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src/Source/LibPNG/png.h  view on Meta::CPAN

PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
    png_inforp info_ptr));

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read one or more rows of image data. */
PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
    png_bytepp display_row, png_uint_32 num_rows));
#endif

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read a row of data. */
PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
    png_bytep display_row));
#endif

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the whole image into memory at once. */
PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
#endif

/* Write a row of image data */
PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
    png_const_bytep row));

/* Write a few rows of image data: (*row) is not written; however, the type
 * is declared as writeable to maintain compatibility with previous versions
 * of libpng and to allow the 'display_row' array from read_rows to be passed
 * unchanged to write_rows.
 */
PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
    png_uint_32 num_rows));

/* Write the image data */
PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));

/* Write the end of the PNG file. */
PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
    png_inforp info_ptr));

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the end of the PNG file. */
PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
#endif

/* Free any memory associated with the png_info_struct */
PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
    png_infopp info_ptr_ptr));

/* Free any memory associated with the png_struct and the png_info_structs */
PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
    png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));

/* Free any memory associated with the png_struct and the png_info_structs */
PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
    png_infopp info_ptr_ptr));

/* Set the libpng method of handling chunk CRC errors */
PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
    int ancil_action));

/* Values for png_set_crc_action() say how to handle CRC errors in
 * ancillary and critical chunks, and whether to use the data contained
 * therein.  Note that it is impossible to "discard" data in a critical
 * chunk.  For versions prior to 0.90, the action was always error/quit,
 * whereas in version 0.90 and later, the action for CRC errors in ancillary
 * chunks is warn/discard.  These values should NOT be changed.
 *
 *      value                       action:critical     action:ancillary
 */
#define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
#define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
#define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
#define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
#define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
#define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */

/* These functions give the user control over the scan-line filtering in
 * libpng and the compression methods used by zlib.  These functions are
 * mainly useful for testing, as the defaults should work with most users.
 * Those users who are tight on memory or want faster performance at the
 * expense of compression can modify them.  See the compression library
 * header file (zlib.h) for an explination of the compression functions.
 */

/* Set the filtering method(s) used by libpng.  Currently, the only valid
 * value for "method" is 0.
 */
PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
    int filters));

/* Flags for png_set_filter() to say which filters to use.  The flags
 * are chosen so that they don't conflict with real filter types
 * below, in case they are supplied instead of the #defined constants.
 * These values should NOT be changed.
 */
#define PNG_NO_FILTERS     0x00
#define PNG_FILTER_NONE    0x08
#define PNG_FILTER_SUB     0x10
#define PNG_FILTER_UP      0x20
#define PNG_FILTER_AVG     0x40
#define PNG_FILTER_PAETH   0x80
#define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
                         PNG_FILTER_AVG | PNG_FILTER_PAETH)

/* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
 * These defines should NOT be changed.
 */
#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

#ifdef 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.
 */
PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
    int heuristic_method, int num_weights, png_const_doublep filter_weights,
    png_const_doublep filter_costs))
PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
    (png_structrp png_ptr, int heuristic_method, int num_weights,
    png_const_fixed_point_p filter_weights,
    png_const_fixed_point_p filter_costs))
#endif /* WRITE_WEIGHTED_FILTER */