39,59 €
Mehr erfahren.
- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Building Android applications would usually mean that you spend all of your time working in Java. There are however times when this is not the most efficient or best method for the application being built. This is where Android NDK comes in. Android NDK allows the developer to write in Native C/C++, giving you the power to reuse code and libraries and also, in most cases, increase the speed and efficiency of your application.The "Android Native Development Kit Cookbook" will help you understand the development, building, and debugging of your native Android applications. We will discover and learn JNI programming and essential NDK APIs such as OpenGL ES, and the native application API. We will then explore the process of porting existing libraries and software to NDK. By the end of this book you will be able to build your own apps in NDK apps."Android Native Development Kit Cookbook" begins with basic recipes that will help you in the building and debugging of native apps, and JNI programming. The recipes cover various topics of application development with Android NDK such as OpenGL programming and Multimedia programming. We will begin with a simple recipe, Hello NDK, before moving on to cover advanced topics with recipes on OpenGL ES that focus on 2D and 3D graphics, as well as recipes that discuss working with NDK and external APIs. If you are looking for ways to make your application available in Android and take measures to boost your application's performance, then this Cookbook is for you.
Das E-Book können Sie in Legimi-Apps oder einer beliebigen App lesen, die das folgende Format unterstützen:
Seitenzahl: 418
Veröffentlichungsjahr: 2013
Ähnliche
Table of Contents
Android Native Development Kit Cookbook
Android Native Development Kit Cookbook
Copyright © 2013 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: March 2013
Production Reference: 1140313
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham B3 2PB, UK.
ISBN 978-1-84969-150-5
www.packtpub.com
Cover Image by Artie Ng (<[email protected]>)
Credits
Author
Feipeng Liu
Reviewers
Roger Belk
Frank Grützmacher
Sylvain Ratabouil
Acquisition Editor
Martin Bell
Commissioning Editor
Shreerang Deshpande
Lead Technical Editor
Mayur Hule
Technical Editors
Lubna Shaikh
Worrell Lewis
Project Coordinator
Leena Purkait
Proofreader
Aaron Nash
Indexer
Monica Ajmera Mehta
Graphics
Aditi Gajjar
Valentina D'silva
Production Coordinator
Shantanu Zagade
Cover Work
Shantanu Zagade
About the Author
Feipeng Liu is a technology enthusiast who is focused on multimedia systems and applications. He started mobile applications development in 2008 on Windows Mobile. Since Feb 2010, he has been developing apps for Android with NDK. His Android apps have been used by many users. One of his apps, video converter Android, has reached one million downloads within 10 months. Feipeng received his B.ENG in Electrical and Electronic Engineering degree from Nanyang Technological University, and Master of Computing degree in the Department of Computer Science from National University of Singapore.
I would like to thank Shreerang Deshpande for offering me the opportunity to author this book and for helping me throughout the writing, and Leena Purkait for keeping track of its progress and coordination, Mayur Hule, Lubna Shaikh, and Worrell Lewis for editing the book drafts! I would like to express my gratitude to other Packt Publishing staff who helped with the book! My grateful thanks are also extended to Roger, Frank and Sylvain, who offered great suggestions during the review.
I also would like to thank Assoc. Prof. Wei Tsang Ooi in National University of Singapore, the supervisor of my master project. A lot of stuff in this book is based on the things I learnt during the project.
Last but not least, I would like to thank my parents Zhulan Shen and Yi Liu, and Ms. Yang Xiaoqing for the support and understanding during the writing of the book.
About the Reviewers
Roger Belk is a 45-year-old self-taught Android developer with 20 + apps in Google’s Play Store under the developer name BigTexApps. He started out using Google’s & MIT’s App Inventor and then after two years of learning to use AI, he taught himself to use Java to build Android apps. He has reviewed two other books, Google App Inventor, Ralph Roberts, Packt Publishing (ISBN 978-1-84969-212-0) and Android 3.0 Animation, Alex Shaw, Packt Publishing (ISBN 978-1-84951-528-3).
