Book Image

Canvas Cookbook

Book Image

Canvas Cookbook

Overview of this book

With the growing popularity of HTML5 Canvas, this book offers tailored recipes to help you develop portable applications, presentations, and games. The recipes are simple yet creative and build on each other. At every step, the book inspires the reader to develop his/her own recipe. From basic to advanced, every aspect of Canvas API has been covered to guide readers to develop their own application, presentation, or game.
Table of Contents (16 chapters)
Canvas Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Drawing circles


Again, there is no direct function to draw a circle. It should be drawn using the function for drawing an arc. We saw a drawing of a circle in the previous chapter through the example of drawing arc2. The output of the circle recipe looks like this:

How to do it…

The recipe is very simple. It calls the drawCircle() function in a loop to draw multiple circles as you see here. The recipe is as follows.

The HTML code:

<html>
<head>
<title>circles</title>
<script src="circles.js"></script>
</head>
<body onload="init()">
<canvas id="MyCanvasArea" width="300" height="300" style="border:2px solid blue;" >
   your browser does not support canvas
</canvas>
<h1>Circles</h1>
</body>
</html>

The JavaScript code:

function init(){
  var can=document.getElementById("MyCanvasArea");
  var ctx=can.getContext("2d");
  //call to the function to draw Circle
  for(i=1,x=15,y=20,r=10;i<=6;i++,x+=r*2,y+=r*2,r=r+10...