如何在不创建窗口的情况下将WPF UserControl渲染为位图

最终使用没有实际窗口的HwndHost。

void cwind()    {        Application myapp = new Application();        mrenderer = new WPFRenderer();        mrenderer.Width = 256;        mrenderer.Height = 256;        HwndSourceParameters myparms = new HwndSourceParameters();        HwndSource msrc = new HwndSource(myparms);        myparms.HwndSourceHook = new HwndSourceHook(ApplicationMessageFilter);        msrc.RootVisual = mrenderer;        myapp.Run();    }    static IntPtr ApplicationMessageFilter(IntPtr hwnd, int message, IntPtr wParam, IntPtr lParam, ref bool handled)    {        return IntPtr.Zero;    }