basiccombopopup.java

gcc的组建

    // TODO: We need to handle the shouldScroll parameter somehow.
    int index = list.locationToIndex(anEvent.getPoint());
    // Check for valid index.
    if (index >= 0)
      list.setSelectedIndex(index);
  }

  /**
   * InvocationMouseHandler is a listener that listens to mouse events
   * occuring in the combo box. Note that this listener doesn't listen to
   * mouse events occuring in the popup portion of the combo box, it only
   * listens to main combo box part(area that displays selected item).  This
   * listener is responsible for showing and hiding popup portion  of the
   * combo box.
   */
  protected class InvocationMouseHandler extends MouseAdapter
  {
    /**
     * Creates a new InvocationMouseHandler object.
     */
    protected InvocationMouseHandler()
    {
      // Nothing to do here.
    }

    /**
     * This method is invoked whenever mouse is being pressed over the main
     * part of the combo box. This method will show popup if  the popup is
     * not shown on the screen right now, and it will hide popup otherwise.
     *
     * @param e MouseEvent that should be handled
     */
    public void mousePressed(MouseEvent e)
    {
      if (comboBox.isEnabled())
        togglePopup();
    }

    /**
     * This method is invoked whenever mouse event was originated in the combo
     * box and released either in the combBox list of items or in the combo
     * box itself.
     *
     * @param e MouseEvent that should be handled
     */
    public void mouseReleased(MouseEvent e)
    {
      // Get component over which mouse was released
      Component src = (Component) e.getSource();
      int x = e.getX();
      int y = e.getY();
      Component releasedComponent = SwingUtilities.getDeepestComponentAt(src,
                                                                         x, y);

      // if mouse was released inside the bounds of combo box then do nothing,
      // Otherwise if mouse was released inside the list of combo box items
      // then change selection and close popup
      if (! (releasedComponent instanceof JComboBox))
        {
          // List model contains the item over which mouse is released,
          // since it is updated every time the mouse is moved over a different
          // item in the list. Now that the mouse is released we need to
          // update model of the combo box as well. 	  
          comboBox.setSelectedIndex(list.getSelectedIndex());

          if (isAutoScrolling)
            stopAutoScrolling();
          hide();
        }
    }
  }

  /**
   * InvocationMouseMotionListener is a mouse listener that listens to mouse
   * dragging events occuring in the combo box.
   */
  protected class InvocationMouseMotionHandler extends MouseMotionAdapter
  {
    /**
     * Creates a new InvocationMouseMotionHandler object.
     */
    protected InvocationMouseMotionHandler()
    {
      // Nothing to do here.
    }

    /**
     * This method is responsible for highlighting item in the drop down list
     * over which the mouse is currently being dragged.
     */
    public void mouseDragged(MouseEvent e)
    {
      // convert point of the drag event relative to combo box list component
      // figure out over which list cell the mouse is currently being dragged
      // and highlight the cell. The list model is changed but the change has 
      // no effect on combo box's data model. The list model is changed so 
      // that the appropriate item would be highlighted in the combo box's 
      // list.
      if (BasicComboPopup.this.isVisible())
        {
	  int cbHeight = (int) comboBox.getPreferredSize().getHeight();
	  int popupHeight = BasicComboPopup.this.getSize().height;

	  // if mouse is dragged inside the the combo box's items list.
	  if (e.getY() > cbHeight && ! (e.getY() - cbHeight >= popupHeight))
	    {
	      int index = list.locationToIndex(new Point(e.getX(),
	                                                 (int) (e.getY()
	                                                 - cbHeight)));

	      int firstVisibleIndex = list.getFirstVisibleIndex();

	      // list.locationToIndex returns item's index that would
	      // be located at the specified point if the first item that
	      // is visible is item 0. However in the JComboBox it is not 
	      // necessarily the case since list is contained in the 
	      // JScrollPane so we need to adjust the index returned. 
	      if (firstVisibleIndex != 0)
		// FIXME: adjusted index here is off by one. I am adding one
		// here to compensate for that. This should be
		// index += firstVisibleIndex. Remove +1 once the bug is fixed.
		index += firstVisibleIndex + 1;

	      list.setSelectedIndex(index);
	    }
	  else
	    {
	      // if mouse is being dragged at the bottom of combo box's list 
	      // of items or at the very top then scroll the list in the 
	      // desired direction.
	      boolean movingUP = e.getY() < cbHeight;
	      boolean movingDown = e.getY() > cbHeight;

	      if (movingUP)
	        {
		  scrollDirection = SCROLL_UP;
		  startAutoScrolling(SCROLL_UP);
	        }
	      else if (movingDown)
	        {
		  scrollDirection = SCROLL_DOWN;
		  startAutoScrolling(SCROLL_DOWN);
	        }
	    }
        }
    }
  }

