How do I bind a control to visualbrush in MVVM?

Question

I have a visualbrush, where I want to set the visual to an element. A current example of my visual brush:

<VisualBrush Viewport="0,0,0.5,0.5" Visual="{Binding ElementName=Panel}"></VisualBrush>

However, I want to change the value in Visual, so that at different times, it can be showing the visual of different controls. My first idea was having:

Visual="{Binding ElementName={Binding VisElName}}"

But first off thats not allowed, and secondly my viewmodel would need to know the name of my elements. Is there a way to do this in MVVM, so that I can change the visual to another element at will?

Answer 1

That kind of depends on what's the actual logic that drives the change in the visual. For example, if it's some kind of business logic related state, you can expose a State property in your view model and use a converter to bind to it.

If it doesn't depend on a BL state, it would be OK MVVM-wise to modify the visual from the view's code behind, since it's considered to be purely view logic:

XAML

<VisualBrush x:Name="myBrush" Viewport="0,0,0.5,0.5" />

Code behind

myBrush.Visual = myPanel;