1QObject(3qt) QObject(3qt)
2
6 QObject - The base class of all Qt objects
7
9 All the functions in this class are reentrant when Qt is built with
10 thread support.</p>
11 #include <qobject.h>
13 Inherits Qt.
15 Inherited by QAccel, QAccessibleObject, QAction, QApplication,
17 QAssistantClient, QDataPump, QAxObject, QAxScript, QAxScriptManager,
18 QWidget, QCanvas, QStyle, QClipboard, QCopChannel, QDns, QLayout,
19 QDragObject, QEditorFactory, QEventLoop, QFileIconProvider,
20 QNetworkProtocol, QWSKeyboardHandler, QNetworkOperation, QNPInstance,
21 QObjectCleanupHandler, QProcess, QServerSocket, QSessionManager,
22 QSignal, QSignalMapper, QSocket, QSocketNotifier, QSound, QSqlDatabase,
23 QSqlDriver, QSqlForm, QStyleSheet, QTimer, QToolTipGroup, QTranslator,
24 QUrlOperator, and QValidator.
25 Public Members
27 QObject ( QObject * parent = 0, const char * name = 0 )
28 virtual ~QObject ()
29 virtual const char * className () const
30 virtual QMetaObject * metaObject () const
31 virtual bool event ( QEvent * e )
32 virtual bool eventFilter ( QObject * watched, QEvent * e )
33 bool isA ( const char * clname ) const
34 bool inherits ( const char * clname ) const
35 const char * name () const
36 const char * name ( const char * defaultName ) const
37 virtual void setName ( const char * name )
38 bool isWidgetType () const
39 bool highPriority () const
40 bool signalsBlocked () const
41 void blockSignals ( bool block )
42 int startTimer ( int interval )
43 void killTimer ( int id )
44 void killTimers ()
45 QObject * child ( const char * objName, const char * inheritsClass = 0,
46 bool recursiveSearch = TRUE )
47 const QObjectList * children () const
48 QObjectList * queryList ( const char * inheritsClass = 0, const char *
49 objName = 0, bool regexpMatch = TRUE, bool recursiveSearch = TRUE )
50 const
51 virtual void insertChild ( QObject * obj )
52 virtual void removeChild ( QObject * obj )
53 void installEventFilter ( const QObject * filterObj )
54 void removeEventFilter ( const QObject * obj )
55 bool connect ( const QObject * sender, const char * signal, const char
56 * member ) const
57 bool disconnect ( const char * signal = 0, const QObject * receiver =
58 0, const char * member = 0 )
59 bool disconnect ( const QObject * receiver, const char * member = 0 )
60 void dumpObjectTree ()
61 void dumpObjectInfo ()
62 virtual bool setProperty ( const char * name, const QVariant & value )
63 virtual QVariant property ( const char * name ) const
64 QObject * parent () const
65 Public Slots
67 void deleteLater ()
68 Signals
70 void destroyed ()
71 void destroyed ( QObject * obj )
72 Static Public Members
74 QString tr ( const char * sourceText, const char * comment )
75 QString trUtf8 ( const char * sourceText, const char * comment )
76 const QObjectList * objectTrees ()
77 bool connect ( const QObject * sender, const char * signal, const
78 QObject * receiver, const char * member )
79 bool disconnect ( const QObject * sender, const char * signal, const
80 QObject * receiver, const char * member )
81 Properties
83 QCString name - the name of this object
84 Protected Members
86 const QObject * sender ()
87 virtual void timerEvent ( QTimerEvent * )
88 virtual void childEvent ( QChildEvent * )
89 virtual void customEvent ( QCustomEvent * )
90 virtual void connectNotify ( const char * signal )
91 virtual void disconnectNotify ( const char * signal )
92 virtual bool checkConnectArgs ( const char * signal, const QObject *
93 receiver, const char * member )
94 Static Protected Members
96 QCString normalizeSignalSlot ( const char * signalSlot )
97
99 void * qt_find_obj_child ( QObject * parent, const char * type, const
100 char * name )
101
103 The QObject class is the base class of all Qt objects.
104 QObject is the heart of the Qt object model. The central feature in
106 this model is a very powerful mechanism for seamless object
107 communication called signals and slots. You can connect a signal to a
108 slot with connect() and destroy the connection with disconnect(). To
109 avoid never ending notification loops you can temporarily block signals
110 with blockSignals(). The protected functions connectNotify() and
111 disconnectNotify() make it possible to track connections.
