Book Image

Android Application Development Cookbook - Second Edition

By : Kyle Mew
Book Image

Android Application Development Cookbook - Second Edition

By: Kyle Mew

Overview of this book

The Android OS has the largest installation base of any operating system in the world; there has never been a better time to learn Android development to write your own applications, or to make your own contributions to the open source community! This “cookbook” will make it easy for you to jump to a topic of interest and get what you need to implement the feature in your own application. If you are new to Android and learn best by “doing,” then this book will provide many topics of interest. Starting with the basics of Android development, we move on to more advanced concepts, and we’ll guide you through common tasks developers struggle to solve. The first few chapters cover the basics including Activities, Layouts, Widgets, and the Menu. From there, we cover fragments and data storage (including SQLite), device sensors, the camera, and GPS. Then we move on more advanced topics such as graphics and animation (including OpenGL), multi-threading with AsyncTask, and Internet functionality with Volley. We’ll also demonstrate Google Maps and Google Cloud Messaging (also known as Push Notifications) using the Google API Library. Finally, we’ll take a look at several online services designed especially for Android development. Take your application big-time with full Internet web services without having to become a server admin by leveraging the power of Backend as a Service (BaaS) providers.
Table of Contents (23 chapters)
Android Application Development Cookbook Second Edition
Credits
Disclaimer
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Rotating the triangle with user input


The previous example demonstrated rotating the triangle based on the system clock. This created a continuously rotating triangle, depending on the render mode we used. But what if you wanted to respond to the input from the user?

In this recipe, we'll show how to respond to user input by overriding the onTouchEvent() callback from GLSurfaceView. We'll still rotate the triangle using the Matrix.setRotateM() method, but instead of deriving an angle from the system time, we'll calculate an angle based on the touch location.

Here's a screenshot showing this recipe running on a physical device (to highlight the touch, the Show touches developer option is enabled):

Getting ready

Create a new project in Android Studio and call it: RotateWithUserInput. Use the default Phone & Tablet options and select Empty Activity when prompted for Activity Type.

This recipe demonstrates an alternative approach to the previous recipe and therefore will be based on Applying...