<canvas>: The Graphics Canvas element #
::: section-content
Use the <canvas> with either the
canvas scripting
API or the
WebGL API
to draw graphics and animations.
| Content categories | Flow content, phrasing content, embedded content, palpable content. |
|---|---|
| Permitted content | Transparent but with no interactive content
descendants except for <a> elements,
<button> elements, <input> elements whose type attribute is
checkbox, radio, or button. |
| Tag omission | None, both the starting and ending tag are mandatory. |
| Permitted parents | Any element that accepts phrasing content. |
| Implicit ARIA role | No corresponding role |
| Permitted ARIA roles | Any |
| DOM interface | HTMLCanvasElement |
Attributes #
::: section-content This element's attributes include the global attributes.
heightThe height of the coordinate space in CSS pixels. Defaults to 150.
moz-opaque[Non-standard]{.visually-hidden} [Deprecated]{.visually-hidden}Lets the canvas know whether translucency will be a factor. If the canvas knows there's no translucency, painting performance can be optimized. This is only supported by Mozilla-based browsers; use the standardized
canvas.getContext('2d', { alpha: false })instead.widthThe width of the coordinate space in CSS pixels. Defaults to 300. :::
Usage notes #
Alternative content #
::: section-content
You should provide alternate content inside the <canvas> block. That
content will be rendered both on older browsers that don't support
canvas and in browsers with JavaScript disabled.
:::
Closing </canvas> tag
#
::: section-content
Unlike the
<img> element, the
<canvas>{aria-current=“page”} element requires the
closing tag (</canvas>).
:::
Sizing the canvas using CSS versus HTML #
::: section-content The displayed size of the canvas can be changed using CSS, but if you do this the image is scaled during rendering to fit the styled size, which can make the final graphics rendering end up being distorted.
It is better to specify your canvas dimensions by setting the width
and height attributes directly on the <canvas> elements, either
directly in the HTML or by using JavaScript.
:::
Maximum canvas size #
::: section-content
The exact maximum size of a <canvas> element depends on the browser
and environment. While in most cases the maximum dimensions exceed
10,000 x 10,000 pixels, notably iOS devices limit the canvas size to
only 4,096 x 4,096 pixels. See
canvas size limits in different browsers
and
devices{target="_blank"}
(2021).
::: {#sect1 .notecard .note} Note: Exceeding the maximum dimensions or area renders the canvas unusable — drawing commands will not work. ::: :::
Using an offscreen canvas #
::: section-content
A canvas can be rendered using the
OffscreenCanvas
API where the document and canvas are decoupled. The benefit is that a
worker
thread
can handle canvas rendering and the main thread of your web application
is not blocked by canvas operations. By parallelizing work, other UI
elements of your web application will remain responsive even if you are
running complex graphics on an offscreen canvas. For more information,
see the
OffscreenCanvas
API documentation.
:::
Examples #
HTML #
::: section-content This code snippet adds a canvas element to your HTML document. A fallback text is provided if a browser is unable to read or render the canvas.
::: code-example [html]{.language-name}
<canvas width="120" height="120">
An alternative text describing what your canvas displays.
</canvas>
::: :::
JavaScript #
::: section-content
Then in the JavaScript code, call
HTMLCanvasElement.getContext()
to get a drawing context and start drawing onto the canvas:
::: code-example [js]{.language-name}
const canvas = document.querySelector("canvas");
const ctx = canvas.getContext("2d");
ctx.fillStyle = "green";
// Add a rectangle at (10, 10) with size 100x100 pixels
ctx.fillRect(10, 10, 100, 100);
::: :::
Result #
::: section-content ::: {#sect2 .code-example} ::: iframe ::: ::: :::
Accessibility concerns #
Alternative content #
::: section-content
The <canvas> element on its own is just a bitmap and does not provide
information about any drawn objects. Canvas content is not exposed to
accessibility tools as semantic HTML is. In general, you should avoid
using canvas in an accessible website or app. The following guides can
help to make it more accessible.
