Support other PDF export tools for revealjs (e.g decktape)

[cderv]

Current PDF export mode rom revealjs doesn't work reliable on most browsers. For example on Firefox you will still get garbage resp. wrong page breaks in the printed results after activating this mode. Well, you'll find a warning note about this flaw in the documentation, but it's IMHO still a very disappointing behavior.

I would therefore prefer a more reliable solution, which provides reproducible correct results in arbitrary browsers.

This can be realized in practice by integrating decktape resp. puppeteer, playwright or another similar mechanism into the CLI-tool for the document processing to generate a PDF-document beside the HTML-output and just add a download button in the HTML-menu or -toolbar instead of the present print style-switch entry. That's the way, how for example slidev handles this task in a much more reliable manner (see: https://sli.dev/guide/exporting#pdf).

Originally posted by @mash-graz in #2988 (comment)

Related

• Generate PDF from revealjs presentation (consistent with PDF Export in revealjs) #7018 (comment)

[FeralFlora]

For example on Firefox you will still get garbage resp. wrong page breaks in the printed results after activating this mode.

You aren't kidding. Came here after exporting to PDF on Firefox (hadn't seen the doc warning), which produced terrible results. This is a highly needed improvement.

[jlperla]

FWIW I found the revealjs output with decktape with the screenshot size to be excellent. e.g.

decktape myfile.html myfile.pdf --screenshots-size=1280x720

The only issue real issue are errors about having trouble finding embedded fonts when using adobe acrobat (that don't seem to pop up on other pdf viewers).

[cderv]

For reference, good recipe on using docker decktape: #7018 (reply in thread)

[kjhealy]

I use decktape from inside R to convert the HTML version of quarto presentations to PDF. I'm presently using quarto prerelease v1.4.534. With the most recent version of decktape (3.11), conversion fails because decktape will not stop printing slides. This might possibly be a version of this old decktape issue: astefanutti/decktape#137, or something like it. What happens is that decktape correctly identifies the number of slides in the deck, prints them all in order, but then just repeatedly prints the last slide forever. If you specify the number of slides to print via decktape's --slides switch, it will correctly terminate after that number of slides. If you specify any n > the number of slides, it will repeatedly print the last slide till it reaches n slides.

To reproduce the problem, create a quarto slide document—the default one created from New File > Quarto Presentation ... in RStudio will do fine. Save it as test.qmd. Render the file to HTML, then from the terminal (and with decktape 3.10 or 3.11 installed) do

decktape --chrome-arg=--allow-file-access-from-files reveal ./test.html test.pdf

Decktape should launch, begin rendering as expected, but not stop after the 4th slide. Instead it just keeps going. No file is produced. To make it render properly, do

decktape --chrome-arg=--allow-file-access-from-files --slides 1-4 reveal ./test.html test.pdf

I believe this is a quarto issue rather than a decktape issue as I can render other non-quarto revealjs decks OK, e.g. this one I found at random that seems to have been written in markdown or directly in html and produced by hugo:

decktape reveal https://ksucs-hugo.russfeld.me/0-basic-content/02-reveal-example-slides/ test.pdf

I apologize for not being able to pin down which quarto prerelease version this issue appeared in ... I'm returning to slides that were happily rendering to PDF last semester in preparation for this semester's classes. Happy to open a new bug report if it seems like it deserves one rather than a comment here.