Frank Grützmacher spent some years in the research of distributed electronic design tools and worked for several German blue chip companies such as Deutsche Post and AEG. He was involved in Android platform extensions for a mobile manufacturer. Therefore, on one hand he knows how to build large enterprise apps and on the other hand how to make Android system apps.
He is currently working for the IT daughter of the largest German Telco company.
In the past, he has reviewed Corba- and Java-related books for American and German publishers.
Sylvain Ratabouil is a confirmed IT consultant experienced with C++ and Java technologies. He worked in the space industry and got involved in aeronautic projects at Valtech, where he is now taking part in the digital revolution.
As a technology lover, he is passionate about mobile technologies and cannot live or sleep anymore without his Android smart phone.
www.PacktPub.com
Support files, eBooks, discount offers and more
You might want to visit www.PacktPub.com for support files and downloads related to your book.
Did you know that Packt offers eBook versions of every book published, with PDF and ePub files available? You can upgrade to the eBook version at www.PacktPub.com and as a print book customer, you are entitled to a discount on the eBook copy. Get in touch with us at <[email protected]> for more details.
At www.PacktPub.com, you can also read a collection of free technical articles, sign up for a range of free newsletters and receive exclusive discounts and offers on Packt books and eBooks.
http://PacktLib.PacktPub.com
Do you need instant solutions to your IT questions? PacktLib is Packt’s online digital book library. Here, you can access, read and search across Packt’s entire library of books.
Why Subscribe?
Free Access for Packt account holders
If you have an account with Packt at www.PacktPub.com, you can use this to access PacktLib today and view nine entirely free books. Simply use your login credentials for immediate access.
Preface
Since its first release in 2008, Android has become the largest mobile platform in the world. The total number of apps in Google Play is expected to reach 1,000,000 in mid 2013. Most of the Android apps are written in Java with Android Software Development Kit (SDK). Many developers only write Android code in Java even though they are experienced with C/C++, without realizing what a powerful tool they are giving up.
Android Native Development Kit (NDK) was released in 2009 to help developers write and port native code. It offers a set of cross-compiling tools and a few libraries. Programming in NDK offers two main advantages. Firstly, you can optimize your apps in native code and boost performance. Secondly, you can reuse a large number of existing C/C++ code. Android Native Development Kit is a practical guide to help you write Android native code with NDK. We will start with the basics such as Java Native Interface (JNI), and build and debug a native app (chapter 1 to 3). We will then explore various libraries provided by NDK, including OpenGL ES, Native Application API, OpenSL ES, OpenMAX AL, and so on (Chapters 4 to 7). After that, we will discuss porting existing applications and libraries to Android with NDK (Chapters 8 and 9). Finally, we will demonstrate how to write multimedia apps and games with NDK (Bonus chapters 1 and 2).
What this book covers
Chapter 1, Hello NDK, covers how to set up an Android NDK development environment in Windows, Linux, and MacOS. We will write a "Hello NDK" application at the end of the chapter.
Chapter 2, Java Native Interface, describes the usage of JNI in detail. We will call native methods from the Java code and vice versa.
Chapter 3, Build and Debug NDK Applications, demonstrates building native code from a command line and Eclipse IDE. We will also look at debugging native code with gdb, cgdb, eclipse, and so on.
Chapter 4, Android NDK OpenGL ES API, illustrates OpenGL ES 1.x and 2.0 APIs. We will cover 2D drawing, 3D graphics, texture mapping, EGL, and so on.
Chapter 5, Android Native Application API, discusses Android native application APIs, including managing native windows, accessing sensors, handling input events, managing assets, and so on. We will see how to write a pure native app in this chapter.
Chapter 6, Android NDK Multithreading, depicts Android multithreading API. We will cover creating and terminating native threads, various thread synchronization techniques (mutex, conditional variables, semaphore, and reader/writer lock), thread scheduling, and thread data management.
Chapter 7, Other Android NDK API, discusses a few more Android libraries, including jnigraphics, the dynamic linker library, the zlib compression library, the OpenSL ES library, and the OpenMAX AL library.
Chapter 8, Porting and Using Existing Libraries with Android NDK, describes various techniques of porting and using existing C/C++ libraries with NDK. We will port the boost library at the end of the chapter.
