alexxnica / typesettable

:triangular_ruler: A typesetting library for SVG and Canvas

Typesettable

Overview

Typesettable is a library for measuring, wrapping, and writing text on Canvas, SVG, and HTML.

Canvas and HTML support some rudimentary wrapping, but SVG does not support any. Furthermore, developers often want wrapped text to auto-hyphenate and truncate with ellipses when overflowing the bounding box. Typesettable aims to make this entire process easier.

Typesettable works with native browser APIs and has no external dependencies.

Features

• Measurers efficiently measure the size of a piece of text, taking into account the font styles affecting that text.
• Wrappers calculate how best to fit text into a given space, based on results from the Measurer.
• Writers layout and write text based on specified options such as wrapping, alignment, rotation, and shearing.
• SvgContext, CanvasContext, and HtmlContext implement factories for the IRuler and IPen objects, which encapsulate the functionality for measuring and writing text in SVG, Canvas, and HTML elements.

Installation

npm install --save typesettable

Usage

Example Two Liner

import { Typesetter } from "typesettable";

const typesetter = Typesetter.svg(document.querySelector("svg"));
typesetter.write("Hello World!", 200, 200);

Example SVG, Canvas, & HTML

Use typesetters with both SVG and Canvas elements:

import { Typesetter } from "typesettable";

// A typesetter for SVG elements
const svgTypesetter = Typesetter.svg(document.querySelector("svg"));

// A typesetter for Canvas elements
const canvasTypesetter = Typesetter.canvas(document.querySelector("canvas").getContext("2d"));

// A typesetter for HTML elements
const htmlTypesetter = Typesetter.html(document.querySelector("div.text-container"));

// The dimensions into which the text will be wrapped and truncated
const width = 300;
const height = 50;

// Options for alignment, etc.
const writeOptions = {
  xAlign: "left",
  yAlign: "top",
  textRotation: 0,
  textShear: 0,
};

// Write the text to the elements
svgTypesetter.write("Hello SVG!", width, height, writeOptions);
canvasTypesetter.write("Hello Canvas!", width, height, writeOptions);
htmlTypesetter.write("Hello HTML!", width, height, writeOptions);

Example Shared Cache

If you are typesetting multiple strings of text with the same font style, maintain a cache of Measurer results to improve performance.

Your HTML might look like:

<svg>
  <g class="section-one"></g>
  <g class="section-two" transform="translate(120 0)"></g>
</svg>

To share text measurements between writer, you can use the simple Typesetter interface, which already uses a shared CacheMeasurer. Or, you can compose the components manually like so:

import { CacheMeasurer, SvgContext, Wrapper, Writer } from "typesettable";

const svg = document.querySelector("svg");
const context = new SvgContext(svg);
const measurer = new CacheMeasurer(context);
const wrapper = new Wrapper();
const writer = new Writer(measurer, context, wrapper);
const writeOptions = { xAlign: "center" };

writer.write(
  "This text is in the first section",
  100, 400, writeOptions,
  svg.querySelector("g.section-one")
);

writer.write(
  "This text is in the second section",
  100, 200, writeOptions,
  svg.querySelector("g.section-two")
);

API Docs

See the docs for more detailed examples.