HTML5 Canvas

HTML5 Canvas

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

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

What is HTML Canvas ?

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

The <canvas> 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 <canvas> element.

Chrome Internet Explorer Firefox Safari Opera
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 :

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

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.

Example

<canvas id="myCanvas" width="200" height="100" style="border:1px solid #000000;"></canvas>

Here is an example of a basic, empty canvas :

Your browser does not support the HTML5 canvas tag.

Draw a Line Example

var c = document.getElementById("LineCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(0,0);
ctx.lineTo(200,100);
ctx.stroke();
Your browser does not support the HTML5 canvas tag.

Draw a Circle Example

var c = document.getElementById("CircleCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95,50,40,0,2*Math.PI);
ctx.stroke();
Your browser does not support the HTML5 canvas tag.

Draw a Text Example

var c = document.getElementById("TextCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("W3Professors",10,50);
Your browser does not support the HTML5 canvas tag.

Stroke Text Example

var c = document.getElementById("StrokeTextCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.strokeText("W3Professors",10,50);
Your browser does not support the HTML5 canvas tag.

Draw Linear Gradient Example

var c = document.getElementById("LinearGradientCanvas");
var ctx = c.getContext("2d");

// 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);
Your browser does not support the HTML5 canvas tag.

Draw Circular Gradient Example

var c = document.getElementById("RadialGradientCanvas");
var ctx = c.getContext("2d");

// 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);
Your browser does not support the HTML5 canvas tag.

Draw Image

var c = document.getElementById("ImageCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("scream");
ctx.drawImage(img,10,10);

Image to use :

The Scream

Canvas to fill :

Your browser does not support the HTML5 canvas tag.