ossimJpegStdIOSrc.h File Reference

#include <ossim/base/ossimConstants.h>
#include <cstdio>

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Functions
OSSIM_DLL void	ossimJpegStdIOSrc (jpeg_decompress_struct *cinfo, FILE *infile)
	Method which uses memory instead of a FILE* to read from. More...

Function Documentation

ossimJpegStdIOSrc()

OSSIM_DLL void ossimJpegStdIOSrc	(	jpeg_decompress_struct *	cinfo,
		FILE *	infile
	)

Method which uses memory instead of a FILE* to read from.

Note

Used in place of "jpeg_stdio_src(&cinfo, infile)".

Definition at line 219 of file ossimJpegStdIOSrc.cpp.

References ossimJpegStdIOSourceMgr::buffer, ossimJpegStdIOSourceMgr::infile, INPUT_BUF_SIZE, ossimJpegStdIOSrc_fill_input_buffer(), ossimJpegStdIOSrc_init_source(), ossimJpegStdIOSrc_skip_input_data(), ossimJpegStdIOSrc_term_source(), ossimJpegStdIOSourceMgr::pub, and SIZEOF.

Referenced by ossimJpegTileSource::restart().

   {
      ossimJpegStdIOSourceMgrPtr src;
      
      /* The source object and input buffer are made permanent so that a series
       * of JPEG images can be read from the same file by calling jpeg_stdio_src
       * only before the first one.  (If we discarded the buffer at the end of
       * one image, we'd likely lose the start of the next one.)
       * This makes it unsafe to use this manager and a different source
       * manager serially with the same JPEG object.  Caveat programmer.
       */
      if (cinfo->src == NULL) {  /* first time for this JPEG object? */
         cinfo->src = (struct jpeg_source_mgr *)
         (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                     SIZEOF(ossimJpegStdIOSourceMgr));
         src = (ossimJpegStdIOSourceMgrPtr) cinfo->src;
         src->buffer = (JOCTET *)
         (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
                                     INPUT_BUF_SIZE * SIZEOF(JOCTET));
      }
      
      src = (ossimJpegStdIOSourceMgrPtr) cinfo->src;
      src->pub.init_source = ossimJpegStdIOSrc_init_source;
      src->pub.fill_input_buffer = ossimJpegStdIOSrc_fill_input_buffer;
      src->pub.skip_input_data = ossimJpegStdIOSrc_skip_input_data;
      src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
      src->pub.term_source = ossimJpegStdIOSrc_term_source;
      src->infile = infile;
      src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
      src->pub.next_input_byte = NULL; /* until buffer loaded */
   }