Table Of ContentAndroid Sensor Programming By
Example
Take your Android applications to the next level of
interactivity by exploring the wide variety of Android sensors
Varun Nagpal
BIRMINGHAM - MUMBAI
Android Sensor Programming By Example
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First published: April 2016
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ISBN 978-1-78528-550-9
Credits
Author Copy Editor
Varun Nagpal Angad Singh
Reviewers Project Coordinator
Ahmed Mubarak Al-Haiqi Judie Jose
José Juan Sánchez Hernández
Commissioning Editor Proofreader
Ashwin Nair Safis Editing
Acquisition Editor Indexer
Tushar Gupta Mariammal Chettiyar
Content Development Editor Graphics
Pooja Mhapsekar Abhinash Sahu
Technical Editor Production Coordinator
Vivek Arora Arvindkumar Gupta
About the Author
Varun Nagpal has been developing mobile apps since 2005 and has developed and
contributed to more than 100 professional apps and games on various platforms, such as
Android, iOS, Blackberry, and J2ME. Android app development has been his main area of
expertise, and he has developed apps for a wide variety of Android devices, such as
Android phones, tablets, watches, smart TVs, Android Auto, and Google Glass.
He moved to Chicago in late 2013, and since then, he has become a seasoned mobile
architect. He has worked in different roles (mobile architect, technical lead, senior
developer, and technical consultant) for a variety of various global clients (Allstate, Verizon,
AT&T, Sydbank Denmark, SiS Taiwan, Chams PLC Nigeria, and Nandos South Africa) in
order to implement their mobile solutions. He has SCJP (Core Java) and SCWD (JSP and
Servlets) certifications from Sun Microsystems and MCP (C#) and MCTS (ASP.NET)
certifications from Microsoft. You can find his blogs on mobile technology and white papers
written by him on his website at h t t p : / / w w w . v a r u n n a g p a l . c o m /.
When he's not working, Varun can be found meditating or playing the flute. He also loves
to develop meditation apps and fun games in his free time. He has developed about 40
meditation apps and games available on Google Play (h t t p s : / / p l a y . g o o g l e . c o m / s t o r e
/ a p p s / d e v e l o p e r ? i d = C r e a t i v e . S o f t w a r e . S t u d i o) and the Apple App Store (h t t p s :
/ / i t u n e s . a p p l e . c o m / u s / a r t i s t / c r e a t i v e - s o f t w a r e - s t u d i o / i d 5 7 4 7 4 5 8 2 4) under
the name of Creative Software Studio, his part-time start-up company (h t t p : / / c r e a t i v e s
o f t w a r e s t u d i o . c o m /).
I would like to thank my wife, Ankita, for supporting me at every step, and I want to
apologize to my one-year-old daughter for not giving her enough time while writing this
book. I would also like to acknowledge my parents for their encouragement. Finally, I want
to thank the editor, each member of the Packt Publishing team, and the technical reviewers
for the effort and enthusiasm they showed while working on this book.
About the Reviewers
Ahmed Mubarak Al-Haiqi received his PhD (he investigated sensor-based side channels
on Android) and MEng (in computer and communications engineering) degrees from the
National University of Malaysia. Before pursuing his graduate studies, he worked as a
database developer for several years with governmental organizations in Aden, Yemen,
where he completed a BEng and majored in computer engineering and science. He is
currently involved in conducting academic research on mobile security, machine learning,
next generation networking trends, as well as interdisciplinary topics.
José Juan Sánchez Hernández received an MSc degree in computer science from the
University of Almería in 2008. He is a member of the Supercomputing-Algorithms Research
Group at the University of Almería, and he is currently working toward a PhD in the area
of image coding and transmission.
In his spare time, he enjoys designing and developing native mobile apps for Android,
experimenting and making stuff with Arduino and Raspberry Pi, and learning new things.
He is also the cofounder of Android Almería Developers Group and an active member of
HackLab Almería, where he organizes programming talks and hackathons.
