Crate harfbuzz_rs

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Expand description

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

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::*;


let path = "path/to/some/font_file.otf";
let index = 0; //< face index in the font file
let face = Face::from_file(path, index)?;
let mut font = Font::new(face);

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

// The results of the shaping operation are stored in the `output` buffer.

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

assert_eq!(positions.len(), infos.len());

// 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

Re-exports§

Modules§

Structs§

  • 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.
  • A type that can be used to serialize a GlyphBuffer.
  • An iterator over the codepoints stored in a UnicodeBuffer.
  • A wrapper around hb_face_t.
  • A feature tag with an accompanying range specifying on which subslice of shapes input it should be applied.
  • A type representing a single font (i.e. a specific combination of typeface, font-size and font-variation settings)
  • A GlyphBuffer contains the resulting output information of the shaping process.
  • A set of flags that may be set during shaping on each glyph.
  • GlyphPosition is the structure that holds the positions of the glyph in both horizontal and vertical directions. All positions in GlyphPosition are relative to the current point.
  • A smart pointer that wraps a singly owned harfbuzz object.
  • Flags used for serialization with a BufferSerializer.
  • A smart pointer that wraps an atomically reference counted HarfBuzz object.
  • A type to represent 4-byte SFNT tags.
  • A UnicodeBuffer can be filled with unicode text and corresponding cluster indices.
  • A variation selector which can be applied to a specific font.

Enums§

  • Defines the direction in which text is to be read.
  • The serialization format used in BufferSerializer.
  • An Error generated when a Tag fails to parse from a &str with the from_str function.
  • This type provides an interface to create one of the buffer types from a raw harfbuzz pointer.

Traits§

  • 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.

Functions§

  • Shape the contents of the buffer using the provided font and activating all OpenType features given in features.

Type Aliases§