Qml Ui

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This page is intended to serve as an ongoing development guide in relation to using QML as the engine for LinuxMCE's user interface. We shall outline relevant documents relating to QML as well as specifics for designing a skin. Please note, if you are reading this, then this is in fact an ongoing guide and as such information is apt to change. Personal notes are to be kept in the discussion area of this page, please post only code, links, or other relevant data to UI development. This message will self-destruct in 10 seconds.

QML KnowledgeBase

An Overview of what QML is http://labs.qt.nokia.com/2009/05/13/qt-declarative-ui/ A document on styling and whats important, skinning - http://developer.qt.nokia.com/wiki/QmlStyling

Stay tuned to this development space

Downloads & Initial setup

Working with QOrbiter requires pre-requisites depending on platform and what you intend to do. To work on just the design aspect, please follow the 'Design Work' instructions To compile it yourself, check 'compiling from source' To get up and running, you need the following:

Compiling from source

  • Qt libraries for the version you are targeting


Design Work

If you are looking to do design work on skins only, please use one of the pre-built binary packages to make your life easier.

Setting it up

I installed qt creator into home, although the default location is opt. Installing it into home will allow you get up and running right away but if installed into opt you will need to export some paths as described below.

  • SVN Checkout of the current /src tree from the svn
  • you need to install subversion
sudo apt-get install subversion
  • you then check out the source tree by entering this:
svn co http://svn.linuxmce.org/svn/branches/LinuxMCE-1004/src

and the web part like this

svn co http://svn.linuxmce.org/svn/branches/LinuxMCE-1004/web

If you downloaded the SDK, please run

sudo apt-get install build-essential

before installing Qt SDK. It includes many packages needed

  • Install QT SDK as outlined
  • If building Qt libraries from source, you may run into dependency issues, but they are easily resolved.

After you've started QT SDK, some configuration is required to load the orbiter. First, you need to load the project itself. Navigate through your source tree to QOrbiter/Qorbiter_src. In this directory, you will find a .pro file named QOrbiter_src.pro. Open this and it will load the project into qt Creator. It should go without saying, but read the README!

Next, open the qOrbiter project and setup the Build Settings. Do this by clicking the "Projects" button from the left side menu. You need to add to the "Additional arguments:" line for qmake under Build Steps. Do this by clicking the "Details" button to the right of qmake: and additional arguments. These are the current options:

"CONFIG+=opengl"         :: enables opengl
"CONFIG+=ANDROID"        :: android

Please ensure you include the quotes for the "CONFIG+= whatever"

For example, after adding the above arguments, my "Effective qmake call:" box looks like this, where [username] is my ubuntu login name:

 qmake /home/[username]/src/qOrbiter/qObiter_src/qObiter_src.pro -r -spec linux-g++ "CONFIG+=opengl"

Next, ensure 'shadow build' is checked in this same menu. Then you need to set the path to '../build-output'

Setting up for android development

Install necessitas as well as some java specific packages that it will ask you to install if not already installed. Once, done, open the project just like a normal Qt creator project and run it. NOTE you need to pay attention to the instructions in the necessitas installation guide on running your Qt project, specifically who and what Ministro is and does, and two how to configure the run options.

Notes From The Trenches

While trying to get qOrbiter to build for Qt 4.7.4 I had two problems.

qOrbiter started, selection of qOrbiter device worked, but after the following errors were thrown out:

(file:///usr/src/lmce-1004/qOrbiter/QOrbiter-build-4.7.4/qml/desktop/default/main.qml:2:1: plugin cannot be loaded for module
"Qt.labs.shaders": The plugin '/usr/src/lmce-1004/qOrbiter/QOrbiter-build-4.7.4/imports/Qt/labs/shaders/libqmlshadersplugin.so'
uses incompatible Qt library. (4.8.2) [release]
    import Qt.labs.shaders 1.0

and/or there was a problem with libAudioVisual.so

Both problems had the same reason. The svn contained shared object libraries which were build using 4.8.2 and automatically copied into the build output. MORE TO FOLLOW

API Development

Currently we are developing (actively) the api for the QML engine to utilize to communicate with the DCERouter backend. The purpose of this API is simply to abstract away the c++ from the user interface code, allowing for easily customized visual styles and user experiences.

Initial experiments http://wiki.linuxmce.org/index.php/Qml http://forum.linuxmce.org/index.php?topic=11722.0


If you are interested in playing with skinning only you can find the skinning document QOrbiter Development Page.


Part of this process is finding the deficiencies in the DCE code / api itself and going back to the source so to speak to refine how data structures are passed. This is an involved process involving the LinuxMCE database, server code, and many other variables. The entire api for QOrbiter is generated by the DCEGen tool that is part of LinuxMCE. it literally reads device definitions from the LinuxMCE database and creates C++ stub code to be expanded later as the software device is completed. Part of the task of creating QOrbiter was talking to that api in an efficient manner.


In addition to the UI development, there is also an active effort to utilize c++ as much as possible to extend the functionality of QOrbiter. With this in mind, it should be understood that this is also something under active development.

  • Datagrids - Custom DataModel has been implemented.
  • Screen Handlers - Handled by native qt functions
  • Mouse Handlers - Not needed as of yet

Current Architecture

A very high level overview is as follows:

  • QOrbiter is a c++ / QML based application capable of communicating with the DCERouter (server) over network sockets to control various aspects of the LinuxMCE home automation system.
  • It consists of
    • Statically compiled, threaded DCE code, normally produced as standalone libraries, but made static in this case for portability, comprised mainly of STL C++
    • Qt C++ serving as the 'translator' or bridge from the DCE code to the Qt Gui
    • QML Skinning engine that allows for dynamic changing of visual styles and user created styles without need for re-compilation
    • Multimedia player limited only by its platforms media abilities based on Phonon / Gstreamer