basicscrollpaneui.java

java1.6众多例子参考

                if (baseline > 0) {
                    return y + baseline;
                }
            }
        }
        return -1;
    }

    /**
     * Returns an enum indicating how the baseline of the component
     * changes as the size changes.
     *
     * @throws NullPointerException {@inheritDoc}
     * @see javax.swing.JComponent#getBaseline(int, int)
     * @since 1.6
     */
    public Component.BaselineResizeBehavior getBaselineResizeBehavior(
            JComponent c) {
        super.getBaselineResizeBehavior(c);
        // Baseline is either from the header, in which case it's always
        // the same size and therefor can be created as CONSTANT_ASCENT.
        // If the header doesn't have a baseline than the baseline will only
        // be valid if it's BaselineResizeBehavior is
        // CONSTANT_ASCENT, so, return CONSTANT_ASCENT.
        return Component.BaselineResizeBehavior.CONSTANT_ASCENT;
    }


    /**
     * Listener for viewport events.
     */
    public class ViewportChangeHandler implements ChangeListener
    {

        // NOTE: This class exists only for backward compatability. All
        // its functionality has been moved into Handler. If you need to add
        // new functionality add it to the Handler, but make sure this      
        // class calls into the Handler.

	public void stateChanged(ChangeEvent e) {
            getHandler().stateChanged(e);
	}
    }

    protected ChangeListener createViewportChangeListener() {
	return getHandler();
    }


    /**
     * Horizontal scrollbar listener.
     */
    public class HSBChangeListener implements ChangeListener
    {

        // NOTE: This class exists only for backward compatability. All
        // its functionality has been moved into Handler. If you need to add
        // new functionality add it to the Handler, but make sure this      
        // class calls into the Handler.

	public void stateChanged(ChangeEvent e)
	{
            getHandler().stateChanged(e);
	}
    }

    /**
     * Returns a <code>PropertyChangeListener</code> that will be installed
     * on the horizontal <code>JScrollBar</code>.
     */
    private PropertyChangeListener createHSBPropertyChangeListener() {
        return getHandler();
    }

    protected ChangeListener createHSBChangeListener() {
	return getHandler();
    }


    /**
     * Vertical scrollbar listener.
     */
    public class VSBChangeListener implements ChangeListener
    {

        // NOTE: This class exists only for backward compatability. All
        // its functionality has been moved into Handler. If you need to add
        // new functionality add it to the Handler, but make sure this      
        // class calls into the Handler.

	public void stateChanged(ChangeEvent e)
	{
            getHandler().stateChanged(e);
	}
    }


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

    protected ChangeListener createVSBChangeListener() {
	return getHandler();
    }

    /**
     * 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 {

        // NOTE: This class exists only for backward compatability. All
        // its functionality has been moved into Handler. If you need to add
        // new functionality add it to the Handler, but make sure this      
        // class calls into the Handler.

        /**
         * 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) {
            getHandler().mouseWheelMoved(e);
        }
    }

    /**
     * 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 getHandler();
    }

    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
    {

        // NOTE: This class exists only for backward compatability. All
        // its functionality has been moved into Handler. If you need to add
        // new functionality add it to the Handler, but make sure this      
        // class calls into the Handler.

        public void propertyChange(PropertyChangeEvent e)
        {
            getHandler().propertyChange(e);
	}
    }



    /**
     * 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 getHandler();
    }


    private static class Actions extends UIAction {
        private static final String SCROLL_UP = "scrollUp";
        private static final String SCROLL_DOWN = "scrollDown";
        private static final String SCROLL_HOME = "scrollHome";
        private static final String SCROLL_END = "scrollEnd";
        private static final String UNIT_SCROLL_UP = "unitScrollUp";
        private static final String UNIT_SCROLL_DOWN = "unitScrollDown";
        private static final String SCROLL_LEFT = "scrollLeft";
        private static final String SCROLL_RIGHT = "scrollRight";
        private static final String UNIT_SCROLL_LEFT = "unitScrollLeft";
        private static final String UNIT_SCROLL_RIGHT = "unitScrollRight";


        Actions(String key) {
            super(key);
        }

        public void actionPerformed(ActionEvent e) {
            JScrollPane scrollPane = (JScrollPane)e.getSource();
            boolean ltr = scrollPane.getComponentOrientation().isLeftToRight();
            String key = getName();

            if (key == SCROLL_UP) {
                scroll(scrollPane, SwingConstants.VERTICAL, -1, true);
            }
            else if (key == SCROLL_DOWN) {
                scroll(scrollPane, SwingConstants.VERTICAL, 1, true);
            }
            else if (key == SCROLL_HOME) {
                scrollHome(scrollPane);
            }
            else if (key == SCROLL_END) {
                scrollEnd(scrollPane);
            }
            else if (key == UNIT_SCROLL_UP) {
                scroll(scrollPane, SwingConstants.VERTICAL, -1, false);
            }
            else if (key == UNIT_SCROLL_DOWN) {
                scroll(scrollPane, SwingConstants.VERTICAL, 1, false);
            }
            else if (key == SCROLL_LEFT) {
                scroll(scrollPane, SwingConstants.HORIZONTAL, ltr ? -1 : 1,
                       true);
            }
            else if (key == SCROLL_RIGHT) {
                scroll(scrollPane, SwingConstants.HORIZONTAL, ltr ? 1 : -1,
                       true);
            }
            else if (key == UNIT_SCROLL_LEFT) {
                scroll(scrollPane, SwingConstants.HORIZONTAL, ltr ? -1 : 1,
                       false);
            }
            else if (key == UNIT_SCROLL_RIGHT) {
                scroll(scrollPane, SwingConstants.HORIZONTAL, ltr ? 1 : -1,
                       false);
            }
        }

        private void scrollEnd(JScrollPane scrollpane) {
	    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));
		}
	    }
        }

        private void scrollHome(JScrollPane scrollpane) {
	    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));
		}
            }
        }

	private void scroll(JScrollPane scrollpane, int orientation,