View source for Qt4 and Hildon home widget interaction

The code in this wiki page is taken from the [http://maemo.org/packages/view/dlh/ dlh application] and the [http://maemo.org/packages/view/dlh-widget/ dlh widget]. Since it is FOSS, the source code is available for anyone to adapt freely.

== Service ==
The com.nokia.dlh.service file defines the D-Bus service provided by the [[Qt-Maemo|Qt4]] application:

 [D-BUS Service]
 Name=com.nokia.dlh
 Exec=/opt/maemo/usr/bin/dlh

There's a reference to this service in the dlh.desktop file too:
 X-Osso-Service=com.nokia.dlh

== Application ==

In the class definition of the objects which will interact with the home widget you need the Q_CLASSINFO macro:

 class Widget : public QWidget
 {
     Q_OBJECT
     Q_CLASSINFO("D-Bus Interface", "com.nokia.dlh")
     [...]

The slots have the same name of the D-Bus messages; Q_NOREPLY mark a method to be called and not wait for it to finish processing before returning (see Qt docs):

 Q_NOREPLY void CallStartDialog();

The class constructor contains the service and the object registration:

 QDBusConnection::sessionBus().registerService("com.nokia.dlh");
 QDBusConnection::sessionBus().registerObject("/com/nokia/dlh",this, QDBusConnection::ExportAllContents);

== Home Widget ==

Some defines:

 #define DLH_SERVICE "com.nokia.dlh"
 #define DLH_OBJECT  "/com/nokia/dlh"
 #define DLH_IFACE   "com.nokia.dlh"

In the init function you have to initialize the osso library (see [http://maemo.org/api_refs/5.0/5.0-final/libosso/ libosso docs]):

 osso_context = osso_initialize ("com.nokia.dlh-widget", "0.1", 0, NULL);

When you want to execute the Qt object's slot ''CallStartDialog'' from the home widget you will use the following instruction:

 osso_rpc_run(osso_context,
              DLH_SERVICE,
              DLH_OBJECT,
              DLH_IFACE,
              "CallStartDialog", NULL, DBUS_TYPE_INVALID);

That's all!

[[Category:Development]]
[[Category:Qt]]