Again thanks for your attention !
I read the post you mentioned and it is a good explanation and my code
seem to follow it.
Here it's the my code again but without attachments:
------
int Fl_JPEG_Image::encode(Fl_Image *img, int quality,
unsigned char **outbuffer, int &outlen){
#ifdef HAVE_LIBJPEG
int imgw = img->w(), imgh = img->h(), imgd = img->d();
outlen = imgw * imgh * imgd;
struct jpeg_compress_struct cinfo = {0};
struct jpeg_error_mgr jerr;
if (imgd == 3) cinfo.in_color_space = JCS_RGB;
else if (imgd == 1) cinfo.in_color_space = JCS_GRAYSCALE;
else return -1;
*outbuffer = NULL;
unsigned long sz_outlen = outlen+8*1024; //safe margin to avoid
reallocations
/* create our in-memory output buffer to hold the jpeg */
*outbuffer = (unsigned char *) malloc(sz_outlen); //safe margin
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_compress(&cinfo);
jpeg_mem_dest(&cinfo, outbuffer, &sz_outlen);
cinfo.image_width = imgw;
cinfo.image_height = imgh;
cinfo.input_components = imgd;
jpeg_set_defaults(&cinfo);
jpeg_set_quality (&cinfo, quality, true);
jpeg_start_compress(&cinfo, true);
uchar * row_pointer;
uchar *idata = (uchar *)img->data()[0];
/* main code to write jpeg data */
int iwd = imgw * imgd;
while (cinfo.next_scanline < cinfo.image_height) {
row_pointer = idata + cinfo.next_scanline * iwd;
(void) jpeg_write_scanlines(&cinfo, &row_pointer, 1);
}
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
outlen = sz_outlen;
// FILE* outfile = fopen("test.jpeg", "wb");
// if (outfile){
// fwrite(*outbuffer, outlen,1 ,outfile);
// fclose(outfile);
// }
return 0;
#else
return -1;
#endif // HAVE_LIBJPEG
}
------
#if defined(HAVE_LIBPNG) && defined(HAVE_LIBZ)
/* structure to store PNG image bytes */
typedef struct {
uchar *buffer;
size_t size;
size_t size_allocated;
} mem_encode;
void my_png_write_data(png_structp png_ptr, png_bytep data, png_size_t
length){
mem_encode* p=(mem_encode*)png_get_io_ptr(png_ptr);
size_t nsize = p->size + length;
/* allocate or grow buffer */
if(nsize > p->size_allocated){
int alloc_size = nsize * 2;
if(p->buffer)
p->buffer = (uchar*)realloc(p->buffer, alloc_size);
else
p->buffer = (uchar*)malloc(alloc_size);
if(!p->buffer) {
png_error(png_ptr, "Write Error");
return;
}
p->size_allocated = alloc_size;
}
/* copy new bytes to end of buffer */
memcpy(p->buffer + p->size, data, length);
p->size += length;
}
/* This is optional but included to show how png_set_write_fn() is called
*/
void my_png_flush(png_structp png_ptr){}
#endif // HAVE_LIBPNG && HAVE_LIBZ
int Fl_PNG_Image::encode(Fl_Image *img, unsigned char **outbuffer, int
&outlen){
#if defined(HAVE_LIBPNG) && defined(HAVE_LIBZ)
int imgw = img->w(), imgh = img->h(), imgd = img->d();
outlen = imgw * imgh * imgd;
png_structp pp; // PNG data
png_infop info; // PNG image info
mem_encode state;
/* initialise - put this before png_write_png() call */
state.buffer = NULL;
state.size = 0;
state.size_allocated = 0;
if( !((imgd == 1) || (imgd ==3) || (imgd ==4))) return -1;
pp = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
if(!pp) return -1;
info = png_create_info_struct(pp);
if (!info){
png_destroy_write_struct(&pp, 0);
return -1;
