Changing the pen color of the chalkboard plugin of reveal.js in RStudio

[grayknight2]

I´m trying to change the pen color for the chalkboard plugin of reveal.js in RStudio. I have the following code:

title: "Presentation"
author: "Me"
date: "2018"
output:
  revealjs::revealjs_presentation:
    theme: league
    transition: convex
    highlight: zenburn
    self_contained: false
    reveal_plugins: ["notes", "zoom", "chalkboard"]
    css: slides.css
    reveal_options:
      chalkboard:
        theme: whiteboard
        color: ['rgba(255, 0, 0, 0.3)'] # red
      previewLinks: true
      slideNumber: true
  beamer_presentation:
    toc: false
    incremental: false 

The color parameter should do the trick, but no matter what color I set I always get a black pen color if I set that parameter (default color is blue). How could I set It to any color I want?

Following the plugin documentation It says I should use:
color: ['rgba(255, 0, 0, 0.3)', 'rgba(255, 0, 0, 0.3)'] # red, red

This works with "actual" reveal.js, but this gives an error in RStudio, that's why I'm setting only one color. Is there a bug within the RStudio implementation?

[okrebs]

I have the same issue. I recognized that setting the option "color: ['rgba(255, 0, 0, 0.3)']" or any similar option that contains [ ] these brackets are removed in the produced html code.

Thus it will read " color: 'rgba(255, 0, 0, 0.3)'" in the given example. With a single 'wrong' string the pen color then defaults to black.

Setting multiple colors, e.g. "color: ['rgba(255, 0, 0, 0.3)', 'rgba(0, 255, 0, 0.3)']" is, in the produced html code, turned into "color: 'rgba(255, 0, 0, 0.3)', 'rgba(0, 255, 0, 0.3)'" which results in an error an unuseable html code (due to another option being expected after the ',')

Escaping the brackets like so "/[" does not work since they are then kept together with the escape character in the final html code. Does anyone know which part of the code removes the brackets [ ] from the values passed to options?

[atusy]

I opened a PR to fix this issue. You can try it by installing the patched version with

remotes::install_github("rstudio/revealjs#62")

[cderv]

For the record, PR number is #88 so it was

remotes::install_github("rstudio/revealjs#88")

but this is now merged so this is enough

remotes::install_github("rstudio/revealjs")