c#通过调用系统库函数获取计算机物理屏幕尺寸

#region Win32 API
        [DllImport("user32.dll")]
        static extern IntPtr GetDC(IntPtr ptr);
        [DllImport("gdi32.dll")]
        static extern int GetDeviceCaps( IntPtr hdc,  int nIndex );
        [DllImport("user32.dll", EntryPoint = "ReleaseDC")]
        static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDc);
        #endregion
        #region DeviceCaps常量
        const int DESKTOPVERTRES = 117;
        const int DESKTOPHORZRES = 118;
        #endregion
        /// <summary>
        /// 获取物理屏幕的大小
        /// </summary>
        /// <returns>屏幕的宽度和高度</returns>