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

Detecting a point in a path


This is another example of a mouse event, but another new concept is introduced here: how to find whether a point lies in a given path. The output of the recipe is as follows:

How to do it

The recipe is as follows:

The HTML code:

<html>
<head>
  <title>Point In Path Example</title>
  <script src="pointinpath.js"></script>
</head>
<body onload=init()>
  <canvas width="400" height="400" id="MyCanvasArea" style="border:2px solid blue;">
    Canvas tag is not supported by your browser
  </canvas>
  <br>
  <h1>click inside the rectangle to spot</h1>
  <br>
  <form>
    <input type="button" onclick="init();" value="Reset" >
  </form>
</body>
</html>

The JavaScript code:

var ctx;
var can;
function init(){
  can=document.getElementById("MyCanvasArea");
  ctx=can.getContext("2d");
  can.addEventListener("mousedown",doMouseDown,false);
  clear();
  drawRectangle(...