basicscrollpaneui.java

java jdk 1.4的源码

        return sbPropertyChangeListener;
    }

    protected ChangeListener createHSBChangeListener() {
	return new HSBChangeListener();
    }


    /**
     * Vertical scrollbar listener.
     */
    public class VSBChangeListener implements ChangeListener
    {
	public void stateChanged(ChangeEvent e)
	{
	    JViewport viewport = scrollpane.getViewport();
	    if (viewport != null) {
		BoundedRangeModel model = (BoundedRangeModel)(e.getSource());
		Point p = viewport.getViewPosition();
		p.y = model.getValue();
		viewport.setViewPosition(p);
	    }
	}
    }


    /**
     * PropertyChangeListener for the ScrollBars.
     */
    private class ScrollBarPropertyChangeHandler implements
                               PropertyChangeListener {
        // Listens for changes in the model property and reinstalls the
        // horizontal/vertical PropertyChangeListeners.
        public void propertyChange(PropertyChangeEvent e) {
            String propertyName = e.getPropertyName();
            Object source = e.getSource();

            if ("model".equals(propertyName)) {
                JScrollBar sb = scrollpane.getVerticalScrollBar();
                BoundedRangeModel oldModel = (BoundedRangeModel)e.
                                     getOldValue();
                ChangeListener cl = null;

                if (source == sb) {
                    cl = vsbChangeListener;
                }
                else if (source == scrollpane.getHorizontalScrollBar()) {
                    sb = scrollpane.getHorizontalScrollBar();
                    cl = hsbChangeListener;
                }
                if (cl != null) {
                    if (oldModel != null) {
                        oldModel.removeChangeListener(cl);
                    }
                    if (sb.getModel() != null) {
                        sb.getModel().addChangeListener(cl);
                    }
                }
            }
            else if ("componentOrientation".equals(propertyName)) {
                if (source == scrollpane.getHorizontalScrollBar()) {
		    JScrollBar hsb = scrollpane.getHorizontalScrollBar();
 		    JViewport viewport = scrollpane.getViewport();
                    Point p = viewport.getViewPosition();
                    if (scrollpane.getComponentOrientation().isLeftToRight()) {
                        p.x = hsb.getValue();
                    } else {
                        p.x = viewport.getViewSize().width - viewport.getExtentSize().width - hsb.getValue();
                    }
                    viewport.setViewPosition(p);
                }
            }
        }
    }

    /**
     * Returns a <code>PropertyChangeListener</code> that will be installed
     * on the vertical <code>JScrollBar</code>.
     */
    private PropertyChangeListener createVSBPropertyChangeListener() {
        return getSBPropertyChangeListener();
    }

    protected ChangeListener createVSBChangeListener() {
	return new VSBChangeListener();
    }

    /**
     * MouseWheelHandler is an inner class which implements the 
     * MouseWheelListener interface.  MouseWheelHandler responds to 
     * MouseWheelEvents by scrolling the JScrollPane appropriately.
     * If the scroll pane's
     * <code>isWheelScrollingEnabled</code>
     * method returns false, no scrolling occurs.
     * 
     * @see javax.swing.JScrollPane#isWheelScrollingEnabled
     * @see #createMouseWheelListener
     * @see java.awt.event.MouseWheelListener
     * @see java.awt.event.MouseWheelEvent
     * @since 1.4
     */
    protected class MouseWheelHandler implements MouseWheelListener {
        /**
         * Called when the mouse wheel is rotated while over a
         * JScrollPane.
         *
         * @param e     MouseWheelEvent to be handled
         * @since 1.4
         */
        public void mouseWheelMoved(MouseWheelEvent e) {
            if (scrollpane.isWheelScrollingEnabled() &&
                e.getScrollAmount() != 0) {
                JScrollBar toScroll = scrollpane.getVerticalScrollBar();
                int direction = 0;
                // find which scrollbar to scroll, or return if none
                if (toScroll == null || !toScroll.isVisible()) { 
                    toScroll = scrollpane.getHorizontalScrollBar();
                    if (toScroll == null || !toScroll.isVisible()) { 
                        return;
                    }
                }
                direction = e.getWheelRotation() < 0 ? -1 : 1;
                if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
                    BasicScrollBarUI.scrollByUnits(toScroll, direction,
                                                         e.getScrollAmount());
                }
                else if (e.getScrollType() ==
                         MouseWheelEvent.WHEEL_BLOCK_SCROLL) {
                    BasicScrollBarUI.scrollByBlock(toScroll, direction);
                }
            }
        }
    }

