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# File 'ext/lilimg/lilimg.c', line 24
static VALUE jpeg_to_gif(VALUE self, VALUE buf) {
rb_check_type(buf, T_STRING);
int size = RSTRING_LEN(buf);
char * jpeg = StringValuePtr(buf);
unsigned int first, second;
first = jpeg[0];
second = jpeg[1];
if (first != 0xFF || second != 0xD8) {
rb_raise(rb_eRuntimeError, "Not a JPEG image!");
return Qnil;
}
njInit();
if (njDecode(jpeg, size)) {
free((void*)jpeg);
rb_raise(rb_eRuntimeError, "Error decoding input file (size %d)", size);
return Qnil;
}
free((void*)jpeg);
unsigned char * pixels = njGetImage();
if (!pixels) {
rb_raise(rb_eRuntimeError, "Couldn't decode image.");
return Qnil;
}
char * out;
size_t bufsize;
FILE * fp = open_memstream(&out, &bufsize);
// FILE * fp = fopen("output.gif", "wb");
if (!fp) {
rb_raise(rb_eRuntimeError, "Cannot initialize memstream");
return Qnil;
}
unsigned char * rgba = rgb_to_rgba(pixels, njGetWidth(), njGetHeight());
int maxColors = 8;
jo_gif_t gif = jo_gif_start(fp, njGetWidth(), njGetHeight(), 0, maxColors);
jo_gif_frame(&gif, rgba, 0, 0);
jo_gif_end(&gif);
VALUE rstr;
rstr = rb_str_new(out, bufsize);
free(rgba);
free(out);
njDone();
return rstr;
}
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