Window


1   /*
2    * Copyright 2007 Google Inc.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5    * use this file except in compliance with the License. You may obtain a copy of
6    * the License at
7    * 
8    * http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations under
14   * the License.
15   */
16  package com.google.gwt.user.client;
17  
18  import com.google.gwt.core.client.GWT;
19  import com.google.gwt.core.client.GWT.UncaughtExceptionHandler;
20  
21  import java.util.ArrayList  ;
22  import java.util.Iterator  ;
23  
24  /**
25   * This class provides access to the browser window's methods, properties, and
26   * events.
27   */
28  public class Window {
29  
30    private static ArrayList   closingListeners = new ArrayList  ();
31    private static ArrayList   resizeListeners = new ArrayList  ();
32  
33    static {
34      init();
35    }
36  
37    /**
38     * Adds a listener to receive window closing events.
39     * 
40     * @param listener the listener to be informed when the window is closing
41     */
42    public static void addWindowCloseListener(WindowCloseListener listener) {
43      closingListeners.add(listener);
44    }
45  
46    /**
47     * Adds a listener to receive window resize events.
48     * 
49     * @param listener the listener to be informed when the window is resized
50     */
51    public static void addWindowResizeListener(WindowResizeListener listener) {
52      resizeListeners.add(listener);
53    }
54  
55    /**
56     * Displays a message in a modal dialog box.
57     * 
58     * @param msg the message to be displayed.
59     */
60    public static native void alert(String   msg) /*-{
61      $wnd.alert(msg);
62    }-*/;
63  
64    /**
65     * Displays a message in a modal dialog box, along with the standard 'OK' and
66     * 'Cancel' buttons.
67     * 
68     * @param msg the message to be displayed.
69     * @return <code>true</code> if 'OK' is clicked, <code>false</code> if
70     *         'Cancel' is clicked.
71     */
72    public static native boolean confirm(String   msg) /*-{
73      return $wnd.confirm(msg);
74    }-*/;
75  
76    /**
77     * Use this method to explicitly disable the window's scrollbars. Applications
78     * that choose to resize their user-interfaces to fit within the window's
79     * client area will normally want to disable window scrolling.
80     * 
81     * @param enable <code>false</code> to disable window scrolling
82     */
83    public static native void enableScrolling(boolean enable) /*-{
84      $doc.body.style.overflow = enable ? 'auto' : 'hidden';
85    }-*/;
86  
87    /**
88     * Gets the height of the browser window's client area.
89     * 
90     * @return the window's client height
91     */
92    public static native int getClientHeight() /*-{
93      // Non-IE browsers || IE standard mode || IE quirks mode.
94      return $wnd.innerHeight || $doc.documentElement.clientHeight || 
95          $doc.body.clientHeight;
96    }-*/;
97  
98    /**
99     * Gets the width of the browser window's client area.
100    * 
101    * @return the window's client width
102    */
103   public static native int getClientWidth() /*-{
104     // Non-IE browsers || IE standard mode || IE quirks mode.
105     return $wnd.innerWidth || $doc.documentElement.clientWidth || $doc.body.clientWidth;
106   }-*/;
107 
108   /**
109    * Gets the window's scroll left.
110    * 
111    * @return window's scroll left
112    */
113   public static native int getScrollLeft() /*-{
114     // Standard mode || Quirks mode.  
115     return $doc.documentElement.scrollLeft || $doc.body.scrollLeft
116   }-*/;
117 
118   /**
119    * Get the window's scroll top.
120    * 
121    * @return the window's scroll top
122    */
123   public static native int getScrollTop() /*-{
124     // Standard mode || Quirks mode. 
125     return $doc.documentElement.scrollTop || $doc.body.scrollTop;
126   }-*/;
127 
128   /**
129    * Gets the browser window's current title.
130    * 
131    * @return the window's title.
132    */
133   public static native String   getTitle() /*-{
134     return $doc.title;
135   }-*/;
136 
137   /**
138    * Opens a new browser window. The "name" and "features" arguments are
139    * specified <a HREF=
140    * 'http://www.mozilla.org/docs/dom/domref/dom_window_ref76.html'>here</a>.
141    * 
142    * @param url the URL that the new window will display
143    * @param name the name of the window (e.g. "_blank")
144    * @param features the features to be enabled/disabled on this window
145    */
146   public static native void open(String   url, String   name, String   features) /*-{
147     $wnd.open(url, name, features);
148   }-*/;
149 
150   /**
151    * Displays a request for information in a modal dialog box, along with the
152    * standard 'OK' and 'Cancel' buttons.