Chapter 9, Porting Existing Applications to Android with NDK, provides a step-by-step guide for porting an existing application to Android with NDK. We use an open source image resizing program as an example.
Bonus Chapter 1, Developing Multimedia Applications with NDK, demonstrates how to write multimedia applications with the ffmpeg library. We will port the ffmpeg library and use the library APIs to write a frame grabber application.
Bonus Chapter 2, Developing Games with NDK, discusses writing games with NDK. We will port the Wolfenstein 3D game to show how to set up game display, add game control, and enable audio effects for a game.
You can download the bonus chapters from http://www.packtpub.com/sites/default/files/downloads/Developing_Multimedia_Applications_with_NDK.pdf and http://www.packtpub.com/sites/default/files/downloads/Developing_Games_with_NDK.pdf.
What you need for this book
A computer with Windows, Ubuntu Linux, or MacOS installed is necessary (Linux or MacOS is preferable). Although we can run Android apps with an emulator, it is slow and inefficient for Android development. Therefore, it is recommended to have an Android device.
The book assumes a basic understanding of C and C++ programming languages. You should also be familiar with Java and Android SDK.
Note that the sample code of this book is based on Android ndk r8 unless otherwise stated, since it is the latest version of NDK at the time of writing. By the time the book is published, there should be newer versions. The code should also run on any newer versions. Therefore we can install NDK r8 or later.
Who this book is for
The book is written for anyone who is interested in writing native code for Android. The chapters are arranged from basic to intermediate to advanced, and they are relatively independent. Readers who are new to NDK are recommended to read from the beginning to the end, while readers who are familiar with NDK can pick up any specific chapters or even specific recipes.
Conventions
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text are shown as follows: "Windows NDK comes with a new ndk-build.cmd build script."
A block of code is set as follows:
When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
Any command-line input or output is written as follows:
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Go to Control Panel | System and Security | System | Advanced system settings."
Note
Warnings or important notes appear in a box like this.
Tip
Tips and tricks appear like this.
Reader feedback
Feedback from our readers is always welcome. Let us know what you think about this book—what you liked or may have disliked. Reader feedback is important for us to develop titles that you really get the most out of.
To send us general feedback, simply send an e-mail to <[email protected]>, and mention the book title via the subject of your message.
If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide on www.packtpub.com/authors.
Customer support
Now that you are the proud owner of a Packt book, we have a number of things to help you to get the most from your purchase.
Downloading the example code
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.
Errata
Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you would report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting http://www.packtpub.com/submit-errata, selecting your book, clicking on the erratasubmissionform link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded on our website, or added to any list of existing errata, under the Errata section of that title. Any existing errata can be viewed by selecting your title from http://www.packtpub.com/support.
Piracy
Piracy of copyright material on the Internet is an ongoing problem across all media. At Packt, we take the protection of our copyright and licenses very seriously. If you come across any illegal copies of our works, in any form, on the Internet, please provide us with the location address or website name immediately so that we can pursue a remedy.
Please contact us at <[email protected]> with a link to the suspected pirated material.
We appreciate your help in protecting our authors, and our ability to bring you valuable content.
Questions
You can contact us at <[email protected]> if you are having a problem with any aspect of the book, and we will do our best to address it.
Chapter 1. Hello NDK
In this chapter, we will cover the following recipes:
Introduction
Android NDK is a toolset that allows developers to implement a part of or an entire Android application in a native language, such as C, C++, and assembly. Before we start our journey to NDK, it is important to understand the advantages of NDK.
First of all, NDK may improve application performance. This is usually true for many processor-bound applications. Many multimedia applications and video games use native code for processor-intensive tasks.
The performance improvements can come from three sources. Firstly, the native code is compiled to a binary code and run directly on OS, while Java code is translated into Java byte-code and interpreted by Dalvik Virtual Machine (VM). At Android 2.2 or higher, a Just-In-Time (JIT) compiler is added to Dalvik VM to analyze and optimize the Java byte-code while the program is running (for example, JIT can compile a part of the byte-code to binary code before its execution). But in many cases, native code still runs faster than Java code.
