Introduction

Kontact is a KDE PIM (personal information management) framework that allows embedding several pim applications like kmail and korganizer as plugins into one window. Kontact plugins are KParts that get loaded at runtime. So, this is a good time to learn how to write a kPart... Read on.

Writing a KPart

We will write a "hello world"-KPart here. And we will write a MainWindow to hold this KPart. A KPart also gives you the flexibility to be integrated into kontact or konqueror, but we will do this later. So, the "hello world"-KPart only consists of a pushbutton labeled "hello world". We chose a pushbutton because it is the easiest viewable thing to create. It does not trigger an action on your click. The following is what you do

write a subclass mypart of KParts::Part
- because setWidget is protected
- use a Widget in it and use setWidget to get your widget into the KPart
write a subclass mypartmainwindow of KParts::MainWindow
- because createGUI is protected (and you may want createGUI later)
write main.cpp
- use new mypart(mw) to get your part into your main window

We will use 4 files to do this:

CMakeLists.txt to ease building work
main.cpp to show our MainWindow
mypart.h to declare our classes
mypart.cpp to implement our classes

CMakeLists.txt

PROJECT( kdepart )
FIND_PACKAGE(KDE4 REQUIRED)
INCLUDE_DIRECTORIES(${KDE4_INCLUDES} .)

SET(kdepartSources main.cpp mypart.cpp)

KDE4_ADD_EXECUTABLE(kdepart ${kdepartSources})

TARGET_LINK_LIBRARIES(kdepart ${KDE4_KDEUI_LIBS} 
  ${KDE4_KPARTS_LIBS})

main.cpp

include <kapplication.h>
include <kaboutdata.h>
include <kparts/mainwindow.h>
include <kparts/part.h>
include <kcmdlineargs.h>
include "mypart.h"

int main (int argc, char *argv[])
{

 const QByteArray& ba=QByteArray("test");
 const KLocalizedString name=ki18n("myName");
 KAboutData aboutData( ba, ba, name, ba, name);
 KCmdLineArgs::init( argc, argv, &aboutData );
 KApplication khello;
 mypartmainwindow* mw=new mypartmainwindow();
 mw->show();
 khello.exec();

}

mypart.h

include <KParts/Part>
include <KParts/MainWindow>

class mypart:public KParts::Part
{

   Q_OBJECT

public:

 mypart(QObject *parent=0);

};
class mypartmainwindow:public KParts::MainWindow
{

   Q_OBJECT

public:

 mypartmainwindow(QWidget* parent=0,
                  Qt::WindowFlags f=KDE_DEFAULT_WINDOWFLAGS);

};

mypart.cpp

include <kdebug.h>
include <KPushButton>
include "mypart.h"

mypart::mypart(QObject* parent)
{

 kDebug() << "Entering mypart";
 QWidget* mywidget=new QWidget();
 new KPushButton("hello world",mywidget);  
 setWidget(mywidget);

}
mypartmainwindow::mypartmainwindow(QWidget* parent,

                                  Qt::WindowFlags f)

 kDebug() << "Entering mypartmainwindow";
 mypart* mypart1=new mypart(this);
 mypart1->embed(this);

}

Compiling your KPart

To compile, link and run the code above, use

cmake . && make && ./kdepart

Using your KPart

To use your KPart, we need an object file, ending in .so. So, let's modify CMakeLists.txt a bit:

PROJECT( kdepart )
FIND_PACKAGE(KDE4 REQUIRED)
INCLUDE_DIRECTORIES(${KDE4_INCLUDES} .)

SET(kdepartSources main.cpp mypart.cpp)

KDE4_ADD_EXECUTABLE(kdepart ${kdepartSources})

TARGET_LINK_LIBRARIES(kdepart ${KDE4_KDEUI_LIBS}
  ${KDE4_KPARTS_LIBS})

set(kdepartplugin_PART_SRCS ${kdepartSources})

kde4_add_plugin(kdepartplugin ${kdepartSources})

target_link_libraries(kdepartplugin ${KDE4_KDEUI_LIBS}
  ${KDE4_KPARTS_LIBS} )

You can use konqueror to display your kpart: konqueror -> Settings -> Configure Konqueror -> Web browsing -> Plugins

Kontact integration

To integrate your KPart into kontact, you will need to have a .desktop file. This can be e.g. here:

$ ls /home/kde-devel/kde/share/kde4/services/kontact/
akregatorplugin.desktop     knotesplugin.desktop
akregatorplugin3.2.desktop  korganizerplugin.desktop
journalplugin.desktop       newstickerplugin.desktop
kaddressbookplugin.desktop  plannerplugin.desktop
karmplugin.desktop          specialdatesplugin.desktop
kmailplugin.desktop         summaryplugin.desktop
kmobiletools.desktop        todoplugin.desktop
knodeplugin.desktop         weatherplugin.desktop

You will also need your plugin, maybe here:

$ find /home/kde-devel/kde/lib/ -iname "karmpart*"
/home/kde-devel/kde/lib/kde4/karmpart.so

You will also need to make your KPart a subclass of Kontact::Plugin

Development/Tutorials/Writing kontact plugins