Programming Google Glass: Build Great Glassware Apps with the Mirror API and GDK

299 Pages·2016·9.58 MB·English

by  Redmond E.

Under Construction: The book you’re reading is still under
development. As part of our Beta book program, we’re releasing
ß this copy well before a normal book would be released. That
way you’re able to get this content a couple of months before
it’s available in finished form, and we’ll get feedback to make
the book even better. The idea is that everyone wins!
Be warned: The book has not had a full technical edit, so it will contain errors.
It has not been copyedited, so it will be full of typos, spelling mistakes, and the
occasional creative piece of grammar. And there’s been no effort spent doing
layout, so you’ll find bad page breaks, over-long code lines, incorrect hyphen-
ation, and all the other ugly things that you wouldn’t expect to see in a finished
book. It also doesn't have an index. We can’t be held liable if you use this book
to try to create a spiffy application and you somehow end up with a strangely
shaped farm implement instead. Despite all this, we think you’ll enjoy it!
Download Updates: Throughout this process you’ll be able to get updated
ebooks from your account at pragprog.com/my_account. When the book is com-
plete, you’ll get the final version (and subsequent updates) from the same ad-
dress.
Send us your feedback: In the meantime, we’d appreciate you sending us your
feedback on this book at pragprog.com/titles/erpgg2/errata, or by using the links
at the bottom of each page.
Thank you for being part of the Pragmatic community!
Andy & Dave
Programming Google Glass,
Second Edition
Build Great Glassware Apps with the Mirror API and GDK
Eric Redmond
The Pragmatic Bookshelf
Dallas, Texas • Raleigh, North Carolina
Many of the designations used by manufacturers and sellers to distinguish their products
are claimed as trademarks. Where those designations appear in this book, and The Pragmatic
Programmers, LLC was aware of a trademark claim, the designations have been printed in
initial capital letters or in all capitals. The Pragmatic Starter Kit, The Pragmatic Programmer,
Pragmatic Programming, Pragmatic Bookshelf, PragProg and the linking g device are trade-
marks of The Pragmatic Programmers, LLC.
Every precaution was taken in the preparation of this book. However, the publisher assumes
no responsibility for errors or omissions, or for damages that may result from the use of
information (including program listings) contained herein.
Our Pragmatic courses, workshops, and other products can help you and your team create
better software and have more fun. For more information, as well as the latest Pragmatic
titles, please visit us at https://pragprog.com.
For international rights, please contact [email protected].
Copyright © 2015 The Pragmatic Programmers, LLC.
All rights reserved.
No part of this publication may be reproduced, stored in a retrieval system, or
transmitted, in any form, or by any means, electronic, mechanical, photocopying,
recording, or otherwise, without the prior consent of the publisher.
Printed in the United States of America.
ISBN-13: 978-1-941222-18-8
Encoded using the finest acid-free high-entropy binary digits.
Book version: P1.0—February 13, 2015
Contents
Changes in the Beta Releases . . . . . . . . vii
Preface . . . . . . . . . . . . . . ix
1. Wrapping Your Head Around Glass . . . . . . . 1
Getting to Know Glass 1
Learning to Navigate 2
Glass Hardware 7
Glass Software 8
Wrap-Up 9
Part I — The Mirror API
2. The Google App Engine PaaS . . . . . . . . 13
Setting Up GAE 14
Making a Web App 16
Deploying to the Web 20
Fancy Templates 22
Wrap-Up 24
3. Authorizing Your Glassware . . . . . . . . . 27
Activating Your Mirror API 28
A Short Primer on OAuth 2.0 30
Applying OAuth to Create Glassware 34
Wrap-Up 40
4. Building the Timeline . . . . . . . . . . 41
Mirror HTTP Requests 41
Timeline Items 45
Multicards: Bundles and Paginating 51
Menus 54
•
Contents iv
Cron Jobs 56
Wrap-Up 58
5. Tracking Movement and User Responses . . . . . . 59
Geolocation 59
Using Location 62
Subscriptions 66
Accepting Notifications 68
Custom Menu Items 72
Wrap-Up 74
6. Making Glass Social . . . . . . . . . . . 75
Creating Contacts 75
Sharing Assets with Glassware 77
Getting and Setting Attachments 81
Wrap-Up 85
7. Designing for Glass . . . . . . . . . . . 87
A Little UX 87
Design Layout 89
Look and Feel 92
Wireframes and Mock-Ups 94
Wrap-Up 97
8. Turning a Web App to Glassware . . . . . . . . 99
ChittrChattr App 99
Glassifying the Actions 103
