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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QSessionManager Class Reference</h1>
<p>The QSessionManager class provides access to the session manager.
<a href="#details">More...</a>
<p><tt>#include <<a href="qsessionmanager-h.html">qsessionmanager.h</a>></tt>
<p>Inherits <a href="qobject.html">QObject</a>.
<p><a href="qsessionmanager-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li class=fn>QString <a href="#sessionId"><b>sessionId</b></a> () const</li>
<li class=fn>QString <a href="#sessionKey"><b>sessionKey</b></a> () const</li>
<li class=fn>void * <a href="#handle"><b>handle</b></a> () const</li>
<li class=fn>bool <a href="#allowsInteraction"><b>allowsInteraction</b></a> ()</li>
<li class=fn>bool <a href="#allowsErrorInteraction"><b>allowsErrorInteraction</b></a> ()</li>
<li class=fn>void <a href="#release"><b>release</b></a> ()</li>
<li class=fn>void <a href="#cancel"><b>cancel</b></a> ()</li>
<li class=fn>enum <a href="#RestartHint-enum"><b>RestartHint</b></a> { RestartIfRunning, RestartAnyway, RestartImmediately, RestartNever }</li>
<li class=fn>void <a href="#setRestartHint"><b>setRestartHint</b></a> ( RestartHint hint )</li>
<li class=fn>RestartHint <a href="#restartHint"><b>restartHint</b></a> () const</li>
<li class=fn>void <a href="#setRestartCommand"><b>setRestartCommand</b></a> ( const QStringList & command )</li>
<li class=fn>QStringList <a href="#restartCommand"><b>restartCommand</b></a> () const</li>
<li class=fn>void <a href="#setDiscardCommand"><b>setDiscardCommand</b></a> ( const QStringList & )</li>
<li class=fn>QStringList <a href="#discardCommand"><b>discardCommand</b></a> () const</li>
<li class=fn>void <a href="#setManagerProperty-2"><b>setManagerProperty</b></a> ( const QString & name, const QString & value )</li>
<li class=fn>void <a href="#setManagerProperty"><b>setManagerProperty</b></a> ( const QString & name, const QStringList & value )</li>
<li class=fn>bool <a href="#isPhase2"><b>isPhase2</b></a> () const</li>
<li class=fn>void <a href="#requestPhase2"><b>requestPhase2</b></a> ()</li>
</ul>
<hr><a name="details"></a><h2>Detailed Description</h2>
The QSessionManager class provides access to the session manager.
<p>
<p> The session manager is responsible for session management, most
importantly for interruption and resumption. A "session" is a kind
of record of the state of the system, e.g. which applications were
run at start up and which applications are currently running. 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. Use <a href="qsettings.html">QSettings</a> to save and restore an individual
application's settings, e.g. window positions, recently used files,
etc.
<p> QSessionManager provides an interface between the application and
the session manager so that the program can work well with the
session manager. In Qt, session management requests for action
are handled by the two virtual functions <a href="qapplication.html#commitData">QApplication::commitData</a>()
and <a href="qapplication.html#saveState">QApplication::saveState</a>(). Both provide a reference to
a session manager object as argument, to allow the application
to communicate with the session manager.
<p> During a session management action (i.e. within commitData() and
saveState()), no user interaction is possible <em>unless</em> the
application got explicit permission from the session manager. You
ask for permission by calling <a href="#allowsInteraction">allowsInteraction</a>() or, if it's really
urgent, <a href="#allowsErrorInteraction">allowsErrorInteraction</a>(). Qt does not enforce this, but the
session manager may.
<p> You can try to abort the shutdown process by calling <a href="#cancel">cancel</a>(). The
default commitData() function does this if some top-level window
rejected its closeEvent().
<p> For sophisticated session managers provided on Unix/X11, QSessionManager
offers further possibilites to fine-tune an application's session
management behavior: <a href="#setRestartCommand">setRestartCommand</a>(), <a href="#setDiscardCommand">setDiscardCommand</a>(),
<a href="#setRestartHint">setRestartHint</a>(), <a href="qobject.html#setProperty">setProperty</a>(), <a href="#requestPhase2">requestPhase2</a>(). See the respective
function descriptions for further details.
<p>See also <a href="application.html">Main Window and Related Classes</a> and <a href="environment.html">Environment Classes</a>.
<hr><h2>Member Type Documentation</h2>
<h3 class=fn><a name="RestartHint-enum"></a>QSessionManager::RestartHint</h3>
<p> This enum type defines the circumstances under which this
application wants to be restarted by the session manager. The
current values are
<ul>
<li><tt>QSessionManager::RestartIfRunning</tt> - if the application is still running when
the session is shut down, it wants to be restarted at the start of
the next session.
<li><tt>QSessionManager::RestartAnyway</tt> - the 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.)
<li><tt>QSessionManager::RestartImmediately</tt> - the application wants to be started
immediately whenever it is not running.
