C# 無邊框表單隨意拖動和改變尺寸

const int WM_NCHITTEST = 0x0084;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;protected override void WndProc(ref Message m){    base.WndProc(ref m);    switch (m.Msg)    {        case WM_NCHITTEST:            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;    }}