The issue of handling Powerpoint events with C#

Question

I have the follow code:

===============================================================
using Microsoft.Office.Interop.PowerPoint;
using System;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Input;
using System.Windows.Threading;
using PPTApplication = Microsoft.Office.Interop.PowerPoint.Application;
using PPTPresentation = Microsoft.Office.Interop.PowerPoint.Presentation;

namespace PPTTEST
{
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public partial class MainWindow : Window
{
private DispatcherTimer timer = new DispatcherTimer();

    public PPTApplication MyApplication { get; set; }

    public StatusEnum Status { get; set; } = StatusEnum.Invalid;

    public MainWindow()
    {
        InitializeComponent();
        timer.Tick += new EventHandler(Timer_Tick);
        timer.Interval = TimeSpan.FromSeconds(1);
        timer.Start();
    }

    private void Timer_Tick(object sender, EventArgs e)
    {
        if (Status == StatusEnum.Invalid)
        {
            try
            {
                MyApplication = (PPTApplication)Marshal.GetActiveObject("PowerPoint.Application");
                Status = StatusEnum.Ready;
                MyApplication.SlideShowBegin += OnSlideShowBegin;
                MyApplication.SlideShowEnd += OnSlideShowEnd;
            }
            catch
            {
                Status = StatusEnum.Invalid;
                return;
            }
        }
        try   
        {
            ///confirm the ppt is closed or not
            string  ss = MyApplication.Caption;
            if (Status == StatusEnum.Ready)
            {
                ///handle the job1
            }
            else
            {
                ///handle the job2              
            }
        }
        catch(COMException ex)
        {
            Status = StatusEnum.Invalid;
            MyApplication = null;            
            return;
        }
    }

    private void OnSlideShowEnd(PPTPresentation Pres)
    {
        if (Status == StatusEnum.Running)
        {
            Status = StatusEnum.Ready;              
        }
    }

    private void OnSlideShowBegin(SlideShowWindow SlideShowWindow)
    {
        if (Status == StatusEnum.Ready)
        {
            Status = StatusEnum.Running;
        }
    }

    public enum StatusEnum
    {
        Invalid, Ready, Running
    }
}

}

However, it faces some problems. When I running the code, then open the ppt and press F5 quickly. The event OnSlideShowBegin can't be trigger. But if I wait for at least 5 second before press F5, the event OnSlideShowBegin can be trigger. What is this reason?

Answer 1

Hi WenKong-1218,
>> string ss = MyApplication.Caption;
Based on your code, I didn't find that you check that the ppt is closed or not anywhere.
You can try to confirm it before triggering OnSlideShowBegin event.

if (ss==" your application caption" &&Status == StatusEnum.Init)  

And as Viorel said, using a timer with smaller interval to test:

timer.Interval = TimeSpan.FromMilliseconds(10);  

Best Regards,
Daniel Zhang

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