gdtools

Font metrics calculation

The package gdtools provides functionalities to get font metrics and to generate base64 encoded string from raster matrix. It is used by package ‘flextable’ and ‘rvg’ to allow font metric calculation but can also be used to compute the exact size a text would have with specific font options (size, bold, italic).

library(gdtools)
str_extents(c("a string", "a longer string"), 
  fontsize = 24, bold = TRUE, italic = TRUE)
#>           [,1]     [,2]
#> [1,]  86.68359 22.60547
#> [2,] 166.68750 22.60547

Font management

Another set of functions is provided to support the collection of fonts from ‘Google Fonts’ in a cache. Their use is simple within ‘R Markdown’ documents and ‘shiny’ applications but also with graphic productions generated with the ‘ggiraph’, ‘ragg’ and ‘svglite’ packages or with tabular productions from the ‘flextable’ package.

Function register_gfont() is used to register a font with the system.

# Download to a user cache and register the font with systemfonts
# no need to download the font again
register_gfont(family = "Open Sans")

Function addGFontHtmlDependency() is used to add a font to a ‘html’ document.

Utility to install a font

If you need a ‘Google Font’ to be installed on your machine, you can use install_gfont_script(). This is a rare use case but can be useful in some specific situations, e.g. when you need to install a font on a server and make it available to all users. It can also be useful when you are working with a docker image and want to install a font when the image is built.

install_gfont_script("Fira Sans", file = "firafont.sh")

You then have to run ./firafont.sh.

Font ‘Liberation Sans’

If you don’t have web access, you can use font ‘Liberation Sans’ that is available when using this package. That can be useful when you are working with visual tests and don’t want to rely on an internet connection or when you need a font for a ‘shiny’ application and or graphics produced with packages ‘ggiraph’, ‘ragg’ or ‘svglite’.

Installation

You can install the released version of gdtools from CRAN with:

install.packages("gdtools")

And the development version from GitHub with:

# install.packages("remotes")
remotes::install_github("davidgohel/gdtools")