The Mirror Code 105
Wrap-Up 109
Part II — Glass Development Kit
9. Introducing the GDK . . . . . . . . . . 113
Choosing the GDK by Use-Case 114
Setup a GDK Dev Environment 116
An Android Primer 120
Wrap-Up 122
10. An Android Introduction on Glass . . . . . . . 125
Generating a Simple Android App 125
Basic Android SDK+GDK 131
The Activity Component 135
•
Contents v
Service, Broadcast Receiver, and Content Provider 139
Wrap-Up 145
11. Live Cards . . . . . . . . . . . . . 147
Planning a Live Card Project 147
Implementing a Live Card Glassware 152
A Card Menu 156
Launching an App with Voice 159
Updating RemoteViews 162
Wrap-Up 164
12. Advanced Rendering and Navigation . . . . . . 167
High Frequency Rendering 167
Scrolling Through Multiple Cards 176
Gestures and Sound Effects 180
Launching the Balloon Count Scroller from the Menu 183
Taking Photos with the Camera 185
Wrap-Up 188
13. Voice and Video Immersions . . . . . . . . 189
An Immersion App 189
A Speech-to-Text Caption App 192
Sending Data to a Web Service 197
Adding Geolocation 202
A QR Code Reading Camera 205
Wrap-Up 216
14. Creating an Immersive Game . . . . . . . . 219
Start The Game with a Splash Screen 220
Gesture and Sensor Inputs 223
Rendering Visuals and Playing Audio 229
Game Logic 235
Wrap-Up 242
15. Preparing For the Real World . . . . . . . . 245
Testing Glass Apps 245
Debugging and Profiling 251
Command-line Power Tools 255
Monkeyrunner 260
Signing your Glassware 262
Wrap-Up 263
•
Contents vi
16. Turning an Android App to Glassware . . . . . . 265
Notoriety App 266
Designing a GDK Glassware UI 270
The GDK Code 274
Wrap-Up 282
A1. HTTP and HTML Resources . . . . . . . . 283
Timeline 283
Timeline Attachments 288
Locations 288
Subscriptions 289
Contacts 291
Map Parameters 293
HTML 293
Index . . . . . . . . . . . . . . 295
Changes in the Beta Releases
P1.0, Feb 13, 2015
• Replaced all ADT examples in Part Two with Android Studio.
• Due to Google’s recent announcement that the Glass Explorer program
has ended, thus suspending any further purchase of Google Glass, we
are following suit and suspending production of our book, Programming
Google Glass. Thanks to everyone who took the leap of faith with us and
reviewed or purchased the beta.
Beta 3, Dec 15
• Added the final chapter, Chapter 16, Turning an Android App to Glassware,
on page 265.
Beta 2, November 13
• Added Chapter 15, Preparing For the Real World, on page 245.
• Updated with XE changes and added a few minor clarifications
Beta 1, October 21
report erratum • discuss
Preface
Google Glass is the new wearable computer that everyone is talking about.
Some people love it, some hate it, but folks can’t seem to help but talk about
it. In short, Glass is a head-mounted computer with an optical display, a
camera, several sensors, and a voice or touch interface. You can walk around,
hands-free, check your email, watch or take videos, play games, and most
anything else you can do with a smartphone. Equally important, it’s gaining
traction for enterprise purposes, from fast-food restaurant employee training
to use in surgical settings.
You can program Glassware (Glass applications) in two ways: by using the
HTTP-based Mirror API web-service, or by creating native applications using
the Glass Development Kit (GDK). This book covers how to program both.
You’ll get a glimpse of what Glass is and what it is not, and how users can
interface with Glass. In Part One of this book you’ll learn how to develop a
Glass application fast, by using the Mirror API to manipulate timeline cards
and menus, track a Glass’s geolocation, create rich interactions by responding
to user inputs, and capture or serve user images and videos. In Part Two
you’ll learn how to shape user experience with the GDK by interacting with
Glass hardware, from voice-to-text inputs, to QR code reading with the live
camera, to building your own video game with fine-grained sensor inputs.
You’ll see how to properly design new Glassware or update existing applica-
tions to become Glassware. This is the book to read if you want a shortcut to
this brave new world.
What’s the Big Deal with Glass?
Imagine a world where computers did not exist, but the abilities that comput-
ers provided did. Rather than pulling a phone out of your pocket to talk with
someone, you’d simply speak their name and you’d be connected. Or instead
of taking out a laptop to play a video game, you would merely ask to play a
game and it would appear. Or rather than sitting in front of a television screen
report erratum • discuss