readerwriterjpeg.cpp

最新osg包

#include <osg/Image>
#include <osg/Notify>
#include <osg/Geode>
#include <osg/GL>

#include <osgDB/Registry>
#include <osgDB/FileNameUtils>
#include <osgDB/FileUtils>

#include <sstream>

/****************************************************************************
 *
 * Follows is code extracted from the simage library.  Original Authors:
 *
 *      Systems in Motion,
 *      <URL:http://www.sim.no>
 *
 *      Peder Blekken <[e-mail]>
 *      Morten Eriksen <[e-mail]>
 *      Marius Bugge Monsen <[e-mail]>
 *
 * The original COPYING notice
 *
 *      All files in this library are public domain, except simage_rgb.cpp which is
 *      Copyright (c) Mark J Kilgard <[e-mail]>. I will contact Mark
 *      very soon to hear if this source also can become public domain.
 *
 *      Please send patches for bugs and new features to: <[e-mail]>.
 *
 *      Peder Blekken
 *
 *
 * Ported into the OSG as a plugin, Robert Osfield Decemeber 2000.
 * Note, reference above to license of simage_rgb is not relevent to the OSG
 * as the OSG does not use it.  Also for patches, bugs and new features
 * please send them direct to the OSG dev team rather than address above.
 *
 **********************************************************************/

/*
 * Based on example code found in the libjpeg archive
 *
 */

#include <stdio.h>

extern "C"
{
    #include <jpeglib.h>
    #include "jerror.h"
}

#include <setjmp.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>

namespace osgDBJPEG
{

#define ERR_NO_ERROR 0
#define ERR_OPEN     1
#define ERR_MEM      2
#define ERR_JPEGLIB  3

static int jpegerror = ERR_NO_ERROR;

/* CODE FOR READING/WRITING JPEG FROM STREAMS
 *  This code was taken directly from jdatasrc.c and jdatadst.c (libjpeg source)
 *  and modified to use a std::istream/ostream* instead of a FILE*
 */

/* Expanded data source object for stdio input */

typedef struct {
    struct jpeg_source_mgr pub;    /* public fields */
    std::istream * infile;        /* source stream */
    JOCTET * buffer;              /* start of buffer */
    boolean start_of_file;        /* have we gotten any data yet? */
} stream_source_mgr;

typedef stream_source_mgr * stream_src_ptr;

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

/*
 * Initialize source --- called by jpeg_read_header
 * before any data is actually read.
 */

void init_source (j_decompress_ptr cinfo)
{
  stream_src_ptr src = (stream_src_ptr) 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;
}


/*
 * Fill the input buffer --- called whenever buffer is emptied.
 *
 * In typical applications, this should read fresh data into the buffer
 * (ignoring the current state of next_input_byte & bytes_in_buffer),
 * reset the pointer & count to the start of the buffer, and return TRUE
 * indicating that the buffer has been reloaded.  It is not necessary to
 * fill the buffer entirely, only to obtain at least one more byte.
 *
 * There is no such thing as an EOF return.  If the end of the file has been
 * reached, the routine has a choice of ERREXIT() or inserting fake data into
 * the buffer.  In most cases, generating a warning message and inserting a
 * fake EOI marker is the best course of action --- this will allow the
 * decompressor to output however much of the image is there.  However,
 * the resulting error message is misleading if the real problem is an empty
 * input file, so we handle that case specially.
 *
 * In applications that need to be able to suspend compression due to input
 * not being available yet, a FALSE return indicates that no more data can be
 * obtained right now, but more may be forthcoming later.  In this situation,
 * the decompressor will return to its caller (with an indication of the
 * number of scanlines it has read, if any).  The application should resume
 * decompression after it has loaded more data into the input buffer.  Note
 * that there are substantial restrictions on the use of suspension --- see
 * the documentation.
 *
 * When suspending, the decompressor will back up to a convenient restart point
 * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
 * indicate where the restart point will be if the current call returns FALSE.
 * Data beyond this point must be rescanned after resumption, so move it to
 * the front of the buffer rather than discarding it.
 */

boolean fill_input_buffer (j_decompress_ptr cinfo)
{
  stream_src_ptr src = (stream_src_ptr) cinfo->src;
  size_t nbytes;

  src->infile->read((char*)src->buffer,INPUT_BUF_SIZE);
  nbytes = src->infile->gcount();

  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;
}


/*
 * Skip data --- used to skip over a potentially large amount of
 * uninteresting data (such as an APPn marker).
 *
 * Writers of suspendable-input applications must note that skip_input_data
 * is not granted the right to give a suspension return.  If the skip extends
 * beyond the data currently in the buffer, the buffer can be marked empty so
 * that the next read will cause a fill_input_buffer call that can suspend.
 * Arranging for additional bytes to be discarded before reloading the input
 * buffer is the application writer's problem.
 */

void skip_input_data (j_decompress_ptr cinfo, long num_bytes)
{
  stream_src_ptr src = (stream_src_ptr) 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) 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;
  }
}


/*
 * An additional method that can be provided by data source modules is the
 * resync_to_restart method for error recovery in the presence of RST markers.
 * For the moment, this source module just uses the default resync method
 * provided by the JPEG library.  That method assumes that no backtracking
 * is possible.
 */


/*
 * Terminate source --- called by jpeg_finish_decompress
 * after all data has been read.  Often a no-op.
 *
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
 * application must deal with any cleanup that should happen even
 * for error exit.
 */
void term_source (j_decompress_ptr /*cinfo*/)
{
  /* no work necessary here */
}

void jpeg_istream_src(j_decompress_ptr cinfo, std::istream *infile)
{
    stream_src_ptr 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(stream_source_mgr));
        src = (stream_src_ptr) cinfo->src;
        src->buffer = (JOCTET *)
            (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,INPUT_BUF_SIZE * sizeof(JOCTET));
    }

    src = (stream_src_ptr) 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->infile = infile;
    src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
    src->pub.next_input_byte = NULL; /* until buffer loaded */
}

/* Expanded data destination object for stdio output */

typedef struct {
  struct jpeg_destination_mgr pub; /* public fields */

  std::ostream * outfile;    /* target stream */
  JOCTET * buffer;          /* start of buffer */
} stream_destination_mgr;

typedef stream_destination_mgr * stream_dest_ptr;

#define OUTPUT_BUF_SIZE  4096    /* choose an efficiently fwrite'able size */


/*
 * Initialize destination --- called by jpeg_start_compress
 * before any data is actually written.
 */

void init_destination (j_compress_ptr cinfo)
{
  stream_dest_ptr dest = (stream_dest_ptr) cinfo->dest;

  /* Allocate the output buffer --- it will be released when done with image */
  dest->buffer = (JOCTET *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, OUTPUT_BUF_SIZE * sizeof(JOCTET));

  dest->pub.next_output_byte = dest->buffer;
  dest->pub.free_in_buffer = OUTPUT_BUF_SIZE;
}


/*
 * Empty the output buffer --- called whenever buffer fills up.
 *
 * In typical applications, this should write the entire output buffer