WPF: TemplateBinding to StrokeThickness of Shape does not work?

Question

Looks like the following Ellipse in ControlTemplate does not get the BorderThickness, but why?

<Window.Resources>
    <ControlTemplate x:Key="EllipseControlTemplate" TargetType="{x:Type TextBox}">
        <Grid>
            <Ellipse 
                Width="{TemplateBinding ActualWidth}" 
                Height="{TemplateBinding ActualHeight}" 
                Stroke="{TemplateBinding Foreground}" 
                StrokeThickness="{TemplateBinding BorderThickness}" />
                <ScrollViewer Margin="0" x:Name="PART_ContentHost" HorizontalAlignment="Center" VerticalAlignment="Center"/>
        </Grid>
    </ControlTemplate>
</Window.Resources>
<Grid>
    <TextBox
        Template="{DynamicResource EllipseControlTemplate}" 
        Foreground="Green"
        BorderThickness="15" />
</Grid>

TemplateBinding to Foreground works just fine, the ellipse is green. But to StrokeThickness it doesn't seem to work, why?

score 16 · Answer 1 · edited Oct 09 '12 at 19:18

16

Another possible solution ... (because i like to only use IValueConverters as a last resort, and changing the DataContext of the Ellipse might not work if you need it to be set to something else):

<Ellipse StrokeThickness="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=BorderThickness.Top}" />

This is equivalent to the original intent (to bind to the TemplatedParent), but using the long-hand markup allows you to specify a Path rather than just a property

edited Oct 09 '12 at 19:18

karthikr

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answered Oct 09 '12 at 19:12

ncsu95

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Nit-pick on this great answer: I think `BorderThickness.Left` actually be the preferred value to use since it is the first value. See [this answer about margin](https://stackoverflow.com/a/8522026/1518546) but [the order is the same for Thickness](https://learn.microsoft.com/en-us/dotnet/api/system.windows.thickness#xaml-values). – John Cummings Feb 13 '18 at 23:41

Massimiliano · Accepted Answer · 2009-11-26T16:54:10.447

8

BorderThickness is not that easy, it is a struct of type Thickness (and can be composite, like BorderThickness=".0,.0,2,2"), while StrokeThickness property is of type double.

You need IValueConverter to make this binding work.

edited Nov 26 '09 at 16:54

answered Nov 26 '09 at 14:35

Massimiliano

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I apologize, I found the answer myself already. See the answer I wrote... You probably meant that. – Ciantic Nov 26 '09 at 14:42
Good for you :) Still, mine was earlier :) – Massimiliano Nov 26 '09 at 14:47
Thats true! I will choose yours as solution if you mention the Type difference, it's the key here. – Ciantic Nov 26 '09 at 14:51

score 1 · Answer 3 · answered Jun 14 '12 at 19:22

1

You can also use the DataContext property of the Ellipse:

<Ellipse DataContext="{TemplateBinding BorderThickness}" StrokeThickness="{Binding Top}" />

Hope this helps!

answered Jun 14 '12 at 19:22

Horacio Nuñez

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score 1 · Answer 4 · answered Nov 26 '09 at 14:41

1

There was naming gotcha: BorderThickness is type of Thickness, and StrokeThickness is type of double. So we need IValueConverter.

answered Nov 26 '09 at 14:41

Ciantic

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WPF: TemplateBinding to StrokeThickness of Shape does not work?

4 Answers4