- Canvas accessibility use cases{target="_blank"}
- Canvas element accessibility issues{target="_blank"}
- HTML Canvas Accessibility in Firefox 13 – by Steve Faulkner{target="_blank"}
- Best practices for interactive canvas elements{target="_blank"} :::
Specifications #
::: _table #
Specification #
HTML Standard
[#
the-canvas-element]{.small}
:::
Browser compatibility #
::: _table #
Desktop Mobile
Chrome Edge Firefox Internet Opera Safari WebView Chrome Firefox for Opera Safari Samsung
Explorer Android Android Android Android on IOS Internet
canvas 1 12 1.5 9 9 2 37 18 4 10.1 1 1.0
\[\"Before Although early \[\"Before
Firefox 5, the versions of Firefox 5, the
canvas width and Apple\'s Safari canvas width and
height were browser don\'t height were
signed integers require the signed integers
instead of closing tag, the instead of
unsigned specification unsigned
integers.\", indicates that integers.\",
\"Before Firefox it is required, \"Before Firefox
6, a \<canvas\> so you should be 6, a \<canvas\>
element with a sure to include element with a
zero width or it for broadest zero width or
height would be compatibility. height would be
rendered as if Before version rendered as if
it had default 2, Safari will it had default
dimensions.\", render the dimensions.\",
\"Before Firefox content of the \"Before Firefox
12, if fallback in 12, if
JavaScript is addition to the JavaScript is
disabled, the canvas itself disabled, the
\<canvas\> unless you use \<canvas\>
element was CSS tricks to element was
being rendered mask it. being rendered
instead of instead of
showing the showing the
fallback content fallback content
as per the as per the
specification. specification.
Since then, the Since then, the
fallback content fallback content
is rendered is rendered
instead.\"\] instead.\"\]
height 1 12 1.5 9 9 2 37 18 4 10.1 1 1.0
\[\"Before Although early \[\"Before
Firefox 5, the versions of Firefox 5, the
canvas width and Apple\'s Safari canvas width and
height were browser don\'t height were
signed integers require the signed integers
instead of closing tag, the instead of
unsigned specification unsigned
integers.\", indicates that integers.\",
\"Before Firefox it is required, \"Before Firefox
6, a \<canvas\> so you should be 6, a \<canvas\>
element with a sure to include element with a
zero width or it for broadest zero width or
height would be compatibility. height would be
rendered as if Before version rendered as if
it had default 2, Safari will it had default
dimensions.\", render the dimensions.\",
\"Before Firefox content of the \"Before Firefox
12, if fallback in 12, if
JavaScript is addition to the JavaScript is
disabled, the canvas itself disabled, the
\<canvas\> unless you use \<canvas\>
element was CSS tricks to element was
being rendered mask it. being rendered
instead of instead of
showing the showing the
fallback content fallback content
as per the as per the
specification. specification.
Since then, the Since then, the
fallback content fallback content
is rendered is rendered
instead.\"\] instead.\"\]
moz-opaque No No 3.5 No No No No No 4 No No No
width 1 12 1.5 9 9 2 37 18 4 10.1 1 1.0
\[\"Before Although early \[\"Before
Firefox 5, the versions of Firefox 5, the
canvas width and Apple\'s Safari canvas width and
height were browser don\'t height were
signed integers require the signed integers
instead of closing tag, the instead of
unsigned specification unsigned
integers.\", indicates that integers.\",
\"Before Firefox it is required, \"Before Firefox
6, a \<canvas\> so you should be 6, a \<canvas\>
element with a sure to include element with a
zero width or it for broadest zero width or
height would be compatibility. height would be
rendered as if Before version rendered as if
it had default 2, Safari will it had default
dimensions.\", render the dimensions.\",
\"Before Firefox content of the \"Before Firefox
12, if fallback in 12, if
JavaScript is addition to the JavaScript is
disabled, the canvas itself disabled, the
\<canvas\> unless you use \<canvas\>
element was CSS tricks to element was
being rendered mask it. being rendered
instead of instead of
showing the showing the
fallback content fallback content
as per the as per the
specification. specification.
Since then, the Since then, the
fallback content fallback content
is rendered is rendered
instead.\"\] instead.\"\]
:::
See also #
::: section-content
- Canvas API
- Canvas tutorial
- Canvas-related demos
- OffscreenCanvas
- Canvas cheat sheet{target="_blank"} (2009)
- Canvas cheat sheet{target="_blank"} (pdf) (2015)
- Canvas cheat sheet{target="_blank"} (pdf) (2020)
- Canvas introduction by Apple{target="_blank"} (2013) :::
::: _attribution
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5
or later.
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/canvas{._attribution-link}
:::