This document provides an overview of Qt and its capabilities on different platforms including desktop, embedded devices, and Android. It discusses Qt's cross-platform abilities, its use of backends and portability layers to support new platforms, and its growing adoption on devices through projects like Necessitas which ports Qt to Android. Examples are given of building user interfaces with QtQuick and integrating C++ and QML.

1. Necessitas
Qt on Android
Johan Thelin
Pelagicore

2. Biography
● Johan Thelin
● Worked with Qt for 10+ years
● Foundations in Qt Development
● Also worked embedded, embedded Linux, enterprise software, web
● Today – senior developer at Pelagicore

3. Pelagicore
● Open source based in-vehicle infotainment
● Member of Linux Foundation
● Ubuntu Core member
● GENIVI member
● Active within MeeGo, etc
● Uses Qt and QtQuick extensively
● Also HTML5, JavaScript and Android

4. What is Qt
“Code less, create more, deploy everywhere”
● A great framework for creating applications
● Truly cross-platform
● Desktop
● Devices
● Licensed for everyone – GPL, LGPL or closed

5. Qt on Desktop
● X11
● OS X
● Windows

6. Qt on Devices
● Linux with X11
● N900, N9
● Linux without X11
● industrial, etc
● Symbian
● WinCE
● more...

7. Who runs Qt?
● Trolltech
● Bought by Nokia
● Nokia Qt Development Frameworks
● Digia develops and licenses Qt Commercial
● Qt is open source – www.qt-project.org
● True open governance!

8. Qt on Devices
● More than the official ports
● Android
● RIM Blackberry
● WebOS
● iOS
● Kindle
● WP7 can support native code mid-2012 :-)

9. Qt on Devices
● More verticals
● Set-top boxes
● Industrial panels
● Tablets
● Your car

10. Finding the Roots of Qt
Backends

11. Backends
● Backends for OS primitives
● Atomic operations, files, etc
● Backends for graphics rendering
● Soft, OpenGL, OpenGL ES, GDI, etc
● Backends for image handling
● Backends for accessibility
● Backends for ...

12. Why Backends
Portability!

13. Portability between Devices
● QPA – Qt Platform Architecture – or something
● Formerly known as Lighthouse
● A backend for porting Qt to new platforms
● Focused at minimal effort, but with possibilities

14. Qt on Android
● Based on Android SDK / NDK
● QPA
● Necessitas - the actual Qt Port
● QtCreator (IDE) adaptations
● The tooling
● Ministro
● The deployment

15. Current Status
● Alpha 3 was just released
● Most of Qt is ported
● OpenGL rendering
● WebKit
● Missing
● Mobility (for many Android Versions)
● Rewriting soft keyboard support
● Android Style and Android Menus
● Development support in non-Linux environments
● Documentation

16. The Near Future
● Planning to release First Beta soon
● Will give a stable API/ABI
“...meaning that an application which uses that version will
run without *any* change, on any further releases! It also
means you can target a billion devices using Qt, much sooner
than you expected :)”

17. Getting Started
● Installation party!
● OpenJDK
● ant 1.8+
● The necessitas installer downloads and installs
– Android SDK + NDK
– Platforms for the SDK, etc
● Setup QtCreator
– Add path to ant

18. Installer

19. Demo Application

20. Demo Application
● Strip out some of the crud from the template
source code – it refers to Symbian

21. Demo Application
void MainWindow::on_pushButton_clicked()
{
static int v = 0;
ui->listWidget->addItem(
QString("Value%1").arg(v++));
}

