How can I change the VisualState in a View from the ViewModel?
- by Decker
I'm new to WPF and MVVM. I think this is a simple question. My ViewModel is performing an asynch call to obtain data for a DataGrid which is bound to an ObservableCollection in the ViewModel. When the data is loaded, I set the proper ViewModel property and the DataGrid displays the data with no problem. However, I want to introduce a visual cue for the user that the data is loading. So, using Blend, I added this to my markup:
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="LoadingStateGroup">
<VisualState x:Name="HistoryLoading">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="HistoryGrid">
<DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="HistoryLoaded">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="WorkingStackPanel">
<DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
I think I know how to change the state in my code-behind (something similar to this):
VisualStateManager.GoToElementState(LayoutRoot, "HistoryLoaded", true);
However, the place where I want to do this is in the I/O completion method of my ViewModel which does not have a reference to it's corresponding View. How would I accomplish this using the MVVM pattern?
