获取键盘或鼠标多久没有对屏幕进行操作了

屏幕保护相关代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using System.Runtime.InteropServices;
using WindowsFormsApplication1.Bus;

namespace WindowsFormsApplication1
{
    public partial class Screen : Form
    {
        public Screen()
        {
            InitializeComponent();
        }

        private static Screen scr = null;

        /// <summary>
        /// 屏保窗体
        /// </summary>
        /// <returns></returns>
        public static Screen GetScreen() {
            if (scr == null) {
                scr = new Screen();
            }
            return scr;
        }

        ProductInfoWS.ProductInfoService ws = new WindowsFormsApplication1.ProductInfoWS.ProductInfoService();

       // KeyboardHook keyHook = new KeyboardHook();   //键盘钩子

        public string FormNum =string.Empty;  

        Thread t;  //定义一个线程
        private void Screen_Load(object sender, EventArgs e)
        {
  
            Max();
            t = new Thread(new ThreadStart(RunImage));
            t.Start();             //启动线程
            timer1.Start();

        }

   

        DataTable dt = null;
     
        string aa = "227";
        //图片轮播方法
        public void RunImage()    //换图片的方法  
        {
          
            string xml=ws.GetImage(Common.DeptID);

            if (!string.IsNullOrEmpty(xml))
            {
                dt = UserBus.ConvertXMLToDataSet(xml).Tables[0];
            }


            if (dt != null && dt.Rows.Count > 0)
            {
                while (true)      //循环````
                {
                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        pictureBox1.ImageLocation = dt.Rows[i]["ImageURL"].ToString();
                       // string ccc = dt.Rows[i]["Minute"].ToString();
                        Thread.Sleep(2000);            //换一次图片让线程休息多少时间具体修改里面的参数例如一秒换一次填1000
                    }
                }

            }
            else 
            {
                pictureBox1.ImageLocation = "http://erp.ozz99.com.cn/SCImg/新浪微博登陆1.jpg";
            }
        }



        [StructLayout(LayoutKind.Sequential)]
        struct LASTINPUTINFO
        {
            [MarshalAs(UnmanagedType.U4)]
            public int cbSize;
            [MarshalAs(UnmanagedType.U4)]
            public uint dwTime;
        }
        [DllImport("user32.dll")]
        static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);
        /// <summary>
        ///获取键盘和鼠标没有操作的时间方法
        /// </summary>
        /// <returns></returns>
        static long GetLastInputTime()
        {
            LASTINPUTINFO vLastInputInfo = new LASTINPUTINFO();
            vLastInputInfo.cbSize = Marshal.SizeOf(vLastInputInfo);
            if (!GetLastInputInfo(ref vLastInputInfo)) 
                return 0;
            return Environment.TickCount - (long)vLastInputInfo.dwTime;

        }

       
        private void Screen_Deactivate(object sender, EventArgs e)
        {



        }

      
        public void timer1_Tick(object sender, EventArgs e)
        {


            if (dt != null && dt.Rows.Count > 0)
            {


                if (GetLastInputTime() > (Convert.ToInt32(dt.Rows[0]["Minute"].ToString()) * 60000))
                {
                    this.TopMost = true;
                    this.WindowState = FormWindowState.Maximized;

                }

            }
            else
            {

                if (GetLastInputTime() >60000)
                {
                    this.TopMost = true;
                    this.WindowState = FormWindowState.Maximized;

                }
               
            }




        }

      
        private void Screen_KeyDown(object sender, KeyEventArgs e)
        {
            this.TopMost = false;
            this.WindowState = FormWindowState.Minimized;
            
        }
 

        //窗体最大化
        public void Max() {

           // this.Opacity = 0.9;
            if (this.WindowState == FormWindowState.Maximized)
            {
                this.WindowState = FormWindowState.Normal;
            }
            else
            {
                this.FormBorderStyle = FormBorderStyle.None;
                this.WindowState = FormWindowState.Maximized;
            }
        
        }

        /// <summary>
        /// 鼠标点击事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            this.TopMost = false;
            this.WindowState = FormWindowState.Minimized;
 

        }




    }
}

 1. 让屏幕永远在最前面：TopMost；

 2. 接口写好后，需要更新引用；

 3. TextBox密码显示：PasswordChar为*；