basiccombopopup.java

gcc的组建

  protected ListSelectionListener createListSelectionListener()
  {
    return new ListSelectionHandler();
  }

  /**
   * Creates ListDataListener. This method returns null, because
   * ListDataHandler class is obsolete and is no longer used.
   *
   * @return null
   */
  protected ListDataListener createListDataListener()
  {
    return null;
  }

  /**
   * This method creates ListMouseListener to listen to mouse events occuring
   * in the combo box's item list.
   *
   * @return MouseListener to listen to mouse events occuring in the combo
   *         box's items list.
   */
  protected MouseListener createListMouseListener()
  {
    return new ListMouseHandler();
  }

  /**
   * Creates ListMouseMotionlistener to listen to mouse motion events occuring
   * in the combo box's list. This listener is responsible for highlighting
   * items in the list when mouse is moved over them.
   *
   * @return MouseMotionListener that handles mouse motion events occuring in
   *         the list of the combo box.
   */
  protected MouseMotionListener createListMouseMotionListener()
  {
    return new ListMouseMotionHandler();
  }

  /**
   * Creates PropertyChangeListener to handle changes in the JComboBox's bound
   * properties.
   *
   * @return PropertyChangeListener to handle changes in the JComboBox's bound
   *         properties.
   */
  protected PropertyChangeListener createPropertyChangeListener()
  {
    return new PropertyChangeHandler();
  }

  /**
   * Creates new ItemListener that will listen to ItemEvents occuring in the
   * combo box.
   *
   * @return ItemListener to listen to ItemEvents occuring in the combo box.
   */
  protected ItemListener createItemListener()
  {
    return new ItemHandler();
  }

  /**
   * Creates JList that will be used to display items in the combo box.
   *
   * @return JList that will be used to display items in the combo box.
   */
  protected JList createList()
  {
    JList l = new JList(comboBox.getModel());
    l.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
    return l;
  }

  /**
   * This method configures the list of comboBox's items by setting  default
   * properties and installing listeners.
   */
  protected void configureList()
  {
    list.setModel(comboBox.getModel());
    list.setVisibleRowCount(comboBox.getMaximumRowCount());
    installListListeners();
  }

  /**
   * This method installs list listeners.
   */
  protected void installListListeners()
  {
    // mouse listener listening to mouse events occuring in the 
    // combo box's list of items.
    listMouseListener = createListMouseListener();
    list.addMouseListener(listMouseListener);

    // mouse listener listening to mouse motion events occuring in the
    // combo box's list of items
    listMouseMotionListener = createListMouseMotionListener();
    list.addMouseMotionListener(listMouseMotionListener);

    listSelectionListener = createListSelectionListener();
    list.addListSelectionListener(listSelectionListener);
  }

  /**
   * This method creates scroll pane that will contain the list of comboBox's
   * items inside of it.
   *
   * @return JScrollPane
   */
  protected JScrollPane createScroller()
  {
    return new JScrollPane();
  }

  /**
   * This method configures scroll pane to contain list of comboBox's  items
   */
  protected void configureScroller()
  {
    scroller.setBorder(null);
    scroller.getViewport().setView(list);
    scroller.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
  }

  /**
   * This method configures popup menu that will be used to display Scrollpane
   * with list of items inside of it.
   */
  protected void configurePopup()
  {
    setBorder(BorderFactory.createLineBorder(Color.BLACK));
    // initialize list that will be used to display combo box's items
    this.list = createList();
    ((JLabel) list.getCellRenderer()).setHorizontalAlignment(SwingConstants.LEFT);
    configureList();

    // initialize scroller. Add list to the scroller.	
    scroller = createScroller();
    configureScroller();

    // add scroller with list inside of it to JPopupMenu
    super.add(scroller);
  }

  /*
   * This method installs listeners that will listen to changes occuring
   * in the combo box.
   */
  protected void installComboBoxListeners()
  {
    // mouse listener that listens to mouse event in combo box
    mouseListener = createMouseListener();
    comboBox.addMouseListener(mouseListener);

    // mouse listener that listens to mouse dragging events in the combo box
    mouseMotionListener = createMouseMotionListener();
    comboBox.addMouseMotionListener(mouseMotionListener);

    // item listener listenening to selection events in the combo box
    itemListener = createItemListener();
    comboBox.addItemListener(itemListener);

    propertyChangeListener = createPropertyChangeListener();
    comboBox.addPropertyChangeListener(propertyChangeListener);
  }

  /**
   * This method installs listeners that will listen to changes occuring in
   * the comb box's data model
   *
   * @param model data model for the combo box for which to install listeners
   */
  protected void installComboBoxModelListeners(ComboBoxModel model)
  {
    // list data listener to listen for ListDataEvents in combo box.
    // This listener is now obsolete and nothing is done here
    listDataListener = createListDataListener();
    comboBox.getModel().addListDataListener(listDataListener);
  }

