Title:	Render Text in Color for Markdown/Quarto Documents
Description:	Provides some simple functions for printing text in color in 'markdown' or 'Quarto' documents, to be rendered as HTML or LaTeX. This is useful when writing about the use of colors in graphs or tables, where you want to print their names in their actual color to give a direct impression of the color, like “red” shown in red, or “blue” shown in blue.
Version:	0.2.1
Date:	2025-11-24
Depends:	R (≥ 4.1.0)
Imports:	colorspace, knitr
Suggests:	quarto, glue, crayon
License:	MIT + file LICENSE
Encoding:	UTF-8
VignetteBuilder:	quarto
RoxygenNote:	7.3.3
Language:	en-US
URL:	https://github.com/friendly/colorize
BugReports:	https://github.com/friendly/colorize/issues
NeedsCompilation:	no
Packaged:	2025-11-24 14:30:40 UTC; friendly
Author:	Michael Friendly [aut, cre], Achim Zeileis [aut], Richard Brath [ctb]
Maintainer:	Michael Friendly <friendly@yorku.ca>
Repository:	CRAN
Date/Publication:	2025-11-27 19:50:07 UTC

Create a Color Box in a Markdown/Quarto Document

Description

The colorbox() function renders text in a colored background for Markdown / Quarto documents. For documents to be rendered in HTML, ...

Usage

colorbox(
  text,
  color = text,
  maincolor = "black",
  bgcolor = "white",
  format = NULL,
  padding = 2
)

Arguments

Details

The function colorbox() is a small convenience function that sets up a color box in LaTeX (via ⁠\colorbox{...}{...}⁠) or HTML (via ⁠<span style=...>...</span>⁠) for a given text. The main convenience is that the function assesses first whether the text in the color box has a better contrast when written in the main font color (default: black) or the background color (default: white). This is decided based on the contrast_ratio() function from the colorspace package using the APCA algorithm.

Additionally, the package canonicalizes all R color specifications to hex color codes (of the form ⁠#rrggbb⁠) which can subsequently be employed easily in both LaTeX and HTML output. The default output format inside Quarto documents processed via knitr is determined using the functions is_latex_output and is_html_output, respectively.

This illustrates the use of colorbox() in a Quarto document:

I'll be using the penguins data quite a lot, so it is useful to set up custom colors like
those used in @fig-penguin-species. My versions are shown in @fig-peng-colors with their
color codes. These are shades of:

* `r colorbox("Adélie", "orange")`: `r colorbox("orange", "orange")`,
* `r colorbox("Chinstrap", "purple")`: `r colorbox("purple", "purple")`, and
* `r colorbox("Gentoo", "green")`: `r colorbox("green", "green")`.

Value

A character string with the input text along with markup for a background color box.

Author(s)

Achim Zeileis

Examples

## basic usage: just supply a color name and let both the background color
## and the output format be decided automatically (the latter does not work
## correctly outside of a quarto/knitr document and hence just returns the text)
colorbox("red")

## emulate behavior in a quarto/knitr document with HTML or LaTeX output
colorbox("red", format = "latex")
colorbox("red", format = "html")

## instead of fully saturated red in sRGB, employ other flavors of red:
## - color 2 in R's default palette
## - color #D55E00 from the Okabe-Ito palette
colorbox("red", color = 2, format = "html")
colorbox("red", color = "#D55E00", format = "html")

## by default, either black or white is used for the text color
## (which ever has the better contrast) but alternatively a different
## main font color (say gray10) and a different background color (say cornsilk)
## can be used for the text
colorbox("red", color = 2, maincolor = "gray10", bgcolor = "cornsilk", format = "html")
colorbox("yellow", color = 7, maincolor = "gray10", bgcolor = "cornsilk", format = "html")

Render text in color for Markdown / Quarto documents

Description

The colorize() function renders text in color for Markdown / Quarto documents. For documents to be rendered in HTML, it uses a CSS ⁠<span>⁠; for documents to be converted to LaTeX and rendered as PDF, it uses ⁠\textcolor{}{}⁠ from the xcolor package.

Usage

colorize(text, color, format = NULL)

colorize_bg(text, color, format = NULL)

Arguments

Details

A companion function, colorize_bg() does the same, but uses the specified color for the background.

The names of colors Note that a color name not defined in the xcolor package will trigger a LaTeX error. e.g., darkgreen is not defined but you can use: ⁠\definecolor{darkgreen}{RGB}{1,50,32}⁠ in a document to be rendered to PDF.

For inline text, in running text, you can use:

 `r colorize("Gentoo", "orange")` and  `r colorize("Adelie", "purple")` are Penguins.
 The `r colorize("red")` points and the `r colorize("blue")` points are nice

In a chunk, you can also define variables with the names of colors, for ease of use:

 red <- colorize('red')
 pink <- colorize("pink")
 blue <- colorize('blue')
 green <- colorize("green")
 yellow <- colorize("yellow")
 

Then, these can be used directly in strings, interpolated by glue::glue(). This is particularly useful in figure captions.

Value

A character string with the input text along with markup for color encoding.

Author(s)

Michael Friendly

Examples

# show what the generated text looks like when encoded for either HTML or LaTeX
colorize("red", format = "html") |> cat()
colorize("red", format = "latex") |> cat()

colorize_bg("blue", format = "html") |> cat()
colorize_bg("blue", format = "latex") |> cat()


 red <- colorize('red')
 blue <- colorize('blue')
 green <- colorize("green")
 glue::glue("There are {red} points, {blue} points and {green} points")