PImage[] animation;

int i = 0;

void setup() {
  String gifPath = "animated.gif";
  animation = AniGifLoader.getFramesFrom(openStream(gifPath));
}

void draw() {
  background(255);
  image(animation[i], 0, 0);
  i = (i + 1) % animation.length;
} 

public static class AniGifLoader {
  
  public static PImage[] getFramesFrom(java.io.InputStream s) {
    
    try {
	
	javax.imageio.stream.ImageInputStream stream = javax.imageio.ImageIO.createImageInputStream(s);
	java.util.Iterator readers = javax.imageio.ImageIO.getImageReaders(stream);
	if (!readers.hasNext()) throw new RuntimeException("no image reader found");
	javax.imageio.ImageReader reader = (javax.imageio.ImageReader) readers.next();
	reader.setInput(stream);
	
	int n = reader.getNumImages(true);
	PImage[] frames = new PImage[n];
	
	for (int i = 0; i < n; i++) {
	  java.awt.image.BufferedImage image = reader.read(i);
	  frames[i] = new PImage(image);
	}
	
	stream.close();
	return frames;
	
    } catch (Exception e) {
	  e.printStackTrace();
	return null;
    }
    
  }
  
}