/*
 * Animation.java
 *
 * Copyright 1998 John Wiseman
 */



/**
  An object that implements the Animator interface can render a "frame" of animation
  specified by an AnimationState.
 */	
  	
interface Animator {
	/** Renders the frame of the animation specified by AnimationState state. */
	public void animate(AnimationState state);
}


/**
  An object that implements the AnimationState interface represents the state the specifies
  a single "frame" of an animation.
 */ 
 
interface AnimationState {
	/** Returns a new AnimationState that is smoothly interpolated between start and end
	    according to the parameter t, which ranges between 0 and 1. */  
	public AnimationState interpolate(AnimationState start, AnimationState end, double t);
}


/** Smoothly drives synchronous and asynchronous animations. */

class AnimationTimer implements Runnable {
	/** The animator. */
	protected Animator animator;
	/** The number of frames per second. */
	public int FPS = 10;
	protected boolean complete = true;


	protected AnimationState start;
	protected AnimationState end;
	protected int duration;

	
	public AnimationTimer(Animator animator) {
		this.animator = animator;
	}
	

	public boolean isComplete() {
		return complete;
	}
		

	/** Performs a smooth synchronous animation beginning with AnimationState start and
	    finishing with end. */
	public void doSyncAnimation(AnimationState start, AnimationState end, int duration) {
		this.start = start;
		this.end = end;
		this.duration = duration;
		doAnimation();
	}


	/** Spawns a new thread and performs a smooth asynchronous animation beginning with
	    AnimationState start and finishing with end. */
	public void doAsyncAnimation(AnimationState start, AnimationState end, int duration) {
		this.start = start;
		this.end = end;
		this.duration = duration;
	
		complete = false;
		(new Thread(this)).start();
	}


	private void doAnimation() {
		// Calculate the required delay between frames to achieve the desired FPS.
		// Makes the simplifying assumption that the time to actually render a frame is 0.
		int frame_delay = 1000 / FPS;
		double dt = ((double) frame_delay) / duration;
		AnimationState current;
		double t;

		// Loop t from 0 to 1.
		for (t = 0.0; t < 1.0; t = t + dt) {
			current = start.interpolate(start, end, t);
			animator.animate(current);
			try {
				Thread.sleep(frame_delay);
			}
			catch (InterruptedException e) {
			}
		}
	}	
	
	public void run() {
		doAnimation();
		complete = true;
	}
}