112 QObjects organize themselves in object trees. When you create a QObject
114 with another object as parent, the object will automatically do an
115 insertChild() on the parent and thus show up in the parent's children()
116 list. The parent takes ownership of the object i.e. it will
117 automatically delete its children in its destructor. You can look for
118 an object by name and optionally type using child() or queryList(), and
119 get the list of tree roots using objectTrees().
120 Every object has an object name() and can report its className() and
122 whether it inherits() another class in the QObject inheritance
123 hierarchy.
124 When an object is deleted, it emits a destroyed() signal. You can catch
126 this signal to avoid dangling references to QObjects. The QGuardedPtr
127 class provides an elegant way to use this feature.
128 QObjects can receive events through event() and filter the events of
130 other objects. See installEventFilter() and eventFilter() for details.
131 A convenience handler, childEvent(), can be reimplemented to catch
132 child events.
133 Last but not least, QObject provides the basic timer support in Qt; see
135 QTimer for high-level support for timers.
136 Notice that the Q_OBJECT macro is mandatory for any object that
138 implements signals, slots or properties. You also need to run the moc
139 program (Meta Object Compiler) on the source file. We strongly
140 recommend the use of this macro in all subclasses of QObject regardless
141 of whether or not they actually use signals, slots and properties,
142 since failure to do so may lead certain functions to exhibit undefined
143 behaviour.
144 All Qt widgets inherit QObject. The convenience function isWidgetType()
146 returns whether an object is actually a widget. It is much faster than
147 inherits( "QWidget" ).
148 Some QObject functions, e.g. children(), objectTrees() and queryList()
150 return a QObjectList. A QObjectList is a QPtrList of QObjects.
151 QObjectLists support the same operations as QPtrLists and have an
152 iterator class, QObjectListIt.
153 See also Object Model.
155
158 Constructs an object called name with parent object, parent.
159 The parent of an object may be viewed as the object's owner. For
161 instance, a dialog box is the parent of the" OK" and "Cancel" buttons
162 it contains.
163 The destructor of a parent object destroys all child objects.
165 Setting parent to 0 constructs an object with no parent. If the object
167 is a widget, it will become a top-level window.
168 The object name is some text that can be used to identify a QObject.
170 It's particularly useful in conjunction with Qt Designer. You can find
171 an object by name (and type) using child(). To find several objects use
172 queryList().
173 See also parent(), name, child(), and queryList().
175
177 Destroys the object, deleting all its child objects.
178 All signals to and from the object are automatically disconnected.
180 Warning: All child objects are deleted. If any of these objects are on
182 the stack or global, sooner or later your program will crash. We do not
183 recommend holding pointers to child objects from outside the parent. If
184 you still do, the QObject::destroyed() signal gives you an opportunity
185 to detect when an object is destroyed.
186 Warning: Deleting a QObject while pending events are waiting to be
188 delivered can cause a crash. You must not delete the QObject directly
189 from a thread that is not the GUI thread. Use the
190 QObject::deleteLater() method instead, which will cause the event loop
191 to delete the object after all pending events have been delivered to
192 the object.
193
195 Blocks signals if block is TRUE, or unblocks signals if block is FALSE.
196 Emitted signals disappear into hyperspace if signals are blocked. Note
198 that the destroyed() signals will be emitted even if the signals for
199 this object have been blocked.
200 Examples:
202
204 receiver, const char * member ) [virtual protected]
205 Returns TRUE if the signal and the member arguments are compatible;
206 otherwise returns FALSE. (The receiver argument is currently ignored.)