<li><tt>QSessionManager::RestartNever</tt> - the application does not want to be restarted
automatically.
</ul><p> The default hint is <a href="#RestartHint-enum">RestartIfRunning</a>.
<hr><h2>Member Function Documentation</h2>
<h3 class=fn>bool <a name="allowsErrorInteraction"></a>QSessionManager::allowsErrorInteraction ()
</h3>
<p> This is similar to <a href="#allowsInteraction">allowsInteraction</a>(), but also tells the session
manager that an error occurred. Session managers may give error
interaction request 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.
<p> <p>See also <a href="#allowsInteraction">allowsInteraction</a>(), <a href="#release">release</a>(), and <a href="#cancel">cancel</a>().
<h3 class=fn>bool <a name="allowsInteraction"></a>QSessionManager::allowsInteraction ()
</h3>
<p> Asks the session manager for permission to interact with the
user. Returns TRUE if interaction is permitted; otherwise
returns FALSE.
<p> 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.
<p> When the interaction is completed we strongly recommend releasing the
user interaction semaphore with a call to <a href="#release">release</a>(). 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.)
<p> 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 <a href="#cancel">cancel</a>().
<p> Here's an example of how an application's <a href="qapplication.html#commitData">QApplication::commitData</a>()
might be implemented:
<p> <pre>
void MyApplication::commitData( QSessionManager& sm ) {
if ( sm.<a href="#allowsInteraction">allowsInteraction</a>() ) {
switch ( QMessageBox::<a href="qmessagebox.html#warning">warning</a>(
yourMainWindow,
<a href="qobject.html#tr">tr</a>("Application Name"),
<a href="qobject.html#tr">tr</a>("Save changes to document Foo?"),
<a href="qobject.html#tr">tr</a>("&Yes"),
<a href="qobject.html#tr">tr</a>("&No"),
<a href="qobject.html#tr">tr</a>("Cancel"),
0, 2) ) {
case 0: // yes
sm.<a href="#release">release</a>();
// save document here; if saving fails, call sm.<a href="#cancel">cancel</a>()
break;
case 1: // continue without saving
break;
default: // cancel
sm.<a href="#cancel">cancel</a>();
break;
}
} else {
// we did not get permission to interact, then
// do something reasonable instead.
}
}
</pre>
<p> If an error occurred within the application while saving its data,
you may want to try <a href="#allowsErrorInteraction">allowsErrorInteraction</a>() instead.
<p> <p>See also <a href="qapplication.html#commitData">QApplication::commitData</a>(), <a href="#release">release</a>(), and <a href="#cancel">cancel</a>().
<h3 class=fn>void <a name="cancel"></a>QSessionManager::cancel ()
</h3>
<p> Tells the session manager to cancel the shutdown process. Applications
should not call this function without first asking the user.
<p> <p>See also <a href="#allowsInteraction">allowsInteraction</a>() and <a href="#allowsErrorInteraction">allowsErrorInteraction</a>().
<p>
<h3 class=fn><a href="qstringlist.html">QStringList</a> <a name="discardCommand"></a>QSessionManager::discardCommand () const
</h3>
<p> Returns the currently set discard command.
<p> Note that if you want to iterate over the list, you should
iterate over a copy, e.g.
<pre>
<a href="qstringlist.html">QStringList</a> list = mySession.discardCommand();
QStringList::Iterator it = list.<a href="qvaluelist.html#begin">begin</a>();
while( it != list.<a href="qvaluelist.html#end">end</a>() ) {
myProcessing( *it );
++it;
}
</pre>
<p> <p>See also <a href="#setDiscardCommand">setDiscardCommand</a>(), <a href="#restartCommand">restartCommand</a>(), and <a href="#setRestartCommand">setRestartCommand</a>().
<h3 class=fn>void * <a name="handle"></a>QSessionManager::handle () const
</h3>
<p> X11 only: returns a handle to the current <tt>SmcConnection</tt>.
<h3 class=fn>bool <a name="isPhase2"></a>QSessionManager::isPhase2 () const
</h3>
<p> Returns TRUE if the session manager is currently performing a second
session management phase; otherwise returns FALSE.
<p> <p>See also <a href="#requestPhase2">requestPhase2</a>().
<h3 class=fn>void <a name="release"></a>QSessionManager::release ()
</h3>
<p> Releases the session manager's interaction semaphore after an
interaction phase.
<p> <p>See also <a href="#allowsInteraction">allowsInteraction</a>() and <a href="#allowsErrorInteraction">allowsErrorInteraction</a>().
<h3 class=fn>void <a name="requestPhase2"></a>QSessionManager::requestPhase2 ()
</h3>
<p> Requests a second session management phase for the application. The
application may then return immediately from the
<a href="qapplication.html#commitData">QApplication::commitData</a>() or <a href="qapplication.html#saveState">QApplication::saveState</a>() function,
and they will be called again once most or all other applications have
finished their session management.
<p> 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.
