processing4/java/examples/Topics/Animation/AnimatedSprite/applet/AnimatedSprite.java

import processing.core.*; 

import java.applet.*; 
import java.awt.*; 
import java.awt.image.*; 
import java.awt.event.*; 
import java.io.*; 
import java.net.*; 
import java.text.*; 
import java.util.*; 
import java.util.zip.*; 
import java.util.regex.*; 

public class AnimatedSprite extends PApplet {

/**
 * Animated Sprite (Shifty + Teddy)
 * by James Patterson. 
 * 
 * Press the mouse button to change animations.
 * Demonstrates loading, displaying, and animating GIF images.
 * It would be easy to write a program to display 
 * animated GIFs, but would not allow as much control over 
 * the display sequence and rate of display. 
 */
 
Animation animation1, animation2;
float xpos, ypos;
float drag = 30.0f;

public void setup() {
  size(200, 200);
  background(255, 204, 0);
  frameRate(24);
  animation1 = new Animation("PT_Shifty_", 38);
  animation2 = new Animation("PT_Teddy_", 60);
}

public void draw() { 
  float difx = mouseX - xpos;
  if (abs(difx) > 1.0f) {
    xpos = xpos + difx/drag;
    xpos = constrain(xpos, 0, width);
  }

  // Display the sprite at the position xpos, ypos
  if (mousePressed) {
    background(153, 153, 0);
    animation1.display(xpos-animation1.getWidth()/2, ypos);
  } else {
    background(255, 204, 0);
    animation2.display(xpos-animation1.getWidth()/2, ypos);
  }
}
// Class for animating a sequence of GIFs

class Animation {
  PImage[] images;
  int imageCount;
  int frame;
  
  Animation(String imagePrefix, int count) {
    imageCount = count;
    images = new PImage[imageCount];

    for (int i = 0; i < imageCount; i++) {
      // Use nf() to number format 'i' into four digits
      String filename = imagePrefix + nf(i, 4) + ".gif";
      images[i] = loadImage(filename);
    }
  }

  public void display(float xpos, float ypos) {
    frame = (frame+1) % imageCount;
    image(images[frame], xpos, ypos);
  }
  
  public int getWidth() {
    return images[0].width;
  }
}

  static public void main(String args[]) {
    PApplet.main(new String[] { "AnimatedSprite" });
  }
}