DataTrigger is not using GoToStateAction in Silverlight - silverlight

Question

The follow XAML represents an object I am trying to build in Expression Blend. I am having trouble with the DataTrigger in the StackPanel - the application does not go to Empty when the trigger matches the data. Further explanation is after this code:
<DataTemplate x:Key="SampleTemplate">
<StackPanel x:Name="SampleStack" Style="{StaticResource DefaultSampleStyle}" Width="64" Height="60">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="VisualStateGroup">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0">
<Storyboard>
<ColorAnimation Duration="0" To="#FFDFE04B" Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)" Storyboard.TargetName="SampleStack" d:IsOptimized="True"/>
</Storyboard>
</VisualTransition>
</VisualStateGroup.Transitions>
<VisualState x:Name="Empty">
<Storyboard>
<ColorAnimation Duration="0" To="#FF4B6FE0" Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)" Storyboard.TargetName="SampleStack" d:IsOptimized="True"/>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<VisualStateManager.CustomVisualStateManager>
<ei:ExtendedVisualStateManager/>
</VisualStateManager.CustomVisualStateManager>
<i:Interaction.Triggers>
<ei:DataTrigger Binding="{Binding IsActive}" Value="False">
<ei:GoToStateAction StateName="Empty" UseTransitions="False"/>
</ei:DataTrigger>
</i:Interaction.Triggers>
<TextBlock x:Name="StartOn" Text="{Binding StartOn, StringFormat=hh:mm}"/><TextBlock x:Name="textBlock" Text="-" />
<TextBlock x:Name="EndOn" Text="{Binding EndOn, StringFormat=hh:mm}"/>
</StackPanel>
</DataTemplate>
If I use an EventTrigger with a Loaded value, the Empty state is correctly applied based on the IsActive binding.
If I use the existing DataTrigger and change a Property on the Stackpanel, such as Height, based on the binding of IsActive this also works.
Am I doing something fundamentally wrong in the XAML? Do you need a more complete example of the XAML to understand the issue?

Answer 1

do you need the GoToStateAction?
I guess, the problem is the Binding "at startup". I added a dispatcher and threw the NotifyPropertyChanged again after one second. Then it works. Propably you can workaround it like this. You wait till the control is loaded and then throw the PropertyChanged again. This is not a nice way and similar to your idea (If I use an EventTrigger with a Loaded value,...)
I would recommend you to use a DataStateBehaviour. If you hav a boolean to decide in which satte you have to go, this is great. It is a behaviour where you can bind the condition to a property and then set a true and a false state.
It would look like this (I did a few adjustments just for testing at my computer):
<DataTemplate x:Key="SampleTemplate">
<StackPanel x:Name="SampleStack" Width="64" Height="60" Background="White">
<i:Interaction.Behaviors>
<ei:DataStateBehavior Binding="{Binding IsChecked}" Value="True" TrueState="Empty" FalseState="Base"/>
</i:Interaction.Behaviors>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="VisualStateGroup">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0"/>
</VisualStateGroup.Transitions>
<VisualState x:Name="Empty">
<Storyboard>
<ColorAnimation Duration="0" To="Red" Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)" Storyboard.TargetName="SampleStack" d:IsOptimized="True"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Base"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<VisualStateManager.CustomVisualStateManager>
<ei:ExtendedVisualStateManager/>
</VisualStateManager.CustomVisualStateManager>
<TextBlock x:Name="StartOn" Text="Test"/>
</StackPanel>
</DataTemplate>
As you can see I added a second state to the VisualStateGroup (There is now empty and base). I would recommend this not only because the DataStateBehaviour needs at least two states in one group. If you have only one state, you have no chance to change the state of this group back to normal, e.g.
I hope this answer helps you.
BR,
TJ