Animator


1   /*
2    * Copyright (c) 2001-2004 JGoodies Karsten Lentzsch. All Rights Reserved.
3    *
4    * Redistribution and use in source and binary forms, with or without 
5    * modification, are permitted provided that the following conditions are met:
6    * 
7    *  o Redistributions of source code must retain the above copyright notice, 
8    *    this list of conditions and the following disclaimer. 
9    *     
10   *  o Redistributions in binary form must reproduce the above copyright notice, 
11   *    this list of conditions and the following disclaimer in the documentation 
12   *    and/or other materials provided with the distribution. 
13   *     
14   *  o Neither the name of JGoodies Karsten Lentzsch nor the names of 
15   *    its contributors may be used to endorse or promote products derived 
16   *    from this software without specific prior written permission. 
17   *     
18   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
19   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 
20   * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
21   * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
22   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
23   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
24   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
25   * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
26   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
27   * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 
28   * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
29   */
30  
31  package com.jgoodies.animation;
32  
33  import java.awt.event.ActionEvent  ;
34  import java.awt.event.ActionListener  ;
35  
36  import javax.swing.Timer  ;
37  
38  /**
39   * Starts and stops an animation and triggers
40   * the animation at a given frame rate.
41   *
42   * @author  Karsten Lentzsch
43   * @version $Revision: 1.3 $
44   */
45  public final class Animator implements ActionListener   {
46  
47      private final Animation animation;
48      private final Timer       timer;
49      private final int       framesPerSecond;
50  
51      private long startTime;
52      private long elapsedTime  = 0;
53  
54      
55      // Instance Creation *****************************************************
56      
57      /**
58       * Constructs an <code>Animator</code> for the given animation and 
59       * frame rate.
60       * 
61       * @param animation         the animation to animate
62       * @param framesPerSecond   the desired frame rate
63       * @throws NullPointerException if the animation is <code>null</code>
64       * @throws IllegalArgumentException if the frame rate is non-positive
65       */
66      public Animator(Animation animation, int framesPerSecond) {
67          if (animation == null)
68              throw new NullPointerException  ("The animation must not be null.");
69  
70          if (framesPerSecond <= 0)
71              throw new IllegalArgumentException  ("The frame rate must be positive.");
72  
73          this.animation = animation;
74          this.framesPerSecond = framesPerSecond;
75          this.timer = createTimer(framesPerSecond);
76      }
77      
78      
79      // ************************************************************************
80  
81      /**
82       * Returns the animator's animation.
83       * 
84       * @return the animator's animation 
85       */
86      public Animation animation() {
87          return animation;
88      }
89      
90  
91      /**
92       * Returns the desired frame rate.
93       * 
94       * @return the desired frame rate per second
95       */
96      public int framesPerSecond() {
97          return framesPerSecond;
98      }
99      
100 
101     /**
102      * Returns the elapsed time since animation start.
103      * 
104      * @return time elapsed since the animation start
105      */
106     public long elapsedTime() {
107         return timer.isRunning()
108             ? System.currentTimeMillis() - startTime + elapsedTime
109             : elapsedTime;
110     }
111     
112 
113     /**
114      * Starts the animator and in turn the animation.
115      */
116     public void start() {
117         if (!timer.isRunning()) {
118             registerStopListener();
119             startTime = System.currentTimeMillis();
120             timer.start();
121         } /*else {
122                 System.out.println("Animator is already running");
123                 } */
124     }
125     
126 
127     /**
128      * Stops the animator.
129      */
130     public void stop() {
131         if (timer.isRunning()) {
132             elapsedTime = elapsedTime();
133             timer.stop();
134         }
135     }
136 
137 
138     /**
139      * Implements the ActionListener interface for use by 
140      * the <code>Timer</code>.
141      * 
142      * @param e  the action event
143      */
144     public void actionPerformed(ActionEvent   e) {
145         animation.animate(elapsedTime());
146     }
147     
148 
149     /**
150      * Returns a string representation for the animator.
151      * 
152      * @return a string representation for the animator
153      */
154     public String   toString() {
155         return "elapsedTime=" + elapsedTime() + "; fps=" + framesPerSecond;
156     }
157     
158     
159     // Helper Code ************************************************************
160     
161     /**
162      * Creates and configures a <code>Timer</code> object.
163      * 
164      * @param fps    the frames per second
165      * @return a <code>Timer</code> with the specified frame rate
166      */
167     private Timer   createTimer(int fps) {
168         int delay = 1000 / fps;
169 
170         Timer   aTimer = new Timer  (delay, this);
171         aTimer.setInitialDelay(0);
172         aTimer.setCoalesce(true);
173         return aTimer;
174     }
175 
176     
177     /**
178      * Registers a listener that stops the animator if the animation stopped.
179      */
180     private void registerStopListener() {
181         animation.addAnimationListener(new AnimationAdapter() {
182             public void animationStopped(AnimationEvent e) {
183                 //System.out.println("All animations stopped.");
184                 stop();
185                 //animation.animate(animation.duration());
186             }
187         });
188     }
189     
190     
191 }
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