207 Warning: We recommend that you use the default implementation and do
209 not reimplement this function.
210
212 0, bool recursiveSearch = TRUE )
213 Searches the children and optionally grandchildren of this object, and
214 returns a child that is called objName that inherits inheritsClass. If
215 inheritsClass is 0 (the default), any class matches.
216 If recursiveSearch is TRUE (the default), child() performs a depth-
218 first search of the object's children.
219 If there is no such object, this function returns 0. If there are more
221 than one, the first one found is retured; if you need all of them, use
222 queryList().
223
225 This event handler can be reimplemented in a subclass to receive child
226 events.
227 Child events are sent to objects when children are inserted or removed.
229 Note that events with QEvent::type() QEvent::ChildInserted are posted
231 (with QApplication::postEvent()) to make sure that the child's
232 construction is completed before this function is called.
233 If a child is removed immediately after it is inserted, the
235 ChildInserted event may be suppressed, but the ChildRemoved event will
236 always be sent. In such cases it is possible that there will be a
237 ChildRemoved event without a corresponding ChildInserted event.
238 If you change state based on ChildInserted events, call
240 QWidget::constPolish(), or do
241 QApplication::sendPostedEvents( this, QEvent::ChildInserted );
243 in functions that depend on the state. One notable example is
244 QWidget::sizeHint().
245 See also event() and QChildEvent.
247 Reimplemented in QMainWindow and QSplitter.
249
251 Returns a list of child objects, or 0 if this object has no children.
252 The QObjectList class is defined in the qobjectlist.h header file.
254 The first child added is the first object in the list and the last
256 child added is the last object in the list, i.e. new children are
257 appended at the end.
258 Note that the list order changes when QWidget children are raised or
260 lowered. A widget that is raised becomes the last object in the list,
261 and a widget that is lowered becomes the first object in the list.
262 See also child(), queryList(), parent(), insertChild(), and
264 removeChild().
265
267 Returns the class name of this object.
268 This function is generated by the Meta Object Compiler.
270 Warning: This function will return the wrong name if the class
272 definition lacks the Q_OBJECT macro.
273 See also name, inherits(), isA(), and isWidgetType().
275 Example: sql/overview/custom1/main.cpp.
277
279 QObject * receiver, const char * member ) [static]
280 Connects signal from the sender object to member in object receiver,
281 and returns TRUE if the connection succeeds; otherwise returns FALSE.
282 You must use the SIGNAL() and SLOT() macros when specifying the signal
284 and the member, for example:
285 QLabel *label = new QLabel;
287 QScrollBar *scroll = new QScrollBar;
288 QObject::connect( scroll, SIGNAL(valueChanged(int)),
289 label, SLOT(setNum(int)) );
290 This example ensures that the label always displays the current scroll
292 bar value. Note that the signal and slots parameters must not contain
293 any variable names, only the type. E.g. the following would not work
294 and return FALSE: QObject::connect( scroll, SIGNAL(valueChanged(int
295 v)), label, SLOT(setNum(int v)) );
296 A signal can also be connected to another signal:
298 class MyWidget : public QWidget
300 {
301 Q_OBJECT
302 public:
303 MyWidget();
304 signals:
305 void myUsefulSignal();
306 private:
307 QPushButton *aButton;
308 };
309 MyWidget::MyWidget()
310 {
311 aButton = new QPushButton( this );
312 connect( aButton, SIGNAL(clicked()), SIGNAL(myUsefulSignal()) );
313 }
314 In this example, the MyWidget constructor relays a signal from a
316 private member variable, and makes it available under a name that
317 relates to MyWidget.
318 A signal can be connected to many slots and signals. Many signals can
320 be connected to one slot.
321 If a signal is connected to several slots, the slots are activated in
323 an arbitrary order when the signal is emitted.
324 The function returns TRUE if it successfully connects the signal to the
326 slot. It will return FALSE if it cannot create the connection, for
327 example, if QObject is unable to verify the existence of either signal
328 or member, or if their signatures aren't compatible.
