DisplayScalingTask


1   /*
2    * DisplayScalingTask.java 
3    * 
4    * Created on 9 June 2003, 15:21 
5    */
6   
7   package com.thoughtriver.open.vectorvisuals.task;
8   
9   import com.thoughtriver.open.vectorvisuals.*;
10  
11  /**
12   * This task can be used to make a <CODE>VVDisplay</CODE>'s view of the
13   * vector world scale to a specific amount over a set period of time.
14   * 
15   * @author Brandon Franklin
16   * @version $Date: 2006/11/25 09:15:42 $
17   */
18  public class DisplayScalingTask extends AnimationTask {
19  
20      /** The <CODE>VVDisplay</CODE> that will be scaled by this task */
21      private final VVDisplay target;
22  
23      /** The scale to seek */
24      private final double scale;
25  
26      /** The starting scale of the view */
27      private double startingScale = 0;
28  
29      /**
30       * Creates a new instance of <CODE>DisplayScalingTask</CODE> with the
31       * specified <CODE>VVDisplay</CODE> as its target, and with the supplied
32       * end-scale and duration settings.
33       * 
34       * @param target the <CODE>VVDisplay</CODE> whose view will be scaled by
35       *        this task
36       * @param scale the scale to end up with
37       * @param duration the number of milliseconds over which the task should
38       *        occur
39       */
40      public DisplayScalingTask(final VVDisplay target, final double scale, final int duration) {
41          super(duration);
42          this.target = target;
43          this.scale = scale;
44      }
45  
46      /**
47       * Called just before the first call to <CODE>update</CODE>. In this
48       * case, the method is overridden to grab the current scale of the world
49       * view.
50       */
51      @Override  
52      protected void init() {
53          startingScale = target.getWorldViewScale();
54      }
55  
56      /**
57       * Causes the task to change its state to reflect the amount of progress
58       * reported. The parameter is a double with valid values between 0.0 and
59       * 1.0.
60       * 
61       * @param progress the amount of progress this <CODE>AnimationTask</CODE>
62       *        should be changed to reflect
63       */
64      @Override  
65      protected void update(final double progress) {
66          double scaleDiff = scale - startingScale;
67          target.setWorldViewScale((scaleDiff * progress) + startingScale);
68      }
69  
70  }
71
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