It gives you access to the letterforms of text from the browser or Node.js.
See https://opentype.js.org/ for a live demo.
- Create a bézier path out of a piece of text.
- Support for composite glyphs (accented letters).
- Support for WOFF, OTF, TTF (both with TrueType
glyf
and PostScriptcff
outlines) - Support for kerning (Using GPOS or the kern table).
- Support for ligatures.
- Support for TrueType font hinting.
- Support arabic text rendering (See issue #364 & PR #359 #361)
- Support for emojis and other SVG or COLR/CPAL color glyphs
- A low memory mode is available as an option (see #329)
- Runs in the browser and Node.js.
Select one of the following sources in the next example:
- https://opentype.js.org/dist/opentype.js
- https://cdn.jsdelivr.net/npm/opentype.js
- https://unpkg.com/opentype.js
<!-- using global declaration -->
<script src="https://your.favorite.cdn/opentype.js"></script>
<script>opentype.parse(...)</script>
<!-- using module declaration (need full path) -->
<script type=module>
import { parse } from "https://unpkg.com/opentype.js/dist/opentype.module.js";
parse(...);
</script>
via npm package manager
npm install opentype.js
const opentype = require('opentype.js');
import opentype from 'opentype.js'
import { load } from 'opentype.js'
Using TypeScript? See this example
If you plan on improving or debugging opentype.js, you can:
- Fork the opentype.js repo
- clone your fork
git clone git://github.com/yourname/opentype.js.git
- move into the project
cd opentype.js
- install needed dependencies with
npm install
- make your changes
- option A: for a simple build, use
npm run build
- option B: for a development server, use
npm run start
and navigate to the/docs
folder
- option A: for a simple build, use
- check if all still works fine with
npm run test
- commit and open a Pull Request with your changes. Thank you!
// case 1: from an URL
const buffer = fetch('/fonts/my.woff').then(res => res.arrayBuffer());
// case 2: from filesystem (node)
const buffer = require('fs').promises.readFile('./my.woff');
// case 3: from an <input type=file id=myfile>
const buffer = document.getElementById('myfile').files[0].arrayBuffer();
// if running in async context:
const font = opentype.parse(await buffer);
console.log(font);
// if not running in async context:
buffer.then(data => {
const font = opentype.parse(data);
console.log(font);
})
WOFF2 Brotli compression perform 29% better than it WOFF predecessor. But this compression is also more complex, and would result in a much heavier (>10×!) opentype.js library (≈120KB => ≈1400KB).
To solve this: Decompress the font beforehand (for example with fontello/wawoff2).
// promise-based utility to load libraries using the good old <script> tag
const loadScript = (src) => new Promise((onload) => document.documentElement.append(
Object.assign(document.createElement('script'), {src, onload})
));
const buffer = //...same as previous example...
// load wawoff2 if needed, and wait (!) for it to be ready
if (!window.Module) {
const path = 'https://unpkg.com/[email protected]/build/decompress_binding.js'
const init = new Promise((done) => window.Module = { onRuntimeInitialized: done});
await loadScript(path).then(() => init);
}
// decompress before parsing
const font = opentype.parse(Module.decompress(await buffer));
This example relies on the deprecated .load()
method
// case 1: from an URL
const font = opentype.load('./fonts/my.woff', {}, {isUrl: true});
// case 2: from filesystem
const font = opentype.load('./fonts/my.woff', {}, {isUrl: false});
// ... play with `font` ...
console.log(font.supported);
Once you have a Font
object (either by using opentype.load()
or by creating a new one from scratch) you can write it
back out as a binary file.
In the browser, you can use Font.download()
to instruct the browser to download a binary .OTF file. The name is based
on the font name.
// Create the bézier paths for each of the glyphs.
// Note that the .notdef glyph is required.
const notdefGlyph = new opentype.Glyph({
name: '.notdef',
advanceWidth: 650,
path: new opentype.Path()
});
const aPath = new opentype.Path();
aPath.moveTo(100, 0);
aPath.lineTo(100, 700);
// more drawing instructions...
const aGlyph = new opentype.Glyph({
name: 'A',
unicode: 65,
advanceWidth: 650,
path: aPath
});
const glyphs = [notdefGlyph, aGlyph];
const font = new opentype.Font({
familyName: 'OpenTypeSans',
styleName: 'Medium',
unitsPerEm: 1000,
ascender: 800,
descender: -200,
glyphs: glyphs});
font.download();
If you want to inspect the font, use font.toTables()
to generate an object showing the data structures that map directly to binary values.
