C-锁图纸

基本上,我已经设置了一个类来处理发送wm_setredraw消息,如下所示:

public static class DrawingLocker
{
    [DllImport("user32", CharSet = CharSet.Auto)]
    private extern static IntPtr SendMessage(IntPtr hWnd, 
            int msg, int wParam, IntPtr lParam);

    private const int WM_SETREDRAW = 11; //0xB

    public static void LockDrawing(IntPtr Handle)
    {
        SendMessage(Handle, WM_SETREDRAW, 0, IntPtr.Zero);
    }

    public static void UnlockDrawing(IntPtr Handle)
    {
        SendMessage(Handle, WM_SETREDRAW, 1, IntPtr.Zero);
    }
}

然后在自定义用户控件中有一个重绘方法:

public void Redraw()
{
    try
    {
        DrawingLocker.LockDrawing(Handle);
        using (Graphics graphics = Graphics.FromHwnd(Handle))
        {
            //Draw Stuff
        }
    }
    finally { DrawingLocker.UnlockDrawing(Handle); }
}

我的问题是,我画的任何东西都没有“画东西”的评论被画出来。我做错什么了? (当影响绘图的值发生变化(包括调整大小)时,将调用Redraw)