Computed Setter Value based on existing value - WPF - wpf

Question

Currently have a setup as below:
<Trigger Property="IsMouseOver" Value="True">
<Setter TargetName="rectName" Property="Stroke" Value="Red"/>
<Setter TargetName="rectName" Property="StrokeThickness" Value="2"/>
</Trigger>
i.e. The trigger changes the Stroke and Thickness of a Rectangle to Red and 2 on MouseOver.
But this must happen only when the Rectangle's Stroke is Black (Few rectangles have transparent stroke)
Is there any way to put this condition on Setter? I'm looking at a less intrusive way of accomplishing this. Any leads?
Is there a construct something like below:
<Setter TargetName="rectName" Property="Stroke" Value="If Black Then Black Else Red"/>

Answer 1

Here this will work, note however this code will throw a stack overflow exception because of the change of the changing colors when you mouse over ie red black red black and so on :/ I would just suggest some other way to keep track of the rect state, maybe a variable in the ViewModel that keeps track of the state and and in the code replace:
<Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=Stroke}" Value="Black" />
With something like:
<Condition Binding="{Path=RectState}" Value="True" />
Otherwise this will crash :) (Sorry writing this in a rush)
<Rectangle Height="100" HorizontalAlignment="Left" Margin="182,152,0,0" Name="rectangle1" VerticalAlignment="Top" Width="200" >
<Rectangle.Style>
<Style TargetType="Rectangle">
<Setter Property="Fill" Value="Transparent" />
<Setter Property="Stroke" Value="Black" />
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsMouseOver}" Value="True" />
<Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=Stroke}" Value="Black" />
</MultiDataTrigger.Conditions>
<MultiDataTrigger.Setters>
<Setter Property="StrokeThickness" Value="2" />
<Setter Property="Stroke" Value="Red" />
</MultiDataTrigger.Setters>
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Rectangle.Style>
</Rectangle>

Answer 2

You can achieve this using MultiTrigger (code below not tested, but should be close enough)
<Style.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="True" />
<Condition Property="Stroke" Value="Black" />
</MultiTrigger.Conditions>
<Setter TargetName="rectName" Property="Stroke" Value="Red" />
<Setter TargetName="rectName" Property="StrokeThickness" Value="2" />
</MultiTrigger>
</Style.Triggers>