/*
 * jpeg.c -- enfle JPEG saver
 * (C)Copyright 1998, 99 by Hiroshi Takekawa
 * This file is part of Enfle.
 *
 * Last Modified: Sun Sep 19 02:00:11 1999.
 * $Id: jpeg.c,v 1.2 1999/09/18 18:29:59 sian Exp $
 *
 * NOTE: This code needs libjpeg version 6 or later.
 *
 * This software is based in part on the work of the Independent JPEG Group
 *
 * Enfle is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Enfle is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#include "enfle.h"
#include "jpeg.h"
#include "plugin.h"

#include <stdio.h>
#include <stdlib.h>

#include <jpeglib.h>
#include <jerror.h>
#include <setjmp.h>

#define JPEG_SAVE_QUALITY 100

#if BITS_IN_JSAMPLE != 8
#  error BITS_IN_JSAMPLE must be 8
#endif

struct my_error_mgr {
  struct jpeg_error_mgr pub;	/* "public" fields */
  jmp_buf setjmp_buffer;	/* for return to caller */
};

typedef struct my_error_mgr *my_error_ptr;

#ifdef PIC
int get_plugininfo(PluginInfo *p)
#else
int saver_jpeg_get_plugininfo(PluginInfo *p)
#endif
{
  p->version = 1;
  p->type = _Saver;
  p->pluginname = "JPEG Format Saver Plugin version 0.1.1";
  p->pluginshortname = FORMAT_NAME;
  p->author = "Hiroshi Takekawa";
  p->dlhandle = NULL; /* set by plugin_load */
  p->functions.saver.save_image = jpeg_save_image;

  return 1;
}

/* my error handler */
METHODDEF(void)
my_error_exit (j_common_ptr cinfo)
{
  /* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
  my_error_ptr myerr = (my_error_ptr)cinfo->err;

  if (cinfo->err->msg_code != JERR_NO_SOI)
    (*cinfo->err->output_message)(cinfo);

  /* Return control to the setjmp point */
  longjmp(myerr->setjmp_buffer, 1);
}

/* write JPEG file */
GLOBAL(int)
jpeg_save_image(Info *info, Image *p, char *outfile)
{
  FILE *fp = NULL;
  struct jpeg_compress_struct *cinfo = malloc(sizeof(struct jpeg_compress_struct));
  struct my_error_mgr jerr;
  JSAMPROW buffer[1]; /* output row buffer */

  if (cinfo == NULL)
    return 0;

  switch (p->type) {
  case _INDEX:
  case _RGB16:
    if (!image_expand(p, _RGB24))
      return 0;
    break;
  case _MONO:
    fprintf(stderr, "binary image save support not yet implemented\n");
    return 0;
  case _GRAY:
  case _RGB24:
    break;
  default:
    fprintf(stderr, "Unknown image type: %d (maybe bug)\n", p->type);
    return 0;
  }

  if ((fp = fopen(outfile, "wb")) == NULL)
    return 0;

  cinfo->err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = my_error_exit;
  /* Establish the setjmp return context for my_error_exit to use. */
  if (setjmp(jerr.setjmp_buffer)) {
    jpeg_destroy_compress(cinfo);
    free(cinfo);
    return 0;
  }

  /* Now we can initialize the JPEG decompression object. */
  jpeg_create_compress(cinfo);
  jpeg_stdio_dest(cinfo, fp);

  cinfo->image_width = p->width;
  cinfo->image_height = p->height;
  if (p->type == _GRAY) {
    cinfo->input_components = 1;
    cinfo->in_color_space = JCS_GRAYSCALE;
  } else {
    cinfo->input_components = 3;
    cinfo->in_color_space = JCS_RGB;
  }
  jpeg_set_defaults(cinfo);
  jpeg_set_quality(cinfo, JPEG_SAVE_QUALITY, TRUE);

  jpeg_start_compress(cinfo, TRUE);

  while (cinfo->next_scanline < cinfo->image_height) {
    buffer[0] = (JSAMPROW)(p->image + p->bytes_per_line * cinfo->next_scanline);
    (void)jpeg_write_scanlines(cinfo, buffer, 1);
  }

  (void)jpeg_finish_compress(cinfo);
  fclose(fp);
  jpeg_destroy_compress(cinfo);
  free(cinfo);

  return 1;
}