colorcomboboxeditor.java

The Definitive Guide to Java Swing, Third Edition by John Zukowski (Author) 源码

import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
public class ColorComboBoxEditor implements ComboBoxEditor {
  final protected JButton editor;
  protected EventListenerList listenerList = new EventListenerList();
  public ColorComboBoxEditor(Color initialColor) {
    editor = new JButton("");
    editor.setBackground(initialColor);
    ActionListener actionListener = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        Color currentBackground = editor.getBackground();
        Color color = JColorChooser.showDialog(
          editor, "Color Chooser", currentBackground);
        if ((color != null) && (currentBackground != color)) {
          editor.setBackground(color);
          fireActionEvent(color);
        }
      }
    } ;
    editor.addActionListener(actionListener);
  }
  public void addActionListener(ActionListener l) {
    listenerList.add(ActionListener.class, l);
  }
  public Component getEditorComponent() {
    return editor;
  }
  public Object getItem() {
    return editor.getBackground();
  }
  public void removeActionListener(ActionListener l) {
    listenerList.remove(ActionListener.class, l);
  }
  public void selectAll() {
    // ignore
  }
  public void setItem(Object newValue) {
    if (newValue instanceof Color) {
      Color color = (Color)newValue;
      editor.setBackground(color);
    }  else {
      // Try to decode
      try {
        Color color = Color.decode(newValue.toString());
        editor.setBackground(color);
      }  catch (NumberFormatException e) {
        // ignore - value unchanged
      }
    }
  }
  protected void fireActionEvent(Color color) {
    Object listeners[] = listenerList.getListenerList();
    for (int i = listeners.length-2; i>=0; i-=2) {
      if (listeners[i] == ActionListener.class) {
        ActionEvent actionEvent =
          new ActionEvent(editor, ActionEvent.ACTION_PERFORMED,
            color.toString());
        ((ActionListener)listeners[i+1]).actionPerformed(actionEvent);
      }
    }
  }
}