/*

 * jdatadst-tj.c

 *

 * This file was part of the Independent JPEG Group's software:

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

 * Modified 2009-2012 by Guido Vollbeding.

 * libjpeg-turbo Modifications:

 * Copyright (C) 2011, 2014, 2016, 2019, 2022-2023, D. R. Commander.

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

 * 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"

void jpeg_mem_dest_tj(j_compress_ptr cinfo, unsigned char **outbuffer,

                      size_t *outsize, boolean alloc);

#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 */

  size_t *outsize;

  unsigned char *newbuffer;     /* newly allocated buffer */

  JOCTET *buffer;               /* start of buffer */

  size_t bufsize;

  boolean alloc;

} 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_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_mem_output_buffer(j_compress_ptr cinfo)

{

  size_t nextsize;

  JOCTET *nextbuffer;

  my_mem_dest_ptr dest = (my_mem_dest_ptr)cinfo->dest;

  if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE);

  /* 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);

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

  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_mem_destination(j_compress_ptr cinfo)

{

  my_mem_dest_ptr dest = (my_mem_dest_ptr)cinfo->dest;

  if (dest->alloc) *dest->outbuffer = dest->buffer;

  *dest->outsize = dest->bufsize - dest->pub.free_in_buffer;

}

/*

 * 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_tj(j_compress_ptr cinfo, unsigned char **outbuffer,

                 size_t *outsize, boolean alloc)

{

  boolean reused = FALSE;

  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->newbuffer = NULL;

    dest->buffer = NULL;

  } else if (cinfo->dest->init_destination != init_mem_destination) {

    /* It is unsafe to reuse the existing destination manager unless it was

     * created by this function.

     */

    ERREXIT(cinfo, JERR_BUFFER_SIZE);

  }

  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;

  if (dest->buffer == *outbuffer && *outbuffer != NULL && alloc)

    reused = TRUE;

  dest->outbuffer = outbuffer;

  dest->outsize = outsize;

  dest->alloc = alloc;

  if (*outbuffer == NULL || *outsize == 0) {

    if (alloc) {

      /* 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;

    } else

      ERREXIT(cinfo, JERR_BUFFER_SIZE);

  }

  dest->pub.next_output_byte = dest->buffer = *outbuffer;

  if (!reused)

    dest->bufsize = *outsize;

  dest->pub.free_in_buffer = dest->bufsize;

}