basicmenuitemui.java

gcc的组建

    acceleratorSelectionForeground = null;
    arrowIcon = null;
    selectionBackground = null;
    selectionForeground = null;
    acceleratorDelimiter = null;
  }

  /**
   * Uninstalls any keyboard actions.
   */
  protected void uninstallKeyboardActions()
  {   
    SwingUtilities.replaceUIInputMap(menuItem,
                                     JComponent.WHEN_IN_FOCUSED_WINDOW, null);
  }

  /**
   * Unregisters all the listeners that this UI delegate was using.
   */
  protected void uninstallListeners()
  {
    menuItem.removeMouseListener(mouseInputListener);
    menuItem.removeMenuDragMouseListener(menuDragMouseListener);
    menuItem.removeMenuKeyListener(menuKeyListener);
    menuItem.removeItemListener(itemListener);
    menuItem.removePropertyChangeListener(propertyChangeListener);
  }

  /**
   * Performs the opposite of installUI. Any properties or resources that need
   * to be cleaned up will be done now. It will also uninstall any listeners it
   * has. In addition, any properties of this UI will be nulled.
   * 
   * @param c
   *          The {@link JComponent} that is having this UI uninstalled.
   */
  public void uninstallUI(JComponent c)
  {
    uninstallListeners();
    uninstallDefaults();
    uninstallComponents(menuItem);
    menuItem = null;
  }

  /**
   * This method calls paint.
   * 
   * @param g
   *          The graphics context used to paint this menu item
   * @param c
   *          The menu item to paint
   */
  public void update(Graphics g, JComponent c)
  {
    paint(g, c);
  }

  /**
   * Return text representation of the specified accelerator
   * 
   * @param accelerator
   *          Accelerator for which to return string representation
   * @return $String$ Text representation of the given accelerator
   */
  private String getAcceleratorText(KeyStroke accelerator)
  {
    // convert keystroke into string format
    String modifiersText = "";
    int modifiers = accelerator.getModifiers();
    char keyChar = accelerator.getKeyChar();
    int keyCode = accelerator.getKeyCode();

    if (modifiers != 0)
      modifiersText = KeyEvent.getKeyModifiersText(modifiers)
                      + acceleratorDelimiter;

    if (keyCode == KeyEvent.VK_UNDEFINED)
      return modifiersText + keyChar;
    else
      return modifiersText + KeyEvent.getKeyText(keyCode);
  }

  /**
   * Calculates and return rectange in which accelerator should be displayed
   * 
   * @param accelerator
   *          accelerator for which to return the display rectangle
   * @param fm
   *          The font metrics used to measure the text
   * @return $Rectangle$ reactangle which will be used to display accelerator
   */
  private Rectangle getAcceleratorRect(KeyStroke accelerator, FontMetrics fm)
  {
    int width = fm.stringWidth(getAcceleratorText(accelerator));
    int height = fm.getHeight();
    return new Rectangle(0, 0, width, height);
  }

  /**
   * Paints accelerator inside menu item
   * 
   * @param g
   *          The graphics context used to paint the border
   * @param menuItem
   *          Menu item for which to draw accelerator
   * @param acceleratorRect
   *          rectangle representing position of the accelerator relative to the
   *          menu item
   * @param acceleratorText
   *          accelerator's text
   */
  private void paintAccelerator(Graphics g, JMenuItem menuItem,
                                Rectangle acceleratorRect,
                                String acceleratorText)
  {
    g.setFont(acceleratorFont);
    FontMetrics fm = g.getFontMetrics(acceleratorFont);

    if (menuItem.isEnabled())
      g.setColor(acceleratorForeground);
    else
      // FIXME: should fix this to use 'disabledForeground', but its
      // default value in BasicLookAndFeel is null.
      g.setColor(Color.gray);

    BasicGraphicsUtils.drawString(g, acceleratorText, 0, acceleratorRect.x,
                                  acceleratorRect.y + fm.getAscent());
  }

  /**
   * This class handles mouse events occuring inside the menu item. Most of the
   * events are forwarded for processing to MenuSelectionManager of the current
   * menu hierarchy.
   */
  protected class MouseInputHandler implements MouseInputListener
  {
    /**
     * Creates a new MouseInputHandler object.
     */
    protected MouseInputHandler()
    {
      // Nothing to do here.
    }

    /**
     * This method is called when mouse is clicked on the menu item. It forwards
     * this event to MenuSelectionManager.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mouseClicked(MouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.processMouseEvent(e);
    }

    /**
     * This method is called when mouse is dragged inside the menu item. It
     * forwards this event to MenuSelectionManager.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mouseDragged(MouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.processMouseEvent(e);
    }

