Swing/AccordionPanel のバックアップの現在との差分(No.6)

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abstract class AbstractExpansionPanel extends JPanel {
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  private final String title;
  private final JLabel label;
  private final JPanel panel;
  public abstract JPanel makePanel();
  public AbstractExpansionPanel(String title) {
    super(new BorderLayout());
    this.title = title;
    label = new JLabel("\u25BC " + title) {
      @Override protected void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D) g.create();
        // Insets ins = getInsets();
        g2.setPaint(new GradientPaint(
            50, 0, Color.WHITE, getWidth(), getHeight(),
            new Color(200, 200, 255)));
        g2.fillRect(0, 0, getWidth(), getHeight());
        g2.dispose();
        super.paintComponent(g);
      }
    };
    label.addMouseListener(new MouseAdapter() {
      @Override public void mousePressed(MouseEvent e) {
        initPanel();
      }
    });
    label.setForeground(Color.BLUE);
    label.setBorder(BorderFactory.createEmptyBorder(2, 5, 2, 2));
    add(label, BorderLayout.NORTH);
    panel = makePanel();
    panel.setVisible(false);
    panel.setOpaque(true);
    panel.setBackground(new Color(240, 240, 255));
    Border outBorder = BorderFactory.createMatteBorder(0, 2, 2, 2, Color.WHITE);
    Border inBorder = BorderFactory.createEmptyBorder(10, 10, 10, 10);
    Border border = BorderFactory.createCompoundBorder(outBorder, inBorder);
    panel.setBorder(border);
    add(panel);
  }

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**サンプルコード [#l8c5ce79]
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 public ExpansionPanel(String title_) {
   title = title_;
   label = new JLabel("↓ "+title) {
     protected void paintComponent(Graphics g) {
       Graphics2D g2 = (Graphics2D)g;
       Insets ins = getInsets();
       g2.setPaint(new GradientPaint(50, 0, Color.white,
                   getWidth(), getHeight(), new Color(200,200,255)));
       g2.fillRect(0, 0, getWidth(), getHeight());
       super.paintComponent(g);
     }
   };
   label.addMouseListener(new MouseAdapter() {
     public void mousePressed(MouseEvent evt) {
       openFlag = !openFlag;
       initPanel();
       fireExpansionEvent();
     }
   });
   label.setForeground(Color.blue);
   label.setBorder(BorderFactory.createEmptyBorder(2,5,2,2));
   panel = makePanel();
   panel.setOpaque(true);
   Border outBorder = BorderFactory.createMatteBorder(0,2,2,2,Color.white);
   Border inBorder  = BorderFactory.createEmptyBorder(10,10,10,10);
   Border border    = BorderFactory.createCompoundBorder(outBorder, inBorder);
   panel.setBorder(border);
   panel.setBackground(new Color(240, 240, 255));
   setLayout(new BorderLayout());
   add(label, BorderLayout.NORTH);
 }
  @Override public Dimension getPreferredSize() {
    Dimension d = label.getPreferredSize();
    if (panel.isVisible()) {
      d.height += panel.getPreferredSize().height;
    }
    return d;
  }

-[[サンプルを起動>http://terai.xrea.jp/swing/accordionpanel/sample.jnlp]]
-[[jarファイル>http://terai.xrea.jp/swing/accordionpanel/sample.jar]]
-[[ソース>http://terai.xrea.jp/swing/accordionpanel/src.zip]]
  @Override public Dimension getMaximumSize() {
    Dimension d = getPreferredSize();
    d.width = Short.MAX_VALUE;
    return d;
  }

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**解説 [#vc8a1e60]
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各パネルはラベルが押されるたびに自身の展開や折りたたみを行い、高さが変更されます。このとき、SpringLayoutを使って全体のレイアウトをやり直しているため、JScrollPaneの中で複数のパネルが開けるようになっています。
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  protected void initPanel() {
    panel.setVisible(!panel.isVisible());
    label.setText(String.format(
        "%s %s", panel.isVisible() ? "\u25B3" : "\u25BC", title));
    revalidate();
    // fireExpansionEvent();
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        panel.scrollRectToVisible(panel.getBounds());
      }
    });
  }
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}
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