329 A signal is emitted for every connection you make, so if you duplicate
331 a connection, two signals will be emitted. You can always break a
332 connection using disconnect().
333 See also disconnect().
335 Examples:
337
339 char * member ) const
340 This is an overloaded member function, provided for convenience. It
341 behaves essentially like the above function.
342 Connects signal from the sender object to this object's member.
344 Equivalent to: QObject::connect(sender, signal, this, member).
346 See also disconnect().
348
350 This virtual function is called when something has been connected to
351 signal in this object.
352 Warning: This function violates the object-oriented principle of
354 modularity. However, it might be useful when you need to perform
355 expensive initialization only if something is connected to a signal.
356 See also connect() and disconnectNotify().
358
360 This event handler can be reimplemented in a subclass to receive custom
361 events. Custom events are user-defined events with a type value at
362 least as large as the "User" item of the QEvent::Type enum, and is
363 typically a QCustomEvent or QCustomEvent subclass.
364 See also event() and QCustomEvent.
366
368 Performs a deferred deletion of this object.
369 Instead of an immediate deletion this function schedules a deferred
371 delete event for processing when Qt returns to the main event loop.
372 Example: table/bigtable/main.cpp.
374
376 This signal is emitted when the object is being destroyed.
377 Note that the signal is emitted by the QObject destructor, so the
379 object's virtual table is already degenerated at this point, and it is
380 not safe to call any functions on the object emitting the signal. This
381 signal can not be blocked.
382 All the objects's children are destroyed immediately after this signal
384 is emitted.
385
387 This is an overloaded member function, provided for convenience. It
388 behaves essentially like the above function.
389 This signal is emitted immediately before the object obj is destroyed,
391 and can not be blocked.
392 All the objects's children are destroyed immediately after this signal
394 is emitted.
395
397 QObject * receiver, const char * member ) [static]
398 Disconnects signal in object sender from member in object receiver.
399 A signal-slot connection is removed when either of the objects involved
401 are destroyed.
402 disconnect() is typically used in three ways, as the following examples
404 demonstrate. <ol type=1>
405 1 Disconnect everything connected to an object's signals:
407 disconnect( myObject, 0, 0, 0 );
409 equivalent to the non-static overloaded function
410 myObject->disconnect();
412 2 Disconnect everything connected to a specific signal:
414 disconnect( myObject, SIGNAL(mySignal()), 0, 0 );
416 equivalent to the non-static overloaded function
417 myObject->disconnect( SIGNAL(mySignal()) );
419 3 Disconnect a specific receiver:
421 disconnect( myObject, 0, myReceiver, 0 );
423 equivalent to the non-static overloaded function
424 myObject->disconnect( myReceiver );
426 0 may be used as a wildcard, meaning "any signal", "any receiving
428 object", or "any slot in the receiving object", respectively.
429 The sender may never be 0. (You cannot disconnect signals from more
431 than one object in a single call.)
432 If signal is 0, it disconnects receiver and member from any signal. If
434 not, only the specified signal is disconnected.
435 If receiver is 0, it disconnects anything connected to signal. If not,
437 slots in objects other than receiver are not disconnected.
438 If member is 0, it disconnects anything that is connected to receiver.
440 If not, only slots named member will be disconnected, and all other
441 slots are left alone. The member must be 0 if receiver is left out, so
442 you cannot disconnect a specifically-named slot on all objects.
443 See also connect().
445
447 0, const char * member = 0 )
448 This is an overloaded member function, provided for convenience. It
449 behaves essentially like the above function.
450 Disconnects signal from member of receiver.
452 A signal-slot connection is removed when either of the objects involved
454 are destroyed.
455
457 This is an overloaded member function, provided for convenience. It
459 behaves essentially like the above function.
460 Disconnects all signals in this object from receiver's member.
462 A signal-slot connection is removed when either of the objects involved
464 are destroyed.
465
467 This virtual function is called when something has been disconnected
468 from signal in this object.
