Font tools

This is the Node.js adapter of python font tools via Pyodide without having to install python and its dependencies.

Font tools library usually used for optimizing fonts – subseting, format converting, deleting of unused variable font axes, etc.

Using as a CLI

You can install the library as a global dependency:

``shell
npm install --global @web-alchemy/fonttools
`

After installing font utilities will be available globally:

`shell
fonttools
pyftsubset
pyftmerge
ttx
`

Also you can use this tool via npx:

`shell
npx -p @web-alchemy/fonttools
npx -p @web-alchemy/fonttools pyftsubset
npx -p @web-alchemy/fonttools pyftmerge
npx -p @web-alchemy/fonttools ttx
`

Example of converting ttf to woff2:

`shell
npx -p @web-alchemy/fonttools pyftsubset \
"./some/path/to/font.ttf" \
"*" \ # keep all glyphs and just convert format
--output-file="./some/path/to/font.woff2" \
--flavor="woff2"
`

Example of converting ttf to woff2 and subseting with text and unicodes options:

`shell
npx -p @web-alchemy/fonttools pyftsubset \
"./some/path/to/font.ttf" \
--output-file="./some/path/to/font.woff2" \
--flavor="woff2" \
--text="The text whose characters will be included in the font file" \
--unicodes="U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD" \
--desubroutinize \
--no-hinting \
--layout-features="*"
`

Example of customizing variable font's axes:

`shell
npx @web-alchemy/fonttools varLib.instancer \
"./src/font.woff2" \
# decrease wght axis range
wght=400:600 \
# delete wdth axis
wdth=drop \
--output="./dist/font.woff2"
`

Using as a module

Library provides few JavaScript specific methods:

`javascript
const {
subset,
instantiateVariableFont,
ttx
} = require('@web-alchemy/fonttools')
`

Example of converting ttf to woff2:

`javascript
const fs = require('node:fs')
const { subset } = require('@web-alchemy/fonttools')

async function main() {
const inputFileBuffer = await fs.promises.readFile('./font.ttf')

const outputFileBuffer = await subset(inputFileBuffer, {
'*': true, // keep all glyphs and just convert format
'flavor': 'woff2',
})

await fs.promises.writeFile('./font.woff2', outputFileBuffer)
}

main()
`

Example of converting ttf to woff2 and subseting with text and unicodes options:

`javascript
const fs = require('node:fs')
const { subset } = require('@web-alchemy/fonttools')

async function main() {
const inputFileBuffer = await fs.promises.readFile('./font.ttf')

const outputFileBuffer = await subset(inputFileBuffer, {
'text': "The text whose characters will be included in the font file",
'unicodes': "U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD",
'flavor': 'woff2',
})

await fs.promises.writeFile('./font.woff2', outputFileBuffer)
}

main()
`

Method subset takes same params as original pyftsubset utility(without dashes --).

Example of customizing variable font's axes:

`javascript
const fs = require('node:fs')
const { instantiateVariableFont } = require('@web-alchemy/fonttools')

async function main() {
const inputFileBuffer = await fs.promises.readFile('./src/font.woff2')

const outputFileBuffer = await instantiateVariableFont(inputFileBuffer, {
wght: [300, 500], // decrease wght axis range
wdth: null // delete wdth axis
})

await fs.promises.writeFile('dist/font.woff2', outputFileBuffer)
}

main()
`

This is port of method varLib.instancer.instantiateVariableFont.

Method ttx can convert binary font files (.otf, .ttf, etc) to the TTX XML format and convert them back to binary format.

Example of converting binary files to xml:

`javascript
const fs = require('node:fs');
const { ttx } = require('@web-alchemy/fonttools');

(async () => {
const outputTtxBuffer = await ttx('./font.ttf'); // also accept URL and Buffer
await fs.promises.writeFile('./font.ttx', outputTtxBuffer);

const outputOtxBuffer = await ttx('./font.otf');
await fs.promises.writeFile('./font.otx', outputOtxBuffer);
})();
`

Example of converting xml files to binary files:

`javascript
const fs = require('node:fs');
const { ttx } = require('@web-alchemy/fonttools');

(async () => {
const ttfBuffer = await ttx('./font.ttx');
await fs.promises.writeFile('./font.ttf', ttfBuffer);

const otfBuffer = await ttx('./font.otx');
await fs.promises.writeFile('./font.otf', otfBuffer);
})();
`

Example of converting xml files to binary files with encoding to woff2:

`javascript
const fs = require('node:fs');
const { ttx } = require('@web-alchemy/fonttools');

(async () => {
const ttfBuffer = await ttx('./font.ttx', [
['--flavor', 'woff2']
]);
await fs.promises.writeFile('./font.woff2', ttfBuffer);

const otfBuffer = await ttx('./font.otx', [
['--flavor', 'woff2']
]);
await fs.promises.writeFile('./font.woff2', otfBuffer);
})();
`

Limitations

- Doesn't support zopfli package for better optimizing woff files.
- In CLI all file paths should be relative to cwd` (current working directory).

References

- Python font tools. Github, Site.
- Pyodide. Github, Site.