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| Tutorial Series | Attica |
| Previous | Getting started with KDE development |
| What's Next | n/a |
| Further Reading | n/a |
In this tutorial you learn how to use Attica to access the Open Collaboration Services in your application.
Our goal is to get a list of friends for any user registered on this site.
With Attica you can easily access services from providers such as openDesktop.org. It implements the freedesktop.org specification for the Open Collaboration Services API.
Attica supports multiple Open Collaboration Service (OCS) providers at the same time. Therefor the first thing to do is getting a ProviderManager and either asking it for a default provider (e.g. openDesktop.org for KDE) or setting a different provider by hand. Let's create a mainwindow class that loads the openDesktop.org provider. Make sure you have the KDE Plugin for Attica built, otherwise openDesktop.org will not be in the list of default providers.
To make setting up the tutorial as easy as possible, here is a complete KDE application. We start with the mainwindow and add things into it.
//mainwindow.h
class MainWindow : public KMainWindow {
Q_OBJECT
public:
MainWindow(QWidget *parent=0);
public Q_SLOTS:
// Here we will get notified, when the provider is loaded void providersChanged();
private:
// ProviderManager is the class that lets us "create" providers Attica::ProviderManager m_manager; // A provider that we will ask for data from openDesktop.org Attica::Provider m_provider;
};
//mainwindow.cpp
MainWindow::MainWindow(QWidget *parent) : KMainWindow(parent) {
// connect to get notified, when new Providers are loaded connect(&m_manager, SIGNAL(providersChanged()), SLOT(providersChanged())); // tell it to get the default Providers m_manager.loadDefaultProviders();
}
// called when a provider was loaded void MainWindow::providersChanged() {
KDE TechBase if (!m_manager.providers().isEmpty()) {
m_provider = m_manager.providerByUrl(QUrl("https://api.opendesktop.org/v1/"));
if (!m_provider.isValid()) {
kDebug() << "Could not find opendesktop.org provider.";
return;
}
// Use a tab widget here, so we can add more in the next tutorial
QTabWidget* mainWidget = new QTabWidget(this);
setCentralWidget(mainWidget);
// Create a widget that will make use of the Provider
// and supply information about a Person
SimplePersonRequest* personWidget = new SimplePersonRequest(m_provider, this);
mainWidget->addTab(personWidget, tr("Person Search"));
}
}
Now we have a simple mainwindow with a tab widget. The real contents is still missing though. The first widget we'll add gives some information about a Person.
Now that we have a Provider, we can ask it for information.
As a first step, let's find out who I am. Entering any user nick into a KLineEdit will look up that Person.
Here is a class that subclasses QWidget and simply contains two labels that show the real name and city for a Person:
class SimplePersonRequest :public QWidget {
Q_OBJECT
public:
SimplePersonRequest(Attica::Provider provider, QWidget* parent = 0);
public Q_SLOTS:
void nickChanged(const QString& nick); void onPersonJobFinished( Attica::BaseJob *job );
private:
KLineEdit* mNickNameLineEdit; QLabel* mNameLabel; QLabel* mLocationLabel; QString mNick; Attica::Provider m_provider;
};
SimplePersonRequest::SimplePersonRequest(Attica::Provider provider, QWidget* parent)
: QWidget(parent) , m_provider(provider)
{
QVBoxLayout* layout = new QVBoxLayout(this); mNickNameLineEdit = new KLineEdit(); layout->addWidget(mNickNameLineEdit);
mNameLabel = new QLabel(this);
mNameLabel->setText("Name");
layout->addWidget(mNameLabel);
mLocationLabel = new QLabel(this);
mLocationLabel->setText("Picture");
layout->addWidget(mLocationLabel);
mNick = "fregl"; mNickNameLineEdit->setText(mNick); connect(mNickNameLineEdit, SIGNAL(returnPressed(QString)), SLOT(nickChanged(QString))); nickChanged(mNick);
}
void SimplePersonRequest::nickChanged(const QString& nick) {
mNick = nick; Attica::ItemJob<Attica::Person>* job = m_provider.requestPerson(mNick); connect(job, SIGNAL(finished(Attica::BaseJob*)), SLOT(onPersonJobFinished(Attica::BaseJob*))); job->start();
}
void SimplePersonRequest::onPersonJobFinished( Attica::BaseJob *job ) {
kDebug() << "onJobFinished";
Attica::ItemJob<Attica::Person> *personJob = static_cast< Attica::ItemJob<Attica::Person> * >( job );
if( personJob->metadata().error() == Attica::Metadata::NoError ) {
Attica::Person p(personJob->result());
mNameLabel->setText(p.firstName() + ' ' + p.lastName());
mLocationLabel->setText(p.city());
} else {
mNameLabel->setText("Could not fetch information.");
}
}
The last thing missing is a small main.cpp and CMakeLists.txt to complete the example and make it compile:
int main (int argc, char *argv[]) {
KAboutData aboutData( "opencollaborationexample", 0,
ki18n("Open Collaboration Services Demo"), "1.0",
ki18n("Show how to use libattica to access the Open Collaboration Services"),
KAboutData::License_GPL,
ki18n("Copyright (c) 2009 Frederik Gladhorn") );
KCmdLineArgs::init( argc, argv, &aboutData );
KApplication app;
MainWindow* window = new MainWindow();
window->show();
return app.exec();
}
project (opencollaborationexample)
include_directories(${KDE4_INCLUDES} ${ATTICA_INCLUDE_DIRS} ${CMAKE_CURRENT_SOURCE_DIR})
set(opencollaborationexample_SRCS
main.cpp mainwindow.cpp simplepersonrequest.cpp
)
kde4_add_executable(opencollaborationexample ${opencollaborationexample_SRCS}) target_link_libraries(opencollaborationexample ${ATTICA_LIBRARIES} ${KDE4_KIO_LIBS} ${KDE4_KDEUI_LIBS})