    /**
     * This method is called when mouse enters menu item. When this happens menu
     * item is considered to be selected and selection path in
     * MenuSelectionManager is set. This event is also forwarded to
     * MenuSelection Manager for further processing.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mouseEntered(MouseEvent e)
    {
      Component source = (Component) e.getSource();
      if (source.getParent() instanceof MenuElement)
        {
          MenuSelectionManager manager = MenuSelectionManager.defaultManager();
          manager.setSelectedPath(getPath());
          manager.processMouseEvent(e);
        }
    }

    /**
     * This method is called when mouse exits menu item. The event is forwarded
     * to MenuSelectionManager for processing.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mouseExited(MouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.processMouseEvent(e);
    }

    /**
     * This method is called when mouse is inside the menu item. This event is
     * forwarder to MenuSelectionManager for further processing.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mouseMoved(MouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.processMouseEvent(e);
    }

    /**
     * This method is called when mouse is pressed. This event is forwarded to
     * MenuSelectionManager for further processing.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mousePressed(MouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.processMouseEvent(e);
    }

    /**
     * This method is called when mouse is released. If the mouse is released
     * inside this menuItem, then this menu item is considered to be chosen and
     * the menu hierarchy should be closed.
     * 
     * @param e
     *          A {@link MouseEvent}.
     */
    public void mouseReleased(MouseEvent e)
    {
      Rectangle size = menuItem.getBounds();
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      if (e.getX() > 0 && e.getX() < size.width && e.getY() > 0
          && e.getY() < size.height)
        {
          manager.clearSelectedPath();
          menuItem.doClick();
        }

      else
        manager.processMouseEvent(e);
    }
  }

  /**
   * This class handles mouse dragged events.
   */
  private class MenuDragMouseHandler implements MenuDragMouseListener
  {
    /**
     * Tbis method is invoked when mouse is dragged over the menu item.
     * 
     * @param e
     *          The MenuDragMouseEvent
     */
    public void menuDragMouseDragged(MenuDragMouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.setSelectedPath(e.getPath());
    }

    /**
     * Tbis method is invoked when mouse enters the menu item while it is being
     * dragged.
     * 
     * @param e
     *          The MenuDragMouseEvent
     */
    public void menuDragMouseEntered(MenuDragMouseEvent e)
    {
      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.setSelectedPath(e.getPath());
    }

    /**
     * Tbis method is invoked when mouse exits the menu item while it is being
     * dragged
     * 
     * @param e the MenuDragMouseEvent
     */
    public void menuDragMouseExited(MenuDragMouseEvent e)
    {
      // TODO: What should be done here, if anything?
    }

    /**
     * Tbis method is invoked when mouse was dragged and released inside the
     * menu item.
     * 
     * @param e
     *          The MenuDragMouseEvent
     */
    public void menuDragMouseReleased(MenuDragMouseEvent e)
    {
      MenuElement[] path = e.getPath();

      if (path[path.length - 1] instanceof JMenuItem)
        ((JMenuItem) path[path.length - 1]).doClick();

      MenuSelectionManager manager = MenuSelectionManager.defaultManager();
      manager.clearSelectedPath();
    }
  }

  /**
   * This class handles key events occuring when menu item is visible on the
   * screen.
   */
  private class MenuKeyHandler implements MenuKeyListener
  {
    /**
     * This method is invoked when key has been pressed
     * 
     * @param e
     *          A {@link MenuKeyEvent}.
     */
    public void menuKeyPressed(MenuKeyEvent e)
    {
      // TODO: What should be done here, if anything?
    }

    /**
     * This method is invoked when key has been pressed
     * 
     * @param e
     *          A {@link MenuKeyEvent}.
     */
    public void menuKeyReleased(MenuKeyEvent e)
    {
      // TODO: What should be done here, if anything?
    }

    /**
     * This method is invoked when key has been typed It handles the mnemonic
     * key for the menu item.
     * 
     * @param e
     *          A {@link MenuKeyEvent}.
     */
    public void menuKeyTyped(MenuKeyEvent e)
    {
      // TODO: What should be done here, if anything?
    }
  }
  
  /**
   * Helper class that listens for item changes to the properties of the {@link
   * JMenuItem}.
   */
  private class ItemHandler implements ItemListener
  {
    /**
     * This method is called when one of the menu item changes.
     *
     * @param evt A {@link ItemEvent}.
     */
    public void itemStateChanged(ItemEvent evt)
    {
      boolean state = false;
      if (menuItem instanceof JCheckBoxMenuItem)
        {
          if (evt.getStateChange() == ItemEvent.SELECTED)
            state = true;
          ((JCheckBoxMenuItem) menuItem).setState(state);
        }
      menuItem.revalidate();
      menuItem.repaint();
    }
  }
}