Pica

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Text shaping and font metrics for Elixir, through harfrust, HarfBuzz's Rust port.

Pica measures text from font files. Register fonts under a family name, then ask, by family and face, for each string's glyphs: which glyph, which characters it came from, and how far it advances with kerning, ligatures and contextual forms applied. It also reports font-wide metrics, glyph bounding boxes, and glyph outlines as drawing commands. Nothing is rendered.

{:ok, font} = Pica.load(File.read!("Lato-Regular.ttf"))
:ok = Pica.register("Lato", plain: font)

{:ok, font} = Pica.lookup("Lato")
Pica.shape(font, "AV", scale: 12 * 64)
#=> [%Pica.Glyph{glyph_id: 3, cluster: 0, x_advance: 479, ...}, %Pica.Glyph{...}]

Installation

def deps do
  [{:pica, "~> 0.1"}]
end

Pica ships prebuilt binaries through rustler_precompiled, so using a release needs no Rust.

Documentation

  • The Pica module documentation: loading, fonts by name, glyphs, shaping and scale.
  • Registering fonts: in an application and in Livebook.
  • Units and scale: what the numbers are, and turning them into a size.

Building from source

A development version (-dev), or PICA_BUILD=1, builds the NIF from source, which needs a Rust toolchain at least as new as rust-version in native/pica/Cargo.toml. Releases follow RELEASE.md.

Licence

MIT; see LICENSE. The Rust crates compiled into the NIF are listed, with their licences, in THIRD_PARTY_NOTICES.md.