Book Image

HTML5 Canvas Cookbook

By : Eric Rowell
Book Image

HTML5 Canvas Cookbook

By: Eric Rowell

Overview of this book

The HTML5 canvas is revolutionizing graphics and visualizations on the Web. Powered by JavaScript, the HTML5 Canvas API enables web developers to create visualizations and animations right in the browser without Flash. Although the HTML5 Canvas is quickly becoming the standard for online graphics and interactivity, many developers fail to exercise all of the features that this powerful technology has to offer.The HTML5 Canvas Cookbook begins by covering the basics of the HTML5 Canvas API and then progresses by providing advanced techniques for handling features not directly supported by the API such as animation and canvas interactivity. It winds up by providing detailed templates for a few of the most common HTML5 canvas applications—data visualization, game development, and 3D modeling. It will acquaint you with interesting topics such as fractals, animation, physics, color models, and matrix mathematics. By the end of this book, you will have a solid understanding of the HTML5 Canvas API and a toolbox of techniques for creating any type of HTML5 Canvas application, limited only by the extent of your imagination.
Table of Contents (19 chapters)
HTML5 Canvas Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Canvas Security
Index

Drawing a line


When learning how to draw with the HTML5 canvas for the first time, most people are interested in drawing the most basic and rudimentary element of the canvas. This recipe will show you how to do just that by drawing a simple straight line.

How to do it...

Follow these steps to draw a diagonal line:

  1. Define a 2D canvas context and set the line style:

    window.onload = function(){
      // get the canvas DOM element by its ID
         var canvas = document.getElementById("myCanvas");
      // declare a 2-d context using the getContext() method of the 
      // canvas object
         var context = canvas.getContext("2d");
        
      // set the line width to 10 pixels
         context.lineWidth = 10;
      // set the line color to blue
         context.strokeStyle = "blue";
  2. Position the canvas context and draw the line:

      // position the drawing cursor
         context.moveTo(50, canvas.height - 50);
      // draw the line
         context.lineTo(canvas.width - 50, 50);
      // make the line visible with the stroke color
         context.stroke();
    };
  3. Embed the canvas tag inside the body of the HTML document:

    <canvas id="myCanvas" width="600" height="250" style="border:1px solid black;">
    </canvas>
    

Note

Downloading the example code

You can run the demos and download the resources for this book from www.html5canvastutorials.com/cookbook or you can download the example code files for all Packt books you have purchased from your account at http://www.PacktPub.com. If you purchased this book elsewhere, you can visit http://www.PacktPub.com/support and register to have the files e-mailed directly to you.