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Re-work TJBUFSIZE() to take into account the level of chrominance subsampling

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DRC
2011-07-12 03:17:23 +00:00
parent 2bfd5d8c7d
commit 489864aefa
41 changed files with 268 additions and 180 deletions
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34
turbojpeg.h
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@@ -437,7 +437,7 @@ DLLEXPORT tjhandle DLLCALL tjInitCompress(void);
* -# set <tt>*jpegBuf</tt> to NULL to tell TurboJPEG to allocate the
* buffer for you, or
* -# pre-allocate the buffer to a "worst case" size determined by
* calling #TJBUFSIZE(). This should ensure that the buffer never has
* calling #tjBufSize(). This should ensure that the buffer never has
* to be re-allocated (setting #TJFLAG_NOREALLOC guarantees this.)
* .
* If you choose option 1, <tt>*jpegSize</tt> should be set to the
@@ -466,15 +466,26 @@ DLLEXPORT int DLLCALL tjCompress2(tjhandle handle, unsigned char *srcBuf,
/**
* The maximum size of the buffer (in bytes) required to hold a JPEG image with
* the given parameters.
* the given parameters. The number of bytes returned by this function is
* larger than the size of the uncompressed source image. The reason for this
* is that the JPEG format uses 16-bit coefficients, and it is thus possible
* for a very high-quality JPEG image with very high frequency content to
* expand rather than compress when converted to the JPEG format. Such images
* represent a very rare corner case, but since there is no way to predict the
* size of a JPEG image prior to compression, the corner case has to be
* handled.
*
* @param width width of the image (in pixels)
* @param height height of the image (in pixels)
* @param jpegSubsamp the level of chrominance subsampling to be used when
* generating the JPEG image (see @ref TJSAMP
* "Chrominance subsampling options".)
*
* @return the maximum size of the buffer (in bytes) required to hold the
* image, or -1 if the arguments are out of bounds.
*/
DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height);
DLLEXPORT unsigned long DLLCALL tjBufSize(int width, int height,
int jpegSubsamp);
/**
@@ -483,14 +494,14 @@ DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height);
*
* @param width width of the image (in pixels)
* @param height height of the image (in pixels)
* @param jpegSubsamp level of chrominance subsampling in the image (see
* @param subsamp level of chrominance subsampling in the image (see
* @ref TJSAMP "Chrominance subsampling options".)
*
* @return the size of the buffer (in bytes) required to hold the image, or
* -1 if the arguments are out of bounds.
*/
DLLEXPORT unsigned long DLLCALL TJBUFSIZEYUV(int width, int height,
int jpegSubsamp);
DLLEXPORT unsigned long DLLCALL tjBufSizeYUV(int width, int height,
int subsamp);
/**
@@ -521,7 +532,7 @@ DLLEXPORT unsigned long DLLCALL TJBUFSIZEYUV(int width, int height,
* @param pixelFormat pixel format of the source image (see @ref TJPF
* "Pixel formats".)
* @param dstBuf pointer to an image buffer which will receive the YUV image.
* Use #TJBUFSIZEYUV() to determine the appropriate size for this buffer
* Use #tjBufSizeYUV() to determine the appropriate size for this buffer
* based on the image width, height, and level of chrominance
* subsampling.
* @param subsamp the level of chrominance subsampling to be used when
@@ -640,7 +651,7 @@ DLLEXPORT int DLLCALL tjDecompress2(tjhandle handle,
* @param jpegBuf pointer to a buffer containing the JPEG image to decompress
* @param jpegSize size of the JPEG image (in bytes)
* @param dstBuf pointer to an image buffer which will receive the YUV image.
* Use #TJBUFSIZEYUV to determine the appropriate size for this buffer
* Use #tjBufSizeYUV to determine the appropriate size for this buffer
* based on the image width, height, and level of subsampling.
* @param flags the bitwise OR of one or more of the @ref TJFLAG_BOTTOMUP
* "flags".
@@ -688,7 +699,7 @@ DLLEXPORT tjhandle DLLCALL tjInitTransform(void);
* -# set <tt>dstBufs[i]</tt> to NULL to tell TurboJPEG to allocate the
* buffer for you, or
* -# pre-allocate the buffer to a "worst case" size determined by
* calling #TJBUFSIZE() with the cropped width and height. This should
* calling #tjBufSize() with the cropped width and height. This should
* ensure that the buffer never has to be re-allocated (setting
* #TJFLAG_NOREALLOC guarantees this.)
* .
@@ -781,6 +792,11 @@ DLLEXPORT char* DLLCALL tjGetErrorStr(void);
#define TJ_FASTUPSAMPLE TJFLAG_FASTUPSAMPLE
#define TJ_YUV 512
DLLEXPORT unsigned long DLLCALL TJBUFSIZE(int width, int height);
DLLEXPORT unsigned long DLLCALL TJBUFSIZEYUV(int width, int height,
int jpegSubsamp);
DLLEXPORT int DLLCALL tjCompress(tjhandle handle, unsigned char *srcBuf,
int width, int pitch, int height, int pixelSize, unsigned char *dstBuf,
unsigned long *compressedSize, int jpegSubsamp, int jpegQual, int flags);