Learn how to develop embedded application with Qt on any devices running Android

1. Qt on Android
Create a cross-platform
application with Qt

2. 2
• Adrien Leravat
• Embedded Software Engineer
Introduction
• Witekio
• French company, German, USA, Taiwan
• BSP / OS porting to ARM (Linux, Windows, Android,
QNX)
• Embedded software architecture and development
• Mobile expertise (cloud, internet of things)

3. 3
Context
• Creating a new application or service
– Multiple targets and OSes.
• Desktop
• Web
• Mobile and touch devices
– Your smartphones, fridge, …
– Android, iOS, WinRT/WP, Embedded OSes
• Meaning: a lot of time !

4. 4
Qt answer
Your own components
• With Qt 5
– Desktop/Server
• Windows, Linux, Mac
• Smartphones
– Android, iOS, WinRT (preview)
• Embedded devices
– Windows CE, Linux, QNX

5. 5
Qt answer
Your own components
• Why choose Qt for Android
– Build once, runs on multiple targets
• Less development, More maintainable
– No Android knowledge needed
• Big Qt features
– Databases, Threads, Networking, …
• Long living framework, large community
• Each 6 months: New major release !

6. 6
Qt for Android
Your own components
• Two way to build Qt applications with Android
• Boot to Qt: Dedicated device running Android
– Android system without all unnecessary features
(Home, Dalvik, …)
– Make us of Android drivers (accelerometer,
camera,…)
• Qt Android application
– Regular application
– Can be published to Android Play Store
– Can be run on a dedicated Android device

7. 7
Qt for Android
Your own components
• Android versions 2.3.3 (API 10) or later
• Download from free at : http://qt-project.org/downloads
• Qt 5
• Qt Creator
– Unified IDE for developing Qt applications
– Build, deploy and debug
• Qt Creator
– Toolchain for ARMv7 and x86 platforms, Qt
Linguist

8. 8
Installation requirements
• External tools needed
– The Android SDK
• Java Development kit for Android
• The Android NDK
– Native code development kit for Android
• Apache Ant v1.8 or later
– Java code compilation
• JDK v6 or later
– Java development kit

9. 9
Installation requirements
• External tools needed
– The Android SDK
– The Android NDK
– Apache Ant v1.8 or later
– JDK v6 or later
• Integration to Qt Creator
– Tools > Options >Android
– Let’s see !

10. 10
Supported Items
• Qt 5 key features, and more !
– Widgets and Qt Quick graphical user interfaces
– Gestures
– Media player, video input
– Sensors: Accelerometer, Gyroscope, Light sensor,
…
– Databases, threads, networking,…
• Not supported: Webkit

11. Creating a new project

12. 12
Project architecture
• New project for Android
– Several projects available: console, native
widgets, Qt Quick graphical application
• Qt Widgets
– No OpenGL hardware acceleration
– Certification needed for your application
– Desktop-only application, leverage all available
widgets
• Qt Quick 2 is preferred, being made
for modern devices
– Gestures, animations
– Design oriented
– Very easy to use

13. 13
Project architecture
• New project for Android

14. 14
Project architecture
• Qt Quick project
– Project file configuration .pro
– C++ sources and headers .cpp/.h
– QML and javascript (GUI) .qml/.js

15. 15
Project architecture
• Interface with Android
– Done automatically
– The activity contains the
entry point of the
application
– Load Qt application and
execute native code
– Ministro

16. 16
Project architecture
• AndroidManifest.xml
– Provide meta-information about the app
– Let you change application permissions

17. Polishing with effectsUsing Qt Quick

18. 18
Qt Quick Design
• Perfectly fitted for Android
– Gestures, animations
– Network transparent, sensors
• Design oriented
– GUI conception accessible to designers
– Simples components to create your own UI
– Completely separate UI and logic

19. 19
Qt Quick Design
• Completely separate UI and logic
– Allows switching UI at runtime
• Access C++ through bindings and functions
– C++ and UI data automatically synchronized
Development
Source code
.cpp/.h
Application
C++ Data
Objects
User interface
.qml .
Scripts
.js
Application
User interface
.qml .
Scripts
.js
Rectangle {
width: height*2; height: 200;
color: “white”
Text {
anchors.fill: parent
text: “Hello world!”
color: “black”
font.pixelSize: 20
}
}

20. 20
Sensors and Gestures
• Sensors and gestures can be entirely managed
from QML
• Great ease of use, no knowledge of Android
needed at all
• Let’s try!
PinchArea {
width:200
height: 200
GridView {
// Some large content
}
}
Pinch / Zoom gesture
Accelerometer {
dataRate: 2
active: true
onReadingChanged{
// Use reading.x/y/z
}
}
Using accelerometer

21. 21
Adapting to screen
• Devices come in various resolution and size
• QtQuick2ApplicationViewer::screen()
– Height and width in pixels
– Physical height and width
SmartphoneTablet

22. 22
Adapting to screen
• Relative size and position
– Height: parent.height /2
– Limited hard to maintain
• Different QML files
– Very customizable for
each resolutions/size
SmartphoneTabletQt Quick components

23. 23
Adapting to screen
• Automatic layouting
– Layout, Row, Grid, …
– Resize and/or move component in allocated space
• Anchors
– Anchors button left
with left the border
– Use anchors to constrain
size
SmartphoneTabletQt Quick components

24. Deployment

25. 25
Deployment
• Deploying your application on Android
– Direct deployment to device
• Most convenient for development
• Needs the device to be connected (USB)
– Simulator
– Bundle Qt libraries and files into the apk
• Stand-alone and distributable application package
– Using Ministro
• Minimize the size of the APK

26. 26
Deployment
• Ministro
– Available on Google Play
– Application asks Ministro for Qt components
– Ministro download components
• If not installed
• If newer versions exist
– Qt Open Source
• GPLv3+ license for the APK
• BSD License for the API
• Install LGPLv2.1 / GPLV3 Qt libraries

27. 27
Deployment
• Simulator
– Let’s you create and simulate various Android
devices
– Simulate different screen size
– Very convenient for development

28. 28
Deployment
• Finally
– Connect your device
– Hit “Play” !
Embedded device Smartphone
Simulator

29. 29
Conclusion
• Qt is a powerful technology, covering more and
more devices and Oses
• Opens new opportunity and ways of doing
software development
• Became an interesting and powerful alternative
to native Android