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8  * particular file as subject to the "Classpath" exception as provided
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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).
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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      */
MouseInfo()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      */
getPointerInfo()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.AWT.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 
areScreenDevicesIndependent(GraphicsDevice[] gds)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      */
getNumberOfButtons()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 }
136