C# 改变无边框窗体尺寸大小的方法

const int HTLEFT = ;
const int HTRIGHT = ;
const int HTTOP = ;
const int HTTOPLEFT = ;
const int HTTOPRIGHT = ;
const int HTBOTTOM = ;
const int HTBOTTOMLEFT = 0x10;
const int HTBOTTOMRIGHT = ;
protected override void WndProc(ref Message m)
{
    switch (m.Msg)
    {
        case 0x0084:
            base.WndProc(ref m);
            Point vPoint = new Point((int)m.LParam & 0xFFFF,
                (int)m.LParam >>  & 0xFFFF);
            vPoint = PointToClient(vPoint);
            if (vPoint.X <= )
                if (vPoint.Y <= )
                    m.Result = (IntPtr)HTTOPLEFT;
                else if (vPoint.Y >= ClientSize.Height - )
                    m.Result = (IntPtr)HTBOTTOMLEFT;
                else m.Result = (IntPtr)HTLEFT;
            else if (vPoint.X >= ClientSize.Width - )
                if (vPoint.Y <= )
                    m.Result = (IntPtr)HTTOPRIGHT;
                else if (vPoint.Y >= ClientSize.Height - )
                    m.Result = (IntPtr)HTBOTTOMRIGHT;
                else m.Result = (IntPtr)HTRIGHT;
            else if (vPoint.Y <= )
                m.Result = (IntPtr)HTTOP;
            else if (vPoint.Y >= ClientSize.Height - )
                m.Result = (IntPtr)HTBOTTOM;
            break;
        case 0x0201://鼠标左键按下的消息
            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();//鼠标放在标题栏内
            base.WndProc(ref m);
            break;
        default:
            base.WndProc(ref m);
            break;
    }
}