Tips for debugging active help
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?
Test your action ahead of time
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.
Ensure the JavaScript is running
You can modify "liveHelp.js" (make a copy of this from the plugins/org.eclipse.help
plugin and change your script statement to refer to your local copy)
to include a call to the alert function as the first statement in the liveAction
function:
function liveAction(pluginId, className, argument)
{
alert("liveAction called");
...
The alert function opens a warning dialog in the browser and can be
used to verify that the liveAction 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.
Debug the active help action
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.
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.
Once you've managed to stop at the breakpoint in your action, you can debug
the action as you would any other Java code.
Make sure your UI code is wrapped in Display.syncExec
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.
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;
}
});
}
