https://github.com/pgaskin/go-hbsubset
Go bindings for HarfBuzz's font subsetter (hb-subset) without cgo.
https://github.com/pgaskin/go-hbsubset
otf sfnt ttf wasm wasm2go webfont
Last synced: 10 days ago
JSON representation
Go bindings for HarfBuzz's font subsetter (hb-subset) without cgo.
- Host: GitHub
- URL: https://github.com/pgaskin/go-hbsubset
- Owner: pgaskin
- License: mit
- Created: 2026-06-30T21:26:30.000Z (24 days ago)
- Default Branch: master
- Last Pushed: 2026-06-30T21:39:35.000Z (24 days ago)
- Last Synced: 2026-06-30T23:22:12.341Z (24 days ago)
- Topics: otf, sfnt, ttf, wasm, wasm2go, webfont
- Language: Go
- Homepage:
- Size: 1.43 MB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# go-hbsubset
[](https://pkg.go.dev/github.com/pgaskin/go-hbsubset)
[](https://github.com/pgaskin/go-hbsubset/actions/workflows/test.yml)
[](https://github.com/pgaskin/go-hbsubset/actions/workflows/attest.yml)
Go bindings for [HarfBuzz](https://github.com/harfbuzz/harfbuzz)'s font subsetter (`hb-subset`) without cgo.
This library wraps a WebAssembly build of HarfBuzz transpiled to Go using [wasm2go](https://github.com/ncruces/wasm2go).
> [!WARNING]
>
> These bindings are still experimental and are subject to change. They have not been tested extensively yet.
The wasm2go blob is fully [reproducible](./src/Dockerfile) and [verified](https://github.com/pgaskin/go-hbsubset/attestations).
To have working IDE integration while working on the bindings, use `bear -- make -C src distclean download all CXX=/path/to/wasi-sdk/bin/wasm32-wasip1-clang++ WASM_OPT=/path/to/binaryen/bin/wasm-opt` to download the Harfbuzz source and generate the `compile_commands.json`.
## Usage
To subset a single font:
```go
import "github.com/pgaskin/go-hbsubset"
out, err := hbsubset.Subset(font, 0, &hbsubset.Options{
Unicodes: []rune("some text"),
})
```
You can specify other options too:
```go
import (
"github.com/pgaskin/go-gfsubsets"
"golang.org/x/text/unicode/rangetable"
)
out, err := hbsubset.Subset(data, 0, &hbsubset.Options{
UnicodeRanges: rangetable.Merge(
gfsubsets.Latin,
&unicode.RangeTable{
R16: []unicode.Range16{
{Stride: 1, Lo: '\u2002', Hi: '\u201E'}, // spaces, smart punctuation
{Stride: 1, Lo: '\u2022', Hi: '\u2022'}, // bullet
{Stride: 1, Lo: '\u2026', Hi: '\u2026'}, // ellipsis
},
},
),
PinAllAxesToDefault: true,
AxisRanges: map[hbsubset.Tag]hbsubset.AxisRange{
hbsubset.MakeTag("wght"): {Min: 100, Max: 900, Default: 400},
},
LayoutFeatures: []hbsubset.Tag{
hbsubset.MakeTag("kern"),
hbsubset.MakeTag("mkmk"),
hbsubset.MakeTag("size"),
hbsubset.MakeTag("liga"),
},
NameIDs: []hbsubset.NameID{
hbsubset.NameUniqueID,
hbsubset.NameCopyright,
hbsubset.NameFontFamily,
hbsubset.NameFontSubfamily,
hbsubset.NameTypographicFamily,
hbsubset.NameTypographicSubfamily,
hbsubset.NameFullName,
hbsubset.NameMacFullName,
hbsubset.NamePostscriptName,
hbsubset.NameManufacturer,
hbsubset.NameDescription,
hbsubset.NameVariationsPSPrefix,
},
LayoutScripts: []hbsubset.Tag{
hbsubset.MakeTag("latn"), // latin
},
NameLanguages: []uint32{
1033, // english
},
})
```
You can reuse a font for multiple subsets (this also lets you access the font metadata):
```go
face, err := hbsubset.NewFace(font, 0)
if err != nil {
return err
}
face.Preprocess()
for _, page := range pages {
out, err := face.Subset(&hbsubset.Options{Unicodes: page})
// ...
}
```
You can use `SubsetWithMapping` to get the renumbered glyphs.
```go
out, m, err := hbsubset.SubsetWithMapping(font, &hbsubset.Options{
Unicodes: []rune("Hi"),
})
new, ok := m.NewGlyph(oldGID)
for old, new := range m.Glyphs() {
// ...
}
```
There are also some helpers to get relevant info (names, axes, glyph mappings, etc) from the font before subsetting (see the docs and [faceinfo.go](./faceinfo.go)).