HTML <canvas> Tag

The HTML <canvas> tag is used for creating graphics on the fly in an HTML document. It can be used for rendering graphs, game graphics, fancy text, or other images.

The tag itself renders a blank canvas. To draw on the canvas, the <canvas> tag is used in conjunction with JavaScript (using the getContext() method).

Any content between the <canvas></canvas> tags is "fallback content"- meaning, it will be displayed only if the canvas cannot be displayed.

The <canvas> tag was introduced in HTML 5.

Syntax

The <canvas> tag is written as <canvas id=""></canvas> with any fallback content inserted between the start and end tag. This fallback content will only be displayed if the browser doesn't support the <canvas> element.

You can also specify the canvas height and width using the height and width attributes respectively. If you don't use these attributes, the canvas will be rendered at the default size, which is a width of 300 and a height of 150.

To make the <canvas> actually display something, you will need to add the id attribute and reference the <canvas>'s id with some JavaScript.

Like this:

Examples

Shapes

Rectangles

Here's an example of using the <canvas> element to draw rectangles with various fills and opacity levels.

Bézier Curves

You can also use the <canvas> element to draw Bézier curves. To do this, use bezierCurveTo, which works similar to the bezier and path tools in computer drawing packages such as Adobe Illustrator, GIMP, and others.

Text

Here's an example of using the <canvas> element being used to draw text.

Images

You can even use the <canvas> element to draw an image. To draw an image, use the drawImage() method. This requires that you supply the URL of an image.

Attributes

Attributes can be added to an HTML element to provide more information about how the element should appear or behave.

The <canvas> element accepts the following attributes.

Global Attributes

The following attributes are standard across all HTML elements. Therefore, you can use these attributes with the <canvas> tag , as well as with all other HTML tags.

• accesskey
• autocapitalize
• class
• contenteditable
• data-*
• dir
• draggable
• hidden
• id
• inputmode
• is
• itemid
• itemprop
• itemref
• itemscope
• itemtype
• lang
• part
• slot
• spellcheck
• style
• tabindex
• title
• translate

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handlers

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

• onabort
• onauxclick
• onblur
• oncancel
• oncanplay
• oncanplaythrough
• onchange
• onclick
• onclose
• oncontextmenu
• oncopy
• oncuechange
• oncut
• ondblclick
• ondrag
• ondragend
• ondragenter
• ondragexit
• ondragleave
• ondragover
• ondragstart
• ondrop
• ondurationchange
• onemptied
• onended
• onerror
• onfocus
• onformdata
• oninput
• oninvalid
• onkeydown
• onkeypress
• onkeyup
• onlanguagechange
• onload
• onloadeddata
• onloadedmetadata
• onloadstart
• onmousedown
• onmouseenter
• onmouseleave
• onmousemove
• onmouseout
• onmouseover
• onmouseup
• onpaste
• onpause
• onplay
• onplaying
• onprogress
• onratechange
• onreset
• onresize
• onscroll
• onsecuritypolicyviolation
• onseeked
• onseeking
• onselect
• onslotchange
• onstalled
• onsubmit
• onsuspend
• ontimeupdate
• ontoggle
• onvolumechange
• onwaiting
• onwheel

Most event handler content attributes can be used on all HTML elements, but some event handlers have specific rules around when they can be used and which elements they are applicable to.

For more detail, see HTML event handler content attributes.