153    * 
154    * @param msg the message to be displayed
155    * @param initialValue the initial value in the dialog's text field
156    * @return the value entered by the user if 'OK' was pressed, or
157    *         <code>null</code> if 'Cancel' was pressed
158    */
159   public static native String   prompt(String   msg, String   initialValue) /*-{
160     return $wnd.prompt(msg, initialValue);
161   }-*/;
162 
163   /**
164    * Removes a window closing listener.
165    * 
166    * @param listener the listener to be removed
167    */
168   public static void removeWindowCloseListener(WindowCloseListener listener) {
169     closingListeners.remove(listener);
170   }
171 
172   /**
173    * Removes a window resize listener.
174    * 
175    * @param listener the listener to be removed
176    */
177   public static void removeWindowResizeListener(WindowResizeListener listener) {
178     resizeListeners.remove(listener);
179   }
180 
181   /**
182    * Sets the size of the margins used within the window's client area. It is
183    * sometimes necessary to do this because some browsers, such as Internet
184    * Explorer, add margins by default, which can confound attempts to resize
185    * panels to fit exactly within the window.
186    * 
187    * @param size the window's new margin size, in CSS units.
188    */
189   public static native void setMargin(String   size) /*-{
190     $doc.body.style.margin = size;
191   }-*/;
192 
193   /**
194    * Sets the browser window's title.
195    * 
196    * @param title the new window title.
197    */
198   public static native void setTitle(String   title) /*-{
199     $doc.title = title;
200   }-*/;
201 
202   static void onClosed() {
203     UncaughtExceptionHandler handler = GWT.getUncaughtExceptionHandler();
204     if (handler != null) {
205       fireClosedAndCatch(handler);
206     } else {
207       fireClosedImpl();
208     }
209   }
210 
211   static String   onClosing() {
212     UncaughtExceptionHandler handler = GWT.getUncaughtExceptionHandler();
213     if (handler != null) {
214       return fireClosingAndCatch(handler);
215     } else {
216       return fireClosingImpl();
217     }
218   }
219 
220   static void onResize() {
221     UncaughtExceptionHandler handler = GWT.getUncaughtExceptionHandler();
222     if (handler != null) {
223       fireResizedAndCatch(handler);
224     } else {
225       fireResizedImpl();
226     }
227   }
228 
229   private static void fireClosedAndCatch(UncaughtExceptionHandler handler) {
230     try {
231       fireClosedImpl();
232     } catch (Throwable   e) {
233       handler.onUncaughtException(e);
234     }
235   }
236 
237   private static void fireClosedImpl() {
238     for (Iterator   it = closingListeners.iterator(); it.hasNext();) {
239       WindowCloseListener listener = (WindowCloseListener) it.next();
240       listener.onWindowClosed();
241     }
242   }
243 
244   private static String   fireClosingAndCatch(UncaughtExceptionHandler handler) {
245     try {
246       return fireClosingImpl();
247     } catch (Throwable   e) {
248       handler.onUncaughtException(e);
249       return null;
250     }
251   }
252 
253   private static String   fireClosingImpl() {
254     String   ret = null;
255     for (Iterator   it = closingListeners.iterator(); it.hasNext();) {
256       WindowCloseListener listener = (WindowCloseListener) it.next();
257 
258       // If any listener wants to suppress the window closing event, then do so.
259       String   msg = listener.onWindowClosing();
260       if (ret == null) {
261         ret = msg;
262       }
263     }
264 
265     return ret;
266   }
267 
268   private static void fireResizedAndCatch(UncaughtExceptionHandler handler) {
269     try {
270       fireResizedImpl();
271     } catch (Throwable   e) {
272       handler.onUncaughtException(e);
273     }
274   }
275 
276   private static void fireResizedImpl() {
277     for (Iterator   it = resizeListeners.iterator(); it.hasNext();) {
278       WindowResizeListener listener = (WindowResizeListener) it.next();
279       listener.onWindowResized(getClientWidth(), getClientHeight());
280     }
281   }
282 
283   private static native void init() /*-{
284     // Magic function defined by the selection script.
285     __gwt_initHandlers(
286       function() {
287         @com.google.gwt.user.client.Window::onResize()();
288       },
289       function() {
290         return @com.google.gwt.user.client.Window::onClosing()();
291       },
292       function() {
293         @com.google.gwt.user.client.Window::onClosed()();
294         $wnd.onresize = null;
295         $wnd.onbeforeclose = null;
296         $wnd.onclose = null;
297       }
298     );
299   }-*/;
300 
301   private Window() {
302   }
303 }
304
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