>
> On 13.05.2011, at 22:01, Domingo Alvarez Duarte wrote:
>
> > I know that that function exists but my case isn't to convert a JPEG =
> image =20
> > to Fl_Image but the opposite convert a FL_Image to a JPEG or PNG.
> >=20
> > Anyway thanks for your attention.
>
Longtime back i have attempted on such task.
i am giving the source for that.
there may be modification required.
your views are welcome.
/* 19thmarch2010
*retrd:14thmay2011
*/
/* a membuff rgb data to jpeg file write routine */
#include <stdio.h>
#include <stdlib.h>
#include <jpeglib.h>
/* compress 'rgb' data and write as a jpeg file
* compression quality is settable between 0 to 100
*/
int write2jpeg(FILE *fileptr,unsigned char *image,int width,int height,int
quality)
{
/* from:libjpeg manual
* Allocate and initialize a JPEG compression object
* Specify the destination for the compressed data (eg, a file)
* Set parameters for compression, including image size & colorspace
* jpeg_start_compress(...);
* while (scan lines remain to be written)
* jpeg_write_scanlines(...);
* jpeg_finish_compress(...);
* Release the JPEG compression object
*/
int i,j;
/*Allocate a JPEG compression object-(cinfo here)*/
struct jpeg_compress_struct cinfo;
JSAMPROW row_pointer[1];
/* jpegimage=oneline compressed jpeg image buffer */
JSAMPLE *jpegimage = NULL;
int row_stride;
/* jpeg error manager */
struct jpeg_error_mgr jerr;
/* allocate the jpegimage buffer memory */
if ((jpegimage = malloc(width*3)) == NULL)
{
/* :( */
fprintf(stderr,"jpegwrite--memory allocation error\n");
return(1);
}
/* set the jpeg error handler */
cinfo.err = jpeg_std_error(&jerr);
/* Initialize the JPEG compression object. */
jpeg_create_compress(&cinfo);
/*Specify the destination for the compressed data (eg, a file)*/
jpeg_stdio_dest(&cinfo,fileptr);
/* Set parameters for compression,
* including image size & colorspace
*/
cinfo.image_width = width;
cinfo.image_height = height;
/* 'components' are 'no.of color channels'(RGB=3 here) */
cinfo.input_components = 3;
/* this is in RGB color space */
cinfo.in_color_space = JCS_RGB;
/* set default compression settings */
jpeg_set_defaults(&cinfo);
/* set compression quality */
/* TRUE= limit quality to baseline of JPEG values */
jpeg_set_quality(&cinfo, quality, TRUE);
/* jpeg_start_compress(...); */
jpeg_start_compress(&cinfo, TRUE);
row_stride = width * 3;
row_pointer[0] = jpegimage;
/* initialise 'j' with last row to start, then count down... */
j = cinfo.image_height - 1;
/* while (scan lines remain to be written)
* jpeg_write_scanlines(...);
*/
while (cinfo.next_scanline < cinfo.image_height)
{
for (i=0;i<width;i++)
{
jpegimage[3*i ] = image[j*width+i+0];
jpegimage[3*i+1] = image[j*width+i+1];
jpegimage[3*i+2] = image[j*width+i+2];
}
jpeg_write_scanlines(&cinfo,row_pointer,1);
j--;
}
/* jpeg_finish_compress(...); */
jpeg_finish_compress(&cinfo);
/* Release the JPEG compression object */
jpeg_destroy_compress(&cinfo);
/* free the jpegimage buffer memory */
free(jpegimage);
/* everything went on smoothly... :) */
return(0);
}
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