If you want to get an ArrayBuffer
, use font.toArrayBuffer()
.
A Font represents a loaded OpenType font file. It contains a set of glyphs and methods to draw text on a drawing context, or to get a path representing the text.
glyphs
: an indexed list of Glyph objects.unitsPerEm
: X/Y coordinates in fonts are stored as integers. This value determines the size of the grid. Common values are2048
and4096
.ascender
: Distance from baseline of highest ascender. In font units, not pixels.descender
: Distance from baseline of lowest descender. In font units, not pixels.
Create a Path that represents the given text.
x
: Horizontal position of the beginning of the text. (default:0
)y
: Vertical position of the baseline of the text. (default:0
)fontSize
: Size of the text in pixels (default:72
).options
: {GlyphRenderOptions} passed to each glyph, see below
Options is an optional {GlyphRenderOptions} object containing:
script
: script used to determine which features to apply (default:"DFLT"
or"latn"
)language
: language system used to determine which features to apply (default:"dflt"
)kerning
: if true takes kerning information into account (default:true
)features
: an object with OpenType feature tags as keys, and a boolean value to enable each feature. Currently only ligature features"liga"
and"rlig"
are supported (default:true
).hinting
: if true uses TrueType font hinting if available (default:false
).colorFormat
: the format colors are converted to for rendering (default:"hexa"
). Can be"rgb"
/"rgba"
forrgb()
/rgba()
output,"hex"
/"hexa"
for 6/8 digit hex colors, or"hsl"
/"hsla"
forhsl()
/hsla()
output."bgra"
outputs an object with r, g, b, a keys (r/g/b from 0-255, a from 0-1)."raw"
outputs an integer as used in the CPAL table.fill
: font color, the color used to render each glyph (default:"black"
)
Note: there is also Font.getPaths()
with the same arguments, which returns a list of Paths.
Create a Path that represents the given text.
ctx
: A 2D drawing context, like Canvas.x
: Horizontal position of the beginning of the text. (default:0
)y
: Vertical position of the baseline of the text. (default:0
)fontSize
: Size of the text in pixels (default:72
).options
: {GlyphRenderOptions} passed to each glyph, seeFont.getPath()
Options is an optional object containing:
kerning
: iftrue
, takes kerning information into account (default:true
)features
: an object with OpenType feature tags as keys, and a boolean value to enable each feature. Currently only ligature features"liga"
and"rlig"
are supported (default:true
).hinting
: if true uses TrueType font hinting if available (default:false
).
Draw the points of all glyphs in the text. On-curve points will be drawn in blue, off-curve points will be drawn in red. The arguments are the same as Font.draw()
.
Draw lines indicating important font measurements for all glyphs in the text. Black lines indicate the origin of the coordinate system (point 0,0). Blue lines indicate the glyph bounding box. Green line indicates the advance width of the glyph.
Convert the string to a list of glyph objects. Note that there is no strict 1-to-1 correspondence between the string and glyph list due to possible substitutions such as ligatures. The list of returned glyphs can be larger or smaller than the length of the given string.
Convert the character to a Glyph object. Returns null
if the glyph could not be found. Note that this function assumes that there is a one-to-one mapping between the given character and a glyph; for complex scripts, this might not be the case.
Retrieve the value of the kerning pair between the left glyph (or its index) and the right glyph (or its index). If no kerning pair is found, return 0
. The kerning value gets added to the advance width when calculating the spacing between glyphs.
Returns the advance width of a text.
This is something different than Path.getBoundingBox()
; for example a
suffixed whitespace increases the advancewidth but not the bounding box
or an overhanging letter like a calligraphic 'f' might have a quite larger
bounding box than its advance width.
This corresponds to canvas2dContext.measureText(text).width
fontSize
: Size of the text in pixels (default:72
).options
: {GlyphRenderOptions}, seeFont.getPath()
This allows to manage the palettes and colors in the CPAL table, without having to modify the table manually.
Add a new palette.
colors
: (optional) colors to add to the palette, differences to existing palettes will be filled with the defaultValue.
Deletes a palette by its zero-based index
paletteIndex
: zero-based palette index
Deletes a specific color index in all palettes and updates all layers using that color with the color currently held in the replacement index
colorIndex
: index of the color that should be deletedreplacementIndex
: index (according to the palette before deletion) of the color to replace in layers using the color to be to deleted
Returns the font's cpal table, or false if it does not exist. Used internally.
Mainly used internally. Makes sure that the CPAL table exists or is populated with default values.
colors
: (optional) colors to populate on creation returnstrue
if it was created,false
if it already existed.
