CopperSpice API  1.7.2
QSessionManager Class Reference

The QSessionManager class provides access to the session manager. More...

Inheritance diagram for QSessionManager:
QObject

Public Types

enum  RestartHint
 

Public Methods

bool allowsErrorInteraction ()
 
bool allowsInteraction ()
 
void cancel ()
 
QStringList discardCommand () const
 
bool isPhase2 () const
 
void release ()
 
void requestPhase2 ()
 
QStringList restartCommand () const
 
RestartHint restartHint () const
 
QString sessionId () const
 
QString sessionKey () const
 
void setDiscardCommand (const QStringList &list)
 
void setManagerProperty (const QString &name, const QString &value)
 
void setManagerProperty (const QString &name, const QStringList &value)
 
void setRestartCommand (const QStringList &list)
 
void setRestartHint (RestartHint hint)
 
- Public Methods inherited from QObject
 QObject (QObject *parent=nullptr)
 
 ~QObject ()
 
bool blockSignals (bool block)
 
const QList< QObject * > & children () const
 
bool connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)
 
bool connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)
 
bool disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const
 
bool disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const
 
bool disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const
 
void dumpObjectInfo ()
 
void dumpObjectTree ()
 
QList< QStringdynamicPropertyNames () const
 
virtual bool event (QEvent *event)
 
virtual bool eventFilter (QObject *watched, QEvent *event)
 
template<typename T >
findChild (const QString &childName=QString ()) const
 
template<class T >
QList< T > findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 
template<class T >
QList< T > findChildren (const QString &objName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
 
bool inherits (const QString &className) const
 
void installEventFilter (QObject *filterObj)
 
bool isWidgetType () const
 
bool isWindowType () const
 
void killTimer (int id)
 
const QMetaObjectmetaObject () const
 
void moveToThread (QThread *targetThread)
 
QString objectName () const
 
QObject * parent () const
 
template<class T = QVariant>
property (const QString &name) const
 
void removeEventFilter (QObject *obj)
 
void setObjectName (const QString &name)
 
void setParent (QObject *parent)
 
bool setProperty (const QString &name, const QVariant &value)
 
bool signalsBlocked () const
 
int startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
 
QThreadthread () const
 

Friends

class QApplication
 

Additional Inherited Members

- Public Signals inherited from QObject
void destroyed (QObject *obj=nullptr)
 
void objectNameChanged (const QString &objectName)
 
- Public Slots inherited from QObject
void deleteLater ()
 
- Static Public Methods inherited from QObject
static bool connect (const QObject *sender, const QMetaMethod &signalMethod, const QObject *receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)
 
static bool connect (const QObject *sender, const QString &signalMethod, const QObject *receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())
 
static bool connect (const QObject *sender, const QString &signalMethod, const QString &location, const QObject *receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)
 
template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool connect (const Sender *sender, void (SignalClass::*signalMethod)(SignalArgs...), const Receiver *receiver, SlotReturn (SlotClass::*slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)
 
template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool connect (const Sender *sender, void (SignalClass::*signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)
 
static bool disconnect (const QObject *sender, const QMetaMethod &signalMethod, const QObject *receiver, const QMetaMethod &slotMethod)
 
static bool disconnect (const QObject *sender, const QString &signalMethod, const QObject *receiver, const QString &slotMethod)
 
static bool disconnect (const QObject *sender, const QString &signalMethod, const QString &location, const QObject *receiver, const QString &slotMethod)
 
template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool disconnect (const Sender *sender, void (SignalClass::*signalMethod)(SignalArgs...), const Receiver *receiver, SlotReturn (SlotClass::*slotMethod)(SlotArgs...))
 
template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool disconnect (const Sender *sender, void (SignalClass::*signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)
 
template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool disconnect (const Sender *sender, void (SignalClass::*signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)
 
static QMetaObjectstaticMetaObject ()
 
static QString tr (const char *text, const char *comment=nullptr, std::optional< int > numArg=std::optional< int >())
 
