basiccombopopup.java

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        if (index == -1)
          {
            if (point.y < 0)
              index = 0;
            else
              index = comboBox.getModel().getSize() - 1;
          }
        if (list.getSelectedIndex() != index)
          {
            list.setSelectedIndex(index);
            if (shouldScroll)
              list.ensureIndexIsVisible(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 (SwingUtilities.isLeftMouseButton(e) && comboBox.isEnabled())
        {
          delegateFocus(e);
          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)
    {
      Component component = (Component) e.getSource();
      Dimension size = component.getSize();
      Rectangle bounds = new Rectangle(0, 0, size.width - 1, size.height - 1);
      // 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 (! bounds.contains(e.getPoint()))
        {
          MouseEvent convEvent = convertMouseEvent(e);
          Point point = convEvent.getPoint();
          Rectangle visRect = new Rectangle();
          list.computeVisibleRect(visRect);
          if (visRect.contains(point))
            {
              updateListBoxSelectionForEvent(convEvent, false);
              comboBox.setSelectedIndex(list.getSelectedIndex());
            }
          hide();
        }
      hasEntered = false;
      stopAutoScrolling();
    }
  }

  /**
   * 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)
    {
      if (isVisible())
        {
          MouseEvent convEvent = convertMouseEvent(e);
          Rectangle visRect = new Rectangle();
          list.computeVisibleRect(visRect);
          if (convEvent.getPoint().y >= visRect.y
              && (convEvent.getPoint().y <= visRect.y + visRect.height - 1))
            {
              hasEntered = true;
              if (isAutoScrolling)
                stopAutoScrolling();
              Point point = convEvent.getPoint();
              if (visRect.contains(point))
                {
                  valueIsAdjusting = true;
                  updateListBoxSelectionForEvent(convEvent, false);
                  valueIsAdjusting = false;
                }
            }
          else if (hasEntered)
            {
              int dir = convEvent.getPoint().y < visRect.y ? SCROLL_UP
                                                           : SCROLL_DOWN;
              if (isAutoScrolling && scrollDirection != dir)
                {
                  stopAutoScrolling();
                  startAutoScrolling(dir);
                }
              else if (!isAutoScrolling)
                startAutoScrolling(dir);
            }
          else if (e.getPoint().y < 0)
            {
              hasEntered = true;
              startAutoScrolling(SCROLL_UP);
            }
        }
    }
  }

  /**
   * 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)
    {
      if (e.getStateChange() == ItemEvent.SELECTED && ! valueIsAdjusting)
        {
          valueIsAdjusting = true;
          syncListSelection();
          valueIsAdjusting = false;
          list.ensureIndexIsVisible(comboBox.getSelectedIndex());
        }
    }
  }

  /**
   * 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)
    {
      // Nothing to do here.
    }

    public void mouseReleased(MouseEvent anEvent)
    {
      comboBox.setSelectedIndex(list.getSelectedIndex());
      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)
    {
      Point point = anEvent.getPoint();
      Rectangle visRect = new Rectangle();
      list.computeVisibleRect(visRect);
      if (visRect.contains(point))
        {
          valueIsAdjusting = true;
          updateListBoxSelectionForEvent(anEvent, false);
          valueIsAdjusting = 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(comboBox.getRenderer());
	  if (isVisible())
	    hide();
        }
      if (e.getPropertyName().equals("model"))
        {
          ComboBoxModel oldModel = (ComboBoxModel) e.getOldValue();
          uninstallComboBoxModelListeners(oldModel);
          ComboBoxModel newModel = (ComboBoxModel) e.getNewValue();
          list.setModel(newModel);
          installComboBoxModelListeners(newModel);
          if (comboBox.getItemCount() > 0)
            comboBox.setSelectedIndex(0);
          if (isVisible())
            hide();
        }
    }
  }

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

  /**
   * This method uninstalls listeners installed by the UI
   */
  private void uninstallListeners()
  {
    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.removeItemListener(itemListener);
    itemListener = null;

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

  void syncListSelection()
  {
    int index = comboBox.getSelectedIndex();
    if (index == -1)
      list.clearSelection();
    else
      list.setSelectedIndex(index);
  }

  // --------------------------------------------------------------------
  //  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.
    }
  }
}