4.8 KiB
luaharfbuzz
Lua bindings for Harfbuzz.
Contents
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 in any way. It can be used with any Lua codebase.
luaharfbuzz is currently being used inside HarfTeX, a TeX engine built on top of LuaTeX and designed to use Harfbuzz for shaping text. For more details read this TUGboat journal article titled 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
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 - luacov –
luarocks install luacov - 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.