png_get_IHDR
Name
png_get_IHDR -- get PNG_IHDR chunk information from png_info structure
Synopsis
png_uint_32
png_get_IHDR
(png_structp
png_ptr, png_infop
info_ptr, png_uint_32 *
width, png_uint_32 *
height, int *
bit_depth, int *
color_type, int *
interlace_method, int *
compression_method, int *
filter_method);
Description
png_get_IHDR() gets PNG_IHDR chunk type information from png_info structure.
width | | holds the width of the image in pixels up to
2^31. |
height | | holds the height of the image in pixels up to
2^31. |
bit_depth | | holds the bit depth of one of the image channels. Valid values
are 1, 2, 4, 8, 16 and also depend on the color_type. |
color_type | | describes which color/alpha channels are present.
Supported color types shall include:
PNG_COLOR_TYPE_GRAY (bit depths 1, 2, 4, 8, 16) | PNG_COLOR_TYPE_GRAY_ALPHA (bit depths 8, 16) | PNG_COLOR_TYPE_PALETTE (bit depths 1, 2, 4, 8) | PNG_COLOR_TYPE_RGB (bit_depths 8, 16) | PNG_COLOR_TYPE_RGB_ALPHA (bit_depths 8, 16) | PNG_COLOR_MASK_PALETTE | PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA |
|
filter_method | | holds the filter method. If this argument is NULL, the
filter method will not be retrieved. Valid values after retrieval are
PNG_FILTER_TYPE_BASE | PNG_INTRAPIXEL_DIFFERENCING |
|
compression_method | | holds the compression method. If this argument is NULL, the
compression method will not be retrieved. Valid values after retrieval are
PNG_COMPRESSION_TYPE_BASE |
interlace_method | | holds the interlace method. If this argument is NULL, the
interlacing method will not be retrieved. Valid values after retrieval are
PNG_INTERLACE_NONE | PNG_INTERLACE_ADAM7 |
|
Return Value
On success, png_get_HDR() shall return 1. Otherwise,
png_get_IHDR() shall return 0.