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/* * Copyright (c) 1999, 2007, 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. */ package sun.awt; import java.awt.*;import java.awt.event.InputEvent;import java.awt.event.InvocationEvent; /** * A stateless class which responds to native mouse moves, Component resizes, * Component moves, showing and hiding of Components, minimizing and * maximizing of top level Windows, addition and removal of Components, * and calls to setCursor(). */public abstract class GlobalCursorManager {     class NativeUpdater implements Runnable {        boolean pending = false;         public void run() {            boolean shouldUpdate = false;            synchronized (this) {                if (pending) {                    pending = false;                    shouldUpdate = true;                }            }            if (shouldUpdate) {                _updateCursor(false);            }        }         public void postIfNotPending(Component heavy, InvocationEvent in) {            boolean shouldPost = false;            synchronized (this) {                if (!pending) {                    pending = shouldPost = true;                }            }            if (shouldPost) {                SunToolkit.postEvent(SunToolkit.targetToAppContext(heavy), in);            }        }    }     /**     * Use a singleton NativeUpdater for better performance. We cannot use     * a singleton InvocationEvent because we want each event to have a fresh     * timestamp.     */    private final NativeUpdater nativeUpdater = new NativeUpdater();     /**     * The last time the cursor was updated, in milliseconds.     */    private long lastUpdateMillis;     /**     * Locking object for synchronizing access to lastUpdateMillis. The VM     * does not guarantee atomicity of longs.     */    private final Object lastUpdateLock = new Object();     /**     * Should be called for any activity at the Java level which may affect     * the global cursor, except for Java MOUSE_MOVED events.     */    public void updateCursorImmediately() {        synchronized (nativeUpdater) {            nativeUpdater.pending = false;        }        _updateCursor(false);    }     /**     * Should be called in response to Java MOUSE_MOVED events. The update     * will be discarded if the InputEvent is outdated.     *     * @param   e the InputEvent which triggered the cursor update.     */    public void updateCursorImmediately(InputEvent e) {        boolean shouldUpdate;        synchronized (lastUpdateLock) {            shouldUpdate = (e.getWhen() >= lastUpdateMillis);        }        if (shouldUpdate) {            _updateCursor(true);        }    }     /**     * Should be called in response to a native mouse enter or native mouse     * button released message. Should not be called during a mouse drag.     */    public void updateCursorLater(Component heavy) {        nativeUpdater.postIfNotPending(heavy, new InvocationEvent            (Toolkit.getDefaultToolkit(), nativeUpdater));    }     protected GlobalCursorManager() { }     /**     * Set the global cursor to the specified cursor. The component over     * which the Cursor current resides is provided as a convenience. Not     * all platforms may require the Component.     */    protected abstract void setCursor(Component comp, Cursor cursor,                                      boolean useCache);    /**     * Returns the global cursor position, in screen coordinates.     */    protected abstract void getCursorPos(Point p);     protected abstract Component findComponentAt(Container con, int x, int y);    protected abstract Point getLocationOnScreen(Component com);     /**     * Returns the most specific, visible, heavyweight Component     * under the cursor. This method should return null iff the cursor is     * not over any Java Window.     *     * @param   useCache If true, the implementation is free to use caching     * mechanisms because the Z-order, visibility, and enabled state of the     * Components has not changed. If false, the implementation should not     * make these assumptions.     */    protected abstract Component findHeavyweightUnderCursor(boolean useCache);     /**     * Updates the global cursor. We apply a three-step scheme to cursor     * updates:<p>     *     * (1) InputEvent updates which are outdated are discarded by     * <code>updateCursorImmediately(InputEvent)</code>.<p>     *     * (2) If 'useCache' is true, the native code is free to use a cached     * value to determine the most specific, visible, enabled heavyweight     * because this update is occuring in response to a mouse move. If     * 'useCache' is false, the native code must perform a new search given     * the current mouse coordinates.     *     * (3) Once we have determined the most specific, visible, enabled     * heavyweight, we use findComponentAt to find the most specific, visible,     * enabled Component.     */    private void _updateCursor(boolean useCache) {         synchronized (lastUpdateLock) {            lastUpdateMillis = System.currentTimeMillis();        }         Point queryPos = null, p = null;        Component comp;         try {            comp = findHeavyweightUnderCursor(useCache);            if (comp == null) {                updateCursorOutOfJava();                return;            }             if (comp instanceof Window) {                p = AWTAccessor.getComponentAccessor().getLocation(comp);            } else if (comp instanceof Container) {                p = getLocationOnScreen(comp);            }            if (p != null) {                queryPos = new Point();                getCursorPos(queryPos);                Component c = findComponentAt((Container)comp,                                              queryPos.x - p.x,                                              queryPos.y - p.y);                // If findComponentAt returns null, then something bad has                // happened. For example, the heavyweight Component may                // have been hidden or disabled by another thread. In that                // case, we'll just use the originial heavyweight.                if (c != null) {                    comp = c;                }            }             setCursor(comp, AWTAccessor.getComponentAccessor().getCursor(comp), useCache);         } catch (IllegalComponentStateException e) {            // Shouldn't happen, but if it does, abort.        }    }     protected void updateCursorOutOfJava() {        // Cursor is not over a Java Window. Do nothing...usually        // But we need to update it in case of grab on X.    }}