  /**
   * DOCUMENT ME!
   */
  protected void installKeyboardActions()
  {
    // FIXME: Need to implement
  }

  /**
   * This method always returns false to indicate that  items in the combo box
   * list are not focus traversable.
   *
   * @return false
   */
  public boolean isFocusTraversable()
  {
    return false;
  }

  /**
   * This method start scrolling combo box's list of items  either up or down
   * depending on the specified 'direction'
   *
   * @param direction of the scrolling.
   */
  protected void startAutoScrolling(int direction)
  {
    // FIXME: add timer
    isAutoScrolling = true;

    if (direction == SCROLL_UP)
      autoScrollUp();
    else
      autoScrollDown();
  }

  /**
   * This method stops scrolling the combo box's list of items
   */
  protected void stopAutoScrolling()
  {
    // FIXME: add timer
    isAutoScrolling = false;
  }

  /**
   * This method scrolls up list of combo box's items up and highlights that
   * just became visible.
   */
  protected void autoScrollUp()
  {
    // scroll up the scroll bar to make the item above visible    
    JScrollBar scrollbar = scroller.getVerticalScrollBar();
    int scrollToNext = list.getScrollableUnitIncrement(super.getBounds(),
                                                       SwingConstants.VERTICAL,
                                                       SCROLL_UP);

    scrollbar.setValue(scrollbar.getValue() - scrollToNext);

    // If we haven't reached the begging of the combo box's list of items, 
    // then highlight next element above currently highlighted element	
    if (list.getSelectedIndex() != 0)
      list.setSelectedIndex(list.getSelectedIndex() - 1);
  }

  /**
   * This method scrolls down list of combo box's and highlights item in the
   * list that just became visible.
   */
  protected void autoScrollDown()
  {
    // scroll scrollbar down to make next item visible    
    JScrollBar scrollbar = scroller.getVerticalScrollBar();
    int scrollToNext = list.getScrollableUnitIncrement(super.getBounds(),
                                                       SwingConstants.VERTICAL,
                                                       SCROLL_DOWN);
    scrollbar.setValue(scrollbar.getValue() + scrollToNext);

    // If we haven't reached the end of the combo box's list of items
    // then highlight next element below currently highlighted element
    if (list.getSelectedIndex() + 1 != comboBox.getItemCount())
      list.setSelectedIndex(list.getSelectedIndex() + 1);
  }

  /**
   * This method helps to delegate focus to the right component in the
   * JComboBox. If the comboBox is editable then focus is sent to
   * ComboBoxEditor, otherwise it is delegated to JComboBox.
   *
   * @param e MouseEvent
   */
  protected void delegateFocus(MouseEvent e)
  {
    // FIXME: Need to implement
  }

  /**
   * This method displays combo box popup if the popup is  not currently shown
   * on the screen and hides it if it is  currently visible
   */
  protected void togglePopup()
  {
    if (BasicComboPopup.this.isVisible())
      hide();
    else
      show();
  }

  /**
   * DOCUMENT ME!
   *
   * @param e DOCUMENT ME!
   *
   * @return DOCUMENT ME!
   */
  protected MouseEvent convertMouseEvent(MouseEvent e)
  {
    return null;
  }

  /**
   * Returns required height of the popup such that number of items visible in
   * it are equal to the maximum row count.  By default
   * comboBox.maximumRowCount=8
   *
   * @param maxRowCount number of maximum visible rows in the  combo box's
   *        popup list of items
   *
   * @return height of the popup required to fit number of items  equal to
   *         JComboBox.maximumRowCount.
   */
  protected int getPopupHeightForRowCount(int maxRowCount)
  {
    int totalHeight = 0;
    ListCellRenderer rend = list.getCellRenderer();

    if (comboBox.getItemCount() < maxRowCount)
      maxRowCount = comboBox.getItemCount();

    for (int i = 0; i < maxRowCount; i++)
      {
	Component comp = rend.getListCellRendererComponent(list,
	                                                   comboBox.getModel()
	                                                           .getElementAt(i),
	                                                   -1, false, false);
	Dimension dim = comp.getPreferredSize();
	totalHeight += dim.height;
      }

    return totalHeight;
  }

  /**
   * DOCUMENT ME!
   *
   * @param px DOCUMENT ME!
   * @param py DOCUMENT ME!
   * @param pw DOCUMENT ME!
   * @param ph DOCUMENT ME!
   *
   * @return DOCUMENT ME!
   */
  protected Rectangle computePopupBounds(int px, int py, int pw, int ph)
  {
    return new Rectangle(px, py, pw, ph);
  }

  /**
   * This method changes the selection in the list to the item over which  the
   * mouse is currently located.
   *
   * @param anEvent MouseEvent
   * @param shouldScroll DOCUMENT ME!
   */
  protected void updateListBoxSelectionForEvent(MouseEvent anEvent,
                                                boolean shouldScroll)
  {