Quickstart Example

Files:

• quickstart/main.cpp
• quickstart/quickstart.pro

The following steps outline how to make a simple "hello world" like application that uses Qt Mobility. It is assumed that Qt Mobility has been successfully built and environment variables have been set as per Installation Guide.

One can start using Qt Mobility with 3 simple steps.

1. Include the appropriate headers
2. Use the QTM_USE_NAMESPACE macro (defined in qmobilityglobal.h but implicitly included from any Qt Mobility header)
3. Declare the usage of Qt Mobility and appropriate API(s) in the project(.pro) file

Steps 1 and 2 are shown in the example below:

 #include <QApplication>
 #include <QLabel>

 #include <QSystemInfo> //(1)

 QTM_USE_NAMESPACE //(2)

 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     QSystemInfo s;
     QLabel *label = new QLabel(QObject::tr("hello ").append(s.currentCountryCode()));
     label->show();
     label->resize(100,30);
     return app.exec();
 }

This example uses the QSystemInfo headers to print out the system's current country code. All the domain APIs are wrapped within a Qt Mobility namespace and thus developers need to use the QTM_USE_NAMESPACE macro.

In step 3, to specify that our project is using System Information we declare in the project file:

 CONFIG += mobility
 MOBILITY += systeminfo

The project file states that the application uses Qt Mobility and that it requires the System Information API. By adding mobility to CONFIG qmake finds the mobility.prf file in $QTDIR/mkspecs/features and includes it when processing the current project file. mobility.prf is generated when running the QtMobility configure script and points qmake to the relevant include and prefix paths and ensures that deployment and package dependencies are set. The MOBILITY variable itself is part of mobility.prf and is used to determine the QtMobility library the current project should link to (in this example the SystemInfo library).

Each QtMobility API has its corresponding value which has to be added to MOBILITY. The subsequent table lists the APIs and the corresponding values that can be assigned to MOBILITY.

In addition the Mobility version and installed modules can be checked from within qmake project files. The associated module name for such tests is the same as above:

 load(mobilityconfig)
 contains(MOBILITY_VERSION, 1.1.1) {
     message(Mobility 1.1.1 detected)
 }
 contains(MOBILITY_CONFIG, contacts) {
     message(Contacts API available)
     CONFIG+=mobility
     MOBILITY+=contacts
 } else {
     message(Contacts API not available)
 }

When developing on Symbian we will also need to add the required capabilites to the project file in order to satisfy the Symbian security model. This can be achieved with a line such as the following:

 TARGET.CAPABILITY = CAPABILITY_A CABAPILITY_B

CAPABILITY_A and CAPABILITY_B are place holders for the appropriate Symbian capabilities. A complete list of all Symbian capabilities and their availability to application developers can be found in the Symbian capability documentation.

The subsequent table provides an overview of possibily required capabilities for each Mobility library. Note that not all capabilities are always required when using a particular API. The exact list depends on which parts of an API is utilized by an application.

The complete list of all Symbian capabilities and how they can be obtained can be found in the Symbian developer documentation.

And we're done. If you are using the command line simply enter:

 qmake
 make //or nmake on Windows

to generate the executable which can then be run.

If you are developing for Symbian, to make a debug build for the emulator run:

 qmake
 make debug-winscw

This assumes that qmake is in your %PATH% and Qt has been built for the emulator already.

To make a release build and SIS package for a device run:

 qmake
 make release-gcce
 make sis

For further details on how to build applications for Symbian see The Symbian Platform - Introduction to Qt and Qt Quick Start