如何用曲线包围我的WPF Datagrid标头？

<Style x:Key="CustomDataGridHeaderStyle" TargetType="{x:Type DataGridColumnHeader}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type DataGridColumnHeader}">
                <Grid>
                    <Border BorderThickness="0,0,1,1" BorderBrush="Black">
                        <Border.Background>
                            <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
                                <GradientStop Offset="0" Color="White" />
                                <GradientStop Offset="1" Color="LightGray" />
                            </LinearGradientBrush>
                        </Border.Background>
                    </Border>
                    <Path Data="M0,0 L10,0 L5,10 Z" Fill="Black" Margin="0,0,0,-3" HorizontalAlignment="Center" VerticalAlignment="Bottom" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<DataGrid>
    <DataGrid.Resources>
        <Style TargetType="{x:Type DataGridColumnHeader}" BasedOn="{StaticResource CustomDataGridHeaderStyle}" />
    </DataGrid.Resources>
    <!-- Datagrid的内容列定义 -->
</DataGrid>