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Java > Open Source Codes > org > eclipse > jface > text > IWidgetTokenKeeper


1 /*******************************************************************************
2  * Copyright (c) 2000, 2006 IBM Corporation and others.
3  * All rights reserved. This program and the accompanying materials
4  * are made available under the terms of the Eclipse Public License v1.0
5  * which accompanies this distribution, and is available at
6  * http://www.eclipse.org/legal/epl-v10.html
7  *
8  * Contributors:
9  * IBM Corporation - initial API and implementation
10  *******************************************************************************/
11
12 package org.eclipse.jface.text;
13
14 /**
15  * A widget token keeper may require a widget token from an
16  * {@link org.eclipse.jface.text.IWidgetTokenOwner} and release the token to the
17  * owner after usage. A widget token owner may request the token from the token
18  * keeper. The keeper may deny the return of the token.
19  * <p>
20  * The widget token owner and keeper interplay is used by a text viewer in
21  * order to manage the appearance and disappearance of addition, on-top popup
22  * windows such as text hovers, content assist, etc.
23  *
24  * In order to provide backward compatibility for clients of
25  * <code>IWidgetTokeKeeper</code>, extension interfaces are used as a means
26  * of evolution. The following extension interfaces exist:
27  * <ul>
28  * <li>{@link org.eclipse.jface.text.IWidgetTokenKeeperExtension} since version
29  * 3.0 introducing priorities when requesting a widget token and thus replacing
30  * the non-prioritized scheme. It also allows a client to force a widget token
31  * keeper to accept focus.</li>
32  * </ul>
33  *
34  * @see org.eclipse.jface.text.IWidgetTokenKeeperExtension
35  * @since 2.0
36  */
37 public interface IWidgetTokenKeeper {
38
39     /**
40      * The given widget token owner requests the widget token from this token
41      * keeper. Returns <code>true</code> if the token is released by this
42      * token keeper. Note, the keeper must not call
43      * <code>releaseWidgetToken(IWidgetTokenKeeper)</code> explicitly.
44      * <p>
45      * Replaced by
46      * {@link IWidgetTokenKeeperExtension#requestWidgetToken(IWidgetTokenOwner, int)}.
47      *
48      * @param owner the token owner
49      * @return <code>true</code> if token has been released <code>false</code>
50      * otherwise
51      */
52     boolean requestWidgetToken(IWidgetTokenOwner owner);
53 }
54
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