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;
    }