Crate harfbuzz_rs [−] [src]

harfbuzz_rs is a high-level interface to HarfBuzz, exposing its most important functionality in a safe manner using Rust.

What is HarfBuzz?

HarfBuzz is a library for performing complex text layout. It does not perform any drawing. This is quite a low-level operation. If you want to simply draw some text on the screen choose another library. However if you want to build a library for drawing text on some canvas or need a lot of control on advanced text layout then this is the right library to use.

Getting Started

Add the following to your Cargo.toml:

[dependencies]
harfbuzz_rs = "^0.1"

To shape a simple string of text you just create a Font from a font file, fill a Buffer with some text and call the shape function.

use harfbuzz_rs::*;
use harfbuzz_rs::rusttype::SetRustTypeFuncs;

let path = "path/to/some/font_file.otf";
let index = 0; //< face index in the font file
let face = Face::from_file(path, index).unwrap();
let mut font = Font::new(face);
// Use RustType as provider for font information that harfbuzz needs.
// You can also use a custom font implementation. For more information look
// at the documentation for `FontFuncs`.
font.set_rusttype_funcs();

let output = UnicodeBuffer::new().add_str("Hello World!").shape(&font, &[]);

The results of the shaping operation are stored in the buffer that was also used as input to the shape function.

let positions = output.get_glyph_positions();
let infos = output.get_glyph_infos();

// iterate over the shaped glyphs
for (position, info) in positions.iter().zip(infos) {
    let gid = info.codepoint;
    let cluster = info.cluster;
    let x_advance = position.x_advance;
    let x_offset = position.x_offset;
    let y_offset = position.y_offset;

    // Here you would usually draw the glyphs.
    println!("gid{:?}={:?}@{:?},{:?}+{:?}", gid, cluster, x_advance, x_offset, y_offset);
}

This should print out something similar to the following:

gid41=0@741,0+0
gid70=1@421,0+0
gid77=2@258,0+0
gid77=3@253,0+0
gid80=4@510,0+0
gid1=5@227,0+0
gid56=6@874,0+0
gid80=7@498,0+0
gid83=8@367,0+0
gid77=9@253,0+0
gid69=10@528,0+0
gid2=11@276,0+0

Modules

rusttype

This module allows you to use rusttype to provide the font operations that harfbuzz needs.

Structs

Blob	A `Blob` manages raw data like e.g. file contents. It refers to a slice of bytes that can be either owned by the `Blob` or not.
Face	A wrapper around `hb_face_t`.
Font	A font is the most important concept in harfbuzz.
GlyphBuffer	A `GlyphBuffer` is obtained through the `shape` function of a `UnicodeBuffer`. It contains the resulting output information of the shaping process.
HbArc	A smart pointer that wraps an atomically reference counted HarfBuzz object.
HbBox	A smart pointer that wraps a singly owned harfbuzz object.
InvalidLanguage
Language
Tag	A type to represent 4-byte SFNT tags.
UnicodeBuffer	A `UnicodeBuffer` can be filled with unicode text and corresponding cluster indices.

Enums

Buffer
TagFromStrErr	An Error generated when a `Tag` fails to parse from a `&str` with the `from_str` function.

Traits

FontFuncs	This Trait specifies the font callbacks that harfbuzz uses for its shaping. You shouldn't call these functions yourself. They are exposed through the `Font` wrapper.
HarfbuzzObject	A trait which is implemented for all harffbuzz wrapper structs. It exposes common functionality for converting from and to the underlying raw harfbuzz pointers that are useful for ffi.

Type Definitions

Feature
FontExtents
Glyph
GlyphExtents
GlyphInfo
GlyphPosition
Position