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/************************************************************************
JPEG image file format support.
The I/O code in this file was originally based on the example.c
skeleton code distributed with the JPEG library (release 6b).
$Id: raster-jpeg.cxx 427 2004-09-27 04:45:31Z garland $
************************************************************************/
#include <gfx/gfx.h>
#include <gfx/raster.h>
namespace gfx {
// Quality factors are expressed on a 0--100 scale
int jpeg_output_quality = 100;
}
#ifdef HAVE_LIBJPEG
#include <stdio.h>
extern "C" {
#include <jpeglib.h>
}
namespace gfx
{
bool write_jpeg_image(const char *filename, const ByteRaster& img)
{
FILE *outfile = fopen(filename, "wb");
if( !outfile ) return false;
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, outfile);
cinfo.image_width = img.width();
cinfo.image_height = img.height();
cinfo.input_components = img.channels();
if(img.channels()==1) cinfo.in_color_space = JCS_GRAYSCALE;
else if(img.channels()==3) cinfo.in_color_space = JCS_RGB;
else cinfo.in_color_space = JCS_UNKNOWN;
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, jpeg_output_quality, TRUE);
jpeg_start_compress(&cinfo, TRUE);
int row_stride = img.width() * img.channels();
const unsigned char *scanline = img.head();
while( cinfo.next_scanline < cinfo.image_height )
{
(void) jpeg_write_scanlines(&cinfo, (JSAMPLE **)&scanline, 1);
scanline += row_stride;
}
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
fclose(outfile);
return true;
}
ByteRaster *read_jpeg_image(const char *filename)
{
FILE *infile = fopen(filename, "rb");
if( !infile ) return NULL;
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, infile);
(void) jpeg_read_header(&cinfo, TRUE);
(void) jpeg_start_decompress(&cinfo);
ByteRaster *img = new ByteRaster(cinfo.output_width,
cinfo.output_height,
cinfo.output_components);
int row_stride = cinfo.output_width * cinfo.output_components;
unsigned char *scanline = img->head();
while( cinfo.output_scanline < cinfo.output_height)
{
(void) jpeg_read_scanlines(&cinfo, (JSAMPLE **)&scanline, 1);
scanline += row_stride;
}
(void) jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(infile);
return img;
}
} // namespace gfx
#else
namespace gfx
{
bool write_jpeg_image(const char *, const ByteRaster&) { return false; }
ByteRaster *read_jpeg_image(const char *) { return NULL; }
}
#endif
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