    /**
     * Creates an instance of MouseWheelListener, which is added to the
     * JScrollPane by installUI().  The returned MouseWheelListener is used
     * to handle mouse wheel-driven scrolling.
     *
     * @return      MouseWheelListener which implements wheel-driven scrolling
     * @see #installUI
     * @see MouseWheelHandler
     * @since 1.4
     */
    protected MouseWheelListener createMouseWheelListener() {
        return new MouseWheelHandler();
    }

    protected void updateScrollBarDisplayPolicy(PropertyChangeEvent e) {
	scrollpane.revalidate();
	scrollpane.repaint();
    }


    protected void updateViewport(PropertyChangeEvent e) 
    {
	JViewport oldViewport = (JViewport)(e.getOldValue());
	JViewport newViewport = (JViewport)(e.getNewValue());

	if (oldViewport != null) {
	    oldViewport.removeChangeListener(viewportChangeListener);
	}
	
	if (newViewport != null) {
	    Point p = newViewport.getViewPosition();
	    if (scrollpane.getComponentOrientation().isLeftToRight()) {
		p.x = Math.max(p.x, 0);
	    } else {
		int max = newViewport.getViewSize().width;
		int extent = newViewport.getExtentSize().width;
		if (extent > max) {
		    p.x = max - extent;
		} else {
		    p.x = Math.max(0, Math.min(max - extent, p.x));
		}
	    }
	    p.y = Math.max(p.y, 0);
	    newViewport.setViewPosition(p);
	    newViewport.addChangeListener(viewportChangeListener);
	}
    }


    protected void updateRowHeader(PropertyChangeEvent e) 
    {
	JViewport newRowHead = (JViewport)(e.getNewValue());
	if (newRowHead != null) {
	    JViewport viewport = scrollpane.getViewport();
	    Point p = newRowHead.getViewPosition();
	    p.y = (viewport != null) ? viewport.getViewPosition().y : 0;
	    newRowHead.setViewPosition(p);
	}
    }


    protected void updateColumnHeader(PropertyChangeEvent e) 
    {
	JViewport newColHead = (JViewport)(e.getNewValue());
	if (newColHead != null) {
	    JViewport viewport = scrollpane.getViewport();
	    Point p = newColHead.getViewPosition();
	    if (viewport == null) {
		p.x = 0;
	    } else {
		if (scrollpane.getComponentOrientation().isLeftToRight()) {
		    p.x = viewport.getViewPosition().x;
		} else {
		    p.x = Math.max(0, viewport.getViewPosition().x);
		}
	    }
	    newColHead.setViewPosition(p);
	    scrollpane.add(newColHead, COLUMN_HEADER);
	}
    }

    private void updateHorizontalScrollBar(PropertyChangeEvent pce) {
	updateScrollBar(pce, hsbChangeListener, hsbPropertyChangeListener);
    }

    private void updateVerticalScrollBar(PropertyChangeEvent pce) {
	updateScrollBar(pce, vsbChangeListener, vsbPropertyChangeListener);
    }

    private void updateScrollBar(PropertyChangeEvent pce, ChangeListener cl,
                                 PropertyChangeListener pcl) {
        JScrollBar sb = (JScrollBar)pce.getOldValue();
        if (sb != null) {
            if (cl != null) {
                sb.getModel().removeChangeListener(cl);
            }
            if (pcl != null) {
                sb.removePropertyChangeListener(pcl);
            }
        }
        sb = (JScrollBar)pce.getNewValue();
        if (sb != null) {
            if (cl != null) {
                sb.getModel().addChangeListener(cl);
            }
            if (pcl != null) {
                sb.addPropertyChangeListener(pcl);
            }
	}
    }

    public class PropertyChangeHandler implements PropertyChangeListener
    {
        public void propertyChange(PropertyChangeEvent e)
        {
            String propertyName = e.getPropertyName();

	    if (propertyName.equals("verticalScrollBarDisplayPolicy")) {
		updateScrollBarDisplayPolicy(e);
	    }
	    else if (propertyName.equals("horizontalScrollBarDisplayPolicy")) {
		updateScrollBarDisplayPolicy(e);
	    }
	    else if (propertyName.equals("viewport")) {
		updateViewport(e);
	    }
	    else if (propertyName.equals("rowHeader")) {
		updateRowHeader(e);
	    }
	    else if (propertyName.equals("columnHeader")) {
		updateColumnHeader(e);
	    }
	    else if (propertyName.equals("verticalScrollBar")) {
		updateVerticalScrollBar(e);
	    }
	    else if (propertyName.equals("horizontalScrollBar")) {
		updateHorizontalScrollBar(e);
	    }
	    else if (propertyName.equals("componentOrientation")) {
		scrollpane.revalidate();
		scrollpane.repaint();

		InputMap inputMap = getInputMap(JComponent.
					WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
		SwingUtilities.replaceUIInputMap(scrollpane, JComponent.
				WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, inputMap);

		UIManager.getLookAndFeelDefaults().put("ScrollPane.actionMap",
                                                       null);
		ActionMap actionMap = getActionMap();
		SwingUtilities.replaceUIActionMap(scrollpane, actionMap);
	    }
	}
    }



