jmenubar.java

gcc的组建

  public JMenu getMenu(int index)
  {
    if (getComponentAtIndex(index) instanceof JMenu)
      return (JMenu) getComponentAtIndex(index);
    else
      return null;
  }

  /**
   * Returns number of menu's in this menu bar
   *
   * @return number of menu's in this menu bar
   */
  public int getMenuCount()
  {
    return getComponentCount();
  }

  /**
   * Returns selection model for this menu bar. SelectionModel
   * keeps track of the selected menu in the menu bar. Whenever
   * selected property of selectionModel changes, the ChangeEvent
   * will be fired its ChangeListeners.
   *
   * @return selection model for this menu bar.
   */
  public SingleSelectionModel getSelectionModel()
  {
    return selectionModel;
  }

  /**
   * Method of MenuElement interface. It returns subcomponents
   * of the menu bar, which are all the menues that it contains.
   *
   * @return MenuElement[] array containing menues in this menu bar
   */
  public MenuElement[] getSubElements()
  {
    MenuElement[] subElements = new MenuElement[getComponentCount()];

    for (int i = 0; i < getComponentCount(); i++)
      subElements[i] = (MenuElement) getMenu(i);

    return subElements;
  }

  /**
    * Set the "UI" property of the menu bar, which is a look and feel class
    * responsible for handling the menuBar's input events and painting it.
    *
    * @return The current "UI" property
    */
  public MenuBarUI getUI()
  {
    return (MenuBarUI) ui;
  }

  /**
   * This method returns a name to identify which look and feel class will be
   * the UI delegate for the menu bar.
   *
   * @return The Look and Feel classID. "MenuBarUI"
   */
  public String getUIClassID()
  {
    return "MenuBarUI";
  }

  /**
   * Returns true if menu bar paints its border and false otherwise
   *
   * @return true if menu bar paints its border and false otherwise
   */
  public boolean isBorderPainted()
  {
    return borderPainted;
  }

  /**
   * Returns true if some menu in menu bar is selected.
   *
   * @return true if some menu in menu bar is selected and false otherwise
   */
  public boolean isSelected()
  {
    return selectionModel.isSelected();
  }

  /**
   * This method does nothing by default. This method is need for the
   * MenuElement interface to be implemented.
   *
   * @param isIncluded true if menuBar is included in the selection
   * and false otherwise
   */
  public void menuSelectionChanged(boolean isIncluded)
  {
    // Do nothing - needed for implementation of MenuElement interface
  }

  /**
   * Paints border of the menu bar, if its borderPainted property is set to
   * true.
   *
   * @param g The graphics context with which to paint the border
   */
  protected void paintBorder(Graphics g)
  {
    if (borderPainted)
      getBorder().paintBorder(this, g, 0, 0, getSize(null).width,
                              getSize(null).height);
  }

  /**
   * A string that describes this JMenuBar. Normally only used
   * for debugging.
   *
   * @return A string describing this JMenuBar
   */
  protected String paramString()
  {
    StringBuffer sb = new StringBuffer();
    sb.append(super.paramString());
    sb.append(",margin=");
    if (getMargin() != null)
      sb.append(getMargin());
    sb.append(",paintBorder=").append(isBorderPainted());
    return sb.toString();
  }

  /**
   * Process key events forwarded from MenuSelectionManager. This method
   * doesn't do anything. It is here to conform to the MenuElement interface.
   *
   * @param e event forwarded from MenuSelectionManager
   * @param path path to the menu element from which event was generated
   * @param manager MenuSelectionManager for the current menu hierarchy
   *
   */
  public void processKeyEvent(KeyEvent e, MenuElement[] path,
                              MenuSelectionManager manager)
  {
    // Do nothing - needed for implementation of MenuElement interface
  }

  /**
   * This method overrides JComponent.processKeyBinding to allow the 
   * JMenuBar to check all the child components (recursiveley) to see 
   * if they'll consume the event.
   * 
   * @param ks the KeyStroke for the event
   * @param e the KeyEvent for the event
   * @param condition the focus condition for the binding
   * @param pressed true if the key is pressed 
   */
  protected boolean processKeyBinding(KeyStroke ks, KeyEvent e, int condition,
                                      boolean pressed)
  {
    // See if the regular JComponent behavior consumes the event
    if (super.processKeyBinding(ks, e, condition, pressed))
      return true;
    
    // If not, have to recursively check all the child menu elements to see 
    // if they want it    
    MenuElement[] children = getSubElements();
    for (int i = 0; i < children.length; i++)
      if (processKeyBindingHelper(children[i], ks, e, condition, pressed))
        return true;
    return false;
  }
  
