实现ppt幻灯片播放倒计时

需求：为控制会议时间，采取ppt幻灯片播放倒计时的办法，倒计时5分钟。

分析：用EnumWindows枚举窗口，发现PPT窗口类名有三种：PP12FrameClass、MS-SDIb、screenClass。其中screenClass代表全屏播放窗口。

设计思路：在timer控件中用FindWindow检查有无screenClass的窗口，用TimeSpan倒计时。

设计成一个托盘程序，用一个notifyIcon和contextMenuStrip关联。

代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;
using System.Text.RegularExpressions;
using System.IO;

namespace pptClock
{　　//使用说明：用于ＰＰＴ倒计时的winform。将播放的ＰＰＴ文件名最后加上数字，表示播放限时的分钟数。若数字为０或无数字表示不限时。
    public partial class Form1 : Form
    { 
        //相关的win32 api
        [DllImport("user32.dll")]
        private static extern int GetWindowTextW(IntPtr hWnd, [MarshalAs(UnmanagedType.LPWStr)]StringBuilder lpString, int nMaxCount);
        [DllImport("user32.dll")]
        private static extern int GetClassNameW(IntPtr hWnd, [MarshalAs(UnmanagedType.LPWStr)]StringBuilder lpString, int nMaxCount);       
        [DllImport("user32.dll", EntryPoint = "FindWindow")]
        private extern static IntPtr FindWindow(string lpClassName, string lpWindowName);
        public const int WM_CLOSE = 0x10;
        [DllImport("user32.dll", EntryPoint = "SendMessageA")]
        public static extern int SendMessage(IntPtr hwnd, int wMsg, int wParam, int lParam);
    
  

        //全屏播放ＰＰＴ窗口信息
        public struct WindowInfo
        {
            public IntPtr hWnd;　//ppt窗口句柄
            public string szWindowName;//窗口标题
            public string szClassName;//类名：screenClass ,实际没有用。 
            public int timeL; //播放限时，从文件名中获取
        }              

        public bool hasscreenClass()　　//是否有全屏播放ＰＰＴ
        {
            bool yn = false;
            IntPtr hwnd = FindWindow("screenClass", null);
            if (hwnd != IntPtr.Zero)//有全屏的ＰＰＴ
            {
                yn = true;
                //则将窗口信息保存到wndfullscreen中
                StringBuilder sb = new StringBuilder(256);
                //get hwnd
                wndfullscreen.hWnd = hwnd;
                //get window name
                GetWindowTextW(hwnd, sb, sb.Capacity);
                wndfullscreen.szWindowName = sb.ToString();
                //get window class
                GetClassNameW(hwnd, sb, sb.Capacity);
                wndfullscreen.szClassName = sb.ToString();              
                Match result = Regex.Match(wndfullscreen.szWindowName.ToLower(), @"\d{1,2}(?=.ppt)", RegexOptions.RightToLeft);
                string r = result.Value;
                int timeL;
                if (r != "")
                {
                   timeL = int.Parse(r);
                }else
                {
                    timeL = 0;
                }
                wndfullscreen.timeL = timeL;

            }
            return yn;
        }


        WindowInfo wndfullscreen = new WindowInfo();//用于保存正在全屏播放的窗口信息
        TimeSpan ts = new TimeSpan(0); //保存播放倒计时       
        bool playflag = false; //播放flag;
        bool rtimeflag = false; //是否对播放的ppt限时的flag;

        public Form1()
        {
            InitializeComponent();
        }

        private void 退出ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //this.Hide = true;
            this.ShowInTaskbar = false;          
            timer1.Interval = 1000;       
            this.Top = 0;
            Rectangle ScreenArea = System.Windows.Forms.Screen.GetBounds(this);
            int width1 = ScreenArea.Width; //屏幕宽度
            int width2 = this.Width;
            this.Left = width1 - width2-100;//定位到屏幕右上角
            timer1.Enabled = true;　//开始计时
            this.TopMost = true;//显示在最前
            
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            if (playflag == false && hasscreenClass())//说明是刚开始播放
            {
                playflag = true;
                int timeL = wndfullscreen.timeL;
                if(timeL >0 )
                {
                    rtimeflag = true; //表明要对本ppt进行倒计时 
                    ts = new TimeSpan(0, wndfullscreen.timeL,0);　//设定倒计时时间
                }       
            }
            if (playflag == true && rtimeflag == true) //正在播放且需要进行限时
            {
                ts = ts.Subtract(new TimeSpan(0, 0, 1));//倒计时，每隔一秒减去一秒
                String str = ts.Minutes.ToString() + ":" + ts.Seconds.ToString();
                this.label1.Text = str;
            }else //不限时，则显示时钟
            {
                String str = DateTime.Now.Hour.ToString() + ":"+ DateTime.Now.Minute.ToString() + ":" + DateTime.Now.Second.ToString();
                this.label1.Text = str;

            }
            //用户提前退出ppt
            if (playflag == true && !hasscreenClass())
            {
                playflag = false;
                rtimeflag = false;

            }
            //倒计时结束
            if (ts.TotalSeconds < 0.0  && hasscreenClass())//当倒计时完毕
            {
                IntPtr hwnd_win = wndfullscreen.hWnd;
                SendMessage(hwnd_win, WM_CLOSE, 0, 0);//发送退出消息
                playflag = false;
                rtimeflag = false;

            }


        }

            private void 设置ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            //选择播放目录    
            string fullfname, extension;
            string path = string.Empty;
            System.Windows.Forms.FolderBrowserDialog fbd = new System.Windows.Forms.FolderBrowserDialog();
            if (fbd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                path = fbd.SelectedPath;
            }
           
            if (path != string.Empty)
            {
                DirectoryInfo di = new DirectoryInfo(path);              
                foreach (var fi in di.GetFiles())
                {
                    extension =fi.Extension.ToLower();
                    if(extension == ".ppt" || extension == ".pptx")
                    {
                        try
                        {
                            fullfname = fi.FullName;
                            //修改文件名加上“限时”
                            if (fullfname.Contains("安全环保部"))
                            {
                                fi.MoveTo(fullfname + "_限时8" + extension);
                            }
                            else
                            {
                                fi.MoveTo(fullfname + "_限时5" + extension);
                            }
                            //打开目录
                            System.Diagnostics.Process.Start(fi.DirectoryName);
                        }
                        catch { }
                       
                    }
                   
                }

            }
    


          
        }

   
      
    }
}

 补充：增加了可拖动窗口的代码如下：

//处理拖动
protected override void WndProc(ref Message m)
{
if(m.Msg == 0x0201){//鼠标左键按下
m.Msg = 0x00A1; //更改消息为非客户区按下鼠标
m.LParam = IntPtr.Zero; //默认值
m.WParam = new IntPtr(2); //鼠标放在标题栏内

}
base.WndProc(ref m);
}