Canvas API

Added in HTML5, the HTML <canvas> element can be used to draw graphics via scripting in JavaScript. For example, it can be used to draw graphs, make photo compositions, create animations, or even do real-time video processing or rendering.

Mozilla applications gained support for <canvas> starting with Gecko 1.8 (i.e. Firefox 1.5). The element was originally introduced by Apple for the OS X Dashboard and Safari. Internet Explorer supports <canvas> from version 9 onwards; for earlier versions of IE, a page can effectively add support for <canvas> by including a script from Google's Explorer Canvas project. Google Chrome and Opera 9 also support <canvas>.

The <canvas> element is also used by WebGL to draw hardware-accelerated 3D graphics on web pages.

Example

This is just a simple code snippet which uses the CanvasRenderingContext2D.fillRect() method.

HTML

<canvas id="canvas"></canvas>

JavaScript

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');

ctx.fillStyle = 'green';
ctx.fillRect(10, 10, 100, 100);

Edit the code below and see your changes update live in the canvas:

Reference

The interfaces related to the WebGLRenderingContext are referenced under WebGL.

CanvasCaptureMediaStream is related.

Guides and tutorials

Canvas tutorial

A comprehensive tutorial covering both the basic usage of <canvas> and its advanced features.

Code snippets: Canvas

Some extension developer-oriented code snippets involving <canvas>.

Demo: A basic ray-caster

A demo of ray-tracing animation using canvas.

Manipulating video using canvas

Combining <video> and <canvas> to manipulate video data in real time.

Pixel manipulation with canvas

How to use ImageBitmap to directly examine and alter pixels in the canvas's bitmap.

Drawing DOM objects into a canvas

How to draw DOM content, such as HTML elements, into a canvas.

Resources

Generic

• HTML5 Canvas Deep Dive
• Canvas Handbook

Libraries

• Fabric.js is an open-source canvas library with SVG parsing capabilities.
• Kinetic.js is an open-source canvas library focused on interactivity for desktop and mobile applications.
• Paper.js is an open source vector graphics scripting framework that runs on top of the HTML5 Canvas.
• Origami.js is an open source lightweight canvas library.
• libCanvas is powerful and lightweight canvas framework.
• p5.js has a full set of canvas drawing functionality for artists, designers, educators and beginners.
• Processing.js is a port of the Processing visualization language.
• PlayCanvas is an open source game engine.
• Pixi.js is an open source game engine.
• PlotKit is a charting and graphing library.
• Rekapi is an animation key-framing API for Canvas.
• PhiloGL is a WebGL framework for data visualization, creative coding and game development.
• JavaScript InfoVis Toolkit creates interactive 2D Canvas data visualizations for the Web.
• EaselJS is a free/open source library to make it easier to use canvas for games and art
• Scrawl-canvas is another open-source javascript library for creating and manipulating 2d canvas elements
• heatmap.js is an open source library to create canvas based heatmaps
• The ZIM framework provides conveniences, components and controls for coding creativity on the canvas — includes accessibility and hundreds of colorful tutorials.
• Pts.js is a new library for creative coding and visualization in canvas and svg.

Specifications

See also

• WebGL