basiccomboboxui.java

gcc的组建

  }

  /**
   * Creates and returns a layout manager for the combo box.  Subclasses can 
   * override this method to provide a different layout.
   *
   * @return a layout manager for the combo box.
   */
  protected LayoutManager createLayoutManager()
  {
    return new ComboBoxLayoutManager();
  }

  /**
   * Creates a component that will be responsible for rendering the
   * selected component in the combo box.
   *
   * @return A renderer for the combo box.
   */
  protected ListCellRenderer createRenderer()
  {
    return new BasicComboBoxRenderer();
  }

  /**
   * Creates the component that will be responsible for displaying/editing
   * the selected item in the combo box. This editor is used only when combo 
   * box is editable.
   *
   * @return A new component that will be responsible for displaying/editing
   *         the selected item in the combo box.
   */
  protected ComboBoxEditor createEditor()
  {
    return new BasicComboBoxEditor.UIResource();
  }

  /**
   * Installs the components for this JComboBox. ArrowButton, main
   * part of combo box (upper part) and popup list of items are created and
   * configured here.
   */
  protected void installComponents()
  {
    // create drop down list of items
    popup = createPopup();
    listBox = popup.getList();

    // set editor and renderer for the combo box. Editor is used
    // only if combo box becomes editable, otherwise renderer is used
    // to paint the selected item; combobox is not editable by default. 
    comboBox.setRenderer(createRenderer());

    // create and install arrow button
    arrowButton = createArrowButton();
    configureArrowButton();
    comboBox.add(arrowButton);

    ComboBoxEditor currentEditor = comboBox.getEditor();
    if (currentEditor == null || currentEditor instanceof UIResource)
      {
        currentEditor = createEditor();
        comboBox.setEditor(currentEditor);
      } 
    editor = currentEditor.getEditorComponent();

    comboBox.revalidate();
  }

  /**
   * Uninstalls components from this {@link JComboBox}.
   * 
   * @see #installComponents()
   */
  protected void uninstallComponents()
  {
    // uninstall arrow button
    unconfigureArrowButton();
    comboBox.remove(arrowButton);
    arrowButton = null;

    listBox = null;
    popup = null;

    comboBox.setRenderer(null);

    // if the editor is not an instanceof UIResource, it was not set by the
    // UI delegate, so don't clear it...
    ComboBoxEditor currentEditor = comboBox.getEditor();
    if (currentEditor instanceof UIResource)
      {
        comboBox.setEditor(null);
        editor = null;
      }
  }

  /**
   * Adds the current editor to the combo box.
   */
  public void addEditor()
  {
    comboBox.add(editor);
  }

  /**
   * Removes the current editor from the combo box.
   */
  public void removeEditor()
  {
    comboBox.remove(editor);
  }

  /**
   * Configures the editor for this combo box.
   */
  protected void configureEditor()
  {
    editor.setFont(comboBox.getFont());
    comboBox.getEditor().setItem(comboBox.getSelectedItem());
    // FIXME: Need to implement. Set font and add listeners.
  }

  /**
   * Unconfigures the editor for this combo nox.  This method is not implemented.
   */
  protected void unconfigureEditor()
  {
    // FIXME: Need to implement    
  }

  /**
   * Configures the arrow button.
   * 
   * @see #configureArrowButton()
   */
  public void configureArrowButton()
  {
    arrowButton.setEnabled(comboBox.isEnabled());
    arrowButton.setFont(comboBox.getFont());
  }

  /**
   * Unconfigures the arrow button.
   * 
   * @see #configureArrowButton()
   *
   * @specnote The specification says this method is implementation specific
   *           and should not be used or overridden.
   */
  public void unconfigureArrowButton()
  {
    // Nothing to do here yet.
  }

  /**
   * Creates an arrow button for this {@link JComboBox}.  The arrow button is
   * displayed at the right end of the combo box and is used to display/hide
   * the drop down list of items.
   *
   * @return A new button.
   */
  protected JButton createArrowButton()
  {
    return new BasicArrowButton(BasicArrowButton.SOUTH, buttonBackground, 
            buttonShadow, buttonDarkShadow, buttonHighlight);
  }

  /**
   * Returns <code>true</code> if the popup is visible, and <code>false</code>
   * otherwise.
   *
   * @param c The JComboBox to check
   *
   * @return <code>true</code> if popup part of the JComboBox is visible and 
   *         <code>false</code> otherwise.
   */
  public boolean isPopupVisible(JComboBox c)
  {
    return popup.isVisible();
  }

  /**
   * Displays/hides the {@link JComboBox}'s list of items on the screen.
   *
   * @param c The combo box, for which list of items should be
   *        displayed/hidden
   * @param v true if show popup part of the jcomboBox and false to hide.
   */
  public void setPopupVisible(JComboBox c, boolean v)
  {
    if (v)
      {
        popup.show();
        popup.getList().requestFocus();
      }
    else
      popup.hide();
  }

  /**
   * JComboBox is focus traversable if it is editable and not otherwise.
   *
   * @param c combo box for which to check whether it is focus traversable
   *
   * @return true if focus tranversable and false otherwise
   */
  public boolean isFocusTraversable(JComboBox c)
  {
    if (!comboBox.isEditable())
      return true;

    return false;
  }

  /**
   * Paints given menu item using specified graphics context
   *
   * @param g The graphics context used to paint this combo box
   * @param c comboBox which needs to be painted.
   */
  public void paint(Graphics g, JComponent c)
  {
    Rectangle rect = rectangleForCurrentValue();
    paintCurrentValueBackground(g, rect, hasFocus);
    paintCurrentValue(g, rect, hasFocus);
  }

