fltk/src/Fl_JPEG_Image.cxx

//
// "$Id$"
//
// Fl_JPEG_Image routines.
//
// Copyright 1997-2009 by Easy Software Products.
// Image support by Matthias Melcher, Copyright 2000-2009.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library 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
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//
// Contents:
//
//   Fl_JPEG_Image::Fl_JPEG_Image() - Load a JPEG image file.
//

//
// Include necessary header files...
//

#include <FL/Fl_JPEG_Image.H>
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>


// Some releases of the Cygwin JPEG libraries don't have a correctly
// updated header file for the INT32 data type; the following define
// from Shane Hill seems to be a usable workaround...

#if defined(WIN32) && defined(__CYGWIN__)
#  define XMD_H
#endif // WIN32 && __CYGWIN__


extern "C"
{
#ifdef HAVE_LIBJPEG
#  include <jpeglib.h>
#endif // HAVE_LIBJPEG
}


//
// Custom JPEG error handling structure...
//

#ifdef HAVE_LIBJPEG
struct fl_jpeg_error_mgr {
  jpeg_error_mgr	pub_;		// Destination manager...
  jmp_buf		errhand_;	// Error handler
};
#endif // HAVE_LIBJPEG


//
// Error handler for JPEG files...
//

#ifdef HAVE_LIBJPEG
extern "C" {
  static void
  fl_jpeg_error_handler(j_common_ptr dinfo) {	// I - Decompressor info
    longjmp(((fl_jpeg_error_mgr *)(dinfo->err))->errhand_, 1);
  }

  static void
  fl_jpeg_output_handler(j_common_ptr) {	// I - Decompressor info (not used)
  }
}
#endif // HAVE_LIBJPEG


/**
  The constructor loads the JPEG image from the given jpeg filename.
  <P>The inherited destructor free all memory and server resources that are used by  the image.
*/
Fl_JPEG_Image::Fl_JPEG_Image(const char *jpeg)	// I - File to load
  : Fl_RGB_Image(0,0,0) {
#ifdef HAVE_LIBJPEG
  FILE				*fp;	// File pointer
  jpeg_decompress_struct	dinfo;	// Decompressor info
  fl_jpeg_error_mgr		jerr;	// Error handler info
  JSAMPROW			row;	// Sample row pointer

  // the following variables are pointers allocating some private space that
  // is not reset by 'setjmp()'
  char* max_finish_decompress_err;      // count errors and give up afer a while
  char* max_destroy_decompress_err;     // to avoid recusion and deadlock

  // Clear data...
  alloc_array = 0;
  array = (uchar *)0;

  // Open the image file...
  if ((fp = fopen(jpeg, "rb")) == NULL) return;

  // Setup the decompressor info and read the header...
  dinfo.err                = jpeg_std_error((jpeg_error_mgr *)&jerr);
  jerr.pub_.error_exit     = fl_jpeg_error_handler;
  jerr.pub_.output_message = fl_jpeg_output_handler;

  // Setup error loop variables
  max_finish_decompress_err = (char*)malloc(1);   // allocate space on the frame for error counters
  max_destroy_decompress_err = (char*)malloc(1);  // otherwise, the variables are reset on the longjmp
  *max_finish_decompress_err=10;
  *max_destroy_decompress_err=10;

  if (setjmp(jerr.errhand_))
  {
    // JPEG error handling...
    // if any of the cleanup routines hits another error, we would end up 
    // in a loop. So instead, we decrement max_err for some upper cleanup limit.
    if ( ((*max_finish_decompress_err)-- > 0) && array)
      jpeg_finish_decompress(&dinfo);
    if ( (*max_destroy_decompress_err)-- > 0)
      jpeg_destroy_decompress(&dinfo);

    fclose(fp);

    w(0);
    h(0);
    d(0);

    if (array) {
      delete[] (uchar *)array;
      array = 0;
      alloc_array = 0;
    }

    free(max_destroy_decompress_err);
    free(max_finish_decompress_err);
    
    return;
  }

  jpeg_create_decompress(&dinfo);
  jpeg_stdio_src(&dinfo, fp);
  jpeg_read_header(&dinfo, 1);

  dinfo.quantize_colors      = (boolean)FALSE;
  dinfo.out_color_space      = JCS_RGB;
  dinfo.out_color_components = 3;
  dinfo.output_components    = 3;

  jpeg_calc_output_dimensions(&dinfo);

  w(dinfo.output_width); 
  h(dinfo.output_height);
  d(dinfo.output_components);

  array = new uchar[w() * h() * d()];
  alloc_array = 1;

  jpeg_start_decompress(&dinfo);

  while (dinfo.output_scanline < dinfo.output_height) {
    row = (JSAMPROW)(array +
                     dinfo.output_scanline * dinfo.output_width *
                     dinfo.output_components);
    jpeg_read_scanlines(&dinfo, &row, (JDIMENSION)1);
  }

  jpeg_finish_decompress(&dinfo);
  jpeg_destroy_decompress(&dinfo);

  free(max_destroy_decompress_err);
  free(max_finish_decompress_err);

  fclose(fp);
#endif // HAVE_LIBJPEG
}

//
// End of "$Id$".
//