ossimJpegMemSrc.cpp File Reference

#include <ossim/imaging/ossimJpegMemSrc.h>
#include <cstdio>
#include <csetjmp>
#include <jpeglib.h>
#include <jerror.h>

Go to the source code of this file.

Classes
struct	ossimJpegSourceMgr
	for jmp_buf More...

Typedefs
typedef ossimJpegSourceMgr *	ossimJpegSourceMgrPtr

Functions
void	init_source (j_decompress_ptr)
boolean	fill_input_buffer (j_decompress_ptr cinfo)
void	skip_input_data (j_decompress_ptr cinfo, long num_bytes)
void	term_source (j_decompress_ptr)
void	ossimJpegMemorySrc (jpeg_decompress_struct *cinfo, const ossim_uint8 *buffer, std::size_t bufsize)
	Method which uses memory instead of a FILE* to read from. More...

Typedef Documentation

ossimJpegSourceMgrPtr

typedef ossimJpegSourceMgr* ossimJpegSourceMgrPtr

Definition at line 50 of file ossimJpegMemSrc.cpp.

Function Documentation

fill_input_buffer()

boolean fill_input_buffer

(

j_decompress_ptr

cinfo

)

Definition at line 79 of file ossimJpegMemSrc.cpp.

References ossimJpegSourceMgr::eoi_buffer, ossimJpegSourceMgr::pub, and TRUE.

Referenced by ossimJpegMemorySrc(), and skip_input_data().

{
  ossimJpegSourceMgrPtr src = (ossimJpegSourceMgrPtr) cinfo->src;

  WARNMS(cinfo, JWRN_JPEG_EOF);

  /* Create a fake EOI marker */
  src->eoi_buffer[0] = (JOCTET) 0xFF;
  src->eoi_buffer[1] = (JOCTET) JPEG_EOI;
  src->pub.next_input_byte = src->eoi_buffer;
  src->pub.bytes_in_buffer = 2;

  return TRUE;
}

init_source()

void init_source

(

j_decompress_ptr

)

Definition at line 58 of file ossimJpegMemSrc.cpp.

Referenced by ossimJpegMemorySrc().

{
  /* No work, since jpeg_memory_src set up the buffer pointer and count.
   * Indeed, if we want to read multiple JPEG images from one buffer,
   * this *must* not do anything to the pointer.
   */
}

ossimJpegMemorySrc()

void ossimJpegMemorySrc	(	jpeg_decompress_struct *	cinfo,
		const ossim_uint8 *	buffer,
		std::size_t	bufsize
	)

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

Note

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

"unsigned char = JOCTET

Definition at line 148 of file ossimJpegMemSrc.cpp.

References fill_input_buffer(), init_source(), ossimJpegSourceMgr::pub, skip_input_data(), and term_source().

Referenced by ossimJpegCodec::decodeJpeg(), and ossimJpegCodec::getColorSpace().

{
  ossimJpegSourceMgrPtr src;

  /* The source object is made permanent so that a series of JPEG images
   * can be read from a single buffer by calling jpeg_memory_src
   * only before the first 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(ossimJpegSourceMgr));
  }

  src = (ossimJpegSourceMgrPtr) cinfo->src;
  src->pub.init_source = init_source;
  src->pub.fill_input_buffer = fill_input_buffer;
  src->pub.skip_input_data = skip_input_data;
  src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
  src->pub.term_source = term_source;

  src->pub.next_input_byte = buffer;
  src->pub.bytes_in_buffer = bufsize;
}

skip_input_data()

void skip_input_data	(	j_decompress_ptr	cinfo,
		long	num_bytes
	)

Definition at line 104 of file ossimJpegMemSrc.cpp.

References fill_input_buffer(), if(), and ossimJpegSourceMgr::pub.

Referenced by ossimJpegMemorySrc().

{
  ossimJpegSourceMgrPtr src = (ossimJpegSourceMgrPtr) cinfo->src;

  if (num_bytes > 0) {
    while (num_bytes > (long) src->pub.bytes_in_buffer) {
      num_bytes -= (long) src->pub.bytes_in_buffer;
      (void) fill_input_buffer(cinfo);
      /* note we assume that fill_input_buffer will never return FALSE,
       * so suspension need not be handled.
       */
    }
    src->pub.next_input_byte += (size_t) num_bytes;
    src->pub.bytes_in_buffer -= (size_t) num_bytes;
  }
}

term_source()

void term_source

(

j_decompress_ptr

)

Definition at line 139 of file ossimJpegMemSrc.cpp.

Referenced by ossimJpegMemorySrc().

{
  /* no work necessary here */
}