  /**
   * Returns preferred size for the combo box.
   *
   * @param c comboBox for which to get preferred size
   *
   * @return The preferred size for the given combo box
   */
  public Dimension getPreferredSize(JComponent c)
  {
    // note:  overriding getMinimumSize() (for example in the MetalComboBoxUI 
    // class) affects the getPreferredSize() result, so it seems logical that
    // this method is implemented by delegating to the getMinimumSize() method
    return getMinimumSize(c);
  }

  /**
   * Returns the minimum size for this {@link JComboBox} for this
   * look and feel.
   *
   * @param c The {@link JComponent} to find the minimum size for.
   *
   * @return The dimensions of the minimum size.
   */
  public Dimension getMinimumSize(JComponent c)
  {
    Dimension d = getDisplaySize();
    int arrowButtonWidth = d.height;
    Dimension result = new Dimension(d.width + arrowButtonWidth, d.height);
    return result;
  }

  /** The value returned by the getMaximumSize() method. */
  private static final Dimension MAXIMUM_SIZE = new Dimension(32767, 32767);
  
  /**
   * Returns the maximum size for this {@link JComboBox} for this
   * look and feel.
   *
   * @param c The {@link JComponent} to find the maximum size for
   *
   * @return The maximum size (<code>Dimension(32767, 32767)</code>).
   */
  public Dimension getMaximumSize(JComponent c)
  {
    return MAXIMUM_SIZE;
  }

  public int getAccessibleChildrenCount(JComponent c)
  {
    // FIXME: Need to implement
    return 0;
  }

  public Accessible getAccessibleChild(JComponent c, int i)
  {
    // FIXME: Need to implement
    return null;
  }

  /**
   * Returns true if the specified key is a navigation key and false otherwise
   *
   * @param keyCode a key for which to check whether it is navigation key or
   *        not.
   *
   * @return true if the specified key is a navigation key and false otherwis
   */
  protected boolean isNavigationKey(int keyCode)
  {
    return false;
  }

  /**
   * Selects next possible item relative to the current selection
   * to be next selected item in the combo box.
   */
  protected void selectNextPossibleValue()
  {
    int index = comboBox.getSelectedIndex();
    if (index != comboBox.getItemCount() - 1)
      comboBox.setSelectedIndex(index + 1);
  }

  /**
   * Selects previous item relative to current selection to be
   * next selected item.
   */
  protected void selectPreviousPossibleValue()
  {
    int index = comboBox.getSelectedIndex();
    if (index != 0)
      comboBox.setSelectedIndex(index - 1);
  }

  /**
   * Displays combo box popup if the popup is not currently shown
   * on the screen and hides it if it is currently shown
   */
  protected void toggleOpenClose()
  {
    setPopupVisible(comboBox, ! isPopupVisible(comboBox));
  }

  /**
   * Returns the bounds in which comboBox's selected item will be
   * displayed.
   *
   * @return rectangle bounds in which comboBox's selected Item will be
   *         displayed
   */
  protected Rectangle rectangleForCurrentValue()
  {
    Rectangle cbBounds = SwingUtilities.getLocalBounds(comboBox);
    Rectangle abBounds = arrowButton.getBounds();   
    Rectangle rectForCurrentValue = new Rectangle(cbBounds.x, cbBounds.y,
      cbBounds.width - abBounds.width, cbBounds.height);
    return rectForCurrentValue;
  }

  /**
   * Returns the insets of the current border.
   *
   * @return Insets representing space between combo box and its border
   */
  protected Insets getInsets()
  {
    return new Insets(0, 0, 0, 0);
  }

  /**
   * Paints currently selected value in the main part of the combo
   * box (part without popup).
   *
   * @param g graphics context
   * @param bounds Rectangle representing the size of the area in which
   *        selected item should be drawn
   * @param hasFocus true if combo box has focus and false otherwise
   */
  public void paintCurrentValue(Graphics g, Rectangle bounds, boolean hasFocus)
  {
    if (! comboBox.isEditable())
      {
	Object currentValue = comboBox.getSelectedItem();
	boolean isPressed = arrowButton.getModel().isPressed();

	/* Gets the component to be drawn for the current value.
	 * If there is currently no selected item we will take an empty
	 * String as replacement.
	 */
        Component comp = comboBox.getRenderer().getListCellRendererComponent(
                listBox, (currentValue != null ? currentValue : ""), -1,
                isPressed, hasFocus);
        if (! comboBox.isEnabled())
          {
            comp.setBackground(UIManager.getColor(
                                               "ComboBox.disabledBackground"));
            comp.setForeground(UIManager.getColor(
                                               "ComboBox.disabledForeground"));
            comp.setEnabled(false);
          }
        comp.setBounds(0, 0, bounds.width, bounds.height);
        comp.setFont(comboBox.getFont());
        comp.paint(g);
        
        comboBox.revalidate();
      }
    else
      comboBox.getEditor().setItem(comboBox.getSelectedItem());
  }

  /**
   * Paints the background of part of the combo box, where currently
   * selected value is displayed. If the combo box has focus this method
   * should also paint focus rectangle around the combo box.
   *
   * @param g graphics context
   * @param bounds Rectangle representing the size of the largest item  in the
   *        comboBox
   * @param hasFocus true if combo box has fox and false otherwise
   */
  public void paintCurrentValueBackground(Graphics g, Rectangle bounds,
                                          boolean hasFocus)
  {
    // background is painted by renderer, so it seems that nothing
    // should be done here.
  }

  /**
   * Returns the default size for the display area of a combo box that does 
   * not contain any elements.  This method returns the width and height of
   * a single space in the current font, plus a margin of 1 pixel. 
   *
   * @return The default display size.
   * 
   * @see #getDisplaySize()
   */
  protected Dimension getDefaultSize()
  {
    // There is nothing in the spec to say how this method should be