QtEmbedded

Qt tales from the embeddedtrenchesCabledogs (savago, igolivei)2011

About us

Adenilson Cavalcanti (Savago): KDE-pim, KDE-Plasma, IMTK, libgcal,amora

Igor Trindade Oliveira (igolive): KDE-pim, KDE-plasma, Gallium

Structure

A problem is given

A solution is proposed

Discussion

Topics

1 Kinectic scrolling pain

2 Meego UI without libmeegotouch?

3 Sliding Widgets

4 JSON parsing

5 D-BUS

6 Responsiveness

7 Symbian on Linux

Kinetic Scrolling

Kinetic example: iPhone 2007

Prior art?Bill Buxton: Two-handed input in HCI, 1982Canola 2007

A personal favorite: Canola 2007

What about Qt? flickable 2008

How scrolling works?

How kinetic scrolling works?

Displacement is defined in factor of:

attenuation given by Easing curve

time elapsed between the drag event

other factors (e.g. friction, etc)

optimizations: clipping, lazy loading, ring buffer, snapshots, etc

Demo timeC++: toyflick

Looking at the pros

Currently known Qt-basedimplementations

Ariya’s Flickable 2008

toyflick 2009

Plasma ScrollWidget 2009

IMTK ImtkKinecticListView 2010

QML Flickable 2010

Meego UI withoutlibmeegotouch?

Meego app

Ok, somewhat old example...

Can it run on Symbian?Short answer: NOT!Long answer: it could be ported...

You have 1 day!

Solution: cheat!

You have 1 day!

Solution: cheat!

You have 1 day!

Solution: cheat!

You have 1 day!

Solution: cheat!

You have 1 day!

Solution: cheat!

UI elements

Final result

Pure blood Qt runs everywhere!

’Minor’ details: 7 months ago

Forgot the Buttons...

Rescalable button backgrounds

Borders on background

Centered Icons

Layouts/sizeHints sometimes are tricky

Centered Icons

’Minor’ details: today

Rescalable button backgrounds: QML BorderImage

Borders: QML BorderImage

Centered Icons: maybe Qt components

Layouts/sizeHints: QML anchors

Demo timeC++: frame

Animated layout items

Sliding widgets

Example: iPhone contact list

How to do it?

step1: have a specialized layout

step2: put widget side by side

step3: make both visible...

step4: animate!

step5: hide the old widget

Demo timeC++: slider

QGraphicsLayout is not a QObjectMultiple heritance is nasty!

Parenting issues of widgets

No documentation, of course...

Qt Components has PageStack

JSON parsing

Qt doesn’t parse JSON?

SAY WHAAAT!!?

Solution: QJSON

Really easy to use

Tested on embedded platforms

License is LGPL

Use it. Really.

Solution: QJSON

Really easy to use

License is LGPL

Use it. Really.

Solution: QJSON

Really easy to use

License is LGPL

Use it. Really.

Solution: QJSON

Really easy to use

License is LGPL

Use it. Really.

The-BUS

Rules of thumb

Small batches of items

Marshalling/de-marshall: operator<<

Your itemmust be a QObject

D-Feet is your friend

Rules of thumb

Responsiveness

Simple! Threads!

Why sometimes is a bad idea...

Hard to debug

Resource consumption

Embedded limitations

Hard to debug

"Are for people who can’t use statemachines."

Solution: Divide and conquer

"Are for people who can’t use statemachines."

Solution: Divide and conquer

Demo timeD-BUS server

JSON data

QML UI

Symbian: Can Tux sing theBlues?

Symbian?

Demo timeCompiling a shared library

Compiling an app

The end?

Vacations, of course!

Vacations

By the way...

Thanks!E-mail: [email protected]

Site: http://savago.wordpress.com

Site: http://www.openbossa.org.br

QtEmbedded

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