This function compresses grayscale bitmap data using D-Type's grayscale bitmap compression algorithm.
Parameter | Description |
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engine |
Handle of the previously created Standard Engine instance. |
bitmap_addr |
A valid pointer to the memory buffer at which the non-compressed bitmap grayscale bitmap data begins and to which the function will place compressed bitmap data. |
bitmap_len |
Length of the non-compressed bitmap data (actual length), in bytes. Note: If compressing grayscale bitmap data of glyph images in the bitmap cache obtained by dtGlyphDoOutput, dtGlyphDoOutputFrac, dtCharDoOutput or dtCharDoOutputFrac, simply set this parameter to memory_bitmap.l |
The function returns the difference between the non-compressed and compressed bitmap size, i.e. the reduction amount. This is always a non-negative number.