22. Demo Application

23. Demo Application
● From project directory
$ ls -l android/bin/
total 1988
-rw-rw-r-- 1 e8johan e8johan 179 2011-11-10 21:42 build.prop
drwxrwxr-x 3 e8johan e8johan 4096 2011-11-10 21:42 classes
-rw-rw-r-- 1 e8johan e8johan 33396 2011-11-10 21:42 classes.dex
-rw-rw-r-- 1 e8johan e8johan 2251 2011-11-10 21:42 classes.dex.d
drwxrwxr-x 6 e8johan e8johan 4096 2011-11-10 21:42 res
-rw-rw-r-- 1 e8johan e8johan 431594 2011-11-10 21:42 Widgetdemo.ap_
-rw-rw-r-- 1 e8johan e8johan 2045 2011-11-10 21:42 Widgetdemo.ap_.d
-rw-rw-r-- 1 e8johan e8johan 767735 2011-11-10 21:42 Widgetdemo-debug.apk
-rw-rw-r-- 1 e8johan e8johan 767731 2011-11-10 21:42 Widgetdemo-debug-unaligned.apk
-rw-rw-r-- 1 e8johan e8johan 305 2011-11-10 21:42 Widgetdemo-debug-unaligned.apk.d

24. First Run on Phone
● Installs Ministro – Installs Qt – Resumes
https://market.android.com/details?id=eu.licentia.necessitas.ministro

25. Second Run
It simply works!

26. More on Ministro
● Qt libraries are shared among all Qt apps on
the device
● From the beta release, the ABI is stable, i.e. Qt
can be upgraded separately from apps

27. Configurability
● Android target SDK
● API levels
● Application icon
● Permissions
● What your app wants to be able to do
● Libraries
● Which Qt modules are needed
● More...

28. Debugging
● Yes! :-)
● Android NDK comes with gdb
● Works with QtCreator
● Requires some tweaking
● Described in the Necessitas Wiki

29. Qt and Device UIs
Got to show you this!

30. User Interface Development
● Classic – standard widgets, etc
● Rectangular areas
● Non-overlapping
● Clipping their children
● Provides familiarity
● Device UIs
● Blend with the device
● Provide a brand feel
● etc

31. Building Modern UIs
● No more widgets!
● Canvas / scene
● Timers everywhere
● Multiple simultaneous transitions
● Complex, interconnected state machines
● Pain! :-)

32. History of Qt and Modern UIs
● QCanvas
● QGraphicsView
● QTimeLine
● QGraphicsItemAnimation
● An animation framework
● A state machine framework
● The birth of QtQuick

33. QtQuick
● What is QtQuick?
● A run-time for QML
● Tooling
● What is QML
● Declarative
● JavaScript

34. QML
import QtQuick 1.0
Rectangle {
Rectangle {
MouseArea {
}
}
}

35. QML
Rectangle {
width: 500
height: 500
Rectangle {

36. QML
Rectangle {
Rectangle {
id: box
color: "red"
width: 100
height: 100
x: 200

37. QML
MouseArea {
anchors.fill: parent
onClicked: {
if(box.state=="up")
box.state="down";
else
box.state="up";
}
}

38. QML
Rectangle {
state: "up"
states: [
State {
name: "up"
PropertyChanges { target: box; y: 50 }
},
State {
name: "down"
PropertyChanges { target: box; y: 350 }
}
]

39. Demo

40. QML
Behavior on y {
PropertyAnimation {
duration: 1000
easing.type: Easing.OutBounce
}
}

41. Demo

42. Integrate with C++
● QObjects to QtQuick
QObject *foo = …;
setProperty(“foo”, foo);
● C++ classes in QtQuick
class Foo : public QObject { … };
qmlRegisterType<Foo>("FooLib", 1, 0, "Foo");
Foo { property: value }
● QtMediaHub - http://gitorious.org/qtmediahub

43. QtMediaHub

44. Of course QtQuick works on Android too.
With hardware accelerated graphics.

45. Qt 5
● A great opportunity to …
● … get rid of API limitations
● … split the repos into more independent parts
● … take advantage of modern C++
● Widgets and QML are peers
● More acceleration, shaders, etc – amazing
performance

46. A new Dawn
● Truly Open Source – a www.qt-project.org
● Qt for Desktop
● Windows / X11 / OS X... more
● Qt for Devices
● Symbian / Maemo / MeeGo / Android / Blackberry /
iOS / Kindle... more

47. Thank you!
johan.thelin@pelagicore.com
We're hiring!
http://pelagicore.com/career.html