fontquiver installs a set of fonts with permissive licences. It is useful for packages that needs controlled versions of fonts.
Get the development version from github with:
# install.packages("devtools")
devtools::install_github("lionel-/fontquiver")
fontquiver is an interface to fonts installed as R packages. It
provides convenient and structured access, for instance, to the
Bitstream Vera font family installed with the
fontBitstreamVera
package, or the Liberation family that comes with
fontLiberation.
The fonts too heavy to be distributed on CRAN can be accessed by
fontquiver through Github-only packages such as
fontDejaVu. Each package
bundles a set of fonts (or fontset as they are called in fontquiver)
which typically includes bold and italic faces for sans and serif
fonts, but may also include more exotic variations (condensed, ultra
light, etc). Call fontset_list() to check which fontsets are
currently installed on your computer.
Fonts installed in the R library can be useful for a variety of
purposes. They can be used in web applications with the
htmlFontDependency() tool. They are also helpful to create
reproducible outputs. An example of this is the vdiffr package which
relies on fontquiver to create SVGs that are reproducible across
platforms. Without fontquiver fonts, the SVGs generated by svglite
would have slight differences depending on the versions of the system
fonts used to compute text metrics.
The standard categories of fonts in R are the sans, serif, and
mono families and the plain, italic, bold, and bolditalic
faces. However, font nomenclatures are extremely rich and go well
beyond those 12 categories. For example the DéjàVu set contains a font
whose variant and style are Serif Condensed and Extra Light. For
this reason, fontquiver uses the categories provided by the font util
fc-scan from
Fontconfig.
The terms "variants" and "styles" refer to those categories while
"families" and "faces" refer to R's categories.
To check which variants and styles are available for a given fontset:
fontset_variants("DejaVu")
fontset_styles("Bitstream Vera", variant = "Serif")
fontquiver provides several getters to access font objects. They all
take a fontset name as argument. They may also take variant/style
or family/face arguments.
font() takes a fontest, a variant and a style, and returns an atomic
font object. Those objects contain fields such as ttf, fullname,
or version:
font("Bitstream Vera", "Sans", "Roman")
font("Bitstream Vera", "Serif", "Bold")$ttf
The other getters return collections of fonts. font_variants()
returns a tree of lists with the outer list containing all variants of
a fontset and the inner lists containing all styles for a given
variant. Similarly, font_families() returns a tree of fonts
structured according to families and faces:
font_variants("Liberation")
font_families("Liberation")
If you need a specific variant or family, font styles() and
font_faces() return a list of fonts:
font_styles("DejaVu", "Sans Condensed")
font_faces("DejaVu", "Mono")
The htmlFontDependency() tool takes any font object or collection of
font objects. It copies the relevant fonts in woff format to a
temporary directory and creates a CSS linking to those fonts.
# install.packages("htmltools")
# Create font dependency
liberation <- font_families("Liberation")
mono <- font_styles("DejaVu", "Sans Mono")
html_dep <- htmlFontDependency(liberation, mono)
span_mono <- htmltools::tags$span(
style = "font-family:'Deja Vu Sans Mono'; font-style:italic;",
"Text rendered with monospace italic font"
)
span_bold <- htmltools::tags$span(
style = "font-family:'Bitstream Vera Sans'; font-weight:700;",
"Text rendered with sans bold font"
)
# Add font dependency to an HTML object and print
text <- htmltools::div(span_mono, span_bold, html_dep)
htmltools::html_print(text)
You can supply fontquiver fonts to svglite:
svglite::stringSVG(user_fonts = font_families("Liberation"), {
plot(1:10)
})
See the fonts vignette in the svglite package for more about this.