1 /*
   2  * Copyright (c) 2003, 2015, 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 java.awt;
  27 
  28 import sun.awt.AWTPermissions;
  29 import sun.awt.ComponentFactory;
  30 
  31 /**
  32  * <code>MouseInfo</code>  provides methods for getting information about the mouse,
  33  * such as mouse pointer location and the number of mouse buttons.
  34  *
  35  * @author     Roman Poborchiy
  36  * @since 1.5
  37  */
  38 
  39 public class MouseInfo {
  40 
  41     /**
  42      * Private constructor to prevent instantiation.
  43      */
  44     private MouseInfo() {
  45     }
  46 
  47     /**
  48      * Returns a <code>PointerInfo</code> instance that represents the current
  49      * location of the mouse pointer.
  50      * The <code>GraphicsDevice</code> stored in this <code>PointerInfo</code>
  51      * contains the mouse pointer. The coordinate system used for the mouse position
  52      * depends on whether or not the <code>GraphicsDevice</code> is part of a virtual
  53      * screen device.
  54      * For virtual screen devices, the coordinates are given in the virtual
  55      * coordinate system, otherwise they are returned in the coordinate system
  56      * of the <code>GraphicsDevice</code>. See {@link GraphicsConfiguration}
  57      * for more information about the virtual screen devices.
  58      * On systems without a mouse, returns <code>null</code>.
  59      * <p>
  60      * If there is a security manager, its <code>checkPermission</code> method
  61      * is called with an <code>AWTPermission("watchMousePointer")</code>
  62      * permission before creating and returning a <code>PointerInfo</code>
  63      * object. This may result in a <code>SecurityException</code>.
  64      *
  65      * @exception HeadlessException if GraphicsEnvironment.isHeadless() returns true
  66      * @exception SecurityException if a security manager exists and its
  67      *            <code>checkPermission</code> method doesn't allow the operation
  68      * @see       GraphicsConfiguration
  69      * @see       SecurityManager#checkPermission
  70      * @see       java.awt.AWTPermission
  71      * @return    location of the mouse pointer
  72      * @since     1.5
  73      */
  74     public static PointerInfo getPointerInfo() throws HeadlessException {
  75         if (GraphicsEnvironment.isHeadless()) {
  76             throw new HeadlessException();
  77         }
  78 
  79         SecurityManager security = System.getSecurityManager();
  80         if (security != null) {
  81             security.checkPermission(AWTPermissions.WATCH_MOUSE_PERMISSION);
  82         }
  83 
  84         Toolkit toolkit = Toolkit.getDefaultToolkit();
  85         Point point = new Point(0, 0);
  86         int deviceNum = 0;
  87         if (toolkit instanceof ComponentFactory) {
  88             deviceNum = ((ComponentFactory) toolkit).getMouseInfoPeer().fillPointWithCoords(point);
  89         }
  90 
  91         GraphicsDevice[] gds = GraphicsEnvironment.getLocalGraphicsEnvironment().
  92                                    getScreenDevices();
  93         PointerInfo retval = null;
  94         if (areScreenDevicesIndependent(gds)) {
  95             retval = new PointerInfo(gds[deviceNum], point);
  96         } else {
  97             for (int i = 0; i < gds.length; i++) {
  98                 GraphicsConfiguration gc = gds[i].getDefaultConfiguration();
  99                 Rectangle bounds = gc.getBounds();
 100                 if (bounds.contains(point)) {
 101                     retval = new PointerInfo(gds[i], point);
 102                 }
 103             }
 104         }
 105 
 106         return retval;
 107     }
 108 
 109     private static boolean areScreenDevicesIndependent(GraphicsDevice[] gds) {
 110         for (int i = 0; i < gds.length; i++) {
 111             Rectangle bounds = gds[i].getDefaultConfiguration().getBounds();
 112             if (bounds.x != 0 || bounds.y != 0) {
 113                 return false;
 114             }
 115         }
 116         return true;
 117     }
 118 
 119     /**
 120      * Returns the number of buttons on the mouse.
 121      * On systems without a mouse, returns <code>-1</code>.
 122      *
 123      * @exception HeadlessException if GraphicsEnvironment.isHeadless() returns true
 124      * @return number of buttons on the mouse
 125      * @since 1.5
 126      */
 127     public static int getNumberOfButtons() throws HeadlessException {
 128         if (GraphicsEnvironment.isHeadless()) {
 129             throw new HeadlessException();
 130         }
 131         Object prop = Toolkit.getDefaultToolkit().
 132                               getDesktopProperty("awt.mouse.numButtons");
 133         if (prop instanceof Integer) {
 134             return ((Integer)prop).intValue();
 135         }
 136 
 137         // This should never happen.
 138         assert false : "awt.mouse.numButtons is not an integer property";
 139         return 0;
 140     }
 141 
 142 }