGARG((png_structp png_ptr,
   png_uint_32 size));

/* frees a pointer allocated by png_malloc() */
extern PNG_EXPORT(void,png_free) PNGARG((png_structp png_ptr, png_voidp ptr));

#ifdef PNG_USER_MEM_SUPPORTED
extern PNG_EXPORT(png_voidp,png_malloc_default) PNGARG((png_structp png_ptr,
   png_uint_32 size));
extern PNG_EXPORT(void,png_free_default) PNGARG((png_structp png_ptr,
   png_voidp ptr));
#endif /* PNG_USER_MEM_SUPPORTED */

extern PNG_EXPORT(png_voidp,png_memcpy_check) PNGARG((png_structp png_ptr,
   png_voidp s1, png_voidp s2, png_uint_32 size));

extern PNG_EXPORT(png_voidp,png_memset_check) PNGARG((png_structp png_ptr,
   png_voidp s1, int value, png_uint_32 size));

#if defined(USE_FAR_KEYWORD)  /* memory model conversion function */
extern void *png_far_to_near PNGARG((png_structp png_ptr,png_voidp ptr,
   int check));
#endif /* USE_FAR_KEYWORD */

/* Fatal error in PNG image of libpng - can't continue */
extern PNG_EXPORT(void,png_error) PNGARG((png_structp png_ptr,
   png_const_charp error));

/* The same, but the chunk name is prepended to the error string. */
extern PNG_EXPORT(void,png_chunk_error) PNGARG((png_structp png_ptr,
   png_const_charp error));

/* Non-fatal error in libpng.  Can continue, but may have a problem. */
extern PNG_EXPORT(void,png_warning) PNGARG((png_structp png_ptr,
   png_const_charp message));

/* Non-fatal error in libpng, chunk name is prepended to message. */
extern PNG_EXPORT(void,png_chunk_warning) PNGARG((png_structp png_ptr,
   png_const_charp message));

/* The png_set_<chunk> functions are for storing values in the png_info_struct.
 * Similarly, the png_get_<chunk> calls are used to read values from the
 * png_info_struct, either storing the parameters in the passed variables, or
 * setting pointers into the png_info_struct where the data is stored.  The
 * png_get_<chunk> functions return a non-zero value if the data was available
 * in info_ptr, or return zero and do not change any of the parameters if the
 * data was not available.
 *
 * These functions should be used instead of directly accessing png_info
 * to avoid problems with future changes in the size and internal layout of
 * png_info_struct.
 */
/* Returns "flag" if chunk data is valid in info_ptr. */
extern PNG_EXPORT(png_uint_32,png_get_valid) PNGARG((png_structp png_ptr,
png_infop info_ptr, png_uint_32 flag));

/* Returns number of bytes needed to hold a transformed row. */
extern PNG_EXPORT(png_uint_32,png_get_rowbytes) PNGARG((png_structp png_ptr,
png_infop info_ptr));

/* Returns number of color channels in image. */
extern PNG_EXPORT(png_byte,png_get_channels) PNGARG((png_structp png_ptr,
png_infop info_ptr));

#ifdef PNG_EASY_ACCESS_SUPPORTED
/* Returns image width in pixels. */
extern PNG_EXPORT(png_uint_32, png_get_image_width) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image height in pixels. */
extern PNG_EXPORT(png_uint_32, png_get_image_height) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image bit_depth. */
extern PNG_EXPORT(png_byte, png_get_bit_depth) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image color_type. */
extern PNG_EXPORT(png_byte, png_get_color_type) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image filter_type. */
extern PNG_EXPORT(png_byte, png_get_filter_type) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image interlace_type. */
extern PNG_EXPORT(png_byte, png_get_interlace_type) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image compression_type. */
extern PNG_EXPORT(png_byte, png_get_compression_type) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns image resolution in pixels per meter, from pHYs chunk data. */
extern PNG_EXPORT(png_uint_32, png_get_pixels_per_meter) PNGARG((png_structp
png_ptr, png_infop info_ptr));
extern PNG_EXPORT(png_uint_32, png_get_x_pixels_per_meter) PNGARG((png_structp
png_ptr, png_infop info_ptr));
extern PNG_EXPORT(png_uint_32, png_get_y_pixels_per_meter) PNGARG((png_structp
png_ptr, png_infop info_ptr));

/* Returns pixel aspect ratio, computed from pHYs chunk data.  */
extern PNG_EXPORT(float, png_get_pixel_