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| <title>Tips for debugging active help</title> |
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| <body> |
| |
| <h2>Tips for debugging active help</h2> |
| |
| |
| <p>The code and markup that triggered our active help link looks pretty |
| straightforward. But what do you do if your active help link doesn't seem |
| to work?</p> |
| |
| |
| <h4>Test your action ahead of time</h4> |
| |
| |
| <p>If your action implementation is fairly involved, you should invoke the |
| action yourself with some test code inside Eclipse. This way, you'll know |
| that the action is error-free before invoking it from the JavaScript. </p> |
| |
| |
| <h4>Ensure the JavaScript is running</h4> |
| |
| |
| <p>You can modify "plugins/org.eclipse.help_2.1.0/<b>liveHelp.js</b>" |
| to include a call to the <b>alert</b> function as the first statement in the <b>liveAction</b> |
| function:</p> |
| |
| |
| <pre>function liveAction(pluginId, className, argument) |
| { |
| <b> alert("liveAction called"); |
| ...</b></pre> |
| |
| |
| <p>The <b>alert</b> function opens a warning dialog in the browser and can be |
| used to verify that the <b>liveAction</b> was properly invoked in your |
| HTML. If you don't see a warning dialog when you click on your help link, |
| then you have a problem in the HTML markup.</p> |
| |
| |
| <h4>Debug the active help action</h4> |
| |
| |
| <p>Once you know that the JavaScript is running, you can debug your action from |
| inside Eclipse. To do this, you can set a breakpoint in your help action |
| class and start up a self-hosted Eclipse instance. You must test your |
| active help with the Help browser from the newly launched Eclipse instance, not |
| from your host instance, since the JavaScript from your help HTML calls a |
| servlet on the Eclipse help server that launched the browser.</p> |
| |
| |
| <p>If nothing happens after you've set up the breakpoint and clicked on the |
| active help link, it's likely that your plug-in and active help class were not |
| correctly specified in the JavaScript. </p> |
| |
| |
| <p>Once you've managed to stop at the breakpoint in your action, you can debug |
| the action as you would any other Java code.</p> |
| |
| |
| <h4>Make sure your UI code is wrapped in Display.syncExec</h4> |
| |
| |
| <p>A common runtime problem is improperly accessing UI code from the thread that |
| invokes the active help. If your live help action came from code that ran |
| originally in a UI thread, it will need to be modified to handle the fact that |
| it is running from a non-UI thread. </p> |
| |
| |
| <pre>public void run() { |
| // Active help does not run on the UI thread, so we must use syncExec |
| Display.getDefault().syncExec(new Runnable() { |
| public void run() { |
| //do the UI work in here; |
| } |
| }); |
| } |
| |
| </pre> |
| |
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