469 Warning: This function violates the object-oriented principle of
471 modularity. However, it might be useful for optimizing access to
472 expensive resources.
473 See also disconnect() and connectNotify().
475
477 Dumps information about signal connections, etc. for this object to the
478 debug output.
479 This function is useful for debugging, but does nothing if the library
481 has been compiled in release mode (i.e. without debugging information).
482
484 Dumps a tree of children to the debug output.
485 This function is useful for debugging, but does nothing if the library
487 has been compiled in release mode (i.e. without debugging information).
488
490 This virtual function receives events to an object and should return
491 TRUE if the event e was recognized and processed.
492 The event() function can be reimplemented to customize the behavior of
494 an object.
495 See also installEventFilter(), timerEvent(), QApplication::sendEvent(),
497 QApplication::postEvent(), and QWidget::event().
498 Reimplemented in QWidget.
500
502 Filters events if this object has been installed as an event filter for
503 the watched object.
504 In your reimplementation of this function, if you want to filter the
506 event e, out, i.e. stop it being handled further, return TRUE;
507 otherwise return FALSE.
508 Example:
510 class MyMainWindow : public QMainWindow
512 {
513 public:
514 MyMainWindow( QWidget *parent = 0, const char *name = 0 );
515 protected:
516 bool eventFilter( QObject *obj, QEvent *ev );
517 private:
518 QTextEdit *textEdit;
519 };
520 MyMainWindow::MyMainWindow( QWidget *parent, const char *name )
521 : QMainWindow( parent, name )
522 {
523 textEdit = new QTextEdit( this );
524 setCentralWidget( textEdit );
525 textEdit->installEventFilter( this );
526 }
527 bool MyMainWindow::eventFilter( QObject *obj, QEvent *ev )
528 {
529 if ( obj == textEdit ) {
530 if ( e->type() == QEvent::KeyPress ) {
531 QKeyEvent *k = (QKeyEvent*)ev;
532 qDebug( "Ate key press %d", k->key() );
533 return TRUE;
534 } else {
535 return FALSE;
536 }
537 } else {
538 // pass the event on to the parent class
539 return QMainWindow::eventFilter( obj, ev );
540 }
541 }
542 Notice in the example above that unhandled events are passed to the
544 base class's eventFilter() function, since the base class might have
545 reimplemented eventFilter() for its own internal purposes.
546 Warning: If you delete the receiver object in this function, be sure to
548 return TRUE. Otherwise, Qt will forward the event to the deleted object
549 and the program might crash.
550 See also installEventFilter().
552 Reimplemented in QAccel, QScrollView, and QSpinBox.
554
556 Returns TRUE if the object is a high-priority object, or FALSE if it is
557 a standard-priority object.
558 High-priority objects are placed first in QObject's list of children on
560 the assumption that they will be referenced very often.
561
563 Returns TRUE if this object is an instance of a class that inherits
564 clname, and clname inherits QObject; otherwise returns FALSE.
565 A class is considered to inherit itself.
567 Example:
569 QTimer *t = new QTimer; // QTimer inherits QObject
571 t->inherits( "QTimer" ); // returns TRUE
572 t->inherits( "QObject" ); // returns TRUE
573 t->inherits( "QButton" ); // returns FALSE
574 // QScrollBar inherits QWidget and QRangeControl
575 QScrollBar *s = new QScrollBar( 0 );
576 s->inherits( "QWidget" ); // returns TRUE
577 s->inherits( "QRangeControl" ); // returns FALSE
578 (QRangeControl is not a QObject.)
580 See also isA() and metaObject().
582 Examples:
584
586 Inserts an object obj into the list of child objects.
587 Warning: This function cannot be used to make one widget the child
589 widget of another widget. Child widgets can only be created by setting
590 the parent widget in the constructor or by calling QWidget::reparent().
