WebEngine: how to capture the click on a link?

Question

I need some insight into the inner workings of WebEngine: listeners seem to stop firing under certain conditions.
Problem description:
In my application I have to open certain urls in a new tab or in a different pane. Following jsmith's proposal in a different thread (Re: How to cancel page loading in WebView? I do the following:
- Based on the location of the link clicked, I decide if it has to be opened in place, in a new tab, or in a sort of popup pane (similar to a sheet window in MacOS/X as a fake modal dialog attached to the top of the window).
- To achieve this, I implement a locationProperty listener using "locationProperty().addListener".
- Inside the listener I use "getLoadWorker().cancel()" to stop the current engine from loading the url ...
- ... and load that url in a new tab or the popup pane.
This works fine, but when I return from the other tab or close the popup pane, the location property listener won't fire any more.
The same applies if I cancel in a stateProperty change listener.
Workaround:
As a workaround I can refresh the page using "getEngine().reload()" in a "Platform.runLater" thread, but the flickering is really ugly.
Analysis:
It looks as if the cancel comes too late. The first opportunity to capture the click on a link seems to be "getLoadWorker().stateProperty()" where "Worker.State" is "SCHEDULED"; after that fires the listener on "locationProperty()". In either case "getLoadWorker().cancel()" seems to invalidate the listeners.
I have experimented with another development platform which also uses Webkit. There it's possible to truely cancel out before a link is loaded. So it should be possible in JavaFX as well...
Question:
Does somebody know how I can capture the click on a link without redeveloping the web application (which I can't)?
Cheers,
Thomas

Answer 1

If, after calling getLoadWorker().cancel(), you no longer receive location change notifications upon further clicks on links, it looks like a bug. Feel free to file an issue with Jira.
However, it is probably too fragile to rely on the location property and the cancel method in your case, due to asynchronous nature of page loads.
Look at the WebEngine.createPopupHandler property. The popup handler will only be called if the page decides that a new window needs to be created, so it may not be able to help you fully solve your problem, but it may be worth a try.
Otherwise, consider the approach suggested by irond13. Install DOM event listeners on link objects (<a> tags) and do whatever you want in response to click events. You can do it solely in Java, see Re: Controlling what happens when a user clicks on a hyperlink in a WebView and Re: Communicate from WebView to JavaFX scene for details and example.
Finally, if you do think a more direct callback on WebEngine is a necessity, consider extending http://javafx-jira.kenai.com/browse/RT-17073 or filing a new feature request.