Merge Presentations

• Download SlideMerge.zip - 2.5 MB

Introduction

This article tells how to merge multiple presentation files to one file at a specified position using Office OpenXML SDK.

Overview

Let's copy one presentation to other manually. I have two presentation files: ppt1.pptx and ppt2.pptx. I would copy all slides from ppt2.pptx into ppt1.pptx.

This looks pretty easy if there are only couple of presentations to be copied. Think about the case where you need to copy/merge many presentations. So, I thought of copying these programmatically using Office OpenXML SDK 2.0.

Using the code

The PresentationInfo class contains information of file and its insert position in the destination file.

public class PresentationInfo
{
    public string File { get; set; }
    public short InsertPosition { get; set; }
}

The MergeHandler class contains a method MergeAllSlides which takes parameters source presentation, destination presentation and a list of presentations to be merged, and copies all the slides in these presentations into the destination presentation.

void MergeAllSlides(string parentPresentation, string destinationFileName, List<PresentationInfo> mergingFileList);  

MergeAllSlides does two things. First, it merges all the slides keeping count of source and destination locations of each slide. Later, it re-orders the slides.

// key=>current slide position, value=>new position of the slide
Dictionary<int, int> reOrderPair = new Dictionary<int, int>(); 
foreach (PresentationInfo importedFile in mergingFileList)
{
  try
  {
     int val = (importedFile.InsertPosition - 1) + reOrderPair.Count;
     this.MergeSlides(importedFile, destinationFileName, 
                      ref reOrderPair, ref val, out reOrderConstant);
  }
  catch
  {
     continue; // try merging other presentation files
  }
} 
// re-order the slides to the actual position                                        
foreach (KeyValuePair<int, int> reOrderValue in reOrderPair)
{
    try
    {
        this.ReorderSlides(destinationFileName, reOrderValue.Key, reOrderValue.Value);                    
    }
    catch
    {
        continue;
    } 
}

The caller would need to create the list of PresentationInfo and call MergeAllSlides.

string ppt1 = "ppt1.pptx";
string ppt2 = "ppt2.pptx";
new MergeHandler().MergeAllSlides(ppt1, ppt1, new List<PresentationInfo>()
{
    new PresentationInfo()
    {
        File = ppt2,
        InsertPosition = 2
    }
});

Using the above code, the slides would be inserted in second position.

Point Of Interest

1. As you have observed, during the copy of a slide, the referred master and layout slide is also copied each time. This results in increased file size and additional time overhead. So, the code can further be re-factored to copy master and layout slides only once.
2. I have taken an approach where all slides from ppt2.pptx are copied into ppt1.pptx. This can further be refined to copy only the selected files from ppt2.pptx.
3. To copy multiple presentation files into one file, all we need to do is create multiple PresentationInfo in the list.

new MergeHandler().MergeAllSlides(ppt1, ppt1, new List<PresentationInfo>()
{
    new PresentationInfo()
    {
        File = ppt2,
        InsertPosition = 2
    },
    new PresentationInfo()
    {
        File = @"c:\wip\ppt3",
        InsertPosition = 3
    },
    new PresentationInfo()
    {
        File = @"c:\wip\ppt4",
        InsertPosition = 6
    },
    new PresentationInfo()
    {
        File = @"c:\wip\ppt5",
        InsertPosition = 1
    }
   // you can copy as many presentations as required
});