591 See also removeChild() and QWidget::reparent().
593
595 Installs an event filter filterObj on this object. For example:
596 monitoredObj->installEventFilter( filterObj );
598 An event filter is an object that receives all events that are sent to
600 this object. The filter can either stop the event or forward it to this
601 object. The event filter filterObj receives events via its
602 eventFilter() function. The eventFilter() function must return TRUE if
603 the event should be filtered, (i.e. stopped); otherwise it must return
604 FALSE.
605 If multiple event filters are installed on a single object, the filter
607 that was installed last is activated first.
608 Here's a KeyPressEater class that eats the key presses of its monitored
610 objects:
611 class KeyPressEater : public QObject
613 {
614 ...
615 protected:
616 bool eventFilter( QObject *o, QEvent *e );
617 };
618 bool KeyPressEater::eventFilter( QObject *o, QEvent *e )
619 {
620 if ( e->type() == QEvent::KeyPress ) {
621 // special processing for key press
622 QKeyEvent *k = (QKeyEvent *)e;
623 qDebug( "Ate key press %d", k->key() );
624 return TRUE; // eat event
625 } else {
626 // standard event processing
627 return FALSE;
628 }
629 }
630 And here's how to install it on two widgets:
632 KeyPressEater *keyPressEater = new KeyPressEater( this );
634 QPushButton *pushButton = new QPushButton( this );
635 QListView *listView = new QListView( this );
636 pushButton->installEventFilter( keyPressEater );
637 listView->installEventFilter( keyPressEater );
638 The QAccel class, for example, uses this technique to intercept
640 accelerator key presses.
641 Warning: If you delete the receiver object in your eventFilter()
643 function, be sure to return TRUE. If you return FALSE, Qt sends the
644 event to the deleted object and the program will crash.
645 See also removeEventFilter(), eventFilter(), and event().
647
649 Returns TRUE if this object is an instance of the class clname;
650 otherwise returns FALSE.
651 Example:
653 QTimer *t = new QTimer; // QTimer inherits QObject
655 t->isA( "QTimer" ); // returns TRUE
656 t->isA( "QObject" ); // returns FALSE
657 See also inherits() and metaObject().
659
661 Returns TRUE if the object is a widget; otherwise returns FALSE.
662 Calling this function is equivalent to calling inherits("QWidget"),
664 except that it is much faster.
665
667 Kills the timer with timer identifier, id.
668 The timer identifier is returned by startTimer() when a timer event is
670 started.
671 See also timerEvent(), startTimer(), and killTimers().
673
675 Kills all timers that this object has started.
676 Warning: Using this function can cause hard-to-find bugs: it kills
678 timers started by sub- and superclasses as well as those started by
679 you, which is often not what you want. We recommend using a QTimer or
680 perhaps killTimer().
681 See also timerEvent(), startTimer(), and killTimer().
683
685 Returns a pointer to the meta object of this object.
686 A meta object contains information about a class that inherits QObject,
688 e.g. class name, superclass name, properties, signals and slots. Every
689 class that contains the Q_OBJECT macro will also have a meta object.
690 The meta object information is required by the signal/slot connection
692 mechanism and the property system. The functions isA() and inherits()
693 also make use of the meta object.
694
696 Returns the name of this object. See the "name" property for details.
697
699 This is an overloaded member function, provided for convenience. It
700 behaves essentially like the above function.
701 Returns the name of this object, or defaultName if the object does not
703 have a name.
704
706 protected]
707 Normlizes the signal or slot definition signalSlot by removing
708 unnecessary whitespace.
709
711 Returns a pointer to the list of all object trees (their root objects),
712 or 0 if there are no objects.
713 The QObjectList class is defined in the qobjectlist.h header file.
715 The most recent root object created is the first object in the list and
717 the first root object added is the last object in the list.
718 See also children(), parent(), insertChild(), and removeChild().
720
722 Returns a pointer to the parent object.
723 See also children().
725
727 Returns the value of the object's name property.
728 If no such property exists, the returned variant is invalid.
730 Information about all available properties are provided through the
732 metaObject().
