1 /*
   2  * Copyright (c) 2011, 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.SunToolkit;
  36 
  37 public abstract class LWCursorManager {
  38 
  39     /**
  40      * A flag to indicate if the update is scheduled, so we don't process it
  41      * twice.
  42      */
  43     private final AtomicBoolean updatePending = new AtomicBoolean(false);
  44 
  45     protected LWCursorManager() {
  46     }
  47 
  48     /**
  49      * Sets the cursor to correspond the component currently under mouse.
  50      *
  51      * This method should not be executed on the toolkit thread as it
  52      * calls to user code (e.g. Container.findComponentAt).
  53      */
  54     public final void updateCursor() {
  55         updatePending.set(false);
  56         updateCursorImpl();
  57     }
  58 
  59     /**
  60      * Schedules updating the cursor on the corresponding event dispatch
  61      * thread for the given window.
  62      *
  63      * This method is called on the toolkit thread as a result of a
  64      * native update cursor request (e.g. WM_SETCURSOR on Windows).
  65      */
  66     public final void updateCursorLater(final LWWindowPeer window) {
  67         if (updatePending.compareAndSet(false, true)) {
  68             Runnable r = new Runnable() {
  69                 @Override
  70                 public void run() {
  71                     updateCursor();
  72                 }
  73             };
  74             SunToolkit.executeOnEventHandlerThread(window.getTarget(), r);
  75         }
  76     }
  77 
  78     private void updateCursorImpl() {
  79         final Point cursorPos = getCursorPosition();
  80         final Component c = findComponent(cursorPos);
  81         final Cursor cursor;
  82         final Object peer = LWToolkit.targetToPeer(c);
  83         if (peer instanceof LWComponentPeer) {
  84             final LWComponentPeer<?, ?> lwpeer = (LWComponentPeer<?, ?>) peer;
  85             final Point p = lwpeer.getLocationOnScreen();
  86             cursor = lwpeer.getCursor(new Point(cursorPos.x - p.x,
  87                                                 cursorPos.y - p.y));
  88         } else {
  89             cursor = (c != null) ? c.getCursor() : null;
  90         }
  91         // TODO: default cursor for modal blocked windows
  92         setCursor(cursor);
  93     }
  94 
  95     /**
  96      * Returns the first visible, enabled and showing component under cursor.
  97      *
  98      * @param cursorPos Current cursor position.
  99      * @return Component
 100      */
 101     private static final Component findComponent(final Point cursorPos) {
 102         final LWComponentPeer<?, ?> peer = LWWindowPeer.getPeerUnderCursor();
 103         Component c = null;
 104         if (peer != null) {
 105             c = peer.getTarget();
 106             if (c instanceof Container) {
 107                 final Point p = peer.getLocationOnScreen();
 108                 c = ((Container) c).findComponentAt(cursorPos.x - p.x,
 109                                                     cursorPos.y - p.y);
 110             }

 111             while (c != null) {
 112                 if (c.isVisible() && c.isEnabled() && (c.getPeer() != null)) {
 113                     break;
 114                 }
 115                 c = c.getParent();
 116             }


 117         }
 118         return c;


 119     }
 120 
 121     /**
 122      * Returns the current cursor position.
 123      */
 124     // TODO: make it public to reuse for MouseInfo
 125     protected abstract Point getCursorPosition();
 126 
 127     /**
 128      * Sets a cursor. The cursor can be null if the mouse is not over a Java
 129      * window.
 130      * @param cursor the new {@code Cursor}.
 131      */
 132     protected abstract void setCursor(Cursor cursor);

 133 }
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