- Protected Methods inherited from QObject
virtual void childEvent (QChildEvent *event)
 
virtual void connectNotify (const QMetaMethod &signalMethod) const
 
virtual void customEvent (QEvent *event)
 
virtual void disconnectNotify (const QMetaMethod &signalMethod) const
 
bool isSignalConnected (const QMetaMethod &signalMethod) const
 
int receivers (const QString &signal) const
 
QObject * sender () const
 
int senderSignalIndex () const
 
virtual void timerEvent (QTimerEvent *event)
 
- Properties inherited from QObject
 objectName
 

Detailed Description

The QSessionManager class provides access to the session manager.

A session manager in a desktop environment (in which CopperSpice GUI applications live) keeps track of a session, which is a group of running applications, each of which has a particular state. The state of an application contains (most notably) the documents the application has open and the position and size of its windows.

The session manager is used to save the session, e.g., when the machine is shut down, and to restore a session, e.g., when the machine is started up. We recommend that you use QSettings to save an application's settings, for example, window positions, recently used files, etc. When the application is restarted by the session manager, you can restore the settings.

QSessionManager provides an interface between the application and the session manager so that the program can work well with the session manager. Session management requests for action are handled by the two virtual functions QApplication::commitData() and QApplication::saveState(). Both provide a reference to a session manager object as argument, to allow the application to communicate with the session manager. The session manager can only be accessed through these functions.

No user interaction is possible unless the application gets explicit permission from the session manager. You ask for permission by calling allowsInteraction() or, if it is really urgent, allowsErrorInteraction(). CopperSpice does not enforce this, but the session manager may.

You can try to abort the shutdown process by calling cancel(). The default commitData() function does this if some top-level window rejected its closeEvent().

For sophisticated session managers provided on Unix/X11, QSessionManager offers further possibilities to fine-tune an application's session management behavior: setRestartCommand(), setDiscardCommand(), setRestartHint(), setProperty(), requestPhase2(). See the respective function descriptions for further details.

See also
QApplication, Session Management

Member Enumeration Documentation

This enum type defines the circumstances under which this application wants to be restarted by the session manager. The current values are:

ConstantValueDescription
QSessionManager::RestartIfRunning0If the application is still running when the session is shut down, it wants to be restarted at the start of the next session.
QSessionManager::RestartAnyway1The application wants to be started at the start of the next session, no matter what. (This is useful for utilities that run just after startup and then quit.)
QSessionManager::RestartImmediately2The application wants to be started immediately whenever it is not running.
QSessionManager::RestartNever3The application does not want to be restarted automatically.

The default hint is RestartIfRunning.

Method Documentation

bool QSessionManager::allowsErrorInteraction ( )

Returns true if error interaction is permitted, otherwise returns false.

This is similar to allowsInteraction(), but also enables the application to tell the user about any errors that occur. Session managers may give error interaction requests higher priority, which means that it is more likely that an error interaction is permitted. However, you are still not guaranteed that the session manager will allow interaction.

See also
allowsInteraction(), release(), cancel()
bool QSessionManager::allowsInteraction ( )

Asks the session manager for permission to interact with the user. Returns true if interaction is permitted, otherwise returns false.

The rationale behind this mechanism is to make it possible to synchronize user interaction during a shutdown. Advanced session managers may ask all applications simultaneously to commit their data, resulting in a much faster shutdown.

When the interaction is completed we strongly recommend releasing the user interaction semaphore with a call to release(). This way, other applications may get the chance to interact with the user while your application is still busy saving data. (The semaphore is implicitly released when the application exits.)

If the user decides to cancel the shutdown process during the interaction phase, you must tell the session manager that this has happened by calling cancel().

Here is an example of how an application's QApplication::commitData() might be implemented:

void MyApplication::commitData(QSessionManager& manager)
{
if (manager.allowsInteraction()) {
int retval = QMessageBox::warning(mainWindow, tr("My Application"),
tr("Save changes to document?"), QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel);
switch (retval) {
case QMessageBox::Save:
manager.release();
if (!saveDocument())
manager.cancel();
break;
case QMessageBox::Discard:
break;
case QMessageBox::Cancel:
default:
manager.cancel();
}
} else {
// interaction not allowed, select some default behavior
}
}

If an error occurred within the application while saving its data, you may want to try allowsErrorInteraction() instead.

