Book Image

HTML5 Graphing and Data Visualization Cookbook

By : Ben Fhala
Book Image

HTML5 Graphing and Data Visualization Cookbook

By: Ben Fhala

Overview of this book

The HTML5 canvas tag makes creating any plot shape easy, all you have to do then is fill it with exciting visualizations written in JavaScript or using other visualization tools. "HTML5 Graphing and Data Visualization Cookbook" is the perfect break into the world of Canvas, charts, and graphs in HTML5 and JavaScript. In this book we will go through a journey of getting to know the technology by creating and planning data-driven visualizations. This cookbook is organized in a linear, progressive way so it can be read from start to finish, as well as be used as a resource for specific tasks.This book travels through the steps involved in creating a fully interactive and animated visualization in HTML5 and JavaScript. You will start from very simple "hello world"ù samples and quickly dive deeper into the world of graphs and charts in HTML5. Followed by learning how canvas works and carrying out a group of tasks geared at taking what we learned and implementing it in a variety of chart types. With each chapter the content becomes more complex and our creations become more engaging and interactive.Our goal is that by the end of this book you will have a strong foundation; knowing when to create a chart on your own from scratch and when it would be a good idea to depend on other APIs.We finish our book in our last two chapters exploring Google maps and integrating everything we learnt into a full project.
Table of Contents (17 chapters)
HTML5 Graphing and Data Visualization Cookbook
About the Author
About the Reviewer

Adding an interactive legend

Although we created a legend in the past, our legend was bound to be non-interactive as we had no way to move it around. In this sample, we will create a quick and easy legend that will update its position and fade in and fade out when a user rolls over our chart.

Getting ready

Grab the latest files from our previous recipe, 06.03.fade.html and 06.03.fade.js, and let's jump right in. We will hardcode our values in this example, but a more modular approach of extracting elements that would be dynamic is a great way to make this class reusable.

How to do it...

This time around we will create a method in the LineChart object that will create legends for us. Perform the following steps:

  1. Create the createLegend method:

    LineChart.prototype.createLegend = function (){
      var	can = document.createElement("canvas");
      this.legend = can;