WinForm 无边框窗体改变尺寸及移动窗体

 #region 无边框窗体移动改变大小

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

        public const int WM_SYSCOMMAND = 0x0112;
        public const int SC_MOVE = 0xF010;
        public const int HTCAPTION = 0x0002;
        const int HTLEFT = 10;
        const int HTRIGHT = 11;
        const int HTTOP = 12;
        const int HTTOPLEFT = 13;
        const int HTTOPRIGHT = 14;
        const int HTBOTTOM = 15;
        const int HTBOTTOMLEFT = 0x10;
        const int HTBOTTOMRIGHT = 17;

        public bool ManualResize
        {
            get
            {
                return this.FormBorderStyle == System.Windows.Forms.FormBorderStyle.None
                    && this.WindowState == FormWindowState.Normal;
            }
        }

        protected override void WndProc(ref Message m)
        {
            switch (m.Msg)
            {
                case 0x0084:
                    base.WndProc(ref m);
                    if (ManualResize)
                    {
                        Point vPoint = new Point((int)m.LParam & 0xFFFF,
                            (int)m.LParam >> 16 & 0xFFFF);
                        vPoint = PointToClient(vPoint);
                        if (vPoint.X <= 5)
                            if (vPoint.Y <= 5)
                                m.Result = (IntPtr)HTTOPLEFT;
                            else if (vPoint.Y >= ClientSize.Height - 5)
                                m.Result = (IntPtr)HTBOTTOMLEFT;
                            else m.Result = (IntPtr)HTLEFT;
                        else if (vPoint.X >= ClientSize.Width - 5)
                            if (vPoint.Y <= 5)
                                m.Result = (IntPtr)HTTOPRIGHT;
                            else if (vPoint.Y >= ClientSize.Height - 5)
                                m.Result = (IntPtr)HTBOTTOMRIGHT;
                            else m.Result = (IntPtr)HTRIGHT;
                        else if (vPoint.Y <= 5)
                            m.Result = (IntPtr)HTTOP;
                        else if (vPoint.Y >= ClientSize.Height - 5)
                            m.Result = (IntPtr)HTBOTTOM;
                    }
                    break;
                case 0x0201:    //鼠标左键按下的消息
                    if (ManualResize)
                    {
                        m.Msg = 0x00A1;    //更改消息为非客户区按下鼠标
                        m.LParam = IntPtr.Zero;    //默认值
                        m.WParam = new IntPtr(2);    //鼠标放在标题栏内
                    }
                    base.WndProc(ref m);
                    break;
                default:
                    try
                    {
                        base.WndProc(ref m);
                    }
                    catch (Exception) { }
                    break;
            }
        }
        #endregion

原文地址：https://www.cnblogs.com/yc1224/p/12071963.html