KUniqueApplication Class Reference

from PyKDE4.kdeui import *

Inherits: KApplication → QApplication → QCoreApplication → QObject

Detailed Description

KUniqueApplication is a KApplication which only uses a single process. When a KUniqueApplication is started, it attempts to contact an existing copy of the application. If successful, the program asks the existing process to create a new instance by calling its newInstance() method and then exits. If there is no existing process then the program forks and calls the newInstance() method. When newInstance() is called, the application will typically create a new window or activate an existing one.

Instances of KUniqueApplication can be made to behave like a normal application by passing the StartFlag.NonUniqueInstance flag to start().

Please note that this supports only one process per KDE session. If your application can only be opened once per user or once per host, you need to ensure this independently of KUniqueApplication.

The .desktop file for the application should state X-DBUS-StartupType=Unique, see ktoolinvocation.h

If you use command line options before start() is called, you MUST call addCmdLineOptions() so that the KUniqueApplication-specific command-line options can still work.

If your application is used to open files, it should also support the --tempfile option (see KCmdLineArgs.addTempFileOption()), to delete tempfiles after use. Add X-KDE-HasTempFileOption=true to the .desktop file to indicate this.

See also:: KApplication

Author:: Preston Brown <pbrown@kde.org>

Enumerations
StartFlag	{ NonUniqueInstance }
Methods
	__init__ (self, bool GUIenabled=1, bool configUnique=0)
	__init__ (self, Display display, Qt::HANDLE visual=0, Qt::HANDLE colormap=0, bool configUnique=0)
int	newInstance (self)
bool	restoringSession (self)
Static Methods
	addCmdLineOptions ()
	setHandleAutoStarted ()
bool	start (KUniqueApplication.StartFlags flags)
bool	start ()

Method Documentation

__init__	(	self,
		bool	GUIenabled=1,
		bool	configUnique=0
	)

Constructor. Takes command line arguments from KCmdLineArgs

Parameters:

	GUIenabled	Set to false to disable all GUI stuff. This implies no styles either.
	configUnique	If true, the uniqueness of the application will depend on the value of the "MultipleInstances" key in the "KDE" group of the application config file.

__init__	(	self,
		Display	display,
		Qt::HANDLE	visual=0,
		Qt::HANDLE	colormap=0,
		bool	configUnique=0
	)

Constructor. Takes command line arguments from KCmdLineArgs

Parameters:

	display	Will be passed to Qt as the X display. The display must be valid and already opened.
	visual	Pointer to the X11 visual that should be used by the application. If NULL, the default visual will be used instead.
	colormap	The colormap that should be used by the application. If 0, the default colormap will be used instead.
	configUnique	If true, the uniqueness of the application will depend on the value of the "MultipleInstances" key in the "KDE" group of the application config file.

int newInstance ( self )

Creates a new "instance" of the application.

Usually this will involve making some calls into the GUI portion of your application asking for a new window to be created, possibly with some data already loaded based on the arguments received.

Command line arguments have been passed to KCmdLineArgs before this function is called and can be checked in the usual way.

The default implementation ensures the mainwindow of the already running instance is shown and activated if necessary. If your application has only one mainwindow, you should call this default implementation and only add your special handling if needed.

Note that newInstance() is called also in the first started application process.

For applications that share one process for several mainwindows, the reimplementation could be:

int MyApp.newInstance()
{
KCmdLineArgs.setCwd(QDir.currentPath().toUtf8());
KCmdLineArgs* args = KCmdLineArgs.parsedArgs();
static bool first = true;
if (args->count() > 0) {
for (int i = 0; i < args->count(); ++i) {
openWindow(args->url(i));
}
} else if( !first || !isSessionRestored()) {
openWindow(KUrl()); // create a new window
}
first = false;
args->clear();
return 0;
}

Returns:: An exit value. The calling process will exit with this value.

bool restoringSession ( self )

Returns whether newInstance() is being called while session restoration is in progress.

Static Method Documentation

addCmdLineOptions ( )

Adds command line options specific for KUniqueApplication.

Should be called before calling KUniqueApplication constructor and / or start().

setHandleAutoStarted ( )

Internal:

bool start	(	KUniqueApplication.StartFlags	flags
	)

Forks and registers with D-Bus.

The command line arguments are being sent via D-Bus to newInstance() and will be received once the application enters the event loop.

Typically this is used like:

 int main(int argc, char **argv) {
    KAboutData about("myappname", 0, ki18n("myAppName"), .....);
    KCmdLineArgs.init(argc, argv, &about);
    KCmdLineArgs.addCmdLineOptions( myCmdOptions );
    KUniqueApplication.addCmdLineOptions();

    if (!KUniqueApplication.start()) {
       fprintf(stderr, "myAppName is already running!\n");
       return 0;
    }
    KUniqueApplication a;
    return a.exec();
 }

Note that it's not necessary to call start() explicitly. It will be called automatically before creating KUniqueApplication if it hasn't been called yet, without any performance impact.

Also note that you MUST call KUniqueApplication.addCmdLineOptions(), if you use command line options before start() is called.

Parameters:

flags

Optional flags which control how a new instance of the application is started.

Returns:: true if registration is successful. false if another process was already running.

bool start ( )

Forks and registers with D-Bus.

The command line arguments are being sent via D-Bus to newInstance() and will be received once the application enters the event loop.

Typically this is used like:

 int main(int argc, char **argv) {
    KAboutData about("myappname", 0, ki18n("myAppName"), .....);
    KCmdLineArgs.init(argc, argv, &about);
    KCmdLineArgs.addCmdLineOptions( myCmdOptions );
    KUniqueApplication.addCmdLineOptions();

    if (!KUniqueApplication.start()) {
       fprintf(stderr, "myAppName is already running!\n");
       return 0;
    }
    KUniqueApplication a;
    return a.exec();
 }

Note that it's not necessary to call start() explicitly. It will be called automatically before creating KUniqueApplication if it hasn't been called yet, without any performance impact.

Also note that you MUST call KUniqueApplication.addCmdLineOptions(), if you use command line options before start() is called.

Parameters:

flags

Optional flags which control how a new instance of the application is started.

Returns:: true if registration is successful. false if another process was already running.

Enumeration Documentation

StartFlag

These flags can be used to specify how new instances of unique applications are created.

Enumerator:

NonUniqueInstance = 0x1

KUniqueApplication Class Reference

Detailed Description

Enumerations

Methods

Static Methods

Method Documentation

Static Method Documentation

Enumeration Documentation

Modules