code: func (f *Fpdf) parsegif(r io.Reader) (info *ImageInfoType) {
  	data, err := bufferFromReader(r)
  	if err != nil {
  		f.err = err
  		return
  	}
  	var img image.Image
  	img, err = gif.Decode(data)
  	if err != nil {
  		f.err = err
  		return
  	}
  	pngBuf := new(bytes.Buffer)
  	err = png.Encode(pngBuf, img)
  	if err != nil {
  		f.err = err
  		return
  	}
  	return f.parsepngstream(pngBuf, false)
  }
docs: // parsegif extracts info from a GIF data (via PNG conversion)