font-metrics/README.md

Node.js font metrics parser

# Font metrics parser

Javascript tool for parsing font metrics data.
Each font is loaded via CSS Font Loading API and then parsed from canvas in Chromium browser with `experimentalCanvasFeatures` set to `true`

## Usage
- install package
```javascript
npm install font-metrics --save-dev
```
- include parser via `import`
```javascript
import 'fontParser' from 'font-metrics'
```
 or `require` syntax
```javascript
var fontParser = require('font-metrics')
```
- call parse method
```javascript
fontParser(options).parse();
```

## Options
* fonts {Object[]} Array of objects.
* fonts.fontFamily {String} font-family
* [fonts.src] {String} Custom fonts are expected to have `src` value specified. Each font will be loaded via CSS Font Loading API and then parsed.
* debug {Boolean} Show logs.
* output {String} Output path.
* filename {String} Output filename.
* fontSize {Number} Font size
* [express] {Object} Express options
  * [express.port] {Number} Express port
  * [express.mount] {Object[]} Additional directories that could be mounted to Express server. Usefull for parsing font files saved locally.
  * [express.mount.alias] {String} Local path alias
  * [express.mount.path] {String} Local path that could be used for using static files
* nightmare {Object} Nightmare options. Accepts any options that are valid for Nightmare initialization.
  * show {Boolean} Show browser window. Default: `false`

## Returns
JSON data

#### Usage example

```javascript
var fontMetrics = require('font-metrics');

fontMetrics({
	fonts: [
		{
			fontFamily: 'Arial'
		},
		{
			fontFamily: 'Roboto',
			src: 'https://fonts.gstatic.com/s/roboto/v15/sTdaA6j0Psb920Vjv-mrzH-_kf6ByYO6CLYdB4HQE-Y.woff2'
		},
		{
			fontFamily: 'SteelworksVintageDemo',
			src: 'mounted-path/SteelworksVintageDemo.otf'
		}
	],
	output: './metrics/',
	filename: 'metrics.json',
	express: {
		port: 3412,
		mount: [
			{
				alias: 'mounted-path',
				path: __dirname + '/your-local-dir-with-fonts'
			}
		]
	}
}).parse();
```

#### Output example
```javascript
{
	"metrics": {
		"Arial": {
			"_fontSize": 24,
			"_textBaseline": "alphabetic",
			"actualBoundingBoxAscent": 0,
			"actualBoundingBoxDescent": 24,
			"actualBoundingBoxLeft": 0,
			"actualBoundingBoxRight": 93,
			"alphabeticBaseline": 0,
			"emHeightAscent": 0,
			"emHeightDescent": 0,
			"fontBoundingBoxAscent": 22,
			"fontBoundingBoxDescent": 5,
			"hangingBaseline": -17.600000381469727,
			"ideographicBaseline": 5,
			"width": 93.375
		},
		"Roboto": {
			"_fontSize": 24,
			"_textBaseline": "alphabetic",
			"actualBoundingBoxAscent": 0,
			"actualBoundingBoxDescent": 24,
			"actualBoundingBoxLeft": 0,
			"actualBoundingBoxRight": 85,
			"alphabeticBaseline": 0,
			"emHeightAscent": 0,
			"emHeightDescent": 0,
			"fontBoundingBoxAscent": 22,
			"fontBoundingBoxDescent": 6,
			"hangingBaseline": -17.600000381469727,
			"ideographicBaseline": 6,
			"width": 85.30078125
		},
		"SteelworksVintageDemo": {
			"_fontSize": 24,
			"_textBaseline": "alphabetic",
			"actualBoundingBoxAscent": 0,
			"actualBoundingBoxDescent": 24,
			"actualBoundingBoxLeft": 0,
			"actualBoundingBoxRight": 69,
			"alphabeticBaseline": 0,
			"emHeightAscent": 0,
			"emHeightDescent": 0,
			"fontBoundingBoxAscent": 19,
			"fontBoundingBoxDescent": 7,
			"hangingBaseline": -15.199999809265137,
			"ideographicBaseline": 7,
			"width": 68.9759521484375
		}
	},
	"src": [
		{
			"fontFamily": "Arial"
		},
		{
			"fontFamily": "Roboto",
			"src": "https://fonts.gstatic.com/s/roboto/v15/sTdaA6j0Psb920Vjv-mrzH-_kf6ByYO6CLYdB4HQE-Y.woff2"
		},
		{
			"fontFamily": "SteelworksVintageDemo",
			"src": "mounted-path/SteelworksVintageDemo.otf"
		}
	]
}
```