C#创建鼠标能穿透的窗体

本功能应用广泛，出自一时的兴趣。编出如下代码进行记录，便于以后查阅。主要使用WinApi函数为：SetWindowLong，GetWindowLong，SetLayeredWindowAttributes。

        private const uint WS_EX_LAYERED = 0x80000;
        private const int WS_EX_TRANSPARENT = 0x20;
        private const int GWL_STYLE = (-16);
        private const int GWL_EXSTYLE = (-20);
        private const int LWA_ALPHA = 0x2;

        [DllImport("user32", EntryPoint = "SetWindowLong")]
        private static extern uint SetWindowLong(
        IntPtr hwnd,
        int nIndex,
        uint dwNewLong
        );

        [DllImport("user32", EntryPoint = "GetWindowLong")]
        private static extern uint GetWindowLong(
        IntPtr hwnd,
        int nIndex
        );

        [DllImport("user32", EntryPoint = "SetLayeredWindowAttributes")]
        private static extern int SetLayeredWindowAttributes(
        IntPtr hwnd,
        int crKey,
        int bAlpha,
        int dwFlags
        );

        /// <summary>
        /// 设置窗体具有鼠标穿透效果
        /// </summary>
        public void SetPenetrate()
        {
            this.TopMost = true;
            GetWindowLong(this.Handle, GWL_EXSTYLE);
            SetWindowLong(this.Handle, GWL_EXSTYLE, WS_EX_TRANSPARENT | WS_EX_LAYERED);
            SetLayeredWindowAttributes(this.Handle, 0, 100, LWA_ALPHA);
        } 

　　把SetPenetrate()方法放到Load事件里面就可以把当前窗口设置成具有鼠标穿透效果的窗体。