The MVVM way of presenting controls dynamically - wpf

Question

I have a need to display some kind animation as different processes gets started. My initial idea was to simply add some <ContentControl> tags to the XAML and bind them to a property in the View Model object which then simply assigned this property a ProgressBar, some busy spinner or whatever.
This works but I don't like it. The primary reason I don't like it is because the View Model should not involve itself in presentation matters and this pattern clearly breaks that paradigm.
This is pretty much what my (ugly) code looks like atm:
XAML:
<ContentControl Content="{Binding ProcessAAnimation}" />
In View Model class:
public object ProcessAAnimation
{
get { return _processAAnimation; }
private set
{
_processAAnimation = value;
OnPropertyChanged("ProcessAAnimation");
}
}
public object IsProcessARunning
{
get { return _processARunning; }
private set
{
if (value == _processARunning)
return;
_processRunnings = value;
if (value)
ProcessAAnimation = SomeNiftyAnimationControl();
else
{
if (ProcessAAnimation is IDisposable)
((IDisposable)ProcessAAnimation).Dispose();
ProcessAAnimation = null;
}
}
}
// (clipped: More properties for "Process B", "Process C" and so on)
So, is there a better pattern to achieve this. Preferrably, a pattern where I can create my animation controls dynamically using XAML alone?
Please note that I have already tested a solution where I declare three different animation controls and then bind their Visibility property to the View Model state. That, however, is below par in my book because I don't want to just hide the controls, I want them to be gone unless needed. Besides, that would also make it impossible to dynamically use different types of animations for whatever needs may be.
Anyone?

Answer 1

Well your ViewModel knows about the operation and the progress itself. The rest can be accomplished via Triggers. At least thats the way we do it. So your ViewModel has a property "IsLoadingImage" for example, which is set when your viewmodel starts a BackgroundWorker for loading a big image, it also returns the progress reported by the BackgroundWorker "ImageLoadingProgress" now these two properties are enough to pass to your View. Your view, consists of a Progress bar or a custom control for your special animation. You could now bind the "IsLoadingImage" in a Trigger to toggle the ProgressBar/Animation control visibility and the Value of these is bound to "ImageLoadingProgress".
Like i said, thats how we handle it, and our application makes heavy use of MVVM.
Edit respond to a comment: How to change the template in a trigger
<ControlTemplate x:Name="ActiveTemplate" TargetType="{x:Type MyType}">
<!-- Template when active -->
</ControlTemplate>
<ControlTemplate x:Name="DeactivatedTemplate" TargetType="{x:Type MyType}">
<!-- Template when deactivated -->
</ControlTemplate>
<Style TargetType="{x:Type MyType}">
<Setter Property="Template" Value="{StaticResource DeactivatedTemplate}"/>
<Style.Triggers>
<DataTrigger Binding="{Binding IsActive}" Value="True">
<Setter Property="Template" Value="{StaticResource ActiveTemplate}"/>
</DataTrigger>
</Style.Triggers>
</Style>
This assumes that MyType is a control that can has a ControlTemplate and that the DataContext has a Property IsActive to toggle the Template.