C#: Powerpoint does not Quit?

Question

Hello, I have a script that opens Powerpoint from my application and exports all slides. After that, I need the application to be closed.

I've tried without any luck. Could you please help?

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using Powerpoint = Microsoft.Office.Interop.PowerPoint;
using Microsoft.Office.Core;
using Microsoft.Office.Interop.PowerPoint;
using System.Runtime.InteropServices;

namespace PresentrBuilder
{


class PowerpointConverter
{

    public static void Convert(String file, String safeFile)
    {
        Powerpoint.Application PP;
        Powerpoint.Presentation Presentation;

        PP = new Powerpoint.ApplicationClass();
        PP.Visible = MsoTriState.msoTrue;
        PP.WindowState = Microsoft.Office.Interop.PowerPoint.PpWindowState.ppWindowMinimized;
        Presentation = PP.Presentations.Open(file, MsoTriState.msoFalse, MsoTriState.msoTrue, MsoTriState.msoTrue);

            // Voor elke slide, exporteren
            String exportSlidesPath = Path.Combine(Properties.Settings.Default.CacheDir, @"presentatienaam1\slides");

            // Kijk of de directory bestaat
            if (!Directory.Exists(exportSlidesPath))
            {
                Directory.CreateDirectory(exportSlidesPath);
            }

                // Kijk of er al bestanden in de directory staan
                // Zo ja: verwijderen
                String[] files = Directory.GetFiles(exportSlidesPath, "*.png");
                if (files.Length > 0)
                {
                    foreach (string fileName in files)
                    {
                        File.Delete(Path.Combine(exportSlidesPath, fileName));
                    }
                }

            // Elke slide exporteren
            foreach (Slide slide in Presentation.Slides)
            {
                slide.Export(Path.Combine(exportSlidesPath, "slide_" + slide.SlideIndex + ".png"), "PNG", 1024, 768);
                Marshal.ReleaseComObject(slide);
            }


        GC.Collect();
        GC.WaitForPendingFinalizers();

        Marshal.ReleaseComObject(PP.Presentations);
        Marshal.ReleaseComObject(Presentation.Slides);

        Presentation.Close();
        Marshal.FinalReleaseComObject(Presentation);

        PP.Quit();
        Marshal.FinalReleaseComObject(PP);

    }

}
}

Answer 1

See the discussion on the same topic here: http://stackoverflow.com/questions/1041266/c-and-excel-automation-ending-the-running-instance/1048473#1048473

It covers Excel, but the principles are exactly the same.

Summary: you need to "release" the Presentations, Slides and (multiple) Slide objects. BTW, I wouldn't bother setting the variables to null. That's not necessary or helpful.

Answer 2

As an addition to Gary's answer: In Order to release the collections, you have to assign them to temporary variables. (I used slides and presentations as temp variables in the example below).

// removed using statements...

namespace PresentrBuilder
{


  class PowerpointConverter
  {

  public static void Convert(String file, String safeFile)
  {
    Powerpoint.Application PP;
    Powerpoint.Presentation Presentation;

    PP = new Powerpoint.ApplicationClass();
    // ...
    var presentations = PP.Presentations;
    Presentation = presentations.Open(file, MsoTriState.msoFalse, MsoTriState.msoTrue, MsoTriState.msoTrue);

        // Voor elke slide, exporteren
        // ...

        // Elke slide exporteren
        var slides = Presentation.Slides;
        foreach (Slide slide in slides)
        {
            slide.Export(Path.Combine(exportSlidesPath, "slide_" + slide.SlideIndex + ".png"), "PNG", 1024, 768);
            Marshal.ReleaseComObject(slide);
        }


    GC.Collect();
    GC.WaitForPendingFinalizers();

    Marshal.ReleaseComObject(presentations);
    Marshal.ReleaseComObject(slides);

    Presentation.Close();
    Marshal.FinalReleaseComObject(Presentation);

    PP.Quit();
    Marshal.FinalReleaseComObject(PP);

} } }

Answer 3

If anyone else is struggling with this (not being able to close the PPT after iterating through the slides), even after doing all the garbage collection and releasing resources, I spent the better part of today scratching my head with this one. My solution was, instead of using a foreach to iterate through the slides, i did as follows:

        Microsoft.Office.Interop.PowerPoint.Application powerpoint;
        Microsoft.Office.Interop.PowerPoint.Presentation presentation;
        Microsoft.Office.Interop.PowerPoint.Presentations presentations;

        powerpoint = new Microsoft.Office.Interop.PowerPoint.ApplicationClass();
        powerpoint.Visible = Microsoft.Office.Core.MsoTriState.msoTrue;
        presentations = powerpoint.Presentations;

        presentation = presentations.Open(localPath, MsoTriState.msoFalse, MsoTriState.msoTrue, MsoTriState.msoTrue);


        //String presentationTitle = objPres.Name;
        Microsoft.Office.Interop.PowerPoint.Slides slides = presentation.Slides;
        **for (int i = 1; i <= slides.Count; i++)
        {
            Microsoft.Office.Interop.PowerPoint.Slide slide = slides[i];
            String slideName = slide.Name;
            releaseCOM(slide);
        }**

This is my releaseCOM method:

    private static void releaseCOM(object o)
    {
        try
        {
            System.Runtime.InteropServices.Marshal.FinalReleaseComObject(o);
        }
        catch { }
        finally
        {
            o = null;
        }
    }