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Java > Open Source Codes > com > google > gwt > user > client > ui > HasKeyPreview


1 /*
2  * Copyright 2006 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;
17
18 /**
19  * A class that implements this interface receives a preview of keyboard events
20  * before they are passed to the focused widget.
21  *
22  * @see com.google.gwt.user.client.ui.KeyboardListener
23  */
24 public interface HasKeyPreview {
25
26   /**
27    * Called when a key-down event is received.
28    *
29    * @param key the physical key that was depressed. Constants for this value
30    * are defined in this interface with the KEYCODE prefix.
31    * @param modifiers the modifier keys pressed at when the event occurred. This
32    * value is a combination of the bits defined by
33    * {@link KeyboardListener#MODIFIER_SHIFT},
34    * {@link KeyboardListener#MODIFIER_CTRL}, and
35    * {@link KeyboardListener#MODIFIER_ALT}.
36    */
37   boolean onKeyDownPreview(char key, int modifiers);
38
39   /**
40    * Called when a key-press event is received.
41    *
42    * @param key the Unicode character that was generated by the keyboard action.
43    * @param modifiers the modifier keys pressed at when the event occurred. This
44    * value is a combination of the bits defined by
45    * {@link KeyboardListener#MODIFIER_SHIFT},
46    * {@link KeyboardListener#MODIFIER_CTRL}, and
47    * {@link KeyboardListener#MODIFIER_ALT}.
48    */
49   boolean onKeyPressPreview(char key, int modifiers);
50
51   /**
52    * Called when a key-up event is received.
53    *
54    * @param key the physical key that was released. Constants for this value are
55    * defined in this interface with the KEYCODE prefix.
56    * @param modifiers the modifier keys pressed at when the event occurred. This
57    * value is a combination of the bits defined by
58    * {@link KeyboardListener#MODIFIER_SHIFT},
59    * {@link KeyboardListener#MODIFIER_CTRL}, and
60    * {@link KeyboardListener#MODIFIER_ALT}.
61    */
62   boolean onKeyUpPreview(char key, int modifiers);
63 }
64
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