  /**
   * This is a helper method to recursively check the children of this
   * JMenuBar to see if they will consume a key event via key bindings.  
   * This is used for menu accelerators.
   * @param menuElement the menuElement to check (and check all its children)
   * @param ks the KeyStroke for the event
   * @param e the KeyEvent that may be consumed
   * @param condition the focus condition for the binding
   * @param pressed true if the key was pressed
   * @return true <code>menuElement</code> or one of its children consume
   * the event (processKeyBinding returns true for menuElement or one of
   * its children).
   */
  static boolean processKeyBindingHelper(MenuElement menuElement, KeyStroke ks,
                                         KeyEvent e, int condition,
                                         boolean pressed)
  {
    // First check the menuElement itself, if it's a JComponent
    if (menuElement instanceof JComponent
        && ((JComponent) menuElement).processKeyBinding(ks, e, condition,
                                                        pressed))
      return true;
    
    // If that didn't consume it, check all the children recursively
    MenuElement[] children = menuElement.getSubElements();
    for (int i = 0; i < children.length; i++)
      if (processKeyBindingHelper(children[i], ks, e, condition, pressed))
        return true;
    return false;
  }
  
  /**
   * Process mouse events forwarded from MenuSelectionManager. This method
   * doesn't do anything. It is here to conform to the MenuElement interface.
   *
   * @param event event forwarded from MenuSelectionManager
   * @param path path to the menu element from which event was generated
   * @param manager MenuSelectionManager for the current menu hierarchy
   *
   */
  public void processMouseEvent(MouseEvent event, MenuElement[] path,
                                MenuSelectionManager manager)
  {
    // Do nothing - needed for implementation of MenuElement interface
  }

  /**
   * This method overrides removeNotify() in the Container to
   * unregister this menu bar from the current keyboard manager.
   */
  public void removeNotify()
  {
    KeyboardManager.getManager().unregisterJMenuBar(this);
    super.removeNotify();
  }

  /**
   * Sets painting status of the border. If 'b' is true then menu bar's
   * border will be painted, and it will not be painted otherwise.
   *
   * @param b indicates if menu bar's border should be painted.
   */
  public void setBorderPainted(boolean b)
  {
    if (b != borderPainted)
      {
	boolean old = borderPainted;
	borderPainted = b;
	firePropertyChange("borderPainted", old, b);
	revalidate();
	repaint();
      }
  }

  /**
   * Sets help menu for this menu bar
   *
   * @param menu help menu
   *
   * @specnote The specification states that this method is not yet implemented
   *           and should throw an exception.
   */
  public void setHelpMenu(JMenu menu)
  {
    // We throw an Error here, just as Sun's JDK does.
    throw new Error("setHelpMenu() not yet implemented.");
  }

  /**
   * Sets the menu bar's "margin" bound property,  which represents
   * distance between the menubar's border and its menus.
   * icon. When marging property is modified, PropertyChangeEvent will
   * be fired to menuBar's PropertyChangeListener's.
   *
   * @param m distance between the menubar's border and its menus.
   *
   */
  public void setMargin(Insets m)
  {
    if (m != margin)
      {
	Insets oldMargin = margin;
	margin = m;
	firePropertyChange("margin", oldMargin, margin);
      }
  }

  /**
   * Changes menu bar's selection to the specified menu.
   * This method updates selected index of menu bar's selection model,
   * which results in a model firing change event.
   *
   * @param sel menu to select
   */
  public void setSelected(Component sel)
  {
    int index = getComponentIndex(sel);
    selectionModel.setSelectedIndex(index);
  }

  /**
   * Sets menuBar's selection model to the one specified
   *
   * @param model SingleSelectionModel that needs to be set for this menu bar
   */
  public void setSelectionModel(SingleSelectionModel model)
  {
    if (selectionModel != model)
      {
	SingleSelectionModel oldModel = selectionModel;
	selectionModel = model;
	firePropertyChange("model", oldModel, selectionModel);
      }
  }

  /**
   * Set the "UI" property of the menu bar, which is a look and feel class
   * responsible for handling menuBar's input events and painting it.
   *
   * @param ui The new "UI" property
   */
  public void setUI(MenuBarUI ui)
  {
    super.setUI(ui);
  }

  /**
   * Set the "UI" property to a class constructed, via the {@link
   * UIManager}, from the current look and feel.
   */
  public void updateUI()
  {
    setUI((MenuBarUI) UIManager.getUI(this));
    invalidate();
  }
}