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 );        }    }}