CODEWITHSUNDEEP
c#wpfxamlcolors
jia103
jia103

Reputation: 1134

Best way to change color of several items in a trigger

I'm afraid I don't have the code available here to paste, but I'd appreciate some guidance on best practices.

I currently have a polygon defined in my XAML file in Visual Studio 2010, C#, .NET 4.0. The polygon is defined with a fixed color; however, depending on the value of the binding, the color can change using a trigger.

// non-working code - trying to avoid
<Polygon ... Fill="Red" />
<Grid.Triggers>
   <Trigger ...>
      <Setter Property="..." Value="Yellow" />
   </Trigger>
   <Trigger ...>
      <Setter Property="..." Value="Green" />
   </Trigger>
   <Trigger ...>
      <Setter Property="..." Value="Blue" />
   </Trigger>
</Grid.Triggers>

Now, I need to break up the polygon into several pieces that are joined together to look like one complete shape. I have broken up the polygon into two polygons and a rectangle.

What is the best way to change colors as before such that I don't repeat code?

I don't want a trigger mapping four different enum values to four different colors, and then for each color, defining the same three shapes to be colored.

// non-working code - trying to avoid
<Polygon ... Fill="Red" />
<Polygon ... Fill="Red" />
<Rectangle ... Fill="Red" />
<Grid.Triggers>
   <Trigger ...>
      <Setter Property="..." Value="Yellow" />
      <Setter Property="..." Value="Yellow" />
      <Setter Property="..." Value="Yellow" />
   </Trigger>
   <Trigger ...>
      <Setter Property="..." Value="Green" />
      <Setter Property="..." Value="Green" />
      <Setter Property="..." Value="Green" />
   </Trigger>
   <Trigger ...>
      <Setter Property="..." Value="Blue" />
      <Setter Property="..." Value="Blue" />
      <Setter Property="..." Value="Blue" />
   </Trigger>
</Grid.Triggers>

Is there a way I can define a color as a static resource and use that resource to color my three shapes, and then use the trigger to toggle the R/G/B values of the resource?

// non-working code - trying to do
<SolidColorBrush x:Key="MyBrush" Color="Red"/>
<Polygon ... Fill="{StaticResource MyBrush}" />
<Polygon ... Fill="{StaticResource MyBrush}" />
<Rectangle ... Fill="{StaticResource MyBrush}" />
<Grid.Triggers>
   <Trigger ...>
      <Setter Property="..." Value="Yellow" />
   </Trigger>
   <Trigger ...>
      <Setter Property="..." Value="Green" />
   </Trigger>
   <Trigger ...>
      <Setter Property="..." Value="Blue" />
   </Trigger>
</Grid.Triggers>

Thanks.

Upvotes: 0

Views: 121

Answers (1)

dev hedgehog
dev hedgehog

Reputation: 8791

Best way is called using Binding with Converter instead of having tons of triggers listening to different states. :)

Here is code:

<Window.Resources>
    <local:BelowZeroConverter x:Key="converter"/>
</Window.Resources>

<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Value, Converter={StaticResource converter}}" Value="1">
   <Setter Property="Foreground" Value="Black"></Setter>
</DataTrigger>

Upvotes: 1

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