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tjDecompressHeader3(): Accept tables-only streams

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b3b15cfe74

Closes #604
Closes #605
This commit is contained in:
DRC
2022-06-24 14:03:03 -05:00
parent a405519e96
commit ba22c0f76d
17 changed files with 81 additions and 38 deletions
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25
turbojpeg.h
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@@ -1129,27 +1129,38 @@ DLLEXPORT tjhandle tjInitDecompress(void);
/**
* Retrieve information about a JPEG image without decompressing it.
* Retrieve information about a JPEG image without decompressing it, or prime
* the decompressor with quantization and Huffman tables.
*
* @param handle a handle to a TurboJPEG decompressor or transformer instance
*
* @param jpegBuf pointer to a buffer containing a JPEG image
* @param jpegBuf pointer to a buffer containing a JPEG image or an
* "abbreviated table specification" (AKA "tables-only") datastream. Passing a
* tables-only datastream to this function primes the decompressor with
* quantization and Huffman tables that can be used when decompressing
* subsequent "abbreviated image" datastreams. This is useful, for instance,
* when decompressing video streams in which all frames share the same
* quantization and Huffman tables.
*
* @param jpegSize size of the JPEG image (in bytes)
* @param jpegSize size of the JPEG image or tables-only datastream (in bytes)
*
* @param width pointer to an integer variable that will receive the width (in
* pixels) of the JPEG image
* pixels) of the JPEG image. If <tt>jpegBuf</tt> points to a tables-only
* datastream, then <tt>width</tt> is ignored.
*
* @param height pointer to an integer variable that will receive the height
* (in pixels) of the JPEG image
* (in pixels) of the JPEG image. If <tt>jpegBuf</tt> points to a tables-only
* datastream, then <tt>height</tt> is ignored.
*
* @param jpegSubsamp pointer to an integer variable that will receive the
* level of chrominance subsampling used when the JPEG image was compressed
* (see @ref TJSAMP "Chrominance subsampling options".)
* (see @ref TJSAMP "Chrominance subsampling options".) If <tt>jpegBuf</tt>
* points to a tables-only datastream, then <tt>jpegSubsamp</tt> is ignored.
*
* @param jpegColorspace pointer to an integer variable that will receive one
* of the JPEG colorspace constants, indicating the colorspace of the JPEG
* image (see @ref TJCS "JPEG colorspaces".)
* image (see @ref TJCS "JPEG colorspaces".) If <tt>jpegBuf</tt>
* points to a tables-only datastream, then <tt>jpegColorspace</tt> is ignored.
*
* @return 0 if successful, or -1 if an error occurred (see #tjGetErrorStr2()
* and #tjGetErrorCode().)