/*
 * jpeg.c -- enfle JPEG handler
 * (C)Copyright 1998, 99 by Hiroshi Takekawa
 * This file is part of Enfle.
 *
 * Last Modified: Mon Sep 20 20:06:47 1999.
 * $Id: jpeg.c,v 1.9 1999/09/20 12:55:59 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>

#include "jpegsrc.h"

#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;

int
#ifdef PIC
get_plugininfo(PluginInfo *p)
#else
loader_jpeg_get_plugininfo(PluginInfo *p)
#endif
{
  p->version = 1;
  p->type = _Loader;
  p->pluginname = "JPEG Format Loader Plugin version 0.1.1";
  p->pluginshortname = FORMAT_NAME;
  p->author = "Hiroshi Takekawa";
  p->dlhandle = NULL; /* set by plugin_load */
  p->functions.loader.load_image = jpeg_load_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);
}

/* read JPEG file */
LOCAL(int)
jpeg_decode_image(Info *info, Image *p)
{
  struct jpeg_decompress_struct *cinfo = malloc(sizeof(struct jpeg_decompress_struct));
  struct my_error_mgr jerr;
  JSAMPROW buffer[1]; /* output row buffer */
  int i, j, width, height;

  if (cinfo == NULL)
    return 0;

#ifdef DEBUG
  fprintf(stderr, "jpeg_decode_image() called\n");
#endif

  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_decompress(cinfo);
    free(cinfo);
    return 0;
  }

  /* Now we can initialize the JPEG decompression object. */
  jpeg_create_decompress(cinfo);
  jpeg_archive_src(cinfo, info->ar);
  (void)jpeg_read_header(cinfo, TRUE);

  jpeg_calc_output_dimensions(cinfo);
  p->width = width = cinfo->output_width;
  p->height = height = cinfo->output_height;
  info->format = FORMAT_NAME;

  if (info->if_quantize)
    cinfo->quantize_colors = TRUE;

  jpeg_calc_output_dimensions(cinfo);

  if (cinfo->output_components != 1 && cinfo->output_components != 3) {
    fprintf(stderr, "Can't read %d components-jpeg file\n", cinfo->output_components);
    jpeg_destroy_decompress(cinfo);
    free(cinfo);
    return 0;
  }

  (void)jpeg_start_decompress(cinfo);

  /* JSAMPLEs per row in output buffer */
  p->bytes_per_line = width * cinfo->output_components;
  p->image_size = p->bytes_per_line * height;

  /* allocate memory for image */
#ifdef DEBUG
  fprintf(stderr, "Attempt to allocate memory %d bytes... ", p->image_size);
#endif
  if ((p->image = malloc(p->image_size)) == NULL) {
    fprintf(stderr, "Can't allocate memory for image\n");
    jpeg_destroy_decompress(cinfo);
    free(cinfo);
    return 0;
  }

#ifdef DEBUG
  fprintf(stderr, " ok.\n");
#endif

  /* loading... */
  while (cinfo->output_scanline < height) {
    buffer[0] = (JSAMPROW)&p->image[cinfo->output_scanline * p->bytes_per_line];
    (void)jpeg_read_scanlines(cinfo, buffer, 1);
  }

  if (cinfo->out_color_space == JCS_GRAYSCALE) {
    p->ncolors = 256;
    p->type = _GRAY;
  } else {
    /* Copy colormap. Because jpeg_finish_decompress will release colormap memory */
    if (cinfo->quantize_colors == TRUE) {
      if (cinfo->out_color_components == 1)
	for (j = 0; j < cinfo->actual_number_of_colors; j++)
	  p->colormap[j][0] =
	    p->colormap[j][1] =
	    p->colormap[j][2] = cinfo->colormap[0][j];
      else
	for (j = 0; j < cinfo->actual_number_of_colors; j++)
	  for (i = 0; i < 3; i++)
	    p->colormap[j][i] = cinfo->colormap[i][j];
      p->ncolors = cinfo->actual_number_of_colors;
      p->type = _INDEX;
    } else {
      p->ncolors = 1 << 24;
      p->type = _RGB24;
    }
  }

#ifdef DEBUG
  fprintf(stderr, "%d colors\n", p->ncolors);
#endif

  (void)jpeg_finish_decompress(cinfo);
  jpeg_destroy_decompress(cinfo);
  free(cinfo);

  return 1;
}

GLOBAL(int)
jpeg_load_image(Info *info, Image *p)
{
  if (!jpeg_decode_image(info, p))
    return info->format == NULL ? PROC_NOT : PROC_ERROR;

  info->npics = 1;

  /* set handler */
  info->handler.destroy  = NULL;
  info->handler.alarmset = NULL;
  info->handler.alarm    = NULL;
  info->handler.alarmoff = NULL;

  return PROC_OK;
}