Chapter 2. The Skeleton Cardboard Project

In this chapter, you will learn how to build a skeleton Cardboard project which can be a starting point for other projects in this book. We will begin with an introduction to Android Studio, the Cardboard SDK, and Java programming. We want to make sure that you're up to speed on the tools and Android projects in general. Then, we will walk you through setting up a new Cardboard project so that we don't need to repeat these details in each project. If some or all of this is already familiar to you, great! You might be able to skim it. In this chapter, we will cover the following topics:

What's in an Android app?
The Android project structure
Getting started with Android Studio
Creating a new Cardboard project
Adding the Cardboard Java SDK
Editing the manifest, layout, and MainActivity
Building and running the app

What's in an Android app?

For our projects, we're going to use the powerful Android Studio IDE (an integrated development environment) to build Google Cardboard virtual reality applications that run on Android devices. Woot! Android Studio integrates a number of different tools and processes under one roof.

The result of all your hard work to develop an Android app is an Android application package or an .apk file, which is distributed to users via the Google Play Store or however you choose to distribute your app. This file gets installed on their Android device.

We'll jump to Android Studio itself in a moment. However, in order to shed some light on what's going on here, let's consider this end result .apk file first. What is it really? How'd we get it? Understanding the build process will help.

Keeping this in mind, for fun and to gain perspective, let's start from the end and work our way backward from the APK through the build pipeline to our app source...

The Android project structure

The root directory of your Android project contains various files and subdirectories. Or, should I say, the root folder of your Android project contains various files and subfolders. Ha ha. We'll use the words "folder" and "directory" interchangeably throughout this book, just as Android Studio also seems to do (actually, there is a difference, as discussed at http://stackoverflow.com/questions/29454427/new-directory-vs-new-folder-in-android-studio).

As shown in the Android hierarchy, in the following sample Cardboard project, the root directory contains an app/ subdirectory, which, in turn, contains the following subdirectories:

app/manifests/: This contains the AndroidManifest.xml manifest file that specifies the components of the application, including activities (UI), device permissions, and other configurations
app/java/: This contains subfolders with your application Java files that implement the application's MainActivity...

Getting started with Android Studio

When developing Cardboard apps for Android, there's tons of stuff that you need to track, including all your files and folders, Java classes and objects, and functions and variables. You need a properly organized Java program structure and valid language syntax. You need to set options and manage processes to build and debug your applications. Whew!

Thank goodness we have Android Studio, a powerful IDE (integrated development environment). It's built on top of IntelliJ IDEA by JetBrains, a popular intelligent Java development suite of tools.

It's intelligent because it actually gives you relevant suggestions as you write your code (Ctrl + Space), helps navigate between related references and files (Ctrl + B, Alt + F7) as well as automates refactor operations, such as renaming a class or method (Alt + Enter). In some ways, it may know what you're trying to do, even if you don't. How smart is that?

Installing Android Studio

If you...

Creating a new Cardboard project

With Android Studio installed, let's create a new project. These are the steps you'll follow for any of the projects in this book. We'll just make an empty skeleton and make sure that it can be built and run:

After opening the IDE, you'll see a Welcome screen, as shown in the following screenshot:
Select Start a new Android Studio project, and the New Project screen appears, as follows:
Fill in your Application name:, such as Skeleton, and your Company Domain:, for example, cardbookvr.com. You can also change the Project location. Then, click on Next:
On the Target Android Devices screen, ensure that the Phone and Tablet checkbox is checked. In the Minimum SDK, select API 19: Android 4.4 (KitKat). Then, click on Next:
On the Add an activity to Mobile screen, select Empty Activity. We're going to build this project from scratch. Then, click on Next:
Keep the suggested name, MainActivity. Then, click on Finish.

Your brand new project comes...

Adding the Cardboard Java SDK

Now's a good time to add the Cardboard SDK library .aar files to your project. For the basic projects in this book the libraries you need (at the time of writing v0.7) are:

common.aar
core.aar

Note

Note the SDK includes additional libraries that we do not use in the projects in this book but could be useful for your projects. The audio.aar file is for spatialized audio support. The panowidget and videowidget libraries are meant for 2D apps that want to drop-into VR for things such as viewing a 360-degree image or video.

At the time of writing, to obtain the Cardboard Android SDK client libraries, you can clone the cardboard-java GitHub repository, as explained on the Google Developers Cardboard Getting Started page, Start your own project topic at https://developers.google.com/cardboard/android/get-started#start_your_own_project. Clone the cardboard-java GitHub repository by running the following command:

git clone https://github.com/googlesamples/cardboard...