WinForm特效:桌面上的遮罩层

一个窗体特效，帮你了解几个windows api函数.效果：windows桌面上增加一个简单的遮罩层,其中WS_EX_TRANSPARENT 比较重要，它实现了鼠标穿透的功能。

using System;

using System.Drawing;

using System.Windows.Forms;

using System.Runtime.InteropServices;

namespace WindowsApplication40

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        [DllImport("user32.dll", EntryPoint = "GetWindowLong")]

        public static extern long GetWindowLong(IntPtr hwnd, int nIndex);



        [DllImport("user32.dll", EntryPoint = "SetWindowLong")]

        public static extern long SetWindowLong(IntPtr hwnd, int nIndex, long dwNewLong);



        [DllImport("user32", EntryPoint = "SetLayeredWindowAttributes")]

        private static extern int SetLayeredWindowAttributes(IntPtr Handle, int crKey, byte bAlpha, int dwFlags);



        const int GWL_EXSTYLE = -20;

        const int WS_EX_TRANSPARENT = 0x20;

        const int WS_EX_LAYERED = 0x80000;

        const int LWA_ALPHA = 2;





        private void Form1_Load(object sender, EventArgs e)

        {

            this.BackColor = Color.Silver;

            this.TopMost = true;

            this.FormBorderStyle = FormBorderStyle.None;

            this.WindowState = FormWindowState.Maximized;

            SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE) | WS_EX_TRANSPARENT | WS_EX_LAYERED);

            SetLayeredWindowAttributes(Handle, 0, 128, LWA_ALPHA );



        }

    }

}