int giftest_write(void)
{
struct gif *gif;
struct palette *pal;
struct color colors[4] = {
{ 0, 0, 0, 0xff },
{ 64, 64, 64, 0xff },
{ 128, 128, 128, 0xff },
{ 192, 192, 192, 0xff }
};
uint32_t x,y,i;
uint8_t data;
gif = gif_new("test.gif", GIF_WRITE);
pal = gif_palette_make(4, colors);
gif_screen_put(gif, GIFTEST_WIDTH, GIFTEST_HEIGHT, 2, 0, pal);
gif_image_put(gif, 0, 0, GIFTEST_WIDTH, GIFTEST_HEIGHT, 0, pal);
i=0;
for(y = 0; y < GIFTEST_HEIGHT; y++)
for(x = 0; x < GIFTEST_WIDTH; x++)
{
/* data = i & 0x03;*/
data = (y*x*2 + x*x*8) / 80;
data &= 0x03;
gif_data_put(gif, &data, 1);
i++;
}
gif_close(gif);
gif_save(gif);
return 0;
}
void *
gif_encode(Image *image, int single, int *size)
{
int width = image->columns;
int height = image->rows;
int total = width * height;
GifByteType red[total];
GifByteType green[total];
GifByteType blue[total];
// Quantize the images using IM/GM first, to reduce
// their number of colors to 256.
int count = GetImageListLength(image);
QuantizeInfo info;
GetQuantizeInfo(&info);
info.dither = 0;
info.number_colors = NCOLORS;
QuantizeImage(&info, image);
if (count > 1) {
#ifdef _MAGICK_USES_IM
RemapImages(&info, image->next, image);
#else
MapImages(image->next, image, 0);
#endif
}
if (!acquire_image_pixels(image, red, green, blue)) {
return NULL;
}
size_t frame_size = sizeof(Frame) + total;
Frame *frames = malloc(frame_size * count);
ColorMapObject *palette = GifMakeMapObject(NCOLORS, NULL);
int palette_size = NCOLORS;
// Quantize again using giflib, since it yields a palette which produces
// better compression, reducing the file size by 20%. Note that this second
// quantization is very fast, because the image already has 256 colors, so
// its effect on performance is negligible.
if (GifQuantizeBuffer(width, height, &palette_size, red, green, blue, frames->data, palette->Colors) == GIF_ERROR) {
GifFreeMapObject(palette);
free(frames);
return NULL;
}
frames->width = width;
frames->height = height;
frames->duration = image->delay;
GifColorType *colors = palette->Colors;
Image *cur = image->next;
PixelCache *cache = pixel_cache_new();
unsigned char *p = (unsigned char*)frames;
int ii;
for (ii = 1; ii < count; ii++, cur = cur->next) {
p += frame_size;
Frame *frame = (Frame*)p;
frame->width = width;
frame->height = height;
frame->duration = cur->delay;
GifPixelType *data = frame->data;
if (!aprox_image_pixels(cur, colors, palette_size, cache, data)) {
GifFreeMapObject(palette);
free(frames);
pixel_cache_free(cache);
return NULL;
}
}
pixel_cache_free(cache);
void *ret = gif_save(image, palette, frames, count, frame_size, size);
GifFreeMapObject(palette);
free(frames);
return ret;
}
