HTML5 Canvas

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

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What is Canvas?

The HTML5 canvas element uses JavaScript to draw graphics on a web page.
A canvas is a rectangular area, and you control every pixel of it.
The canvas element has several methods for drawing paths, boxes, circles, characters, and adding images.

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Create a Canvas Element

Add a canvas element to the HTML5 page.
Specify the id, width, and height of the element:

<canvas id="myCanvas" width="200" height="100"></canvas>

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Draw With JavaScript

The canvas element has no drawing abilities of its own. All drawing must be done inside a JavaScript:
<script type="text/javascript">
var c=document.getElementById("myCanvas");
var cxt=c.getContext("2d");
cxt.fillStyle="#FF0000";
cxt.fillRect(0,0,150,75);
</script>

JavaScript uses the id to find the canvas element:

var c=document.getElementById("myCanvas");

Then, create a context object:

var cxt=c.getContext("2d");

The getContext("2d") object is a built-in HTML5 object, with many methods to draw paths, boxes, circles, characters, images and more.
The next two lines draws a red rectangle:

cxt.fillStyle="#FF0000"; cxt.fillRect(0,0,150,75);

The fillStyle method makes it red, and the fillRect method specifies the shape, position, and size.

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Understanding Coordinates

The fillRect method above had the parameters (0,0,150,75).
This means: Draw a 150x75 rectangle on the canvas, starting at the top left corner (0,0).
The canvas' X and Y coordinates are used to position drawings on the canvas.
Mouse over the rectangle below to see the coordinates:

	X
Y

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More Canvas Examples

Below are more examples of drawing on the canvas element:

Example - Line Draw a line by specifying where to start, and where to stop: Try it yourself »

Example - Circle Draw a circle by specifying the size, color, and position: Try it yourself »

Example - Gradient Draw a gradient background with the colors you specify: Try it yourself »

Example - Image

Put an image on the canvas:

Try it yourself »