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+0Re-exports§
pub use crate::font_funcs::FontFuncs;
Modules§
- font_
funcs - Contains the
FontFuncstrait.
Structs§
- Blob
- A
Blobmanages raw data like e.g. file contents. It refers to a slice of bytes that can be either owned by theBlobor not. - Buffer
Serializer - A type that can be used to serialize a
GlyphBuffer. - Codepoints
- An iterator over the codepoints stored in a
UnicodeBuffer. - Face
- A wrapper around
hb_face_t. - Feature
- A feature tag with an accompanying range specifying on which subslice of
shapes input it should be applied. - Font
- A type representing a single font (i.e. a specific combination of typeface, font-size and font-variation settings)
- Font
Extents - Glyph
Buffer - A
GlyphBuffercontains the resulting output information of the shaping process. - Glyph
Flags - A set of flags that may be set during shaping on each glyph.
- Glyph
Info - Glyph
Position GlyphPositionis the structure that holds the positions of the glyph in both horizontal and vertical directions. All positions inGlyphPositionare relative to the current point.- Invalid
Language - Language
- Owned
- A smart pointer that wraps a singly owned harfbuzz object.
- Script
- Segment
Properties - Serialize
Flags - Flags used for serialization with a
BufferSerializer. - Shared
- A smart pointer that wraps an atomically reference counted HarfBuzz object.
- Tag
- A type to represent 4-byte SFNT tags.
- Unicode
Buffer - A
UnicodeBuffercan be filled with unicode text and corresponding cluster indices. - Variation
- A variation selector which can be applied to a specific font.
Enums§
- Cluster
Level - Direction
- Defines the direction in which text is to be read.
- Serialize
Format - The serialization format used in
BufferSerializer. - TagFrom
StrErr - An Error generated when a
Tagfails to parse from a&strwith thefrom_strfunction. - Typed
Buffer - This type provides an interface to create one of the buffer types from a raw harfbuzz pointer.
Traits§
- Harfbuzz
Object - 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
- Shape the contents of the buffer using the provided font and activating all
OpenType features given in
features.