See also
QApplication::commitData(), release(), cancel()
void QSessionManager::cancel ( )

Tells the session manager to cancel the shutdown process. Applications should not call this function without asking the user first.

See also
allowsInteraction(), allowsErrorInteraction()
QStringList QSessionManager::discardCommand ( ) const

Returns the currently set discard command. To navigate through a list you can use a range based for loop.

for (const QString &command : mySession.discardCommand()) {
do_something(command);
}
See also
setDiscardCommand(), restartCommand(), setRestartCommand()
bool QSessionManager::isPhase2 ( ) const

Returns true if the session manager is currently performing a second session management phase, otherwise returns false.

See also
requestPhase2()
void QSessionManager::release ( )

Releases the session manager's interaction semaphore after an interaction phase.

See also
allowsInteraction(), allowsErrorInteraction()
void QSessionManager::requestPhase2 ( )

Requests a second session management phase for the application. The application may then return immediately from the QApplication::commitData() or QApplication::saveState() function, and they will be called again once most or all other applications have finished their session management.

The two phases are useful for applications such as the X11 window manager that need to store information about another application's windows and therefore have to wait until these applications have completed their respective session management tasks.

Note
If another application has requested a second phase it may get called before, simultaneously with, or after your application's second phase.
See also
isPhase2()
QStringList QSessionManager::restartCommand ( ) const

Returns the currently set restart command. To navigate through a list you can use a range based for loop.

for (const QString &command : mySession.restartCommand()) {
do_something(command);
}
See also
setRestartCommand(), restartHint()
RestartHint QSessionManager::restartHint ( ) const

Returns the application's current restart hint. The default is RestartIfRunning.

See also
setRestartHint()
QString QSessionManager::sessionId ( ) const

Returns the identifier of the current session. If the application has been restored from an earlier session, this identifier is the same as it was in the earlier session.

See also
sessionKey(), QApplication::sessionId()
QString QSessionManager::sessionKey ( ) const

Returns the session key in the current session. If the application has been restored from an earlier session, this key is the same as it was when the previous session ended. The session key changes with every call of commitData() or saveState().

See also
sessionId(), QApplication::sessionKey()
void QSessionManager::setDiscardCommand ( const QStringList list)

Sets the discard command to the given list.

See also
discardCommand(), setRestartCommand()
void QSessionManager::setManagerProperty ( const QString name,
const QString value 
)

Low-level write access to the application's identification and state records are kept in the session manager. The property called name has its value set to the string value.

void QSessionManager::setManagerProperty ( const QString name,
const QStringList value 
)

Low-level write access to the application's identification and state record are kept in the session manager. The property called name has its value set to the string list value.

void QSessionManager::setRestartCommand ( const QStringList list)

If the session manager is capable of restoring sessions it will execute the command specified in list in order to restore the application. If this method is not called the default is equivalent to the code shown below.

appname -session id

The -session option is mandatory, otherwise QApplication can not tell whether it has been restored or what the current session identifier is. Refer QApplication::isSessionRestored() and QApplication::sessionId() for details.

If your application is very simple, it may be possible to store the entire application state in additional command line options. This is usually a very bad idea because command lines are often limited to a few hundred bytes. Instead, use QSettings, temporary files, or a database for this purpose. By marking the data with the unique sessionId(), you will be able to restore the application in a future session.

See also
restartCommand(), setDiscardCommand(), setRestartHint()
void QSessionManager::setRestartHint ( RestartHint  hint)

Sets the application's restart hint to hint. On application startup, the hint is set to RestartIfRunning. This method should be called from QApplication::saveState() because most session managers perform a checkpoint shortly after an application's startup.

Note
These flags are only hints, a session manager may or may not respect them.
See also
restartHint()