How to have a one sided border which is a rounded rectangle?-CodePudding

I want to have a one-sided border of any border control like the blue side bar on the left here: . Either gradients don't work or I am missing something about them. Is there an implementable solution to this?

CodePudding user response：

I have made a small sample:

    <Border x:Name="MainBorder" Padding="0,20,0,20" CornerRadius="10,10,10,10" Background="LightGray" HorizontalAlignment="Left" VerticalAlignment="Top">
        <StackPanel Orientation="Horizontal">
            <Border x:Name="SideBorder" BorderThickness="5,5,5,5" CornerRadius="1,1,1,1" BorderBrush="Blue" Height="50" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,8,0,0"></Border>
            <TextBlock x:Name="TestBlock" Text="Text" Margin="50,0,150,0" FontSize="48" HorizontalAlignment="Center" VerticalAlignment="Center"></TextBlock>
        </StackPanel>
    </Border>