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36

answers:

1

I have a DataTemplate with a number of layered text and graphic objects. One of them is a glow effect that comes from the RadialGradientBrush Fill property of a Rectangle. At first, I named the Rectangle and bound to the Fill property and changed it using a DataTrigger. This worked fine, but I have a number of RadialGradientBrush objects in the Resources section and as you can see below, it is a lot to repeat when all I want to do is change the GradientStops. So I removed the Fill binding and added and named a RadialGradientBrush and although I can bind to the brush from Resources, I can't access it in the DataTrigger. I get the 'Cannot find Trigger target' error.

<Rectangle x:Name="Glow" IsHitTestVisible="False" RadiusX="1.5" RadiusY="1.5" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" StrokeThickness="0" Opacity="1.0">
    <Rectangle.Fill>
        <RadialGradientBrush x:Name="GlowGradient" Center="0.5,0.848" GradientOrigin="0.5,0.818" RadiusX="-1.424" RadiusY="-0.622" GradientStops="{StaticResource DefaultGradient}">
            <RadialGradientBrush.RelativeTransform>
                <TransformGroup>
                    <ScaleTransform CenterX="0.5" CenterY="0.848" ScaleX="1" ScaleY="1.8"/>
                    <SkewTransform AngleX="0" AngleY="0" CenterX="0.5" CenterY="0.848"/>
                    <RotateTransform Angle="-33.418" CenterX="0.5" CenterY="0.848"/>
                    <TranslateTransform Y="0.278"/>
                </TransformGroup>
            </RadialGradientBrush.RelativeTransform>
        </RadialGradientBrush>
    </Rectangle.Fill>
</Rectangle>

In the resources, I have several RadialGradientBrush objects like this one.

<RadialGradientBrush x:Key="EscalatedGlow" Center="0.5,0.848" GradientOrigin="0.5,0.818" RadiusX="-1.424" RadiusY="-0.622">
    <RadialGradientBrush.RelativeTransform>
        <TransformGroup>
            <ScaleTransform CenterX="0.5" CenterY="0.848" ScaleX="1" ScaleY="1.8"/>
            <SkewTransform AngleX="0" AngleY="0" CenterX="0.5" CenterY="0.848"/>
            <RotateTransform Angle="-33.418" CenterX="0.5" CenterY="0.848"/>
            <TranslateTransform Y="0.278"/>
        </TransformGroup>
    </RadialGradientBrush.RelativeTransform>
    <GradientStop Color="Aqua" Offset="0.168"/>
    <GradientStop Color="#5E1D96FF" Offset="0.474"/>
    <GradientStop Color="#1101FFFF" Offset="1"/>
</RadialGradientBrush>

I want to replace them with less code for each colour change, so I created some GradientStopCollection objects in the Resources to replace them with.

<GradientStopCollection x:Key="EscalatedGradient">
    <GradientStop Color="Aqua" Offset="0.168"/>
    <GradientStop Color="#5E1D96FF" Offset="0.474"/>
    <GradientStop Color="#1101FFFF" Offset="1"/>
</GradientStopCollection>

Although I can bind to the Resource gradients, the problem is that I can't access the GlowGradient brush to change its GradientStops property. I could previously access the Glow Rectangle using a DataTrigger with the following.

<DataTrigger Binding="{Binding Path=Status}" Value="Escalated">
    <Setter TargetName="Glow" Property="Fill" Value="{StaticResource EscalatedGlow}"/>
</DataTrigger>

When I use the following, I get the 'Cannot find Trigger target' error.

<DataTrigger Binding="{Binding Path=Status}" Value="Escalated">
        <Setter TargetName="GlowGradient" Property="GradientStops" Value="{StaticResource EscalatedGradient}"/>
</DataTrigger>

I'm thinking there just has to be a way to save me from replicating the whole RadialGraientBrush each time I want to change the colours. Is there any way to access the Rectangle Fill brush from the DataTrigger? Any tips anyone? Thanks in advance.

A: 

Did you take a look at this

It looks like if you were to create key names for your colors you would be able to change the gradient then.

Mark Hall
It's not quite what I had in mind, but if I declare the Color objects in shorthand, then it does save on code duplication and that was partly what I was after. I still can't change the gradients from the DataTemplate though and that is my main aim.
Sheridan
I can use Fill.GradientStops as the TargetProperty in a StoryBoard Animation object, but it doesn't work in the Property of a DataTrigger and this is what I need.
Sheridan
That is an interesting problem. It is yelling at you that the property does not exist. What if you create a custom usercontrol base on the rectangle and add a GradientStop Property to it.
Mark Hall