Tip
Java code is run by Dalvik VM on Android. Dalvik VM is specially designed for systems with constrained hardware resources (memory space, processor speed, and so on).
The second source for performance improvements at NDK is that native code allows developers to make use of some processor features that are not accessible at Android SDK, such as NEON, a Single Instruction Multiple Data (SIMD) technology, allowing multiple data elements to be processed in parallel. One particular coding task example is the color conversion for a video frame or a photo. Suppose we are to convert a photo of 1920x1280 pixels from the RGB color space to the YCbCr color space. The naive approach is to apply a conversion formula to every pixel (that is, over two million pixels). With NEON, we can process multiple pixels at one time to reduce the processing time.
The third aspect is that we can optimize the critical code at an assembly level, which is a common practice in desktop software development.
Tip
The advantages of using native code do not come free. Calling JNI methods introduces extra work for the Dalvik VM and since the code is compiled, no runtime optimization can be applied. In fact, developing in NDK doesn't guarantee a performance improvement and can actually harm performance at times. Therefore, we only stated that it may improve the app's performance.
The second advantage of NDK is that it allows the porting of existing C and C++ code to Android. This does not only speed up the development significantly, but also allows us to share code between Android and non-Android projects.
Before we decide to use NDK for an Android app, it is good to know that NDK will not benefit most Android apps. It is not recommended to work in NDK simply because one prefers programming in C or C++ over Java. NDK cannot access lots of APIs available in the Android SDK directly, and developing in NDK will always introduce extra complexity into your application.
With the understanding of the pros and cons of NDK, we can start our journey to Android NDK. This chapter will cover how to set up Android NDK development in Windows, Ubuntu Linux, and Mac OS. For developers who have set up an Android NDK development environment before, a recipe with detailed steps of how to update an NDK development environment is provided. At the end of the chapter, we will write a Hello NDK program with the environment setup.
Setting up an Android NDK development environment in Windows
In this recipe, we will explore how to set up an Android NDK development environment in Windows.
Getting ready
Check the Windows edition and system type. An Android development environment can be set up on Windows XP 32-bit, Windows Vista 32- or 64-bit, and Windows 7 32- or 64-bit.
Android development requires Java JDK 6 or above to be installed. Follow these steps to install and configure Java JDK:
Cygwin is a Linux-like environment for Windows to run software available on Linux. Android NDK development requires Cygwin 1.7 or higher installed to execute some Linux programs; for example, the GNU make.
Since NDK r7, the Windows NDK comes with a new ndk-build.cmd build script, which uses NDK's prebuilt binaries for GNU make, awk, and other tools. Therefore Cygwin is not required for building NDK programs with ndk-build.cmd. However, it is recommended that you still install Cygwin, because ndk-build.cmd is an experimental feature and Cygwin is still needed by the debugging script ndk-gdb.
Follow these steps to install Cygwin:
Eclipse is a powerful software Integrated Development Environment (IDE) with an extensible plugin system. It is the recommended IDE to develop Android apps. Go to http://www.eclipse.org/downloads/, and download the Eclipse Classic or Eclipse IDE for Java developers. Extract the compressed file and it will be ready for use. Note that Android development requires Eclipse 3.6.2 (Helios) or greater.
Tip
The Android developer website provides an Android Developer Tools bundle at http://developer.android.com/sdk/index.html. It includes the Eclipse IDE with the ADT plugin, and the Android SDK. We can download this bundle and skip the SDK installation described in steps 1 to 10 of the following How to do it... section.
How to do it…
The following steps show you how to set up an Android NDK development environment in Windows. We will first set up an SDK development environment. Steps 1 to 10 can be skipped if SDK is already set up.
Tip
Downloading the example code
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.
As an example, the file content on my machine is as follows; note that Progra~1 is the short name for the Program Files folder:
How it works…
In this recipe, we first set up an Android SDK development environment and then the NDK development environment.
Android NDK does not require installation. We downloaded NDK, and configured the path to make it more convenient to use.
Cygwin is not required for Android SDK development, but is essential for NDK development because NDK uses some Linux tools that depend on Cygwin.
NDK plugin in ADT: NDK plugin for Eclipse is available in Android Development Tools (ADT), which allows us to build and debug Android NDK applications easily.
