LONG SetWindowLongA(
  [in] HWND hWnd,
  [in] int  nIndex,
  [in] LONG dwNewLong
);

LONG GetWindowLongA(
  [in] HWND hWnd,
  [in] int  nIndex
);

BOOL SetLayeredWindowAttributes(
  [in] HWND     hwnd, 
  [in] COLORREF crKey,
  [in] BYTE     bAlpha,
  [in] DWORD    dwFlags
);

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

namespace demo189_窗體移動
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        //定義user32.dll參數(shù)值
        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 = 0;

        //更改指定窗口的屬性
        [DllImport("user32", EntryPoint = "SetWindowLong")]
        private static extern uint SetWindowLong(IntPtr hwnd,int nIndex,uint dwNewLong
        );
        //檢索有關(guān)指定窗口的信息
        [DllImport("user32", EntryPoint = "GetWindowLong")]
        private static extern uint GetWindowLong(IntPtr hwnd,int nIndex
        );
        //設(shè)置分層窗口的不透明度和透明度顏色鍵
        [DllImport("user32", EntryPoint = "SetLayeredWindowAttributes")]
        private static extern int SetLayeredWindowAttributes(IntPtr hwnd,int crKey,int bAlpha,int dwFlags
        );

        /// <summary> 
        /// 設(shè)置窗體具有鼠標(biāo)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(m_hWnd,0,(BYTE)220,LWA_ALPHA);
           //SetLayeredWindowAttributes(m_hWnd,RGB(255,0,255),(BYTE)220,LWA_ALPHA|LWA_COLORKEY);
            //SetLayeredWindowAttributes(m_hWnd,RGB(0,255,0),0,LWA_COLORKEY);
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            this.Opacity = 0.7;
            SetPenetrate();
        }
    }
}