WPF drawing that stretches without stretching the Pen - wpf

Question

I need to draw some simple lines within a Border control (or similar) that always stretch to the bounds of the Border. Is there a way to stretch the lines only but not its pen? Without involving lots of C#?
In this version the lines stretch:
<Border>
<Border.Background>
<DrawingBrush>
<DrawingBrush.Drawing>
<DrawingGroup>
<GeometryDrawing Brush="Red">
<GeometryDrawing.Geometry>
<GeometryGroup>
<RectangleGeometry Rect="0,0 100,1000" />
<LineGeometry StartPoint="0,0" EndPoint="100,1000"/>
<LineGeometry StartPoint="100,0" EndPoint="0,1000"/>
</GeometryGroup>
</GeometryDrawing.Geometry>
<GeometryDrawing.Pen>
<Pen Thickness="20" Brush="Black"/>
</GeometryDrawing.Pen>
</GeometryDrawing>
</DrawingGroup>
</DrawingBrush.Drawing>
</DrawingBrush>
</Border.Background>
</Border>
The best solution I have come up with is this:
<Border>
<Grid>
<Path Stretch="Fill" Fill="Red" Stroke="Black" StrokeThickness="4" Data="M0,0 L100,0 100,1000 0,1000 z" />
<Path Stretch="Fill" Stroke="Black" StrokeThickness="4" Data="M 0,0 L0,0 100,1000" />
<Path Stretch="Fill" Stroke="Black" StrokeThickness="4" Data="M 100,0 L100,0 0,1000" />
</Grid>
</Border>
But isn't there a better solution? That doesn't involve extra Grid?

Answer 1

I've done this by scaling a Path's Data, not the visual component.
Place a Path in a Canvas.
Set path.Data to a Geometry representing your data as percentages of the logical range.
Set path.Data.Transform to a ScaleTransform with ScaleX and ScaleY bound to the actual width and height.

Answer 2

Within a line, you can bind the width (or height, depending on which way you are drawing the line) to that of the parent container to achieve what you want.
<Grid x:Name="Grid" Margin="10">
<Border BorderBrush="Black" BorderThickness="1" />
<Line X1="0" X2="{Binding ElementName=Grid, Path=ActualWidth}" Y1="1" Y2="1" Stroke="Red" Margin="0,10,0,0" />
<Line X1="0" X2="{Binding ElementName=Grid, Path=ActualWidth}" Y1="1" Y2="1" Stroke="Green" Margin="0,30,0,0" />
<Line X1="0" X2="{Binding ElementName=Grid, Path=ActualWidth}" Y1="1" Y2="1" Stroke="Blue" Margin="0,50,0,0" />
</Grid>
Edit: Here is another way without using binding
<Border BorderBrush="Black" BorderThickness="1" >
<Path Stroke="Red" StrokeThickness="1" Data="M0,0 1,0Z" Stretch="Fill" />
</Border>

Answer 3

None that I know of. But unless you're doing something really extravagant, it really isn't a lot of effort to override OnRender and draw it yourself:
public class CustomBorder : Border
{
protected override void OnRender(DrawingContext dc)
{
base.OnRender(dc);
dc.DrawLine(new Pen(BorderBrush, BorderThickness.Top), new Point(0, 0), new Point(ActualWidth, ActualHeight));
}
}
Result: