// Copyright (C) 2010 Davis E. King (davis@dlib.net), Nils Labugt
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_JPEG_LOADER_CPp_
#define DLIB_JPEG_LOADER_CPp_
// only do anything with this file if DLIB_JPEG_SUPPORT is defined
#ifdef DLIB_JPEG_SUPPORT
#include "../array2d.h"
#include "../pixel.h"
#include "../dir_nav.h"
#include "jpeg_loader.h"
#include <stdio.h>
#ifdef DLIB_JPEG_STATIC
# include "../external/libjpeg/jpeglib.h"
#else
# include <jpeglib.h>
#endif
#include <sstream>
#include <setjmp.h>
namespace dlib
{
// ----------------------------------------------------------------------------------------
jpeg_loader::
jpeg_loader( const char* filename ) : height_( 0 ), width_( 0 ), output_components_(0)
{
read_image( check_file( filename ), NULL, 0L );
}
// ----------------------------------------------------------------------------------------
jpeg_loader::
jpeg_loader( const std::string& filename ) : height_( 0 ), width_( 0 ), output_components_(0)
{
read_image( check_file( filename.c_str() ), NULL, 0L );
}
// ----------------------------------------------------------------------------------------
jpeg_loader::
jpeg_loader( const dlib::file& f ) : height_( 0 ), width_( 0 ), output_components_(0)
{
read_image( check_file( f.full_name().c_str() ), NULL, 0L );
}
// ----------------------------------------------------------------------------------------
jpeg_loader::
jpeg_loader( const unsigned char* imgbuffer, size_t imgbuffersize ) : height_( 0 ), width_( 0 ), output_components_(0)
{
read_image( NULL, imgbuffer, imgbuffersize );
}
// ----------------------------------------------------------------------------------------
bool jpeg_loader::is_gray() const
{
return (output_components_ == 1);
}
// ----------------------------------------------------------------------------------------
bool jpeg_loader::is_rgb() const
{
return (output_components_ == 3);
}
// ----------------------------------------------------------------------------------------
bool jpeg_loader::is_rgba() const
{
return (output_components_ == 4);
}
// ----------------------------------------------------------------------------------------
struct jpeg_loader_error_mgr
{
jpeg_error_mgr pub; /* "public" fields */
jmp_buf setjmp_buffer; /* for return to caller */
char jpegLastErrorMsg[JMSG_LENGTH_MAX];
};
void jpeg_loader_error_exit (j_common_ptr cinfo)
{
/* cinfo->err really points to a jpeg_loader_error_mgr struct, so coerce pointer */
jpeg_loader_error_mgr* myerr = (jpeg_loader_error_mgr*) cinfo->err;
/* Create the message */
( *( cinfo->err->format_message ) ) ( cinfo, myerr->jpegLastErrorMsg );
/* Return control to the setjmp point */
longjmp(myerr->setjmp_buffer, 1);
}
// ----------------------------------------------------------------------------------------
FILE * jpeg_loader::check_file( const char* filename )
{
if ( filename == NULL )
{
throw image_load_error("jpeg_loader: invalid filename, it is NULL");
}
FILE *fp = fopen( filename, "rb" );
if ( !fp )
{
throw image_load_error(std::string("jpeg_loader: unable to open file ") + filename);
}
return fp;
}
// ----------------------------------------------------------------------------------------
void jpeg_loader::read_image( FILE * file, const unsigned char* imgbuffer, size_t imgbuffersize )
{
jpeg_decompress_struct cinfo;
jpeg_loader_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = jpeg_loader_error_exit;
/* Establish the setjmp return context for my_error_exit to use. */
if (setjmp(jerr.setjmp_buffer))
{
/* If we get here, the JPEG code has signaled an error.
* We need to clean up the JPEG object, and return.
*/
jpeg_destroy_decompress(&cinfo);
if (file != NULL) fclose(file);
throw image_load_error(std::string("jpeg_loader: error while loading image: ") + jerr.jpegLastErrorMsg);
}
jpeg_create_decompress(&cinfo);
if (file != NULL) jpeg_stdio_src(&cinfo, file);
else if (imgbuffer != NULL) jpeg_mem_src(&cinfo, (unsigned char*)imgbuffer, imgbuffersize);
else throw image_load_error(std::string("jpeg_loader: no valid image source"));
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
height_ = cinfo.output_height;
width_ = cinfo.output_width;
output_components_ = cinfo.output_components;
if (output_components_ != 1 &&
output_components_ != 3 &&
output_components_ != 4)
{
if (file != NULL) fclose(file);
jpeg_destroy_decompress(&cinfo);
std::ostringstream sout;
sout << "jpeg_loader: Unsupported number of colors (" << output_components_ << ") in image";
throw image_load_error(sout.str());
}
std::vector<unsigned char*> rows;
rows.resize(height_);
// size the image buffer
data.resize(height_*width_*output_components_);
// setup pointers to each row
for (unsigned long i = 0; i < rows.size(); ++i)
rows[i] = &data[i*width_*output_components_];
// read the data into the buffer
while (cinfo.output_scanline < cinfo.output_height)
{
jpeg_read_scanlines(&cinfo, &rows[cinfo.output_scanline], 100);
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
if (file != NULL) fclose(file);
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_JPEG_SUPPORT
#endif // DLIB_JPEG_LOADER_CPp_