1 /*
   2  * Copyright 2003 Sun Microsystems, Inc.  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.  Sun designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  22  * CA 95054 USA or visit www.sun.com if you need additional information or
  23  * have any questions.
  24  */
  25 
  26 package java.awt;
  27 
  28 import sun.security.util.SecurityConstants;
  29 /**
  30  * <code>MouseInfo</code>  provides methods for getting information about the mouse,
  31  * such as mouse pointer location and the number of mouse buttons.
  32  *
  33  * @author     Roman Poborchiy
  34  * @since 1.5
  35  */
  36 
  37 public class MouseInfo {
  38 
  39     /**
  40      * Private constructor to prevent instantiation.
  41      */
  42     private MouseInfo() {
  43     }
  44 
  45     /**
  46      * Returns a <code>PointerInfo</code> instance that represents the current
  47      * location of the mouse pointer.
  48      * The <code>GraphicsDevice</code> stored in this <code>PointerInfo</code>
  49      * contains the mouse pointer. The coordinate system used for the mouse position
  50      * depends on whether or not the <code>GraphicsDevice</code> is part of a virtual
  51      * screen device.
  52      * For virtual screen devices, the coordinates are given in the virtual
  53      * coordinate system, otherwise they are returned in the coordinate system
  54      * of the <code>GraphicsDevice</code>. See {@link GraphicsConfiguration}
  55      * for more information about the virtual screen devices.
  56      * On systems without a mouse, returns <code>null</code>.
  57      * <p>
  58      * If there is a security manager, its <code>checkPermission</code> method
  59      * is called with an <code>AWTPermission("watchMousePointer")</code>
  60      * permission before creating and returning a <code>PointerInfo</code>
  61      * object. This may result in a <code>SecurityException</code>.
  62      *
  63      * @exception HeadlessException if GraphicsEnvironment.isHeadless() returns true
  64      * @exception SecurityException if a security manager exists and its
  65      *            <code>checkPermission</code> method doesn't allow the operation
  66      * @see       GraphicsConfiguration
  67      * @see       SecurityManager#checkPermission
  68      * @see       java.awt.AWTPermission
  69      * @return    location of the mouse pointer
  70      * @since     1.5
  71      */
  72     public static PointerInfo getPointerInfo() throws HeadlessException {
  73         if (GraphicsEnvironment.isHeadless()) {
  74             throw new HeadlessException();
  75         }
  76 
  77         SecurityManager security = System.getSecurityManager();
  78         if (security != null) {
  79             security.checkPermission(SecurityConstants.WATCH_MOUSE_PERMISSION);
  80         }
  81 
  82         Point point = new Point(0, 0);
  83         int deviceNum = Toolkit.getDefaultToolkit().getMouseInfoPeer().fillPointWithCoords(point);
  84         GraphicsDevice[] gds = GraphicsEnvironment.getLocalGraphicsEnvironment().
  85                                    getScreenDevices();
  86         PointerInfo retval = null;
  87         if (areScreenDevicesIndependent(gds)) {
  88             retval = new PointerInfo(gds[deviceNum], point);
  89         } else {
  90             for (int i = 0; i < gds.length; i++) {
  91                 GraphicsConfiguration gc = gds[i].getDefaultConfiguration();
  92                 Rectangle bounds = gc.getBounds();
  93                 if (bounds.contains(point)) {
  94                     retval = new PointerInfo(gds[i], point);
  95                 }
  96             }
  97         }
  98 
  99         return retval;
 100     }
 101 
 102     private static boolean areScreenDevicesIndependent(GraphicsDevice[] gds) {
 103         for (int i = 0; i < gds.length; i++) {
 104             Rectangle bounds = gds[i].getDefaultConfiguration().getBounds();
 105             if (bounds.x != 0 || bounds.y != 0) {
 106                 return false;
 107             }
 108         }
 109         return true;
 110     }
 111 
 112     /**
 113      * Returns the number of buttons on the mouse.
 114      * On systems without a mouse, returns <code>-1</code>.
 115      *
 116      * @exception HeadlessException if GraphicsEnvironment.isHeadless() returns true
 117      * @return number of buttons on the mouse
 118      * @since 1.5
 119      */
 120     public static int getNumberOfButtons() throws HeadlessException {
 121         if (GraphicsEnvironment.isHeadless()) {
 122             throw new HeadlessException();
 123         }
 124         Object prop = Toolkit.getDefaultToolkit().
 125                               getDesktopProperty("awt.mouse.numButtons");
 126         if (prop instanceof Integer) {
 127             return ((Integer)prop).intValue();
 128         }
 129 
 130         // This should never happen.
 131         assert false : "awt.mouse.numButtons is not an integer property";
 132         return 0;
 133     }
 134 
 135 }