What can you do with html canvas

HTML Canvas Tutorial

The HTML element is used to draw graphics on a web page.

The graphic above is created with .

It shows four elements: a red rectangle, a gradient rectangle, a multicolor rectangle, and a multicolor text.

What is HTML Canvas?

The HTML element is used to draw graphics, on the fly, via scripting (usually JavaScript).

The element is only a container for graphics. You must use a script to actually draw the graphics.

Canvas has several methods for drawing paths, boxes, circles, text, and adding images.

HTML Canvas Can Draw Text

Canvas can draw colorful text, with or without animation.

HTML Canvas Can Draw Graphics

Canvas has great features for graphical data presentation with an imagery of graphs and charts.

HTML Canvas Can be Animated

Canvas objects can move. Everything is possible: from simple bouncing balls to complex animations.

HTML Canvas Can be Interactive

Canvas can respond to JavaScript events.

Canvas can respond to any user action (key clicks, mouse clicks, button clicks, finger movement).

HTML Canvas Can be Used in Games

Canvas’ methods for animations, offer a lot of possibilities for HTML gaming applications.

Canvas Example

In HTML, a element looks like this:

The element must have an id attribute so it can be referred to by JavaScript.

The width and height attribute is necessary to define the size of the canvas.

Tip: You can have multiple elements on one HTML page.

By default, the element has no border and no content.

To add a border, use a style attribute:

Example

The next chapters show how to draw on the canvas.

See Also:

Browser Support

The element is an HTML5 standard (2014).

is supported in all modern browsers:

Chrome	Edge	Firefox	Safari	Opera	IE
Yes	Yes	Yes	Yes	Yes	9-11

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: The Graphics Canvas element

Use the HTML element 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 elements, elements, 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

This element’s attributes include the global attributes.

The height of the coordinate space in CSS pixels. Defaults to 150.

moz-opaque Non-standard Deprecated

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.

The width of the coordinate space in CSS pixels. Defaults to 300.

Usage notes

Alternative content

You should provide alternate content inside the block. That content will be rendered both on older browsers that don’t support canvas and in browsers with JavaScript disabled.

Closing tag

Sizing the canvas using CSS versus HTML

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 elements, either directly in the HTML or by using JavaScript.

Maximum canvas size

The maximum size of a element is very large, but the exact size depends on the browser. The following is some data we’ve collected from various tests and other sources (e.g. Stack Overflow):

Browser	Maximum height	Maximum width	Maximum area
Chrome	32,767 pixels	32,767 pixels	268,435,456 pixels (i.e., 16,384 x 16,384)
Firefox	32,767 pixels	32,767 pixels	472,907,776 pixels (i.e., 22,528 x 20,992)
Safari	32,767 pixels	32,767 pixels	268,435,456 pixels (i.e., 16,384 x 16,384)
IE	8,192 pixels	8,192 pixels	?

Note: Exceeding the maximum dimensions or area renders the canvas unusable — drawing commands will not work.

Using an offscreen canvas

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

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.

canvas width="120" height="120"> An alternative text describing what your canvas displays. canvas> 

JavaScript

Then in the JavaScript code, call HTMLCanvasElement.getContext() to get a drawing context and start drawing onto the canvas:

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

Accessibility concerns

Alternative content

The 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.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Canvas API
• Canvas tutorial
• Canvas-related demos
• OffscreenCanvas
• Canvas cheat sheet (2009)
• Canvas cheat sheet (pdf) (2015)
• Canvas cheat sheet (pdf) (2020)
• Canvas introduction by Apple (2013)

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HTML Canvas Graphics

The HTML element is used to draw graphics on a web page.

The graphic to the left is created with . It shows four elements: a red rectangle, a gradient rectangle, a multicolor rectangle, and a multicolor text.

What is HTML Canvas?

The HTML element is used to draw graphics, on the fly, via JavaScript.

The element is only a container for graphics. You must use JavaScript to actually draw the graphics.

Canvas has several methods for drawing paths, boxes, circles, text, and adding images.

Browser Support

The numbers in the table specify the first browser version that fully supports the element.

Element
	4.0	9.0	2.0	3.1	9.0

Canvas Examples

A canvas is a rectangular area on an HTML page. By default, a canvas has no border and no content.

The markup looks like this:

Note: Always specify an id attribute (to be referred to in a script), and a width and height attribute to define the size of the canvas. To add a border, use the style attribute.

Here is an example of a basic, empty canvas:

Your browser does not support the canvas element.

Example

Add a JavaScript

After creating the rectangular canvas area, you must add a JavaScript to do the drawing.

Draw a Line

Example

Draw a Circle

Example

Draw a Text

Example

Stroke Text

Example

Draw Linear Gradient

Example

// Create gradient
var grd = ctx.createLinearGradient(0, 0, 200, 0);
grd.addColorStop(0, «red»);
grd.addColorStop(1, «white»);

// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);

Draw Circular Gradient

Example

// Create gradient
var grd = ctx.createRadialGradient(75, 50, 5, 90, 60, 100);
grd.addColorStop(0, «red»);
grd.addColorStop(1, «white»);

// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);

Draw Image

HTML Canvas Tutorial

To learn more about , please read our HTML Canvas Tutorial.

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