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Java > Open Source Codes > com > google > gwt > user > client > ui > impl > FocusImpl


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.ui.impl;
17
18 import com.google.gwt.core.client.GWT;
19 import com.google.gwt.user.client.Element;
20
21 /**
22  * Implementation interface for creating and manipulating focusable elements
23  * that aren't naturally focusable in all browsers, such as DIVs.
24  */
25 public class FocusImpl {
26   
27   private static FocusImpl implPanel = (FocusImpl) GWT.create(FocusImpl.class);
28
29   /**
30    * This instance may not be a {@link FocusImplOld}, because that special case
31    * is only needed for things that aren't naturally focusable on some browsers,
32    * such as DIVs. This exact class works for truly focusable widgets on those
33    * browsers.
34    *
35    * The compiler will optimize out the conditional.
36    */
37   private static FocusImpl implWidget = (implPanel instanceof FocusImplOld)
38       ? new FocusImpl() : implPanel;
39   
40   /**
41    * Returns the focus implementation class for creating and manipulating
42    * focusable elements that aren't naturally focusable in all browsers, such as
43    * DIVs.
44    */
45   public static FocusImpl getFocusImplForPanel() {
46     return implPanel;
47   }
48   
49   /**
50    * Returns the focus implementation class for manipulating focusable elements
51    * that are naturally focusable in all browsers, such as text boxes.
52    */
53   public static FocusImpl getFocusImplForWidget() {
54     return implWidget;
55   }
56   
57   /**
58    * Not externally instantiable or extensible.
59    */
60   FocusImpl() {
61   }
62
63   public native void blur(Element elem) /*-{
64     elem.blur();
65   }-*/;
66
67   public native Element createFocusable() /*-{
68     var e = $doc.createElement("DIV");
69     e.tabIndex = 0;
70     return e;
71   }-*/;
72
73   public native void focus(Element elem) /*-{
74     elem.focus();
75   }-*/;
76
77   public native int getTabIndex(Element elem) /*-{
78     return elem.tabIndex;
79   }-*/;
80
81   public native void setAccessKey(Element elem, char key) /*-{
82     elem.accessKey = key;
83   }-*/;
84
85   public native void setTabIndex(Element elem, int index) /*-{
86     elem.tabIndex = index;
87   }-*/;
88 }
89
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