dlibs/dlib/external/libjpeg/jdatadst.c

/*

 * jdatadst.c

 *

 * Copyright (C) 1994-1996, Thomas G. Lane.

 * Modified 2009-2012 by Guido Vollbeding.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains compression data destination routines for the case of

 * emitting JPEG data to memory or to a file (or any stdio stream).

 * While these routines are sufficient for most applications,

 * some will want to use a different destination manager.

 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of

 * JOCTETs into 8-bit-wide elements on external storage.  If char is wider

 * than 8 bits on your machine, you may need to do some tweaking.

 */

/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
#include "jinclude.h"
#include "jpeglib.h"
#include "jerror.h"

#ifndef HAVE_STDLIB_H		/* <stdlib.h> should declare malloc(),free() */
extern void * malloc JPP((size_t size));
extern void free JPP((void *ptr));
#endif


/* Expanded data destination object for stdio output */

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

  FILE * outfile;		/* target stream */
  JOCTET * buffer;		/* start of buffer */
} my_destination_mgr;

typedef my_destination_mgr * my_dest_ptr;

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


/* Expanded data destination object for memory output */

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

  unsigned char ** outbuffer;	/* target buffer */
  unsigned long * outsize;
  unsigned char * newbuffer;	/* newly allocated buffer */
  JOCTET * buffer;		/* start of buffer */
  size_t bufsize;
} my_mem_destination_mgr;

typedef my_mem_destination_mgr * my_mem_dest_ptr;


/*

 * Initialize destination --- called by jpeg_start_compress

 * before any data is actually written.

 */

METHODDEF(void)
init_destination (j_compress_ptr cinfo)
{
  my_dest_ptr dest = (my_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;
}

METHODDEF(void)
init_mem_destination (j_compress_ptr cinfo)
{
  /* no work necessary here */
}


/*

 * Empty the output buffer --- called whenever buffer fills up.

 *

 * In typical applications, this should write the entire output buffer

 * (ignoring the current state of next_output_byte & free_in_buffer),

 * reset the pointer & count to the start of the buffer, and return TRUE

 * indicating that the buffer has been dumped.

 *

 * In applications that need to be able to suspend compression due to output

 * overrun, a FALSE return indicates that the buffer cannot be emptied now.

 * In this situation, the compressor will return to its caller (possibly with

 * an indication that it has not accepted all the supplied scanlines).  The

 * application should resume compression after it has made more room in the

 * output buffer.  Note that there are substantial restrictions on the use of

 * suspension --- see the documentation.

 *

 * When suspending, the compressor will back up to a convenient restart point

 * (typically the start of the current MCU). next_output_byte & free_in_buffer

 * indicate where the restart point will be if the current call returns FALSE.

 * Data beyond this point will be regenerated after resumption, so do not

 * write it out when emptying the buffer externally.

 */

METHODDEF(boolean)
empty_output_buffer (j_compress_ptr cinfo)
{
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;

  if (JFWRITE(dest->outfile, dest->buffer, OUTPUT_BUF_SIZE) !=
      (size_t) OUTPUT_BUF_SIZE)
    ERREXIT(cinfo, JERR_FILE_WRITE);

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

  return TRUE;
}

METHODDEF(boolean)
empty_mem_output_buffer (j_compress_ptr cinfo)
{
  size_t nextsize;
  JOCTET * nextbuffer;
  my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;

  /* Try to allocate new buffer with double size */
  nextsize = dest->bufsize * 2;
  nextbuffer = (JOCTET *) malloc(nextsize);

  if (nextbuffer == NULL)
    ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);

  MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);

  if (dest->newbuffer != NULL)
    free(dest->newbuffer);

  dest->newbuffer = nextbuffer;

  dest->pub.next_output_byte = nextbuffer + dest->bufsize;
  dest->pub.free_in_buffer = dest->bufsize;

  dest->buffer = nextbuffer;
  dest->bufsize = nextsize;

  return TRUE;
}


/*

 * Terminate destination --- called by jpeg_finish_compress

 * after all data has been written.  Usually needs to flush buffer.

