Development/Tutorials/Decibel/Handling TextChannels
Abstract
This tutorial will walk you through the process of creating a simple application that uses Decibel's TextChannels to communicate via arbitrary instant messaging networks using telepathy. From the result of this tutorial, only a few more lines of code are needed to produce a functioning text based instant messaging client.
This tutorial is based on the simpleclient demo included with Decibel. An explanation of using the simpleclient demo can be found here.
In this tutorial, we only pick out the important parts of the source code to discuss. The complete working source code for this example can be found here in KDE's SVN Repository.
ChannelHandler class
The first class we will need to create is an implementation of the Decibel::ChannelHandler interface.
The Class Definition
Here is the class definition for our implementation of the Decibel::ChannelHandler interface. It is explained below.
class MyTextChannelHandler : public Decibel::ChannelHandler
{
Q_OBJECT
public:
explicit MyTextChannelHandler(QObject * parent = 0);
~MyTextChannelHandler();
bool handleChannel(QtTapioca::Connection *, QtTapioca::Channel *, const bool);
public slots:
void onMessageReceived();
void onCloseChannel();
private:
QtTapioca::Connection * m_connection;
QtTapioca::TextChannel * m_channel;
};
We must inherit from Decibel::ChannelHandler which is the interface definition for handling incoming Channels. We reimplement the constructor, Destructor and the handleChannel() method as well as adding two slots of our own. We also create the member variables m_connecion and m_channel which will hold the QtTapioca::Connection and QtTapioca::Channel objects that are received by the handleChannel method.
The Class Implementation
Now that we have defined our Decibel::ChannelHandler subclass, we need to implement its methods.
Constructor
MyTextChannelHandler::MyTextChannelHandler(QObject * parent) :
ChannelHandler(parent),
m_connection(0),
m_channel(0)
{ }
The constructor is very simple. We just pass the parent object on to the parent class and initialise our member variables to 0.
Destructor
MyTextChannelHandler::~MyTextChannelHandler()
{ }
The destructor is even simpler. We don't need to do anything in it because Qt will handle the deletion of child objects automatically.
handleChannel()
bool MyTextChannelHandler::handleChannel(QtTapioca::Connection * connection,
QtTapioca::Channel * channel,
const bool)
{
Q_ASSERT(connection != 0);
Q_ASSERT(channel != 0);
if (m_connection != 0) { return false; }
m_channel = dynamic_cast<QtTapioca::TextChannel*>(channel);
if (m_channel == 0)
{
return false;
}
m_connection = connection;
connect(m_channel, SIGNAL(messageReceived(const QtTapioca::TextChannel *, const QtTapioca::TextChannel::Message &)),
this, SLOT(onMessageReceived()));
connect(m_channel, SIGNAL(closed()), this, SLOT(onCloseChannel()));
onMessageReceived();
return true;
}
onCloseChannel()
void MyTextChannelHandler::onCloseChannel()
{
m_connection = 0;
m_channel = 0;
}
onMessageReceived()
void MyTextChannelHandler::onMessageReceived()
{
QList<QtTapioca::TextChannel::Message> message_list = m_channel->pendingMessages();
for (QList<QtTapioca::TextChannel::Message>::const_iterator
message = message_list.constBegin();
message != message_list.constEnd(); ++message)
{
if (message->type() == QtTapioca::TextChannel::Message::Normal &&
message->contents() == QString("ping?"))
{ m_channel->sendMessage(QString("pong!")); }
m_channel->acknowledge(*message);
}
}
The main() function
int main(int argc, char ** argv)
{
QCoreApplication app(argc, argv);
app.setOrganizationName(Decibel::organisation_name);
app.setApplicationName("SimpleClient");
MyTextChannelHandler thandler(&app);
Decibel::registerTypes();
QDBusConnection::sessionBus().registerService(Decibel::organisation_name + '.' + "SimpleClient");
QDBusConnection::sessionBus().registerObject("/TextChannelHandler", thandler);
return app.exec();
}
The .component File
[Component]
Name=Simpleclient
Protocols=
Types=0
Targets=
Service%20Name=org.kde.SimpleClient
Object%20Path=/TextChannelHandler
The .service File
[D-BUS Service]
Name=org.kde.SimpleClient
Exec=@DEMO_INSTALL_DIR@/decibel_simpleclient_demo
CMakeLists.txt
SET(QT_DONT_USE_QTGUI "YES")
INCLUDE(${QT_USE_FILE})
SET(SERVICE_FILE "org.kde.SimpleClient.service")
INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/include
${CMAKE_BINARY_DIR}/src/client
${CMAKE_SOURCE_DIR}/src/client
${QT_QTCORE_INCLUDE_DIR}
${TELEPATHY_QT_INCLUDE_DIR}
${TAPIOCA_QT_INCLUDE_DIR}
${CMAKE_CURRENT_BINARY_DIR}
${CMAKE_CURRENT_SOURCE_DIR}
)
CONFIGURE_FILE("${CMAKE_CURRENT_SOURCE_DIR}/${SERVICE_FILE}.cmake"
"${CMAKE_CURRENT_BINARY_DIR}/${SERVICE_FILE}"
)
- ######### simpleclient demo #########
SET(simpleclient_SRCS
simpleclient.cpp
mytextchannelhandler.cpp
)
SET(simpleclient_MOC_HDRS
mytextchannelhandler.h
)
QT4_WRAP_CPP(simpleclient_MOC_SRCS ${simpleclient_MOC_HDRS})
ADD_EXECUTABLE(decibel_simpleclient_demo ${simpleclient_SRCS}
${simpleclient_MOC_SRCS}
)
TARGET_LINK_LIBRARIES(decibel_simpleclient_demo
${QT_LIBRARIES}
${TAPIOCA_QT_LIBRARIES}
decibel
)
INSTALL(TARGETS decibel_simpleclient_demo DESTINATION ${DEMO_INSTALL_DIR})
INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/${SERVICE_FILE}
DESTINATION ${DBUS_SERVICES_INSTALL_DIR}
)
INSTALL(FILES org.kde.SimpleClient.TextChannel.component
DESTINATION ${COMPONENT_SEARCH_DIR}
)
Running our Application
TODO