jtogglebuttonmenuitem.java

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

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

public class JToggleButtonMenuItem extends JToggleButton implements MenuElement {
  Color savedForeground = null;
  private static MenuElement NO_SUB_ELEMENTS[] = new MenuElement[0];
  public JToggleButtonMenuItem() {
    init();
  }
  public JToggleButtonMenuItem(String label) {
    super(label);
    init();
  }
  public JToggleButtonMenuItem(String label, Icon icon) {
    super(label, icon);
    init();
  }
  public JToggleButtonMenuItem(Action action) {
    super(action);
    init();
  }
  private void init() {
    updateUI();
    setRequestFocusEnabled(false);
    // Borrows heavily from BasicMenuUI
    MouseInputListener mouseInputListener = new MouseInputListener() {
      // If mouse released over this menu item, activate it
      public void mouseReleased(MouseEvent mouseEvent) {
        MenuSelectionManager menuSelectionManager = 
          MenuSelectionManager.defaultManager();
        Point point = mouseEvent.getPoint();
        if ((point.x >= 0) && 
            (point.x < getWidth()) && 
            (point.y >= 0) && 
            (point.y < getHeight())) {
          menuSelectionManager.clearSelectedPath();
          // component automatically handles "selection" at this point
          // doClick(0); // not necessary
        } else {
          menuSelectionManager.processMouseEvent(mouseEvent);
        }
      }
      // If mouse moves over menu item, add to selection path, so it becomes armed
      public void mouseEntered(MouseEvent mouseEvent) {
        MenuSelectionManager menuSelectionManager = MenuSelectionManager.defaultManager();
        menuSelectionManager.setSelectedPath(getPath());
      }
      // When mouse moves away from menu item, disarm it and select something else
      public void mouseExited(MouseEvent mouseEvent) {
        MenuSelectionManager menuSelectionManager = 
          MenuSelectionManager.defaultManager();
        MenuElement path[] = menuSelectionManager.getSelectedPath();
        if (path.length > 1) {
          MenuElement newPath[] = new MenuElement[path.length-1];
          for(int i=0, c=path.length-1; i<c; i++) {
            newPath[i] = path[i];
          }
          menuSelectionManager.setSelectedPath(newPath);
        }
      }
      // Pass along drag events
      public void mouseDragged(MouseEvent mouseEvent) {
        MenuSelectionManager.defaultManager().processMouseEvent(mouseEvent);
      }
      public void mouseClicked(MouseEvent mouseEvent) {
      }
      public void mousePressed(MouseEvent mouseEvent) {
      }
      public void mouseMoved(MouseEvent mouseEvent) {
      }
    };
    addMouseListener(mouseInputListener);
    addMouseMotionListener(mouseInputListener);
  }

  // MenuElement methods
  public Component getComponent() {
    return this;
  }

  public MenuElement[] getSubElements() {
    // no subelements
    return NO_SUB_ELEMENTS;
  }

  public void menuSelectionChanged(boolean isIncluded) {
    ButtonModel model = getModel();
    // only change armed state if different
    if(model.isArmed() != isIncluded) {
      model.setArmed(isIncluded);
    }

    if (isIncluded) {
      savedForeground = getForeground();
      if (!savedForeground.equals(Color.BLUE)) {
        setForeground(Color.BLUE);
      } else {
        // In case foreground blue, use something different
        setForeground(Color.RED);
      }
    } else {
      setForeground(savedForeground);
      // if null, get foreground from installed look and feel
      if (savedForeground == null) {
        updateUI();
      }
    }
  }

  public void processKeyEvent(KeyEvent keyEvent, 
                              MenuElement path[], 
                              MenuSelectionManager manager) {
    // If user presses space while menu item armed, select it
    if (getModel().isArmed()) {
      int keyChar = keyEvent.getKeyChar();
      if (keyChar == KeyEvent.VK_SPACE) {
        manager.clearSelectedPath();
        doClick(0); // inherited from AbstractButton
      }
    }
  }
  public void processMouseEvent(MouseEvent mouseEvent, MenuElement path[], MenuSelectionManager manager) {
    // For when mouse dragged over menu and button released
    if (mouseEvent.getID() == MouseEvent.MOUSE_RELEASED) {
      manager.clearSelectedPath();
      doClick(0); // inherited from AbstractButton
    }
  }

  // Borrows heavily from BasicMenuItemUI.getPath()
  private MenuElement[] getPath() {
    MenuSelectionManager menuSelectionManager = 
      MenuSelectionManager.defaultManager();
    MenuElement oldPath[] = menuSelectionManager.getSelectedPath();
    MenuElement newPath[];
    int oldPathLength = oldPath.length;
    if (oldPathLength == 0)
      return new MenuElement[0];
    Component parent = getParent();
    if (oldPath[oldPathLength-1].getComponent() == parent) {
      // Going deeper under the parent menu
      newPath = new MenuElement[oldPathLength+1];
      System.arraycopy(oldPath, 0, newPath, 0, oldPathLength);
      newPath[oldPathLength] = this;
     } else {
       // Sibling/child menu item currently selected
       int newPathPosition;
       for (newPathPosition = oldPath.length-1; newPathPosition >= 0; newPathPosition--) {
         if (oldPath[newPathPosition].getComponent() == parent) {
           break;
         }
       }
       newPath = new MenuElement[newPathPosition+2];
       System.arraycopy(oldPath, 0, newPath, 0, newPathPosition+1);
       newPath[newPathPosition+1] = this;
     }
     return newPath;
   }
}