ossimJpegStdIOSrc.cpp File Reference

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

Go to the source code of this file.

Classes
struct	ossimJpegStdIOSourceMgr

Macros
#define	INPUT_BUF_SIZE   4096 /* choose an efficiently fread'able size */
	for jmp_buf More...
#define	JFREAD(file, buf, sizeofbuf)   ((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))
#define	SIZEOF(object)   ((size_t) sizeof(object))

Typedefs
typedef ossimJpegStdIOSourceMgr *	ossimJpegStdIOSourceMgrPtr

Functions
void	ossimJpegStdIOSrc_init_source (j_decompress_ptr cinfo)
boolean	ossimJpegStdIOSrc_fill_input_buffer (j_decompress_ptr cinfo)
void	ossimJpegStdIOSrc_skip_input_data (j_decompress_ptr cinfo, long num_bytes)
void	ossimJpegStdIOSrc_term_source (j_decompress_ptr cinfo)
void	ossimJpegStdIOSrc (jpeg_decompress_struct *cinfo, FILE *infile)
	Method which uses memory instead of a FILE* to read from. More...

Macro Definition Documentation

INPUT_BUF_SIZE

#define INPUT_BUF_SIZE   4096 /* choose an efficiently fread'able size */

for jmp_buf

for jpeg stuff

Definition at line 43 of file ossimJpegStdIOSrc.cpp.

Referenced by ossimJpegStdIOSrc(), and ossimJpegStdIOSrc_fill_input_buffer().

JFREAD

#define JFREAD	(		file,
			buf,
			sizeofbuf
	)		((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))

Definition at line 45 of file ossimJpegStdIOSrc.cpp.

Referenced by ossimJpegStdIOSrc_fill_input_buffer().

SIZEOF

#define SIZEOF

(

object

)

((size_t) sizeof(object))

Definition at line 56 of file ossimJpegStdIOSrc.cpp.

Referenced by ossimJpegStdIOSrc().

Typedef Documentation

ossimJpegStdIOSourceMgrPtr

typedef ossimJpegStdIOSourceMgr* ossimJpegStdIOSourceMgrPtr

Definition at line 71 of file ossimJpegStdIOSrc.cpp.

Function Documentation

ossimJpegStdIOSrc()

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 */
   }

ossimJpegStdIOSrc_fill_input_buffer()

boolean ossimJpegStdIOSrc_fill_input_buffer

(

j_decompress_ptr

cinfo

)

Definition at line 126 of file ossimJpegStdIOSrc.cpp.

References ossimJpegStdIOSourceMgr::buffer, FALSE, ossimJpegStdIOSourceMgr::infile, INPUT_BUF_SIZE, JFREAD, ossimJpegStdIOSourceMgr::pub, ossimJpegStdIOSourceMgr::start_of_file, and TRUE.

Referenced by ossimJpegStdIOSrc(), and ossimJpegStdIOSrc_skip_input_data().

   {
      ossimJpegStdIOSourceMgrPtr src = (ossimJpegStdIOSourceMgrPtr) cinfo->src;
      size_t nbytes;
      
      nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE);
      
      if (nbytes <= 0) {
         if (src->start_of_file)  /* Treat empty input file as fatal error */
            ERREXIT(cinfo, JERR_INPUT_EMPTY);
         WARNMS(cinfo, JWRN_JPEG_EOF);
         /* Insert a fake EOI marker */
         src->buffer[0] = (JOCTET) 0xFF;
         src->buffer[1] = (JOCTET) JPEG_EOI;
         nbytes = 2;
      }
      
      src->pub.next_input_byte = src->buffer;
      src->pub.bytes_in_buffer = nbytes;
      src->start_of_file = FALSE;
      
      return TRUE;
   }

ossimJpegStdIOSrc_init_source()

void ossimJpegStdIOSrc_init_source

(

j_decompress_ptr

cinfo

)

Definition at line 80 of file ossimJpegStdIOSrc.cpp.

References ossimJpegStdIOSourceMgr::start_of_file, and TRUE.

Referenced by ossimJpegStdIOSrc().

   {
      ossimJpegStdIOSourceMgrPtr src = (ossimJpegStdIOSourceMgrPtr) cinfo->src;
      
      /* We reset the empty-input-file flag for each image,
       * but we don't clear the input buffer.
       * This is correct behavior for reading a series of images from one source.
       */
      src->start_of_file = TRUE;
   }

ossimJpegStdIOSrc_skip_input_data()

void ossimJpegStdIOSrc_skip_input_data	(	j_decompress_ptr	cinfo,
		long	num_bytes
	)

Definition at line 164 of file ossimJpegStdIOSrc.cpp.

References if(), ossimJpegStdIOSrc_fill_input_buffer(), and ossimJpegStdIOSourceMgr::pub.

Referenced by ossimJpegStdIOSrc().

   {
      ossimJpegStdIOSourceMgrPtr src = (ossimJpegStdIOSourceMgrPtr) cinfo->src;
      
      /* Just a dumb implementation for now.  Could use fseek() except
       * it doesn't work on pipes.  Not clear that being smart is worth
       * any trouble anyway --- large skips are infrequent.
       */
      if (num_bytes > 0) {
         while (num_bytes > (long) src->pub.bytes_in_buffer) {
            num_bytes -= (long) src->pub.bytes_in_buffer;
            (void) ossimJpegStdIOSrc_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;
      }
   }

ossimJpegStdIOSrc_term_source()

void ossimJpegStdIOSrc_term_source

(

j_decompress_ptr

cinfo

)

Definition at line 205 of file ossimJpegStdIOSrc.cpp.

Referenced by ossimJpegStdIOSrc().

   {
      (void)cinfo;
      /* no work necessary here */
   }