| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML> |
| <HEAD> |
| |
| <meta name="copyright" content="Copyright (c) IBM Corporation and others 2000, 2005. This page is made available under license. For full details see the LEGAL in the documentation book that contains this page." > |
| |
| <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> |
| <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"> |
| |
| <LINK REL="STYLESHEET" HREF="../book.css" CHARSET="ISO-8859-1" TYPE="text/css"> |
| <TITLE> |
| Honoring single click support |
| </TITLE> |
| |
| <link rel="stylesheet" type="text/css" HREF="../book.css"> |
| </HEAD> |
| <BODY BGCOLOR="#ffffff"> |
| <h2>Honoring single click support</h2> |
| <p>The General <b>Preferences</b> allow users to specify whether views should |
| open their objects on single or double click. </p> |
| |
| |
| <p><img src="images/singleclick.png" alt="General "Open mode" preferences with disclaimer that the preference may not take effect in all views" border="0"></p> |
| |
| |
| <p>Why the disclaimer about this preference not working for all views? |
| Because views contributed by plug-ins must explicitly support this preference in |
| their implementation.</p> |
| |
| |
| <p>Recall that a view can be implemented by creating SWT controls and writing |
| standard SWT code, or by using <a href="jface_viewers.htm"> JFace viewers</a> |
| to handle the low level details. Honoring |
| the single click preference can be done at either level. Most views that |
| open other objects present them in a structured, list-like view. We'll |
| focus on that kind of view for now. If your view displays objects in a |
| different manner, you'll likely use the SWT-level concepts to support single |
| click.</p> |
| |
| |
| <h3>Single click in JFace viewers</h3> |
| |
| |
| <p>If you are using a <a href="jface_viewers.htm#listviewer">JFace list-oriented |
| viewer</a> to present your objects, supporting single click is |
| straightforward. Instead of using <b>addDoubleClickListener</b> to trigger |
| opening the items in your view, use <b>addOpenListener</b>. The open |
| listener honors the current workbench preference, firing the open event when the |
| specified mouse event occurs.</p> |
| |
| |
| <p>You may still wish to use <b>addDoubleClickListener</b> for non-open actions, |
| such as expanding the items in a tree on double-click.</p> |
| |
| |
| <h3>Single click in SWT controls</h3> |
| |
| |
| <p>JFace provides a utility class, <a href="../reference/api/org/eclipse/jface/util/OpenStrategy.html"><b>OpenStrategy</b></a>, |
| to handle the logistics of single and double click at the SWT control level. |
| The <a href="../reference/api/org/eclipse/jface/util/OpenStrategy.html"><b>OpenStrategy</b></a> |
| is configured by the General <b>Preferences</b> dialog so that it honors the |
| current workbench open preference. In fact, the JFace viewers use this class |
| to implement the open listener. </p> |
| |
| |
| <p>You must create an <a href="../reference/api/org/eclipse/jface/util/OpenStrategy.html"><b>OpenStrategy</b></a> |
| and associate it with your SWT control. The <a href="../reference/api/org/eclipse/jface/util/OpenStrategy.html"><b>OpenStrategy</b></a> |
| will hook the appropriate events and interpret them based on the user |
| preferences. Your job is to add an open listener to the strategy that |
| implements the code for open. In this way, you are shielded from knowledge |
| about which widget event triggered the open event.</p> |
| |
| |
| <pre>OpenStrategy openHandler = new OpenStrategy(control); |
| openHandler.addOpenListener(new IOpenEventListener() { |
| public void handleOpen(SelectionEvent e) { |
| // code to handle the open event. |
| ... |
| } |
| }</pre> |
| <p>The other workbench preferences for open (select on hover, |
| open using arrow keys) are also handled by <a href="../reference/api/org/eclipse/jface/util/OpenStrategy.html"><b>OpenStrategy</b></a>. |
| This means that the "right thing" will happen if you use JFace viewers |
| or the <a href="../reference/api/org/eclipse/jface/util/OpenStrategy.html"><b>OpenStrategy</b></a> |
| class to implement open behavior.</p> |
| <h3>Activating editors on open</h3> |
| <p>When handling an open event, you should use <b>OpenStrategy.activateOnOpen() </b>to |
| determine whether an opened editor should be activated by default. |
| Activating an editor switches the focus from the view to the editor, which can |
| be particularly confusing and undesirable in single click mode. </p> |
| |
| |
| |
| </BODY> |
| </HTML> |