 *

 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding

 * application must deal with any cleanup that should happen even

 * for error exit.

 */

METHODDEF(void)
term_destination (j_compress_ptr cinfo)
{
  my_dest_ptr dest = (my_dest_ptr) cinfo->dest;
  size_t datacount = OUTPUT_BUF_SIZE - dest->pub.free_in_buffer;

  /* Write any data remaining in the buffer */
  if (datacount > 0) {
    if (JFWRITE(dest->outfile, dest->buffer, datacount) != datacount)
      ERREXIT(cinfo, JERR_FILE_WRITE);
  }
  fflush(dest->outfile);
  /* Make sure we wrote the output file OK */
  if (ferror(dest->outfile))
    ERREXIT(cinfo, JERR_FILE_WRITE);
}

METHODDEF(void)
term_mem_destination (j_compress_ptr cinfo)
{
  my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;

  *dest->outbuffer = dest->buffer;
  *dest->outsize = dest->bufsize - dest->pub.free_in_buffer;
}


/*

 * Prepare for output to a stdio stream.

 * The caller must have already opened the stream, and is responsible

 * for closing it after finishing compression.

 */

GLOBAL(void)
jpeg_stdio_dest (j_compress_ptr cinfo, FILE * outfile)
{
  my_dest_ptr dest;

  /* The destination object is made permanent so that multiple JPEG images

   * can be written to the same file without re-executing jpeg_stdio_dest.

   * This makes it dangerous to use this manager and a different destination

   * manager serially with the same JPEG object, because their private object

   * sizes may be different.  Caveat programmer.

   */
  if (cinfo->dest == NULL) {	/* first time for this JPEG object? */
    cinfo->dest = (struct jpeg_destination_mgr *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
				  SIZEOF(my_destination_mgr));
  }

  dest = (my_dest_ptr) cinfo->dest;
  dest->pub.init_destination = init_destination;
  dest->pub.empty_output_buffer = empty_output_buffer;
  dest->pub.term_destination = term_destination;
  dest->outfile = outfile;
}


/*

 * Prepare for output to a memory buffer.

 * The caller may supply an own initial buffer with appropriate size.

 * Otherwise, or when the actual data output exceeds the given size,

 * the library adapts the buffer size as necessary.

 * The standard library functions malloc/free are used for allocating

 * larger memory, so the buffer is available to the application after

 * finishing compression, and then the application is responsible for

 * freeing the requested memory.

 */

GLOBAL(void)
jpeg_mem_dest (j_compress_ptr cinfo,
	       unsigned char ** outbuffer, unsigned long * outsize)
{
  my_mem_dest_ptr dest;

  if (outbuffer == NULL || outsize == NULL)	/* sanity check */
    ERREXIT(cinfo, JERR_BUFFER_SIZE);

  /* The destination object is made permanent so that multiple JPEG images

   * can be written to the same buffer without re-executing jpeg_mem_dest.

   */
  if (cinfo->dest == NULL) {	/* first time for this JPEG object? */
    cinfo->dest = (struct jpeg_destination_mgr *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
				  SIZEOF(my_mem_destination_mgr));
  }

  dest = (my_mem_dest_ptr) cinfo->dest;
  dest->pub.init_destination = init_mem_destination;
  dest->pub.empty_output_buffer = empty_mem_output_buffer;
  dest->pub.term_destination = term_mem_destination;
  dest->outbuffer = outbuffer;
  dest->outsize = outsize;
  dest->newbuffer = NULL;

  if (*outbuffer == NULL || *outsize == 0) {
    /* Allocate initial buffer */
    dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE);
    if (dest->newbuffer == NULL)
      ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
    *outsize = OUTPUT_BUF_SIZE;
  }

  dest->pub.next_output_byte = dest->buffer = *outbuffer;
  dest->pub.free_in_buffer = dest->bufsize = *outsize;
}