}
if (setjmp(png_jmpbuf(pp))){
png_destroy_write_struct(&pp, &info);
return -1;
}
//png_init_io(pp, fp);
/* if my_png_flush() is not needed, change the arg to NULL */
png_set_write_fn(pp, &state, my_png_write_data, my_png_flush);
png_set_compression_level(pp, Z_BEST_COMPRESSION);
png_set_IHDR(pp, info, imgw, imgh, 8,
imgd == 1 ? PNG_COLOR_TYPE_GRAY : PNG_COLOR_TYPE_RGB,
PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
png_set_sRGB(pp, info, PNG_sRGB_INTENT_PERCEPTUAL);
png_set_sRGB_gAMA_and_cHRM(pp, info, PNG_INFO_sRGB);
png_write_info(pp, info);
uchar *idata = (uchar *)img->data()[0];
int iwd = imgw * imgd;
for (int y = 0; y < imgh; y++)
{
png_write_row(pp, (png_byte *)(idata + y * iwd));
}
png_write_end(pp, info);
png_destroy_write_struct(&pp, 0);
/* cleanup */
//if(state.buffer) free(state.buffer);
*outbuffer = state.buffer;
outlen = state.size;
// FILE* outfile = fopen("test.png", "wb");
// if (outfile){
// fwrite(*outbuffer, outlen,1 ,outfile);
// fclose(outfile);
// }
return 0;
#else
return -1;
#endif // HAVEHAVE_LIBPNG && HAVE_LIBZ
}
-----
# data file for the Fltk User Interface Designer (fluid)
version 1.0300
header_name {.h}
code_name {.cxx}
decl {\#include <FL/Fl_Shared_Image.H>} {private local
}
decl {\#include <FL/Fl_JPEG_Image.H>} {private local
}
decl {\#include <FL/Fl_PNG_Image.H>} {private local
}
decl {\#include <FL/Fl_File_Chooser.H>} {private local
}
decl {Fl_Image *img_loaded = 0;} {private local
}
decl {Fl_Image *img_saved = 0;} {private local
}
decl {unsigned char *memory_img = 0;} {selected private local
}
decl {int memory_img_len = 0;} {selected private local
}
Function {load_image(Fl_Widget *w)} {open return_type void
} {
code {char *img_fname = fl_file_chooser("Image file?","*.{jpg,png}", "");
if(img_fname){
btnLoaded->image(0);
btnSaved->image(0);
delete(img_loaded);
delete(img_saved);
if(memory_img){
free(memory_img);
memory_img = 0;
memory_img_len = 0;
}
const char * img_ext = fl_filename_ext(img_fname);
printf("%s:%s\\n",img_fname, img_ext);
if(stricmp(img_ext, ".jpg") == 0){
printf("%s is jpg\\n",img_fname);
img_loaded = new Fl_JPEG_Image(img_fname);
int result = Fl_JPEG_Image::encode(img_loaded, 85, &memory_img,
memory_img_len);
printf("%d:%d\\n", result, memory_img_len);
if(result == 0){
img_saved = new Fl_JPEG_Image("simgjpg", memory_img);
}
} else if(stricmp(img_ext, ".png") == 0){
printf("%s is png\\n",img_fname);
img_loaded = new Fl_PNG_Image(img_fname);
int result = Fl_PNG_Image::encode(img_loaded, &memory_img,
memory_img_len);
printf("%d:%d\\n", result, memory_img_len);
if(result == 0){
img_saved = new Fl_PNG_Image("simgpng", memory_img,
memory_img_len);
}
}
btnLoaded->image(img_loaded);
btnLoaded->redraw();
btnSaved->image(img_saved);
btnSaved->redraw();
}} {}
}
Function {} {open
} {
code {fl_register_images();} {}
Fl_Window {} {
label {Image Load & Save} open
xywh {56 119 553 337} type Double visible
} {
Fl_Button btnLoaded {
label Loaded
callback {load_image(o);}
dirty_name btnLoaded
xywh {20 30 235 240} align 64
}
Fl_Button btnSaved {
label Saved
dirty_name btnSaved
xywh {295 30 235 240} align 64
}
}
}
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