WPF Change Path Data in storyboard - wpf

Question

So I have a path setup like this
<Grid x:Name="arrowPanel">
<Path x:Name="arrow" Data="M0,4 H8 M4,4 V8Z" Stroke="Black" StrokeThickness="2" Height="8" RenderTransformOrigin="0.5,0.5" Stretch="None" Width="8">
<!--Not sure what to do here -->
</Path>
</Grid>
I have a storyboard setup like this
<VisualStateGroup x:Name="ExpandStateGroup">
<VisualState x:Name="Expanded">
<Storyboard>
<!-- Something to change the data to this 'M0,5 H10'(A minus sign)-->
</Storyboard>
</VisualState>
<VisualState x:Name="Collapsed">
<Storyboard>
<!-- Something to change the data back to it's original 'M0,5 H10 M5,5 V10Z' (A plus sign)-->
</Storyboard>
</VisualState>
</VisualStateGroup>
I do not know how to alter the data aspect of the path to make these transformations.

Answer 1

You could use an ObjectAnimationUsingKeyFrames to "animate" the Data property of the Path:
<Storyboard>
<ObjectAnimationUsingKeyFrames Duration="0"
Storyboard.TargetName="arrow" Storyboard.TargetProperty="Data">
<DiscreteObjectKeyFrame>
<DiscreteObjectKeyFrame.Value>
<Geometry>M0,5 H10</Geometry>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
</Storyboard>

Answer 2

In order to get the results I was looking for I created two paths that occupied the same area. One with the plus sign and the other with the minus sign (The plus sign without the vertical path).
Object:
<Grid>
<Grid x:Name="plusSignPanel">
<!-- Minus -->
<Path Data="M0,4 H8" Stroke="Red" StrokeThickness="2" Height="8" RenderTransformOrigin="0.5,0.5" Stretch="None" Width="8"/>
<!-- Plus -->
<Path x:Name="plusSign" Data="M0,4 H8 M4,4 V8Z" Stroke="Black" StrokeThickness="2" Height="8" RenderTransformOrigin="0.5,0.5" Stretch="None" Width="8"/>
</Grid>
</Grid>
And then all I did was change the color from black to transparent using the coloranimation on the plus sign for expanded state and vice versa with the collapsed state:
Animation:
<VisualStateGroup x:Name="ExpandStateGroup">
<VisualState x:Name="Expanded">
<Storyboard>
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="plusSign" Storyboard.TargetProperty="(Path.Stroke).(SolidColorBrush.Color)" To="Transparent"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Collapsed">
<Storyboard>
<ColorAnimation Duration="0:0:0.1" Storyboard.TargetName="plusSign" Storyboard.TargetProperty="(Path.Stroke).(SolidColorBrush.Color)" To="Black"/>
</Storyboard>
</VisualState>
</VisualStateGroup>