733 See also setProperty(), QVariant::isValid(), metaObject(),
735 QMetaObject::propertyNames(), and QMetaObject::property().
736 Example: qutlook/centralwidget.cpp.
738
740 * objName = 0, bool regexpMatch = TRUE, bool recursiveSearch = TRUE )
741 const
742 Searches the children and optionally grandchildren of this object, and
743 returns a list of those objects that are named or that match objName
744 and inherit inheritsClass. If inheritsClass is 0 (the default), all
745 classes match. If objName is 0 (the default), all object names match.
746 If regexpMatch is TRUE (the default), objName is a regular expression
748 that the objects's names must match. The syntax is that of a QRegExp.
749 If regexpMatch is FALSE, objName is a string and object names must
750 match it exactly.
751 Note that inheritsClass uses single inheritance from QObject, the way
753 inherits() does. According to inherits(), QMenuBar inherits QWidget but
754 not QMenuData. This does not quite match reality, but is the best that
755 can be done on the wide variety of compilers Qt supports.
756 Finally, if recursiveSearch is TRUE (the default), queryList() searches
758 nth-generation as well as first-generation children.
759 If all this seems a bit complex for your needs, the simpler child()
761 function may be what you want.
762 This somewhat contrived example disables all the buttons in this
764 window:
765 QObjectList *l = topLevelWidget()->queryList( "QButton" );
767 QObjectListIt it( *l ); // iterate over the buttons
768 QObject *obj;
769 while ( (obj = it.current()) != 0 ) {
770 // for each found object...
771 ++it;
772 ((QButton*)obj)->setEnabled( FALSE );
773 }
774 delete l; // delete the list, not the objects
775 The QObjectList class is defined in the qobjectlist.h header file.
777 Warning: Delete the list as soon you have finished using it. The list
779 contains pointers that may become invalid at almost any time without
780 notice (as soon as the user closes a window you may have dangling
781 pointers, for example).
782 See also child(), children(), parent(), inherits(), name, and QRegExp.
784
786 Removes the child object obj from the list of children.
787 Warning: This function will not remove a child widget from the screen.
789 It will only remove it from the parent widget's list of children.
790 See also insertChild() and QWidget::reparent().
792
794 Removes an event filter object obj from this object. The request is
795 ignored if such an event filter has not been installed.
796 All event filters for this object are automatically removed when this
798 object is destroyed.
799 It is always safe to remove an event filter, even during event filter
801 activation (i.e. from the eventFilter() function).
802 See also installEventFilter(), eventFilter(), and event().
804
806 Returns a pointer to the object that sent the signal, if called in a
807 slot activated by a signal; otherwise it returns 0. The pointer is
808 valid only during the execution of the slot that calls this function.
809 The pointer returned by this function becomes invalid if the sender is
811 destroyed, or if the slot is disconnected from the sender's signal.
812 Warning: This function violates the object-oriented principle of
814 modularity. However, getting access to the sender might be useful when
815 many signals are connected to a single slot. The sender is undefined if
816 the slot is called as a normal C++ function.
817
819 Sets the object's name to name.
820
822 [virtual]
823 Sets the value of the object's name property to value.
824 Returns TRUE if the operation was successful; otherwise returns FALSE.
826 Information about all available properties is provided through the
828 metaObject().
829 See also property(), metaObject(), QMetaObject::propertyNames(), and
831 QMetaObject::property().
832 Example: qutlook/centralwidget.cpp.
834
836 Returns TRUE if signals are blocked; otherwise returns FALSE.
837 Signals are not blocked by default.
839 See also blockSignals().
841
843 Starts a timer and returns a timer identifier, or returns zero if it
844 could not start a timer.
845 A timer event will occur every interval milliseconds until killTimer()
847 or killTimers() is called. If interval is 0, then the timer event
848 occurs once every time there are no more window system events to
849 process.
850 The virtual timerEvent() function is called with the QTimerEvent event
852 parameter class when a timer event occurs. Reimplement this function to
853 get timer events.
