Unit JcAPIstd |
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Functions |
jpeg_start_compress - Compression initialization.
jpeg_write_raw_data - Alternate entry point to write raw data.
jpeg_write_scanlines - Write some scanlines of data to the JPEG compressor.
Types |
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Compression initialization. Before calling this, all parameters and a data destination must be set up. We require a write_all_tables parameter as a failsafe check when writing multiple datastreams from the same compression object. Since prior runs will have left all the tables marked sent_table=TRUE, a subsequent run would emit an abbreviated stream (no tables) by default. This may be what is wanted, but for safety's sake it should not be the default behavior: programmers should have to make a deliberate choice to emit abbreviated images. Therefore the documentation and examples should encourage people to pass write_all_tables=TRUE; then it will take active thought to do the wrong thing. } {GLOBAL
Alternate entry point to write raw data. Processes exactly one iMCU row per call, unless suspended. } {GLOBAL
Write some scanlines of data to the JPEG compressor. The return value will be the number of lines actually written. This should be less than the supplied num_lines only in case that the data destination module has requested suspension of the compressor, or if more than image_height scanlines are passed in. Note: we warn about excess calls to jpeg_write_scanlines() since this likely signals an application programmer error. However, excess scanlines passed in the last valid call are *silently* ignored, so that the application need not adjust num_lines for end-of-image when using a multiple-scanline buffer. } {GLOBAL
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