Stretch="UniformToFill"
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="Microsoft.Samples.Graphics.RectangleExample" WindowTitle="Example"> <Canvas> <Ellipse Fill="Yellow" Stroke="Blue" Grid.Column="2" Stretch="UniformToFill "></Ellipse> </Canvas> </Page>