public partial class RemainingTimeUC : UserControl
    {

        public RemainingTimeUC()
        {
            InitializeComponent();
        }
        Form ParantForm = null;
        private void RemainingTimeUC_Load(object sender, EventArgs e)
        {
           //获得用户控件所在的窗体
            ParantForm = this.FindForm();
        }
        #region timerUC_Tick事件
        private void timerUC_Tick(object sender, EventArgs e)
        {
            try
            {
                int TotalSecond = 60;//设置时间为60s
                var remainTime = TotalSecond - MouseKeyBoardOperate.GetLastInputTime();//总时间-用户未操作的时间
                this.labRT.Text = remainTime.ToString(CultureInfo.InvariantCulture);//显示离关闭的剩余时间

                if (remainTime == 30)
                {
                    this.labRT.ForeColor = Color.Orange;
                }
                if (remainTime <= 9)
                {
                    this.labRT.ForeColor = Color.Red;
                    this.labRT.Text = "0" + remainTime;
                }
                if (remainTime == 59)
                    this.labRT.ForeColor = Color.White;
                if (remainTime == 0)
                {
                    ParantForm.Close();
                }
            }
            catch (Exception ex)
            {
                LogHelper.WriteLog(this.Name + "timerUC_Tick", ex.Message);
            }

        }
        #endregion
    }

//
//此方法不知道是哪位前辈写的，借用一下
//
public class MouseKeyBoardOperate
{
/// <summary>
/// 创建结构体用于返回捕获时间
/// </summary>
[StructLayout(LayoutKind.Sequential)]
struct Lastinputinfo
{
/// <summary>
/// 设置结构体块容量
/// </summary>
[MarshalAs(UnmanagedType.U4)]
public int cbSize;

/// <summary>
/// 抓获的时间
/// </summary>
[MarshalAs(UnmanagedType.U4)]
public uint dwTime;
}

[DllImport("user32.dll")]
private static extern bool GetLastInputInfo(ref Lastinputinfo plii);

/// <summary>
/// 获取键盘和鼠标没有操作的时间
/// </summary>
/// <returns>用户上次使用系统到现在的时间间隔，单位为秒</returns>
public static long GetLastInputTime()
{
var vLastInputInfo = new Lastinputinfo();
vLastInputInfo.cbSize = Marshal.SizeOf(vLastInputInfo);
if (!GetLastInputInfo(ref vLastInputInfo))
{
return 0;
}
else
{
var count = Environment.TickCount - (long)vLastInputInfo.dwTime;
var icount = count / 1000;
return icount;
}
}