HTML5 Canvas

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Your browser does not support the <canvas> element.

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 scripting (usually Javascript).

The <canvas> 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.

Browser Support

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

Element
<canvas> 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:

Basic Canvas Example

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

NOTE: It goes without saying that throughout these excercises you have been reminded of using the proper HTML document structure for the working examples. Primarily for designating the different elements such as the style block, the division id and the actual HTML. Make sure that you enclose the canvas elements in a canvas tags and for this example you will have to make sure that the drawing scripts are enclosed in script tags.

Drawing with Javascript

var c = document.getElementById ("myCanvas");
var ctx = c.getContext("2d");
ctx.fillstyle = "#FF0000";
ctx.fillRect(0,0,150,75);
Try it yourself »

Draw a line

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(0,0);
ctx.lineTo(200,100);
ctx.stroke();
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Draw a Circle

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95,50,40,0,2*Math.PI);
ctx.stroke();
Try it yourself »

Draw a Text

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("Hello World",10,50);
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Stroke Text

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.strokeText("Hello World",10,50);
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Draw linear Gradient

var c = document.getElementById("myCanvas");
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);
Try it yourself »

Draw Circular Gradient

var c = document.getElementById("myCanvas");
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);
Try it yourself »

Draw Image

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("scream");
ctx.drawImage(img,10,10);
Try it yourself »

 







HTML5 SVG

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What is SVG?

the HTML <svg> Element

The HTML <svg> element (introduced in HTML5) is a container for SVG graphics.

SVG has several methods for drawing paths, boxes, circles, text, and graphic images.

Browser Support

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

Element
<svg> 4.0 9.0 3.0 3.2 10.1

SVG Circle

Example

<!DOCTYPE html>
<html>
<body>

<svg width="100" height="100">
  <circle cx="50" cy="50" r="40" stroke="green" stroke-width="4" fill= "yellow" />
</svg>

</body>
</html>
Try it yourself »

SVG Rectangle



Example


<svg width="400" height="100">
  <rect width="400" height="100" style="fill:rgb(0,0,255);stroke-width: 10;stroke:rgb(0,0,0)" />
</svg>

Try it yourself »

SVG Rounded Rectangle

Sorry, your browser does not support inline SVG.

Example


<svg width="400" height="180">
  <rect x="50" y="20" rx="20" ry="20" width="150" height="150"
  style="fill:red;stroke:black;stroke-width:5;opacity:0.5" />
</svg>

Try it yourself »

SVG Star

Sorry, your browser does not support inline SVG.

Example


<svg width="300" height="200">
  <polygon points="100,10 40,198 190,78 10,78 160,198"
  style="fill:lime;stroke:purple;stroke-width:5;fill-rule:evenodd;"/>
</svg>

Try it yourself »

SVG Logo

SVG Sorry, your browser does not support inline SVG.

Example


<svg height="130" width="500">
  <defs>
    <linearGradient id="grad1" x1="0%" y1="0%" x2="100%" y2="0%">
      <stop offset="0%" style="stop- color:rgb(255,255,0);stop-opacity:1" />
      <stop offset="100%" style="stop-color:rgb(255,0,0);stop-opacity:1" />
    </linearGradient>
  </defs>
  <ellipse cx="100" cy="70" rx="85" ry="55" fill="url (#grad1)" />
  <text fill="#ffffff" font-size="45" font-family="Verdana" x="50" y="86">SVG</text>
  Sorry, your browser does not support inline SVG.
</svg>

Try it yourself »

Differences Between SVG and Canvas

SVG is a language for describing 2D graphics in XML.

Canvas draws 2D graphics, on the fly (with a Javascript).

SVG is XML based, which means that every element is available within the SVG DOM. You can attach Javascript event handlers for an element.

In SVG, each drawn shape is remembered as an object. If attributes of an SVG object are changed, the browser can automatically re-render the shape.

Canvas is rendered pixel by pixel. In canvas, once the graphic is drawn, it is forgotten by the browser. If its position should be changed, the entire scene needs to be redrawn, including any objects that might have been covered by the graphic.

Comparison of Canvas and SVG

The table below shows some important differences between Canvas and SVG:

Canvas SVG
  • Resolution dependent
  • No support for event handlers
  • Poor text rendering capabilities
  • You can save the resulting image as .png or .jpg
  • Well suited for graphic-intensive games
  • Resolution independent
  • Support for event handlers
  • Best suited for applications with large rendering areas (Google Maps)
  • Slow rendering if complex (anything that uses the DOM a lot will be slow)
  • Not suited for game applications


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