判断控件是否出现了滚动条

收藏自：https://blog.csdn.net/ltolll/article/details/7637995

经测试，有效。

  private const int WS_HSCROLL = 0x100000;
        private const int WS_VSCROLL = 0x200000;
        private const int GWL_STYLE = (-16);

        [System.Runtime.InteropServices.DllImport("user32", CharSet = System.Runtime.InteropServices.CharSet.Auto)]
        private static extern int GetWindowLong(IntPtr hwnd, int nIndex);

        /// <summary>
        /// 判断是否出现垂直滚动条
        /// </summary>
        /// <param name="ctrl">待测控件</param>
        /// <returns>出现垂直滚动条返回true，否则为false</returns>
        internal static bool IsVerticalScrollBarVisible(Control ctrl)
        {
            if (!ctrl.IsHandleCreated)
                return false;

            return (GetWindowLong(ctrl.Handle, GWL_STYLE) & WS_VSCROLL) != 0;
        }

        /// <summary>
        /// 判断是否出现水平滚动条
        /// </summary>
        /// <param name="ctrl">待测控件</param>
        /// <returns>出现水平滚动条返回true，否则为false</returns>
        internal static bool IsHorizontalScrollBarVisible(Control ctrl)
        {
            if (!ctrl.IsHandleCreated)
                return false;
            return (GetWindowLong(ctrl.Handle, GWL_STYLE) & WS_HSCROLL) != 0;
        }