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：
  1 using System;
  2 using System.Collections.Generic;
  3 using System.ComponentModel;
  4 using System.Data;
  5 using System.Drawing;
  6 using System.Linq;
  7 using System.Text;
  8 using System.Windows.Forms;
  9 using System.Threading;
 10 using System.Runtime.InteropServices;
 11 using WindowsFormsApplication1.Bus;
 12 
 13 namespace WindowsFormsApplication1
 14 {
 15     public partial class Screen : Form
 16     {
 17         public Screen()
 18         {
 19             InitializeComponent();
 20         }
 21 
 22         private static Screen scr = null;
 23 
 24         /// <summary>
 25         /// 屏保窗体
 26         /// </summary>
 27         /// <returns></returns>
 28         public static Screen GetScreen() {
 29             if (scr == null) {
 30                 scr = new Screen();
 31             }
 32             return scr;
 33         }
 34 
 35         ProductInfoWS.ProductInfoService ws = new WindowsFormsApplication1.ProductInfoWS.ProductInfoService();
 36 
 37        // KeyboardHook keyHook = new KeyboardHook();   //键盘钩子
 38 
 39         public string FormNum =string.Empty;  
 40 
 41         Thread t;  //定义一个线程
 42         private void Screen_Load(object sender, EventArgs e)
 43         {
 44   
 45             Max();
 46             t = new Thread(new ThreadStart(RunImage));
 47             t.Start();             //启动线程
 48             timer1.Start();
 49 
 50         }
 51 
 52    
 53 
 54         DataTable dt = null;
 55      
 56         string aa = "227";
 57         //图片轮播方法
 58         public void RunImage()    //换图片的方法  
 59         {
 60           
 61             string xml=ws.GetImage(Common.DeptID);
 62 
 63             if (!string.IsNullOrEmpty(xml))
 64             {
 65                 dt = UserBus.ConvertXMLToDataSet(xml).Tables[0];
 66             }
 67 
 68 
 69             if (dt != null && dt.Rows.Count > 0)
 70             {
 71                 while (true)      //循环````
 72                 {
 73                     for (int i = 0; i < dt.Rows.Count; i++)
 74                     {
 75                         pictureBox1.ImageLocation = dt.Rows[i]["ImageURL"].ToString();
 76                        // string ccc = dt.Rows[i]["Minute"].ToString();
 77                         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
 78                     }
 79                 }
 80 
 81             }
 82             else 
 83             {
 84                 pictureBox1.ImageLocation = "http://erp.ozz99.com.cn/SCImg/新浪微博登陆1.jpg";
 85             }
 86         }
 87 
 88 
 89 
 90         [StructLayout(LayoutKind.Sequential)]
 91         struct LASTINPUTINFO
 92         {
 93             [MarshalAs(UnmanagedType.U4)]
 94             public int cbSize;
 95             [MarshalAs(UnmanagedType.U4)]
 96             public uint dwTime;
 97         }
 98         [DllImport("user32.dll")]
 99         static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);
100         /// <summary>
101         ///获取键盘和鼠标没有操作的时间方法
102         /// </summary>
103         /// <returns></returns>
104         static long GetLastInputTime()
105         {
106             LASTINPUTINFO vLastInputInfo = new LASTINPUTINFO();
107             vLastInputInfo.cbSize = Marshal.SizeOf(vLastInputInfo);
108             if (!GetLastInputInfo(ref vLastInputInfo)) 
109                 return 0;
110             return Environment.TickCount - (long)vLastInputInfo.dwTime;
111 
112         }
113 
114        
115         private void Screen_Deactivate(object sender, EventArgs e)
116         {
117 
118 
119 
120         }
121 
122       
123         public void timer1_Tick(object sender, EventArgs e)
124         {
125 
126 
127             if (dt != null && dt.Rows.Count > 0)
128             {
129 
130 
131                 if (GetLastInputTime() > (Convert.ToInt32(dt.Rows[0]["Minute"].ToString()) * 60000))
132                 {
133                     this.TopMost = true;
134                     this.WindowState = FormWindowState.Maximized;
135 
136                 }
137 
138             }
139             else
140             {
141 
142                 if (GetLastInputTime() >60000)
143                 {
144                     this.TopMost = true;
145                     this.WindowState = FormWindowState.Maximized;
146 
147                 }
148                
149             }
150 
151 
152 
153 
154         }
155 
156       
157         private void Screen_KeyDown(object sender, KeyEventArgs e)
158         {
159             this.TopMost = false;
160             this.WindowState = FormWindowState.Minimized;
161             
162         }
163  
164 
165         //窗体最大化
166         public void Max() {
167 
168            // this.Opacity = 0.9;
169             if (this.WindowState == FormWindowState.Maximized)
170             {
171                 this.WindowState = FormWindowState.Normal;
172             }
173             else
174             {
175                 this.FormBorderStyle = FormBorderStyle.None;
176                 this.WindowState = FormWindowState.Maximized;
177             }
178         
179         }
180 
181         /// <summary>
182         /// 鼠标点击事件
183         /// </summary>
184         /// <param name="sender"></param>
185         /// <param name="e"></param>
186         private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
187         {
188             this.TopMost = false;
189             this.WindowState = FormWindowState.Minimized;
190  
191 
192         }
193 
194 
195 
196 
197     }
198 }
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*；