Use a rectangle shape as a clip in XAML

Question

Is there a way that I can use a normal Rectangle (shape) as part of a clip for another object in XAML. It seems like I should be able to, but the solution is eluding me..

<Canvas>

        <Rectangle Name="ClipRect" RadiusY="10" RadiusX="10" Stroke="Black" StrokeThickness="0" Width="32.4" Height="164"/>

<!-- This is the part that I cant quite figure out.... -->
<Rectangle Width="100" Height="100" Clip={Binding ElementName=ClipRect, Path="??"/>

</Canvas>

I know that I can use a 'RectangleGeometry' type approach, but I am more interested in the solution in terms of the code presented above.

Etesian

Take a look at #1322240 – Cetane

Answer 1

Try Shape.RenderedGeometry Property.

<Rectangle Width="100" Height="100"
           Clip="{Binding ElementName=ClipRect, Path=RenderedGeometry}" />

Repulsion

Answer 2

ClipRect.DefiningGeometry nd ClipRect.RenderedGeometry contain only the RadiusX and RadiusY values but not also Rect.

I'm not sure what exactly you want to achieve (it's not clear to me from your sample) but you could write an IValueConverter which would extract the info you require from the referenced Rectangle:

public class RectangleToGeometryConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var rect = value as Rectangle;

        if (rect == null || targetType != typeof(Geometry))
        {
            return null;
        }

        return new RectangleGeometry(new Rect(new Size(rect.Width, rect.Height)))
        { 
            RadiusX = rect.RadiusX, 
            RadiusY = rect.RadiusY 
        };
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

You would then use this converter in your binding definition:

<Rectangle Width="100" Height="100" 
            Clip="{Binding ElementName=ClipRect, Converter={StaticResource RectangleToGeometryConverter}}">

Of course you need to add the converter to your resources first:

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

Elviselvish

In my example I am trying to clip one Rectangle with the other. I'm trying to avoid converters / workarounds. – Etesian

@Etesian The only way to avoid converters (workarounds as you call them), is to find a Rectangle property which contains the info you need. If RenderedGeometry and DefiningGeometry don't have it, you won't be able to avoid at least some code. I find a converter the least "evil" since it's essentially still markup. – Elviselvish