Tip
The NDK plugin is only available for ADT 20.0.0 or later, which was released on June 2012. You may want to update your Eclipse ADT in order to use the NDK plugin.
There's more…
We installed Eclipse IDE as a part of our development environment. Eclipse is the recommended IDE for developing Android applications, and it comes with lots of useful tools and utilities to help our development. However, it is not a compulsory component of the development environment.
Setting up an Android NDK development environment in Ubuntu Linux
This recipe depicts how to set up an Android NDK development environment in Ubuntu Linux.
Getting ready
Check your Ubuntu version and make sure it is version 8.04 or later.
GNU C Library (glibc) 2.7 or above is required. It is usually installed with Linux by default. Two simple methods can check the version of glibc:
The following output will be displayed:
We need to enable 32-bit application execution if we are using a 64-bit machine. Start a terminal, and enter the following command:We will use Eclipse as our IDE. Please refer to the Setting up an Android NDK development environment in Windows recipe for instructions.
How to do it…
The following steps indicate the procedure of setting up an Android NDK development environment on Ubuntu Linux:
How it works…
We first set up Android SDK and then Android NDK. Ensure that the path is set properly, so that the tools can be accessed without referring to the SDK and NDK directories.
The .bashrc file is a startup file read by the bash shell when you start a new terminal. The export commands appended the Android SDK and NDK directory locations to the environment variable PATH. Therefore, every time a new bash shell starts, PATH is set properly for SDK and NDK tools.
There's more…
The following are a few more tips on setting up an NDK development environment:
The following is an example for switching to Oracle JDK 1.6.0:
Setting up an Android NDK development environment in Mac OS
This recipe describes how to set up an Android NDK development environment in Mac OS.
Getting ready
Android development requires Mac OS X 10.5.8 or higher, and it works on the x86 architecture only. Ensure that your machine meets these requirements before getting started.
Register an Apple developer account, then go to https://developer.apple.com/xcode/ to download Xcode, which contains a lot of developer tools, including the make utility required for Android NDK development. After the download is complete, run the installation package and make sure that the UNIX Development option is selected for installation.
As usual, Java JDK 6 or above is required. Mac OS X usually ships with a full JDK. We can verify that your machine has the required version by using the following command:
How to do it…
Setting up an Android NDK development environment on Mac OS X is similar to setting it up on Ubuntu Linux. The following steps explain how we can do this:
How it works…
The steps to set up an Android NDK development environment on Mac OS X are similar to Ubuntu Linux, since both of them are Unix-like operating systems. We first installed Android SDK, then Android NDK.
Updating Android NDK
When there is a new release of NDK, we may want to update NDK in order to take advantage of the new features or bug fixes with the new release. This recipe talks about how to update Android NDK in Windows, Ubuntu Linux, and Mac OS.
Getting ready
Please read the previous recipes in this chapter, depending on the platform of your choice.
How to do it…
In Windows, follow these instructions to update Android NDK:
In Ubuntu Linux, follow these instructions to update Android NDK:
In Mac OS, the steps are almost identical to Ubuntu Linux, except that we need to append the path to ~/.profile instead of ~/.bashrc.
How it works…
NDK installation is completed by simply downloading and extracting the NDK file, and configuring the path properly. Therefore, updating NDK is as simple as updating the configured path to the new NDK folder.
There's more…
Sometimes, updating NDK requires updating SDK first. Since this book focuses on Android NDK, explaining how to update SDK is beyond the scope of this book. You can refer to the Android developer website at http://developer.android.com/sdk/index.html, for details on how to do it.
At times, we may feel the need to use an old version of NDK to build certain applications because of compatibility issues. Therefore, it may be useful to keep multiple versions of Android NDK and switch between them by changing the path or simply using the full path to refer to a specific version of NDK.
Chapter 2. Java Native Interface
In this chapter, we will cover the following recipes:
Introduction
Programming with Android NDK is essentially writing code in both Java and native languages such as C, C++, and assembly. Java code runs on Dalvik Virtual Machine (VM), while native code is compiled to binaries running directly on the operating system. Java Native Interface (JNI)