  /**
   * ItemHandler is an item listener that listens to selection events occuring
   * in the combo box. FIXME: should specify here what it does when item is
   * selected or deselected in the combo box list.
   */
  protected class ItemHandler extends Object implements ItemListener
  {
    /**
     * Creates a new ItemHandler object.
     */
    protected ItemHandler()
    {
      // Nothing to do here.
    }

    /**
     * This method responds to the selection events occuring in the combo box.
     *
     * @param e ItemEvent specifying the combo box's selection
     */
    public void itemStateChanged(ItemEvent e)
    {
      // TODO: What should be done here?
    }
  }

  /**
   * ListMouseHandler is a listener that listens to mouse events occuring in
   * the combo box's list of items. This class is responsible for hiding
   * popup portion of the combo box if the mouse is released inside the combo
   * box's list.
   */
  protected class ListMouseHandler extends MouseAdapter
  {
    protected ListMouseHandler()
    {
      // Nothing to do here.
    }

    public void mousePressed(MouseEvent e)
    {
      // TODO: What should be do here?
    }

    public void mouseReleased(MouseEvent anEvent)
    {
      int index = list.locationToIndex(anEvent.getPoint());
      // Check for valid index.
      if (index >= 0)
        comboBox.setSelectedIndex(index);
      hide();
    }
  }

  /**
   * ListMouseMotionHandler listens to mouse motion events occuring in the
   * combo box's list. This class is responsible for highlighting items in
   * the list when mouse is moved over them
   */
  protected class ListMouseMotionHandler extends MouseMotionAdapter
  {
    protected ListMouseMotionHandler()
    {
      // Nothing to do here.
    }

    public void mouseMoved(MouseEvent anEvent)
    {
      updateListBoxSelectionForEvent(anEvent, false);
    }
  }

  /**
   * This class listens to changes occuring in the bound properties of the
   * combo box
   */
  protected class PropertyChangeHandler extends Object
    implements PropertyChangeListener
  {
    protected PropertyChangeHandler()
    {
      // Nothing to do here.
    }

    public void propertyChange(PropertyChangeEvent e)
    {
      if (e.getPropertyName().equals("renderer"))
        {
	  list.setCellRenderer((ListCellRenderer) e.getNewValue());
	  revalidate();
	  repaint();
        }
      if (e.getPropertyName().equals("dataModel"))
        {
	  list.setModel((ComboBoxModel) e.getNewValue());
	  revalidate();
	  repaint();
        }
    }
  }

  // ------ private helper methods --------------------

  /**
   * This method uninstalls listeners installed by the UI
   */
  private void uninstallListeners()
  {
    uninstallListListeners();
    uninstallComboBoxListeners();
    uninstallComboBoxModelListeners(comboBox.getModel());
  }

  /**
   * This method uninstalls Listeners registered with combo boxes list of
   * items
   */
  private void uninstallListListeners()
  {
    list.removeMouseListener(listMouseListener);
    listMouseListener = null;

    list.removeMouseMotionListener(listMouseMotionListener);
    listMouseMotionListener = null;
  }

  /**
   * This method uninstalls listeners listening to combo box  associated with
   * this popup menu
   */
  private void uninstallComboBoxListeners()
  {
    comboBox.removeMouseListener(mouseListener);
    mouseListener = null;

    comboBox.removeMouseMotionListener(mouseMotionListener);
    mouseMotionListener = null;

    comboBox.removeItemListener(itemListener);
    itemListener = null;

    comboBox.removePropertyChangeListener(propertyChangeListener);
    propertyChangeListener = null;
  }

  // --------------------------------------------------------------------
  //  The following classes are here only for backwards API compatibility
  //  They aren't used.
  // --------------------------------------------------------------------

  /**
   * This class is not used any more.
   */
  public class ListDataHandler extends Object implements ListDataListener
  {
    public ListDataHandler()
    {
      // Nothing to do here.
    }

    public void contentsChanged(ListDataEvent e)
    {
      // Nothing to do here.
    }

    public void intervalAdded(ListDataEvent e)
    {
      // Nothing to do here.
    }

    public void intervalRemoved(ListDataEvent e)
    {
      // Nothing to do here.
    }
  }

  /**
   * This class is not used anymore
   */
  protected class ListSelectionHandler extends Object
    implements ListSelectionListener
  {
    protected ListSelectionHandler()
    {
      // Nothing to do here.
    }

    public void valueChanged(ListSelectionEvent e)
    {
      // Nothing to do here.
    }
  }

  /**
   * This class is not used anymore
   */
  public class InvocationKeyHandler extends KeyAdapter
  {
    public InvocationKeyHandler()
    {
      // Nothing to do here.
    }

    public void keyReleased(KeyEvent e)
    {
      // Nothing to do here.
    }
  }
}