He participated as a mentor in the Google Summer of Code 2015 with the P2PSP
organization. You can find out more about him at h t t p : / / j o s e j u a n s a n c h e z . o r g.
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Table of Contents
Preface 1
Chapter 1: Sensor Fundamentals 7
What are sensors? 8
Types of sensors 8
Types of sensor values 9
Motion, position, and environmental sensors 9
Motion sensors 9
Position sensors 12
Environmental sensors 15
Sensors' coordinate system 17
Android Sensor Stack 18
Components of the sensor framework 20
SensorManager 20
SensorEventListener 20
Sensor 21
SensorEvent 21
Sensor's sampling period, power, and battery consumption 22
The reporting modes of sensors 24
Dealing with specific sensor configuration 24
Checking the availability of the sensor at runtime 25
Declaring the sensor as mandatory feature 25
Sensor availability based on the Android API level 26
Best practice for accessing sensors 27
Summary 28
Chapter 2: Playing with Sensors 29
Understanding the sensor framework callbacks 29
Seeing the big picture 30
Time for action – using sensors in the foreground activity 32
What just happened? 34
Time for action – listing the available sensors on a device 35
What just happened? 37
Time for action – knowing individual sensors' capabilities 38
What just happened? 40
Time for action – getting the sensor values and updating the user
interface 41
What just happened? 44
Time for action – processing the sensor values in the background
service 45
The phone handling algorithm 45
What just happened? 48
Summary 48
Chapter 3: The Environmental Sensors – The Weather Utility App 49
The weather utility app's requirements 50
Understanding environmental sensors 51
Time for action – using the temperature sensor 52
What just happened? 53
Getting air pressure from the phone's pressure sensor 54
Time for action – calculating the altitude using the pressure sensor 54
What just happened? 56
Getting relative humidity from the phone's humidity sensor 56
Time for action – calculating the dew point and absolute humidity 57
What just happened? 62
Time for action – comparing the temperature, humidity, and pressure
values from web services to phone sensors 62
Third-party web service – open weather map 62
Using Google Play Services Location API and AsyncTask 64
What just happened? 70
Summary 70
Chapter 4: The Light and Proximity Sensors 71
Understanding the light and proximity sensors 72
The automatic torch light and screen brightness app requirements 73
Time for action – turning the torch light on and off using the proximity
sensor 74
What just happened? 77
Time for action – adjusting the screen brightness using the light
sensor 77
What just happened? 80
Wake locks, wakeup sensors, and the FIFO queue 81
Wakeup and non-wakeup sensors 81
The sensor's hardware FIFO queue 82
Summary 82
[ ii ]
Chapter 5: The Motion, Position, and Fingerprint Sensors 83
Understanding motion-based sensors 84
The accelerometer sensor 84
The gyroscope sensor 85
The gravity sensor 86
The linear acceleration sensor 86
The significant motion sensor 86
Understanding position-based sensors 87
The magnetometer sensor 88
The orientation sensor 88
The fingerprint sensor 89
Time for action – shake detection using the accelerometer sensor 90
Time for action – the compass using orientation sensor and orientation
APIs 92
Time for action – using the fingerprint sensor 97
What just happened? 103
Summary 103
Chapter 6: The Step Counter and Detector Sensors – The Pedometer
App 104
The pedometer app's requirements 105
Understanding the step counter and step detector sensors 106
The step counter sensor 106
The step detector sensor 106
Time for action – using the step counter sensor in activity 107
Time for action – maintaining step history with the step detector
sensor 108
What just happened? 116
Understanding the walking, jogging, and running signatures using the
accelerometer sensor's data 117
The walking signature using the accelerometer sensor 117
The jogging or fast walking signature using the accelerometer sensor 119
The running signature using the accelerometer sensor 120
The type of step detection algorithm 121
Making it battery- and CPU-efficient using sensor fusion 122
Scope for improvement 122
Time for action – type of step (walking, jogging, and running)
detection using the accelerometer sensor 123
What just happened? 141
[ iii ]
