canvas-text-metrics-polyfill

A polyfill for the enhanced context.measureText() in HTML <canvas> v5 / Canvas 2D Context Level 2. Based on https://github.com/Pomax/fontmetrics.js.

The upcoming version of <canvas> will offer a standard way to get 2D font metrics, via properties added to the TextMetrics object (returned by context.measureText()). This feature was drafted in March 2012, but virtually all current browsers (as of November 2014) still follow the older spec and only provide the TextMetrics.width property.

This library provides a robust polyfill for the missing metrics on clients with pre-Level 2 <canvas>.

API reference

See:

• https://html.spec.whatwg.org/#drawing-text-to-the-bitmap
• http://www.w3.org/TR/2dcontext2/#drawing-text-to-the-bitmap
• https://lists.whatwg.org/pipermail/whatwg-whatwg.org/2012-March/035239.html

Demo

Try the visual test page.

Tests and performance

TBD

Supported browsers

TBD