Toggling PanoramaItem Visibility via Delegate - windows-phone-7

Question

I have a peculiar problem in Windows Phone Development. I have 4 panorama items each of them containing a webBrowser control. On the start of the application, I have only the first panorama item visible while the remaninig are in collapsed state.
Based on the interaction in the first webBrowser, we Notify the WP7 app (webBrowser.ScriptNotify event) and decide which panoramaitems to display. The visiblity is set in the delegate that handles the ScriptNotify event.
the issue I am facing is that though i set the visibility in the delegate to Visible, it doesn't show up in the Panorama. I have tried using Dispatcher in the delegate to change visibility but it hasn't helped:
Deployment.Current.Dispatcher.BeginInvoke(() => {
discussions.Visibility = System.Windows.Visibility.Visible;
});
Can someone suggest what i could be doing incorrectly?

Answer 1

First of all, you shouldn't use a WebBrowser control inside a Panorama. It's very bad performance.
Secondly, Panorama and PivotItems don't have a collapsed state.
And thirdly, the dispatcher have nothing to do with this (unless you're not running the code on the UI thread).
So what you need to do, is to add the PanoramaItems dynamically to the Panorama control. This can be done by databinding (recommended), or directly from C#.

Answer 2

I don't know about performace but i'm sure that a PanoramaItem has a collapsed *visibility* state i tried to toggle it from code and it works like a charm if the initial state is visible.
But if the initial state is collapsed when the panorama loads then it doesn't work anymore. I guess it is because if it is collapsed then it is not included in the panorama and so it won't be visible when you set it to visible.
Maybe that's a bug or i don't know but it is a bit awkward.
To add the PanoramaItem to the Panorama could work.

Answer 3

I'm sorry for not answering the question but the other way around, enforcing the problem :) .
I do have the same problem, one PanoramaItem with an ItemsControl databounded to a collection of the ViewModel. The PanoramaItem visibility property is databounded to {Binding} and a CollectionToVisibility converter is used. During debug with a breakpoint set inside the converter code I managed to see that the return value is ok but the PanoramaItem is not visible when the collections has items.
My investigation took me to realize that in fact when the first get to the Collection occours the return value is null because the Collection data comes from a async call to a service and the converter return value is Visibility.Collapsed, and only when the Collection is populated and the PropertyChanged event is raised, the second get to the Collection property triggers the databind refresh and the return value of the converter is now Visibility.Visible, this leeds me to think that the PanoramaItem isn't included in the Panorama control tree during the applytemplate because the visibility is set to collapsed, and after that the UI never loads the PanoramaItem again.
I made a test to verify this scenario returning in the get of the Collection property an hardcoded list of items so that the first get have items in it and the converter returns Visible in the first get request.Everything works like a charm.I can even string the collection out of items and it gets collapsed and the other way around.
All this is pure Xaml, no code behind.
The intent of this is to hide PanoramaItems that for some reason does not have content to show.

Answer 4

Basically, the panorama keeps an internal list of visible item. This list isn't updated when you set an item to visible. The easiest way to force the control to update this list is setting the MainItem property. So after setting the visibility of your panorama item, just add the following line:
yourPanorama.DefaultItem = yourPanorama.DefaultItem;
(given that the panorama is called yourPanorama)