Question

I am having some issues with WPF not fully repainting a button control when the button is changed from another thread, and I am not sure how to force it to do a full repaint.

The situation is that on receipt of a message (via WCF – but the source isn’t important, except that it is an external thread) I update the foreground color and visibility of a button. WPF immediately repaints the text on the button face, but the surface of the button is not repainted until I click anywhere on the application.

I have tried calling InvalidateVisual() on the button, but that did not help. I think that I am not understanding how a background thread can force a repaint. But the frustrating thing is that something is getting repainted and every other control I am using (text and image controls) are also getting properly repainted when I update them from my same message receipt.

I have now tried sending an empty message to the Dispatcher of the application via Invoke(), but no luck there either.

So I am looking for tips on how to tell WPF that it needs to update the rest of the button and not just the text.

Edit

This is a rough skeleton of my program. Note that I have wrapped the button in a class as there is other related state information I am keeping with it.

class myButton
{
   Button theButton

   void SetButton()
   {
     theButton.Forground = a new color
   }
}

main
{
   myButton.theButton = (Button on WPF canvass)

   RegisterCallback( mycallbackFunction) with WCF client endpoint
}


void myCallbackFunction(message)
{
   if message has button related stuff,  call myButton.SetButton
}

Edit 2

Solved my problem .. it was actually a conflict between a “CanExecute” method and setting the buttons attributes in the callback. Once I removed the “CanExecute” function it all worked.

Answer 1

As per my edit, I had conflict between the buttons CanExecute binding in the XAML and me setting the background color in the callback. I didn’t really need the CanExecute, so getting rid of that solved my problem.