C# 制作透明窗体

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using ControlExs;

namespace TransForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            //// 定义在窗体上，光标显示为手形
            this.Cursor = System.Windows.Forms.Cursors.Hand;
            //// 定义窗体的标题名称 
            this.Text = "透明的WinForm窗体！";
            //// 定义窗体的开始显示位置是屏幕的中间 
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
            //// 窗体的边界是Fixed3D类型
            //this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
            ////以桌面的前景色作为窗体的前景色 
            this.ForeColor = System.Drawing.SystemColors.Desktop;
            //// 定义字体类型，大小 
            this.Font = new System.Drawing.Font("宋体", 9);
            //// 定义背景色为蓝色 
            this.BackColor = System.Drawing.Color.White;
            // 设置窗体的大小 
            //this.ClientSize = new System.Drawing.Size(440, 170);
            // Opacity属性设立窗体的透明程度，只对于视窗2000有效 
            this.Opacity = 0.60;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.SetWindowTransparent(100); 
        }

        private void SetWindowTransparent(byte bAlpha)
        {
            try
            {
                WinAPI.SetWindowLong(this.Handle, (int)WinAPI.WindowStyle.GWL_EXSTYLE, WinAPI.GetWindowLong(this.Handle, (int)WinAPI.WindowStyle.GWL_EXSTYLE) | (uint)WinAPI.ExWindowStyle.WS_EX_LAYERED);
                WinAPI.SetLayeredWindowAttributes(this.Handle, 0, bAlpha, WinAPI.LWA_COLORKEY | WinAPI.LWA_ALPHA);
            }
            catch
            {

            }
        }

        protected override CreateParams CreateParams
        {
            get
            {
                CreateParams cp = base.CreateParams;
                cp.Parent = WinAPI.GetDesktopWindow();
                cp.ExStyle = 0x00000080 | 0x00000008;  //WS_EX_TOOLWINDOW | WS_EX_TOPMOST   
                return cp;
            }
        }
    }
}

 public class WinAPI
    {
        [DllImport("user32.dll")]
        public extern static IntPtr GetDesktopWindow();

        [DllImport("user32.dll")]
        public extern static bool SetLayeredWindowAttributes(IntPtr hwnd, uint crKey, byte bAlpha, uint dwFlags);

        public static uint LWA_COLORKEY = 0x00000001;
        public static uint LWA_ALPHA = 0x00000002;

        [DllImport("user32.dll")]
        public extern static uint SetWindowLong(IntPtr hwnd, int nIndex, uint dwNewLong);

        [DllImport("user32.dll")]
        public extern static uint GetWindowLong(IntPtr hwnd, int nIndex);

        public enum WindowStyle : int { GWL_EXSTYLE = -20 }
        public enum ExWindowStyle : uint { WS_EX_LAYERED = 0x00080000 }
    }