<p> Note that if another application has requested a second phase it
may get called before, simultaneously with, or after your
application's second phase.
<p> <p>See also <a href="#isPhase2">isPhase2</a>().
<h3 class=fn><a href="qstringlist.html">QStringList</a> <a name="restartCommand"></a>QSessionManager::restartCommand () const
</h3>
<p> Returns the currently set restart command.
<p> Note that if you want to iterate over the list, you should
iterate over a copy, e.g.
<pre>
<a href="qstringlist.html">QStringList</a> list = mySession.restartCommand();
QStringList::Iterator it = list.<a href="qvaluelist.html#begin">begin</a>();
while( it != list.<a href="qvaluelist.html#end">end</a>() ) {
myProcessing( *it );
++it;
}
</pre>
<p> <p>See also <a href="#setRestartCommand">setRestartCommand</a>() and <a href="#restartHint">restartHint</a>().
<h3 class=fn><a href="qsessionmanager.html#RestartHint-enum">RestartHint</a> <a name="restartHint"></a>QSessionManager::restartHint () const
</h3>
<p> Returns the application's current restart hint. The default is
<a href="#RestartHint-enum">RestartIfRunning</a>.
<p> <p>See also <a href="#setRestartHint">setRestartHint</a>().
<h3 class=fn><a href="qstring.html">QString</a> <a name="sessionId"></a>QSessionManager::sessionId () const
</h3>
<p> Returns the identifier of the current session.
<p> If the application has been restored from an earlier session, this
identifier is the same as it was in that earlier session.
<p> <p>See also <a href="#sessionKey">sessionKey</a>() and <a href="qapplication.html#sessionId">QApplication::sessionId</a>().
<h3 class=fn><a href="qstring.html">QString</a> <a name="sessionKey"></a>QSessionManager::sessionKey () const
</h3>
<p> Returns the session key in the current session.
<p> If the application has been restored from an earlier session, this
key is the same as it was when the previous session ended.
<p> The session key changes with every call of commitData() or
saveState().
<p> <p>See also <a href="#sessionId">sessionId</a>() and <a href="qapplication.html#sessionKey">QApplication::sessionKey</a>().
<h3 class=fn>void <a name="setDiscardCommand"></a>QSessionManager::setDiscardCommand ( const <a href="qstringlist.html">QStringList</a> & )
</h3>
<p> <p>See also <a href="#discardCommand">discardCommand</a>() and <a href="#setRestartCommand">setRestartCommand</a>().
<h3 class=fn>void <a name="setManagerProperty"></a>QSessionManager::setManagerProperty ( const <a href="qstring.html">QString</a> & name, const <a href="qstringlist.html">QStringList</a> & value )
</h3>
<p> Low-level write access to the application's identification and state
record are kept in the session manager.
<p> The property called <em>name</em> has its value set to the string list <em>value</em>.
<h3 class=fn>void <a name="setManagerProperty-2"></a>QSessionManager::setManagerProperty ( const <a href="qstring.html">QString</a> & name, const <a href="qstring.html">QString</a> & value )
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Low-level write access to the application's identification and state
records are kept in the session manager.
<p> The property called <em>name</em> has its value set to the string <em>value</em>.
<h3 class=fn>void <a name="setRestartCommand"></a>QSessionManager::setRestartCommand ( const <a href="qstringlist.html">QStringList</a> & command )
</h3>
<p> If the session manager is capable of restoring sessions it will
execute <em>command</em> in order to restore the application. The command
defaults to
<p> <pre>
appname -session id
</pre>
<p> The <tt>-session</tt> option is mandatory; otherwise <a href="qapplication.html">QApplication</a> cannot
tell whether it has been restored or what the current session
identifier is. See <a href="qapplication.html#isSessionRestored">QApplication::isSessionRestored</a>() and
<a href="qapplication.html#sessionId">QApplication::sessionId</a>() for details.
<p> 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 <a href="qsettings.html">QSettings</a>, or temporary files
or a database for this purpose. By marking the data with the unique
<a href="#sessionId">sessionId</a>(), you will be able to restore the application in a future
session.
<p> <p>See also <a href="#restartCommand">restartCommand</a>(), <a href="#setDiscardCommand">setDiscardCommand</a>(), and <a href="#setRestartHint">setRestartHint</a>().
<h3 class=fn>void <a name="setRestartHint"></a>QSessionManager::setRestartHint ( <a href="qsessionmanager.html#RestartHint-enum">RestartHint</a> hint )
</h3>
<p> Sets the application's restart hint to <em>hint</em>. On application
startup the hint is set to <a href="#RestartHint-enum">RestartIfRunning</a>.
<p> Note that these flags are only hints, a session manager may or may
not respect them.
<p> We recommend setting the restart hint in <a href="qapplication.html#saveState">QApplication::saveState</a>()
because most session managers perform a checkpoint shortly after an
application's startup.
<p> <p>See also <a href="#restartHint">restartHint</a>().
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