Swing/Crossfade のバックアップの現在との差分(No.1)

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class Crossfade extends JComponent implements ActionListener {
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  private final javax.swing.Timer animator;
  private final ImageIcon icon1;
  private final ImageIcon icon2;
  private int alpha = 10;
  private boolean direction = true;

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#screenshot
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  public Crossfade(ImageIcon icon1, ImageIcon icon2) {
    this.icon1 = icon1;
    this.icon2 = icon2;
    animator = new javax.swing.Timer(50, this);
  }

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**サンプルコード [#s306a237]
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 class Crossfade extends JComponent implements ActionListener {
   private final javax.swing.Timer animator;
   private final ImageIcon icon1;
   private final ImageIcon icon2;
   private int alpha = 10;
   private boolean mode = true;
   public Crossfade(ImageIcon icon1, ImageIcon icon2) {
     this.icon1 = icon1;
     this.icon2 = icon2;
     animator = new javax.swing.Timer(50, this);
   }
   public void animationStart() {
     mode = !mode;
     animator.start();
   }
   public void paintComponent(Graphics g) {
     Graphics2D g2d = (Graphics2D)g;
     g2d.setColor(getBackground());
     g2d.fillRect(0, 0, getWidth(), getHeight());
     g2d.drawImage(icon1.getImage(), 0, 0,
       (int)icon1.getIconWidth(), (int)icon1.getIconHeight(), this);
     g2d.setComposite(makeAlphaComposite());
     g2d.drawImage(icon2.getImage(), 0, 0,
       (int)icon2.getIconWidth(), (int)icon2.getIconHeight(), this);
   }
   private AlphaComposite makeAlphaComposite() {
     if(mode && alpha<10) {
       alpha = alpha + 1;
     }else if(!mode && alpha>0) {
       alpha = alpha - 1;
     }else{
       animator.stop();
     }
     return AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha*0.1f);
   }
   public void actionPerformed(ActionEvent e) {
     repaint();
   }
 }
  public void animationStart() {
    direction = !direction;
    animator.start();
  }

-&jnlp;
-&jar;
-&zip;
  @Override protected void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setPaint(getBackground());
    g2.fillRect(0, 0, getWidth(), getHeight());
    if (direction && alpha < 10) {
      alpha = alpha + 1;
    } else if (!direction && alpha > 0) {
      alpha = alpha - 1;
    } else {
      animator.stop();
    }
    g2.setComposite(AlphaComposite.getInstance(
        AlphaComposite.SRC_OVER, 1f - alpha * .1f));
    g2.drawImage(icon1.getImage(), 0, 0,
        (int) icon1.getIconWidth(), (int) icon1.getIconHeight(), this);
    g2.setComposite(AlphaComposite.getInstance(
        AlphaComposite.SRC_OVER, alpha * .1f));
    g2.drawImage(icon2.getImage(), 0, 0,
        (int) icon2.getIconWidth(), (int) icon2.getIconHeight(), this);
    g2.dispose();
  }

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**解説 [#lc4f6171]
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上記のサンプルでは、二枚目の画像の描画に使用するAlphaCompositeを変化させて上書きすることで、画像が切り替わるようにしています。また、この上書きの規則には、AlphaComposite.SRC_OVERを使っています。
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  @Override public void actionPerformed(ActionEvent e) {
    repaint();
  }
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}
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