Book Image

Opa Application Development

By : Li Wenbo
Book Image

Opa Application Development

By: Li Wenbo

Overview of this book

Opa is a full-stack Open Source web development framework for JavaScript that lets you write secure and scalable web applications. It generates standard Node.js/MongoDB applications, natively supports HTML5 and CSS and automates many aspects of modern web application programming. It handles all aspects of web programming written in one consistent language and compiled to web standards.Opa Application Development is a practical,hands-on guide that provides you with a number of step-by-step exercises. It covers almost all aspects of developing a web application with Opa, which will help you take advantage of the real power of Opa, as well as building a secure, powerful web application rapidly.Opa Application Development dives into all concepts and components required to build a web application with Opa. The first half of this book shows you all of the basic building blocks that you will need to develop an Opa application, including the syntax of Opa, web development aspects, client and server communication and slicing, plugin, database, and so on. By the end of the book you will have yourself created a complete web application along with a game: Pacman!
Table of Contents (18 chapters)
Opa Application Development
About the Author
About the Reviewers

The HTML5 Canvas

First of all, we need a canvas element on which to draw our graphics. The HTML5 Canvas element is an HTML tag similar to the <div>, <a>, and <table> tags, with the exception that its contents are rendered with JavaScript. In Opa, we create a canvas element the exact same way in which we create other HTML elements:

function page(){
    <canvas id=#gamecanvas width="520" height="620" 

This code creates a canvas with the gamecanvas ID. When the canvas element is ready, the Game.gamestart function will be invoked to start the game.

Next we must get the canvas context. It is important for us to understand the difference between the canvas element and the canvas context. The canvas element is a DOM node embedded in the HTML page, whereas the canvas context is an object with properties and methods that you can use to render graphics inside the canvas element. The context can be 2D or 3D (WebGL). In our Pacman game...