C#透明窗体代码详解

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace TransForm  {
    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 = ×;
        public static uint LWA_ALPHA = ×;

        [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 = -
        }

        public enum ExWindowStyle : uint
        {
            WS_EX_LAYERED = ×
        }
     }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace TransForm{  

    public partial class Form1 : Form
    {
        public Form1(){InitializeComponent();}
        private void Form1_Load(object sender, EventArgs e)
        {
            this.SetWindowTransparent();
        } 

        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, , bAlpha,   WinAPI.LWA_COLORKEY | WinAPI.LWA_ALPHA);
            }
            catch
            {

            }
        }

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