Extend all existing palettes and the numPaletteEntries value by a number of color slots
num
: number of additional color slots to add to all palettes
Fills a set of palette colors (from a palette index, or a provided array of CPAL color values) with a set of colors, falling back to the default color value, until a given count. It does not modify the existing palette, returning a new array instead! Use Font.palettes.setColor()
instead if needed.
palette
: palette index or an Array of CPAL color values to fill the palette with, the rest will be filled with the default colorcolors
: array of color values to fill the palette with, in a format supported as an output ofcolorFormat
in {GlyphRenderOptions}, seeFont.getPath()
. CSS color names are also supported in browser context.colorCount
: Number of colors to fill the palette with, defaults to the value of the numPaletteEntries field
Returns an array of arrays of color values for each palette, optionally in a specified color format
colorFormat
: (optional) See {GlyphRenderOptions} atFont.getPath()
, (default:"hexa"
)
Get a specific palette by its zero-based index
index
: zero-based index of the color in the palettepaletteIndex
: zero-based palette index (default: 0)colorFormat
: (optional) See {GlyphRenderOptions} atFont.getPath()
, (default:"hexa"
)
Get a specific palette by its zero-based index
paletteIndex
: zero-based palette indexcolorFormat
: (optional) See {GlyphRenderOptions} atFont.getPath()
, (default:"hexa"
)
Set one or more colors on a specific palette by its zero-based index
index
: zero-based color index to start filling fromcolor
: color value or array of color values in a color notation supported as an output ofcolorFormat
in {GlyphRenderOptions}, seeFont.getPath()
. CSS color names are also supported in browser context.paletteIndex
: zero-based palette index (default: 0)
Converts a color value string to a CPAL integer color value
color
: string in a color notation supported as an output ofcolorFormat
in {GlyphRenderOptions}, seeFont.getPath()
. CSS color names are also supported in browser context.
This allows to manage the color glyph layers in the COLR table, without having to modify the table manually.
Adds one or more layers to a glyph, at the end or at a specific position.
glyphIndex
: glyph index to add the layer(s) to.layers
: layer object {glyph, paletteIndex}/{glyphID, paletteIndex} or array of layer objects.position
: position to insert the layers at (will default to adding at the end).
Mainly used internally. Ensures that the COLR table exists and is populated with default values.
Gets the layers for a specific glyph
glyphIndex
Returns an array of{glyph, paletteIndex}
layer objects.
Removes one or more layers from a glyph.
glyphIndex
: glyph index to remove the layer(s) fromstart
: index to remove the layer atend
: (optional) if provided, removes all layers from start index to (and including) end index
Sets a color glyph layer's paletteIndex property to a new index
glyphIndex
: glyph in the font by zero-based glyph indexlayerIndex
: layer in the glyph by zero-based layer indexpaletteIndex
: new color to set for the layer by zero-based index in any palette
Mainly used internally. Updates the colr table, adding a baseGlyphRecord if needed, ensuring that it's inserted at the correct position, updating numLayers, and adjusting firstLayerIndex values for all baseGlyphRecords according to any deletions or insertions.
A Glyph is an individual mark that often corresponds to a character. Some glyphs, such as ligatures, are a combination of many characters. Glyphs are the basic building blocks of a font.
font
: A reference to the Font object.name
: The glyph name (e.g."Aring"
,"five"
)unicode
: The primary unicode value of this glyph (can beundefined
).unicodes
: The list of unicode values for this glyph (most of the time this will be1
, can also be empty).index
: The index number of the glyph.advanceWidth
: The width to advance the pen when drawing this glyph.leftSideBearing
: The horizontal distance from the previous character to the origin (0, 0
); a negative value indicates an overhangxMin
,yMin
,xMax
,yMax
: The bounding box of the glyph.path
: The raw, unscaled path of the glyph.
Get a scaled glyph Path object for use on a drawing context.
x
: Horizontal position of the glyph. (default:0
)y
: Vertical position of the baseline of the glyph. (default:0
)fontSize
: Font size in pixels (default:72
).options
: {GlyphRenderOptions}, seeFont.getPath()
font
: a font object, needed for rendering COLR/CPAL fonts to get the layers and colors
Calculate the minimum bounding box for the unscaled path of the given glyph. Returns an opentype.BoundingBox
object that contains x1
/y1
/x2
/y2
.
If the glyph has no points (e.g. a space character), all coordinates will be zero.
