combomenubar.java

自制java的swing组件

/* (swing1.1.1beta2) */
package zb.swing;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

import zb.swing.icons.*;

/**
 * @version 1.0 05/10/99
 */
public class ComboMenuBar
    extends JMenuBar {

  JMenu menu;
  Dimension preferredSize;

  public ComboMenuBar(JMenu menu) {
    this.menu = menu;

    Color color = UIManager.getColor("Menu.selectionBackground");
    UIManager.put("Menu.selectionBackground",
                  UIManager.getColor("Menu.background"));
    menu.updateUI();
    UIManager.put("Menu.selectionBackground", color);

    MenuItemListener listener = new MenuItemListener();
    setListener(menu, listener);

    add(menu);
  }

  class MenuItemListener
      implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      JMenuItem item = (JMenuItem) e.getSource();
      menu.setText(item.getText());
      menu.requestFocus();
    }
  }

  private void setListener(JMenuItem item, ActionListener listener) {
    if (item instanceof JMenu) {
      JMenu menu = (JMenu) item;
      int n = menu.getItemCount();
      for (int i = 0; i < n; i++) {
        setListener(menu.getItem(i), listener);
      }
    }
    else if (item != null) { // null means separator
      item.addActionListener(listener);
    }
  }

  public String getSelectedItem() {
    return menu.getText();
  }

  public void setPreferredSize(Dimension size) {
    preferredSize = size;
  }

  public Dimension getPreferredSize() {
    if (preferredSize == null) {
      Dimension sd = super.getPreferredSize();
      Dimension menuD = getItemSize(menu);
      Insets margin = menu.getMargin();
      Dimension retD = new Dimension(menuD.width,
                                     margin.top + margin.bottom + menuD.height);
      menu.setPreferredSize(retD);
      preferredSize = retD;
    }
    return preferredSize;
  }

  private Dimension getItemSize(JMenu menu) {
    Dimension d = new Dimension(0, 0);
    int n = menu.getItemCount();
    for (int i = 0; i < n; i++) {
      Dimension itemD;
      JMenuItem item = menu.getItem(i);
      if (item instanceof JMenu) {
        itemD = getItemSize( (JMenu) item);
      }
      else if (item != null) {
        itemD = item.getPreferredSize();
      }
      else {
        itemD = new Dimension(0, 0); // separator
      }
      d.width = Math.max(d.width, itemD.width);
      d.height = Math.max(d.height, itemD.height);
    }
    return d;
  }

  public static class ComboMenu
      extends JMenu {
    ArrowIcon iconRenderer;

    public ComboMenu(String label) {
      super(label);
      iconRenderer = new ArrowIcon(SwingConstants.SOUTH, true);
      setBorder(new EtchedBorder());
      setIcon(new BlankIcon(null, 11));
      setHorizontalTextPosition(JButton.LEFT);
      setFocusPainted(true);
    }

    public void paintComponent(Graphics g) {
      super.paintComponent(g);
      Dimension d = this.getPreferredSize();
      int x = Math.max(0, d.width - iconRenderer.getIconWidth() - 3);
      int y = Math.max(0, (d.height - iconRenderer.getIconHeight()) / 2 - 2);
      iconRenderer.paintIcon(this, g, x, y);
    }
  }

  public static JMenu createMenu(String label) {
    return new ComboMenu(label);
  }

}