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 do 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:
Playable code
<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas> <div class="playable-buttons"> <input id="edit" type="button" value="Edit" /> <input id="reset" type="button" value="Reset" /> </div> <textarea id="code" class="playable-code"> ctx.fillStyle = "green"; ctx.fillRect(10, 10, 100, 100);</textarea>
var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); var textarea = document.getElementById("code"); var reset = document.getElementById("reset"); var edit = document.getElementById("edit"); var code = textarea.value; function drawCanvas() { ctx.clearRect(0, 0, canvas.width, canvas.height); eval(textarea.value); } reset.addEventListener("click", function() { textarea.value = code; drawCanvas(); }); edit.addEventListener("click", function() { textarea.focus(); }) textarea.addEventListener("input", drawCanvas); window.addEventListener("load", drawCanvas);
Reference
The interfaces related to the WebGLRenderingContext
are referenced under WebGL.
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.
- Drawing DOM objects into a canvas
- How to draw DOM content, such as HTML elements, into a canvas.
- Manipulating video using canvas
- Combining
<video>
and<canvas>
to manipulate video data in real time.
Resources
Generic
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.
- libCanvas is powerful and lightweight canvas framework.
- 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.
Specifications
Specification | Status | Comment |
---|---|---|
WHATWG HTML Living Standard The definition of 'Canvas' in that specification. |
Living Standard |