Module: Lilimg

Defined in:
lib/lilimg.rb,
ext/lilimg/lilimg.c

Class Method Summary collapse

Class Method Details

.jpeg_to_gif(buf, max_colors) ⇒ Object 



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# File 'ext/lilimg/lilimg.c', line 24

static VALUE jpeg_to_gif(VALUE self, VALUE buf, VALUE max_colors) {
  rb_check_type(buf, T_STRING);

  int maxColors = INT2NUM(max_colors);
  int size = RSTRING_LEN(buf);
  unsigned char * jpeg = (unsigned char *)StringValuePtr(buf);

  if (jpeg[0] != 0xFF || jpeg[1] != 0xD8) {
    rb_raise(rb_eRuntimeError, "Not a JPEG image (%x %x should be FF D8)!", jpeg[0], jpeg[1]);
    return Qnil;
  }

  njInit();

  if (njDecode(jpeg, size)) {
    free(jpeg);
    rb_raise(rb_eRuntimeError, "Error decoding input file (size %d)", size);
    return Qnil;
  }

  unsigned char * pixels = njGetImage();
  if (!pixels) {
    free(jpeg);
    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) {
    free(jpeg);
    rb_raise(rb_eRuntimeError, "Cannot initialize memstream");
    return Qnil;
  }

  unsigned char * rgba = rgb_to_rgba(pixels, njGetWidth(), njGetHeight());
  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 = rb_str_new(out, bufsize);

  // free(jpeg); <-- this will cause all sorts of errors (FIXME)
  free(rgba);
  free(out);
  njDone();

  return rstr;
}

.png_to_gif(buf, max_colors) ⇒ Object 



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# File 'ext/lilimg/lilimg.c', line 77

static VALUE png_to_gif(VALUE self, VALUE buf, VALUE max_colors) {

  rb_check_type(buf, T_STRING);

  int maxColors = INT2NUM(max_colors);
  int size = RSTRING_LEN(buf);
  unsigned char * png = (unsigned char *)StringValuePtr(buf);

  unsigned char png_header[] = {137, 80, 78, 71, 13, 10, 26, 10};
  if (memcmp(png, png_header, 8) != 0) {
    rb_raise(rb_eRuntimeError, "Not a PNG image!");
    return Qnil;
  }

  char * out;
  size_t bufsize;
  FILE * fp = open_memstream(&out, &bufsize);

  if (!fp) {
    free(png);
    rb_raise(rb_eRuntimeError, "Cannot initialize memstream");
    return Qnil;
  }

  unsigned err, w, h;
  LodePNGState state;
  lodepng_state_init(&state);
  unsigned char * rgba;

  err = lodepng_decode(&rgba, &w, &h, &state, png, size);
  if (err) {
    lodepng_state_cleanup(&state);
    free(png);
    free(out); // memstream
    rb_raise(rb_eRuntimeError, "Unable to decode PNG, error code %u\n", err);
    return Qnil;
  }

  // convert rgba data to memstream (fp)
  jo_gif_t gif = jo_gif_start(fp, w, h, 0, maxColors);
  jo_gif_frame(&gif, rgba, 0, 0);
  jo_gif_end(&gif);

  VALUE rstr = rb_str_new(out, bufsize);

  free(rgba); // rgba raw data
  free(png); // png buffer, converted from buf VALUE
  free(out); // memstream
  lodepng_state_cleanup(&state);

  return rstr;
}