Draw the glyph on the given context.
ctx
: The drawing context.x
: Horizontal position of the glyph. (default:0
)y
: Vertical position of the baseline of the glyph. (default:0
)fontSize
: Font size, in pixels (default:72
).options
: {GlyphRenderOptions}, seeFont.getPath()
font
: a font object, needed for rendering COLR/CPAL fonts to get the layers and colors
Draw the points of the glyph on the given context.
On-curve points will be drawn in blue, off-curve points will be drawn in red.
The arguments are the same as Glyph.draw()
.
Draw lines indicating important font measurements for all glyphs in the text.
Black lines indicate the origin of the coordinate system (point 0,0).
Blue lines indicate the glyph bounding box.
Green line indicates the advance width of the glyph.
The arguments are the same as Glyph.draw()
.
Glyph.toPathData(options)
, Glyph.toDOMElement(options)
, Glyph.toSVG(options)
, Glyph.fromSVG(pathData, options)
,
These are currently only wrapper functions for their counterparts on Path objects (see documentation there), but may be extended in the future to pass on Glyph data for automatic calculation.
Gets the color glyph layers for this glyph from the specified font's COLR/CPAL tables
Once you have a path through Font.getPath()
or Glyph.getPath()
, you can use it.
commands
: The path commands. Each command is a dictionary containing a type and coordinates. See below for examples.fill
: The fill color of the Path. Color is a string representing a CSS color. (default:'black'
)stroke
: The stroke color of thePath
. Color is a string representing a CSS color. (default:null
; the path will not be stroked)strokeWidth
: The line thickness of thePath
. (default:1
, but ifstroke
isnull
no stroke will be drawn)
Draw the path on the given 2D context. This uses the fill
, stroke
, and strokeWidth
properties of the Path object.
ctx
: The drawing context.
Calculate the minimum bounding box for the given path. Returns an opentype.BoundingBox
object that contains x1
/y1
/x2
/y2
.
If the path is empty (e.g. a space character), all coordinates will be zero.
Convert the Path to a string of path data instructions. See https://www.w3.org/TR/SVG/paths.html#PathData
options
:decimalPlaces
: The amount of decimal places for floating-point values. (default:2
)optimize
: apply some optimizations to the path data, e.g. removing unnecessary/duplicate commands (true/false, default:true
)flipY
: whether to flip the Y axis of the path data, because SVG and font paths use inverted Y axes. (true
: calculate from bounding box,false
: disable; default:true
)flipYBase
: Base value for the base flipping calculation. You'll probably want to calculate this from the font's ascender and descender values. (default: automatically calculate from the path data's bounding box)
Convert the path to an SVG <path>
element, as a string.
options
: seePath.toPathData()
Retrieve path from SVG path data.
Either overwriting the path data for an existing path:
const path = new Path();
path.fromSVG('M0 0');
Or creating a new Path directly:
const path = Path.fromSVG('M0 0');
pathData
: Either a string of SVG path commands, or (only in browser context) anSVGPathElement
options
:decimalPlaces
,optimize
,flipY
,flipYBase
: seePath.toPathData()
scale
: scaling value applied to all command coordinates (default:1
)x
/y
: offset applied to all command coordinates on the x or y axis (default:0
)
- Move To: Move to a new position. This creates a new contour. Example:
{type: 'M', x: 100, y: 200}
- Line To: Draw a line from the previous position to the given coordinate. Example:
{type: 'L', x: 100, y: 200}
- Curve To: Draw a bézier curve from the current position to the given coordinate. Example:
{type: 'C', x1: 0, y1: 50, x2: 100, y2: 200, x: 100, y: 200}
- Quad To: Draw a quadratic bézier curve from the current position to the given coordinate. Example:
{type: 'Q', x1: 0, y1: 50, x: 100, y: 200}
- Close: Close the path. If stroked, this will draw a line from the first to the last point of the contour. Example:
{type: 'Z'}
We use SemVer for versioning.
MIT
I would like to acknowledge the work of others without which opentype.js wouldn't be possible:
- pdf.js: for an awesome implementation of font parsing in the browser.
- FreeType: for the nitty-gritty details and filling in the gaps when the spec was incomplete.
- ttf.js: for hints about the TrueType parsing code.
- CFF-glyphlet-fonts: for a great explanation/implementation of CFF font writing.
- tiny-inflate: for WOFF decompression.
- Microsoft Typography: the go-to reference for all things OpenType.
- Adobe Compact Font Format spec and the Adobe Type 2 Charstring spec: explains the data structures and commands for the CFF glyph format.
- All contributors.