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25 
26 package java.awt;
27 
28 import sun.awt.AWTPermissions;
29 import sun.awt.ComponentFactory;
30 
31 /**
32  * {@code MouseInfo}  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      */
MouseInfo()44     private MouseInfo() {
45     }
46 
47     /**
48      * Returns a {@code PointerInfo} instance that represents the current
49      * location of the mouse pointer.
50      * The {@code GraphicsDevice} stored in this {@code PointerInfo}
51      * contains the mouse pointer. The coordinate system used for the mouse position
52      * depends on whether or not the {@code GraphicsDevice} 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}. See {@link GraphicsConfiguration}
57      * for more information about the virtual screen devices.
58      * On systems without a mouse, returns {@code null}.
59      * <p>
60      * If there is a security manager, its {@code checkPermission} method
61      * is called with an {@code AWTPermission("watchMousePointer")}
62      * permission before creating and returning a {@code PointerInfo}
63      * object. This may result in a {@code SecurityException}.
64      *
65      * @exception HeadlessException if GraphicsEnvironment.isHeadless() returns true
66      * @exception SecurityException if a security manager exists and its
67      *            {@code checkPermission} 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      */
getPointerInfo()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 
areScreenDevicesIndependent(GraphicsDevice[] gds)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}.
122      * The number of buttons is obtained from the AWT Toolkit
123      * by requesting the {@code "awt.mouse.numButtons"} desktop property
124      * which is set by the underlying native platform.
125      *
126      * @exception HeadlessException if GraphicsEnvironment.isHeadless() returns true
127      * @return number of buttons on the mouse
128      * @see Toolkit#getDesktopProperty
129      * @since 1.5
130      */
getNumberOfButtons()131     public static int getNumberOfButtons() throws HeadlessException {
132         if (GraphicsEnvironment.isHeadless()) {
133             throw new HeadlessException();
134         }
135         Object prop = Toolkit.getDefaultToolkit().
136                               getDesktopProperty("awt.mouse.numButtons");
137         if (prop instanceof Integer) {
138             return ((Integer)prop).intValue();
139         }
140 
141         // This should never happen.
142         assert false : "awt.mouse.numButtons is not an integer property";
143         return 0;
144     }
145 
146 }
147