luaharfbuzz

Lua bindings for Harfbuzz.

Contents

• Overview
• Installing Harfbuzz
• Installing luaharfbuzz
• Documentation
• Sample Code
• Development
• Contact

Overview

HarfBuzz is an OpenType text shaping engine. It is used in software like Qt, Pango, Firefox, Chromium, XeTeX and LibreOffice.

luaharfbuzz provides bindings for the most common types in Harfbuzz. The initial motivation for building it was to use Harfbuzz with the LuaTeX typesetting system. However, the module isn’t tied to LuaTeX. It can be used with any Lua codebase.

As of 2020, luaharfbuzz is bundled with LuaTeX. Additional support to use the HarfBuzz renderer with LuaLaTeX and other formats is available via luaotfload. Read more:

• TUG 2020 — Marcel Krüger — HarfBuzz in LuaLaTeX
• Typesetting Bangla script with LuaLaTeX
• Bringing world scripts to LuaTeX: The HarfBuzz experiment

Installing Harfbuzz

Make sure Harfbuzz libraries and headers are installed. before trying to install luaharfbuzz

OS X

Install via Homebrew

brew install harfbuzz

Ubuntu Linux

apt-get install libharfbuzz0b libharfbuzz-dev

Other Platforms

Send a pull request if you want to include specific instructions to install Harfbuzz on your preferred platform.

Before building the package, LuaRocks populates the HARFBUZZ_INCDIR and HARFBUZZ_LIBDIR to point to the correct locations. If you can populate these variables manually before running LuaRocks, you can install luaharfbuzz on any system that supports Lua and Harfbuzz.

Installing luaharfbuzz

Luarocks

If Luarocks and Harfbuzz are installed, luaharfbuzz can be installed like this:

luarocks install luaharfbuzz

Documentation

• API Docs
• Wiki

Sample Code

Here is some sample code, showcasing the core types and methods in the API.

local harfbuzz = require('harfbuzz')
local serpent  = require('serpent') -- luarocks install serpent

-- Harfbuzz API Version
print("Harfbuzz API version", harfbuzz.version())

-- Shapers available
print("Shapers:", serpent.line({ harfbuzz.shapers() }, {comment = false}))

-- harfbuzz.Face
local face = harfbuzz.Face.new('../fonts/notonastaliq.ttf')
print('\nFace upem = '..face:get_upem())

-- harfbuzz.Font
local font = harfbuzz.Font.new(face)
local xs, xy = font:get_scale()
print("\nDefault font scale = X: "..xs..", Y: "..xy)

-- harfbuzz.Buffer
local text = "یہ" -- U+06CC U+06C1
local buf = harfbuzz.Buffer.new()
buf:add_utf8(text)

-- harfbuzz.shape (Shapes text)
print("\nShaping '"..text.."' set with Noto Nastaliq Urdu")
harfbuzz.shape(font, buf, { language = harfbuzz.Language.new("urd"), script = harfbuzz.Script.new("Arab"), direction = harfbuzz.Direction.RTL})

local glyphs = buf:get_glyphs()
print("No. of glyphs", #glyphs)
print(serpent.line(glyphs, {comment = false}))

local opts = { language = harfbuzz.Language.new("eng"), script = harfbuzz.Script.new("Latn"), direction = harfbuzz.Direction.LTR }
local amiri_face = harfbuzz.Face.new('../fonts/amiri-regular.ttf')
local amiri_font = harfbuzz.Font.new(amiri_face)

-- shaping '123' w/o features
print("\nShaping '123' set with Amiri Regular and no features")
buf= harfbuzz.Buffer.new()
buf:add_utf8("123")
harfbuzz.shape(amiri_font, buf, opts)
glyphs = buf:get_glyphs()
print(serpent.line(glyphs, {comment = false}))

-- shaping '123' with '+numr' (numerators)
print("\nShaping '123' set with Amiri Regular with 'numr' feature turned on")
buf= harfbuzz.Buffer.new()
buf:add_utf8("123")
opts.features = "+numr"
harfbuzz.shape(amiri_font, buf, opts)
glyphs = buf:get_glyphs()
print(serpent.line(glyphs, {comment = false}))

Development

Building

You can build the package for development purposes using LuaRocks as well. It is recommended that you build it to your local tree (using --local) to isolate it from your actual installation.

luarocks --local make

Testing and Linting

In order to make changes to the code and run the tests, the following dependencies need to be installed:

• Busted – luarocks install busted
• luacheck – luarocks install luacheck
• ldoc – luarocks install ldoc

Run the test suite:

make spec

Lint the codebase:

make lint

Generate documentation from sources:

make doc

Contact

Open a Github issue, or email me at deepak.jois@gmail.com.