Is there a way to get notified (e.g., by an event) when a Visual has been (re-)rendered?
Basically, I would like to take a screen shot whenever a Visual's appearance has changed. I assume the rendering thread is taking care of this in the background.
I am trying to avoid grabbing a screen shot periodically since I am only interested in changes (e.g., hovering the cursor over a button would change its appearance).
Any hint is highly appreciated!
This MSDN thread provides quite a bit of information on the subject. Basically it doesn't really work that way and you'll find the exact reasons there.
This is not possible in WPF. Your best bet would be to take a snapshot in memory frequently and compare it with the previous. If you detect a diffrence, persist the snapshot. You could use the CompositionTarget.Rendering event for this. Just make sure that you don't take a snapshot in each event (since it is called as freuqently as the graphics card swaps its buffer).