1 /*
   2  * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.lwawt;
  27 
  28 import java.awt.Component;
  29 import java.awt.Container;
  30 import java.awt.Cursor;
  31 import java.awt.Point;
  32 
  33 import java.util.concurrent.atomic.AtomicBoolean;
  34 
  35 import sun.awt.AWTAccessor;
  36 import sun.awt.SunToolkit;
  37 
  38 public abstract class LWCursorManager {
  39 
  40     /**
  41      * A flag to indicate if the update is scheduled, so we don't process it
  42      * twice.
  43      */
  44     private final AtomicBoolean updatePending = new AtomicBoolean(false);
  45 
  46     protected LWCursorManager() {
  47     }
  48 
  49     /**
  50      * Sets the cursor to correspond the component currently under mouse.
  51      *
  52      * This method should not be executed on the toolkit thread as it
  53      * calls to user code (e.g. Container.findComponentAt).
  54      */
  55     public final void updateCursor() {
  56         updatePending.set(false);
  57         updateCursorImpl();
  58     }
  59 
  60     /**
  61      * Schedules updating the cursor on the corresponding event dispatch
  62      * thread for the given window.
  63      *
  64      * This method is called on the toolkit thread as a result of a
  65      * native update cursor request (e.g. WM_SETCURSOR on Windows).
  66      */
  67     public final void updateCursorLater(final LWWindowPeer window) {
  68         if (updatePending.compareAndSet(false, true)) {
  69             Runnable r = new Runnable() {
  70                 @Override
  71                 public void run() {
  72                     updateCursor();
  73                 }
  74             };
  75             SunToolkit.executeOnEventHandlerThread(window.getTarget(), r);
  76         }
  77     }
  78 
  79     private void updateCursorImpl() {
  80         final Point cursorPos = getCursorPosition();
  81         final Component c = findComponent(cursorPos);
  82         final Cursor cursor;
  83         final Object peer = LWToolkit.targetToPeer(c);
  84         if (peer instanceof LWComponentPeer) {
  85             final LWComponentPeer<?, ?> lwpeer = (LWComponentPeer<?, ?>) peer;
  86             final Point p = lwpeer.getLocationOnScreen();
  87             cursor = lwpeer.getCursor(new Point(cursorPos.x - p.x,
  88                                                 cursorPos.y - p.y));
  89         } else {
  90             cursor = (c != null) ? c.getCursor() : null;
  91         }
  92         setCursor(cursor);
  93     }
  94 
  95     /**
  96      * Returns the first visible, enabled and showing component under cursor.
  97      * Returns null for modal blocked windows.
  98      *
  99      * @param cursorPos Current cursor position.
 100      * @return Component or null.
 101      */
 102     private static final Component findComponent(final Point cursorPos) {
 103         final LWComponentPeer<?, ?> peer = LWWindowPeer.getPeerUnderCursor();
 104         Component c = null;
 105         if (peer != null && peer.getWindowPeerOrSelf().getBlocker() == null) {
 106             c = peer.getTarget();
 107             if (c instanceof Container) {
 108                 final Point p = peer.getLocationOnScreen();
 109                 c = ((Container) c).findComponentAt(cursorPos.x - p.x,
 110                                                     cursorPos.y - p.y);
 111             }
 112             while (c != null) {
 113                 final Object p = AWTAccessor.getComponentAccessor().getPeer(c);
 114                 if (c.isVisible() && c.isEnabled() && p != null) {
 115                     break;
 116                 }
 117                 c = c.getParent();
 118             }
 119         }
 120         return c;
 121     }
 122 
 123     /**
 124      * Returns the current cursor position.
 125      */
 126     // TODO: make it public to reuse for MouseInfo
 127     protected abstract Point getCursorPosition();
 128 
 129     /**
 130      * Sets a cursor. The cursor can be null if the mouse is not over a Java
 131      * window.
 132      * @param cursor the new {@code Cursor}.
 133      */
 134     protected abstract void setCursor(Cursor cursor);
 135 }