Convert slide deck to PowerPoint (pptx) that consists of rendered images

[yhatt]

By using officegen, we might convert from Marpit / Marp Markdown into PowerPoint slide that consists of pre-rendered images.

It's very useful for mixing a traditional presentation deck and the deck made by Marp. In addition, it could use PowerPoint's presenter tool with Marpit's presenter notes.

Exporting PowerPoint deck was mentioned in the old Marp app by yhatt/marp#23. We'll make it wake up.

I suppose it would have to start working after than implemented #71.

ToDo

• [x] Implement #71
• [x] Allow --pptx option and pptx extension in -o option (-o foobar.pptx)
  • [x] Add each rendered images to slides
  • [x] Support presenter note by comments parsed by Marpit

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:warning: People would expect re-editable contents in converted pptx. But it's still super difficult to convert into them with keeping the exact slide design, and there is no solution in FLOSS.

Adobe Acrobat can convert the exported PDF into pptx that includes re-editable contents, and keeps the design to some extent.

[yhatt]

I'm comparing 2 packages for creating pptx. At the moment, I would choose PptxGenJS because a generated pptx has compatibility with many office suites.

officegen

Pros

• Well tested, and supported by many packages.
• Probably active, and stars earned over 1.5k.
• Open-source licensed by MIT.

Cons

• A bit lacked documentation.
• Speaker notes does not apply when opening in Keynote app.
• There is not TypeScript definition.

PptxGenJs

Pros

• Universal JS: Supports many environments (but it would not have meaning in Marp CLI).
• Support background image for slide page and can create PPTX similar to GitPitch's PowerPoint support.
• Most likely active, and already reached stable version.
• Open-source licensed by MIT.

Cons

• npm package includes unnecessary 20MB examples.
• It requires a bit trick to enable TypeScript definition.
• I fear that it was not included any tests.