    /**
     * Creates an instance of PropertyChangeListener that's added to 
     * the JScrollPane by installUI().  Subclasses can override this method
     * to return a custom PropertyChangeListener, e.g.
     * <pre>
     * class MyScrollPaneUI extends BasicScrollPaneUI {
     *    protected PropertyChangeListener <b>createPropertyChangeListener</b>() {
     *        return new MyPropertyChangeListener();
     *    }
     *    public class MyPropertyChangeListener extends PropertyChangeListener {
     *        public void propertyChange(PropertyChangeEvent e) {
     *            if (e.getPropertyName().equals("viewport")) {
     *                // do some extra work when the viewport changes
     *            }
     *            super.propertyChange(e);
     *        }
     *    }
     * }
     * </pre>
     * 
     * @see java.beans.PropertyChangeListener
     * @see #installUI
     */
    protected PropertyChangeListener createPropertyChangeListener() {
        return new PropertyChangeHandler();
    }


    /**
     * Action to scroll left/right/up/down.
     */
    private static class ScrollAction extends AbstractAction {
	/** Direction to scroll. */
	protected int orientation;
	/** 1 indicates scroll down, -1 up. */
	protected int direction;
	/** True indicates a block scroll, otherwise a unit scroll. */
	private boolean block;

	protected ScrollAction(String name, int orientation, int direction,
			       boolean block) {
	    super(name);
	    this.orientation = orientation;
	    this.direction = direction;
	    this.block = block;
	}

	public void actionPerformed(ActionEvent e) {
	    JScrollPane scrollpane = (JScrollPane)e.getSource();
	    JViewport vp = scrollpane.getViewport();
	    Component view;
	    if (vp != null && (view = vp.getView()) != null) {
		Rectangle visRect = vp.getViewRect();
		Dimension vSize = view.getSize();
		int amount;

		if (view instanceof Scrollable) {
		    if (block) {
			amount = ((Scrollable)view).getScrollableBlockIncrement
			         (visRect, orientation, direction);
		    }
		    else {
			amount = ((Scrollable)view).getScrollableUnitIncrement
			         (visRect, orientation, direction);
		    }
		}
		else {
		    if (block) {
			if (orientation == SwingConstants.VERTICAL) {
			    amount = visRect.height;
			}
			else {
			    amount = visRect.width;
			}
		    }
		    else {
			amount = 10;
		    }
		}
		if (orientation == SwingConstants.VERTICAL) {
		    visRect.y += (amount * direction);
		    if ((visRect.y + visRect.height) > vSize.height) {
			visRect.y = Math.max(0, vSize.height - visRect.height);
		    }
		    else if (visRect.y < 0) {
			visRect.y = 0;
		    }
		}
		else {
		    if (scrollpane.getComponentOrientation().isLeftToRight()) {
			visRect.x += (amount * direction);
			if ((visRect.x + visRect.width) > vSize.width) {
			    visRect.x = Math.max(0, vSize.width - visRect.width);
			} else if (visRect.x < 0) {
			    visRect.x = 0;
			}
		    } else {
			visRect.x -= (amount * direction);
                        if (visRect.width > vSize.width) {
                            visRect.x = vSize.width - visRect.width;
                        } else {
                            visRect.x = Math.max(0, Math.min(vSize.width - visRect.width, visRect.x));
			}
		    }
		}
		vp.setViewPosition(visRect.getLocation());
	    }
	}
    }


    /**
     * Action to scroll to x,y location of 0,0.
     */
    private static class ScrollHomeAction extends AbstractAction {
	protected ScrollHomeAction(String name) {
	    super(name);
	}

	public void actionPerformed(ActionEvent e) {
	    JScrollPane scrollpane = (JScrollPane)e.getSource();
	    JViewport vp = scrollpane.getViewport();
	    Component view;
	    if (vp != null && (view = vp.getView()) != null) {
		if (scrollpane.getComponentOrientation().isLeftToRight()) {
		    vp.setViewPosition(new Point(0, 0));
		} else {
		    Rectangle visRect = vp.getViewRect();
		    Rectangle bounds = view.getBounds();
		    vp.setViewPosition(new Point(bounds.width - visRect.width, 0));
		}
	    }
	}
    }


    /**
     * Action to scroll to last visible location.
     */
    private static class ScrollEndAction extends AbstractAction {
	protected ScrollEndAction(String name) {
	    super(name);
	}

	public void actionPerformed(ActionEvent e) {
	    JScrollPane scrollpane = (JScrollPane)e.getSource();
	    JViewport vp = scrollpane.getViewport();
	    Component view;
	    if (vp != null && (view = vp.getView()) != null) {
		Rectangle visRect = vp.getViewRect();
		Rectangle bounds = view.getBounds();
		if (scrollpane.getComponentOrientation().isLeftToRight()) {
		    vp.setViewPosition(new Point(bounds.width - visRect.width,
					     bounds.height - visRect.height));
		} else {
		    vp.setViewPosition(new Point(0, 
					     bounds.height - visRect.height));
		}
	    }
	}
    }
}