[FR] {thematic} support in `bookdown::bs4_book()`

[stephan-koenig]

Hello!

I want to use {thematic} with bookdown::bs4_book() to propagate the styling of the bookdown to plots, tables, etc., to generate a more cohesive look. Would it be possible to extend the use of bookdown::bs4_book() to also support {thematic}? (I had requested this feature on {thematic} before: rstudio/thematic#109)

I have tried the following approach in a bookdown project that only contains an index.Rmd file by adding thematic::thematic_rmd():

--- 
title: "A Minimal Book Example"
author: "John Doe"
date: "`r Sys.Date()`"
description: "A simple bookdown using {thematic}"
site: bookdown::bookdown_site
documentclass: book
output:
  bookdown::bs4_book:
    theme:
      bootswatch: cyborg
---

# About

```{r setup, include = FALSE}
thematic::thematic_rmd()
```

Here a plot:

```{r}
plot(pressure)
```

The output looks like this:

i.e. the plot is not styled like the theme, and I receive the following warnings:

Warning messages:
1: thematic was unable to resolve `bg='auto'`. Try providing an actual color (or `NA`) to the `bg` argument of `thematic_on()`. By the way, 'auto' is only officially supported in `shiny::renderPlot()`, some rmarkdown scenarios (specifically, `html_document()` with `theme!=NULL`), in RStudio, or if `auto_config_set()` is used. 
2: thematic was unable to resolve `fg='auto'`. Try providing an actual color (or `NA`) to the `fg` argument of `thematic_on()`. By the way, 'auto' is only officially supported in `shiny::renderPlot()`, some rmarkdown scenarios (specifically, `html_document()` with `theme!=NULL`), in RStudio, or if `auto_config_set()` is used. 
3: thematic was unable to resolve `accent='auto'`. Try providing an actual color (or `NA`) to the `accent` argument of `thematic_on()`. By the way, 'auto' is only officially supported in `shiny::renderPlot()`, some rmarkdown scenarios (specifically, `html_document()` with `theme!=NULL`), in RStudio, or if `auto_config_set()` is used. 

Thank you,

Stephan

[cderv]

See about what could be done in https://github.com/rstudio/thematic/issues/109#issuecomment-951135523