Configure PowerPoint Compare & Merge in git

Question

PowerPoint has a feature to compare 2 PowerPoint files in the UI. It's in the Review ribbon and then Compare.

I'd like to configure git to be able to compare & merge 2 PowerPoint files from the commandline, pop open PowerPoint, resolve the changes and save.

But unfortunately I can't seem to find a way to open PowerPoint in the compare mode from without many clicks. Anyone happen to know the right way to invoke powerpnt.exe to open in this magic mode?

Adhamh

Similar, but definitely not what I'm after: https://mcmap.net/q/1186990/-is-it-possible-to-diff-powerpoint-version-controlled-with-git/1445598 – Adhamh

Just looked up the in-program compare process and it's very UI intensive. I think you would have to find a way to do a PPT comparison by calling powerpoint.exe via the command line and triggering the compare before even attempting to go any further. Like is it possible to run something like powerpoint.exe --compare file1.ppt file2.ppt? – Neoarsphenamine

Answer 1

After ample research, the conclusion is, while PowerPoint does support a merge mode, there is no way to open it up in that mode with a command-line parameter.

But the API to merge documents is available in the COM object model and thus also from .NET through the Primary Interop Assemblies.

I ended up writing a small open-source project which acts as a proxy between the command-line and PowerPoint to launch and merge files. (currently still a work in progress and rough):

https://github.com/jessehouwing/ppt-diffmerge

ppt-diffmerge-tool --local="$LOCAL" --remote="$REMOTE" --base="$BASE" --output="$RESULT" 

Core piece of code:

PowerPointApplication app = null;
Presentation presentation = null;

try
{
    app = new PowerPointApplication();
    app.PresentationCloseFinal += App_PresentationClose;

    if (!string.IsNullOrWhiteSpace(Output))
    {
        File.Copy(Local, Output, true);
        Local = Output;
    }

    presentation = app.Presentations.Open(Local);

    if (string.IsNullOrWhiteSpace(Base))
    {
        presentation.Merge(Remote);
    }
    else
    {
        presentation.MergeWithBaseline(Remote, Base);
    }

    handle.WaitOne();
}
finally
{
    Marshal.ReleaseComObject(presentation);
    Marshal.ReleaseComObject(app);
}
return 0;

And it's crazy, even supports 3-way merges!

Adhamh