public int getNumFrames() {
        return frameCount;
    }
A header object containing the number of frames in an animated GIF image as well as basic metadata like width and
height that can be used to decode each individual frame of the GIF. Can be shared by one or more
{@link GifDecoder}s to play the same animated GIF in multiple views.
core/src/main/java/com/bumptech/glide/gifdecoder/GifHeader.java