WPF应用中对WindowsFormHost内容进行裁剪

 <Grid>
    <WindowsFormsHost Background="White">
          <Winfrm:WebBrowser x:Name="WinFrmWebBrowser"/>
    </WindowsFormsHost>
    <!--运行时 Ellipse 不会显示出来-->
    <Ellipse Width="100" Height="100" Fill="Red"/>
 </Grid>

<Style TargetType="{x:Type local:MyBrowser}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:MyBrowser}">
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                    <Grid>
                        <Border x:Name="Part_BdrWinfrmHostContainer">
                            <WindowsFormsHost x:Name="Part_WinfrmHost" Background="Gray">
                                <Winfrm:WebBrowser x:Name="Part_WinFrmWebBrowser"/>
                            </WindowsFormsHost>
                        </Border>
                        <Popup x:Name="PART_Popup" IsOpen="True" Placement="Center" 
                               AllowsTransparency="True">
                            <!--所有WPF内容添加至这个Border里面-->
                            <Border x:Name="PART_Content"/>
                        </Popup>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Grid x:Name="GdPopupWays" Grid.Column="1">
    <local:MyBrowser Link="http://www.baidu.com">
        <local:MyBrowser.Content>
            <!--local:OverLayer是自定义的UserControl-->
            <local:OverLayer/>
        </local:MyBrowser.Content>
    </local:MyBrowser>
</Grid>

GraphicsPath path = new GraphicsPath() { FillMode = FillMode.Winding };
path.StartFigure();
path.AddEllipse(new System.Drawing.Rectangle(0, 0, (int)182, (int)182));
path.AddRectangle(new System.Drawing.Rectangle(90, 0, 90, 90));
path.CloseFigure();
this.WinformRtx.Region = new Region(path);

<Grid x:Name="GdMain">
    <Image x:Name="ImgSky" Source="Sky.jpg" Stretch="Fill"/>

    <!--加载Winform的WebBrowser-->
    <WindowsFormsHost Background="White">
        <Winfrm:WebBrowser x:Name="WinFrmWebBrowser"/>
    </WindowsFormsHost>

    <WindowsFormsHost Width="182" Height="182" HorizontalAlignment="Right" 
                      x:Name="WinfrmHostOverlayer" VerticalAlignment="Top" 
                      Background="Transparent">
        <Winfrm:Panel x:Name="WinfrmPanel"/>
    </WindowsFormsHost>
</Grid>

<Grid x:Name="GdMain">
    <Image x:Name="ImgSky" Source="Sky.jpg" Stretch="Fill"/>
    <WindowsFormsHost HorizontalAlignment="Right" 
                      x:Name="WinfrmHostOverlayer" VerticalAlignment="Top" 
                      Background="Transparent">
        <Winfrm:Panel x:Name="WinfrmPanel">
            <!--<Winfrm:WebBrowser x:Name="WinFrmWebBrowser"/>-->
            <!--<Winfrm:Panel x:Name="WinFrmSubPanel"/>-->
        </Winfrm:Panel>
    </WindowsFormsHost>
</Grid>