winform无边框窗体拖拽效果

    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }

        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
        public static extern IntPtr SendMessage(IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);


        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
        public static extern bool ReleaseCapture();

//将此事件绑定到窗体控件上即可拖动
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            const int WM_NCLBUTTONDOWN = 0x00A1;
            const int HTCAPTION = 2;
            if (e.Button == MouseButtons.Left) // 按下的是鼠标左键 
            {
                ReleaseCapture();
                SendMessage(this.Handle, WM_NCLBUTTONDOWN, (IntPtr)HTCAPTION, IntPtr.Zero); // 拖动窗体 
            }
        }

    }