Linux Standard Base Desktop Specification 4.1 | ||
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This interface shall insert unknown chunks into a PNG file.
The parameter png_ptr shall specify the PNG file.
The parameter info_ptr shall specify the PNG info structure.
The parameter unknowns shall specify an array of png_unknown_chunk
structures containing the unknown chunks, as described under png_get_unknown_chunks().
The location
member of a png_unknown_chunk structure can take several
special values (see below).
The parameter num_unknowns shall specify the number of unknown chunks.
The special values for the location
members
of the png_unknown_chunk structures
are as follows.
0 | do not write the chunk | |
PNG_HAVE_IHDR | insert chunk before PLTE | |
PNG_HAVE_PLTE | insert chunk before IDAT | |
PNG_AFTER_IDAT | insert chunk after IDAT |
The location
member of the png_unknown_chunk structure
is set automatically depending on how much of the PNG file has been written.
Its value can be changed after calling this interface.
The chunk is placed within a location according to its position in the array
of structures, as described under png_get_unknown_chunks().
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png_set_unknown_chunk_location | Up | png_set_write_fn |