Autoscroller.java

/*
 * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation. Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

packagejavax.swing;

importjava.awt.*;
importjava.awt.event.*;

importsun.awt.AWTAccessor;
importsun.awt.AWTAccessor.MouseEventAccessor;

/**
 * Autoscroller is responsible for generating synthetic mouse dragged
 * events. It is the responsibility of the Component (or its MouseListeners)
 * that receive the events to do the actual scrolling in response to the
 * mouse dragged events.
 *
 * @author Dave Moore
 * @author Scott Violet
 */
classAutoscrollerimplementsActionListener {
/**
 * Global Autoscroller.
 */
privatestaticAutoscrollersharedInstance = newAutoscroller();

// As there can only ever be one autoscroller active these fields are
// static. The Timer is recreated as necessary to target the appropriate
// Autoscroller instance.
privatestaticMouseEventevent;
privatestaticTimertimer;
privatestaticJComponentcomponent;

//
// The public API, all methods are cover methods for an instance method
//
/**
 * Stops autoscroll events from happening on the specified component.
 */
publicstaticvoidstop(JComponentc) {
sharedInstance._stop(c);
 }

/**
 * Stops autoscroll events from happening on the specified component.
 */
publicstaticbooleanisRunning(JComponentc) {
returnsharedInstance._isRunning(c);
 }

/**
 * Invoked when a mouse dragged event occurs, will start the autoscroller
 * if necessary.
 */
publicstaticvoidprocessMouseDragged(MouseEvente) {
sharedInstance._processMouseDragged(e);
 }


Autoscroller() {
 }

/**
 * Starts the timer targeting the passed in component.
 */
@SuppressWarnings("deprecation")
privatevoidstart(JComponentc, MouseEvente) {
PointscreenLocation = c.getLocationOnScreen();

if (component != c) {
_stop(component);
 }
component = c;
event = newMouseEvent(component, e.getID(), e.getWhen(),
e.getModifiers(), e.getX() + screenLocation.x,
e.getY() + screenLocation.y,
e.getXOnScreen(),
e.getYOnScreen(),
e.getClickCount(), e.isPopupTrigger(),
MouseEvent.NOBUTTON);
MouseEventAccessormeAccessor = AWTAccessor.getMouseEventAccessor();
meAccessor.setCausedByTouchEvent(event,
meAccessor.isCausedByTouchEvent(e));

if (timer == null) {
timer = newTimer(100, this);
 }

if (!timer.isRunning()) {
timer.start();
 }
 }

//
// Methods mirror the public static API
//

/**
 * Stops scrolling for the passed in widget.
 */
privatevoid_stop(JComponentc) {
if (component == c) {
if (timer != null) {
timer.stop();
 }
timer = null;
event = null;
component = null;
 }
 }

/**
 * Returns true if autoscrolling is currently running for the specified
 * widget.
 */
privateboolean_isRunning(JComponentc) {
return (c == component && timer != null && timer.isRunning());
 }

/**
 * MouseListener method, invokes start/stop as necessary.
 */
privatevoid_processMouseDragged(MouseEvente) {
JComponentcomponent = (JComponent)e.getComponent();
booleanstop = true;
if (component.isShowing()) {
RectanglevisibleRect = component.getVisibleRect();
stop = visibleRect.contains(e.getX(), e.getY());
 }
if (stop) {
_stop(component);
 } else {
start(component, e);
 }
 }

//
// ActionListener
//
/**
 * ActionListener method. Invoked when the Timer fires. This will scroll
 * if necessary.
 */
@SuppressWarnings("deprecation")
publicvoidactionPerformed(ActionEventx) {
JComponentcomponent = Autoscroller.component;

if (component == null || !component.isShowing() || (event == null)) {
_stop(component);
return;
 }
PointscreenLocation = component.getLocationOnScreen();
MouseEvente = newMouseEvent(component, event.getID(),
event.getWhen(), event.getModifiers(),
event.getX() - screenLocation.x,
event.getY() - screenLocation.y,
event.getXOnScreen(),
event.getYOnScreen(),
event.getClickCount(),
event.isPopupTrigger(),
MouseEvent.NOBUTTON);
MouseEventAccessormeAccessor = AWTAccessor.getMouseEventAccessor();
meAccessor.setCausedByTouchEvent(e,
meAccessor.isCausedByTouchEvent(event));
component.superProcessMouseMotionEvent(e);
 }

}