WPF: How to prevent data triggered animation at program start? - wpf

Question

I am using a datatrigger to start an animation whenever a property TargetValue in my viewmodel is set to a specific value Value1.
But I don't want this animation to happen during program startup. What is the best way to prevent the animation to run at program start?
Part of the view model:
public enum TargetValue
{
Value1,
Value2,
}
public class MainWindowViewModel : INotifyPropertyChanged, IDisposable
{
public TargetValue _targetValue = TargetValue.Value1;
public TargetValue TargetValue
{
get => _targetValue;
set => SetProperty(ref _targetValue, value);
}
Part of the xaml:
<Border Background="Green" >
<Border.Style>
<Style TargetType="{x:Type Border}">
<Style.Triggers>
<DataTrigger Binding="{Binding TargetValue}" Value="Value1">
<DataTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetProperty="(UIElement.Opacity)">
<LinearDoubleKeyFrame KeyTime="00:00:0" Value="0.5"/>
<LinearDoubleKeyFrame KeyTime="00:00:3" Value="1"/>
</DoubleAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
</DataTrigger>
</Style.Triggers>
</Style>
</Border.Style>
</Border>
Part of the MainWindow.cs:
public partial class MainWindow : Window
{
MainWindowViewModel myViewModel = new MainWindowViewModel();
public MainWindow()
{
InitializeComponent();
DataContext = myViewModel;
}

Answer 1

Add another property to your viewmodel. For example a bool DoAnimation.
Make that false by default.
Use this to drive your animation instead of TargetValue and compare it to a value of true.
In the setter of Value1 you can call a method encapsulating your logic. Which is presumably to check if the value changes to "Value1" and to set DoAnimation to True when that happens.
When you translate your data from your model into the viewmodel, set DoAnimation to false. Do this before you present it to the ui.
You could just put that logic in the constructor.
myViewModel.DoAnimation=false;
DataContext = myViewModel;