854 If multiple timers are running, the QTimerEvent::timerId() can be used
856 to find out which timer was activated.
857 Example:
859 class MyObject : public QObject
861 {
862 Q_OBJECT
863 public:
864 MyObject( QObject *parent = 0, const char *name = 0 );
865 protected:
866 void timerEvent( QTimerEvent * );
867 };
868 MyObject::MyObject( QObject *parent, const char *name )
869 : QObject( parent, name )
870 {
871 startTimer( 50 ); // 50-millisecond timer
872 startTimer( 1000 ); // 1-second timer
873 startTimer( 60000 ); // 1-minute timer
874 }
875 void MyObject::timerEvent( QTimerEvent *e )
876 {
877 qDebug( "timer event, id %d", e->timerId() );
878 }
879 Note that QTimer's accuracy depends on the underlying operating system
881 and hardware. Most platforms support an accuracy of 20 ms; some provide
882 more. If Qt is unable to deliver the requested number of timer clicks,
883 it will silently discard some.
884 The QTimer class provides a high-level programming interface with one-
886 shot timers and timer signals instead of events.
887 See also timerEvent(), killTimer(), killTimers(), QEventLoop::awake(),
889 and QEventLoop::aboutToBlock().
890
892 This event handler can be reimplemented in a subclass to receive timer
893 events for the object.
894 QTimer provides a higher-level interface to the timer functionality,
896 and also more general information about timers.
897 See also startTimer(), killTimer(), killTimers(), and event().
899 Examples:
901
903 Returns a translated version of sourceText, or sourceText itself if
905 there is no appropriate translated version. The translation context is
906 QObject with comment (0 by default). All QObject subclasses using the
907 Q_OBJECT macro automatically have a reimplementation of this function
908 with the subclass name as context.
909 Warning: This method is reentrant only if all translators are installed
911 before calling this method. Installing or removing translators while
912 performing translations is not supported. Doing so will probably result
913 in crashes or other undesirable behavior.
914 See also trUtf8(), QApplication::translate(), and Internationalization
916 with Qt.
917 Example: network/networkprotocol/view.cpp.
919
921 [static]
922 Returns a translated version of sourceText, or
923 QString::fromUtf8(sourceText) if there is no appropriate version. It is
924 otherwise identical to tr(sourceText, comment).
925 Warning: This method is reentrant only if all translators are installed
927 before calling this method. Installing or removing translators while
928 performing translations is not supported. Doing so will probably result
929 in crashes or other undesirable behavior.
930 See also tr() and QApplication::translate().
932 Property Documentation
935 This property holds the name of this object.
936 You can find an object by name (and type) using child(). You can find a
938 set of objects with queryList().
939 The object name is set by the constructor or by the setName() function.
941 The object name is not very useful in the current version of Qt, but
942 will become increasingly important in the future.
943 If the object does not have a name, the name() function returns"
945 unnamed", so printf() (used in qDebug()) will not be asked to output a
946 null pointer. If you want a null pointer to be returned for unnamed
947 objects, you can call name( 0 ).
948 qDebug( "MyClass::setPrecision(): (%s) invalid precision %f",
950 name(), newPrecision );
951 See also className(), child(), and queryList().
953 Set this property's value with setName() and get this property's value
955 with name().
956
959 name )
960 Returns a pointer to the object named name that inherits type and with
961 a given parent.
962 Returns 0 if there is no such child.
964 QListBox *c = (QListBox *) qt_find_obj_child( myWidget, "QListBox",
966 "my list box" );
967 if ( c )
968 c->insertItem( "another string" );
969
972 http://doc.trolltech.com/qobject.html
973 http://www.trolltech.com/faq/tech.html
974
976 Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
977 license file included in the distribution for a complete license
978 statement.
979
981 Generated automatically from the source code.
982
984 If you find a bug in Qt, please report it as described in
985 http://doc.trolltech.com/bughowto.html. Good bug reports help us to
986 help you. Thank you.
987 The definitive Qt documentation is provided in HTML format; it is
989 located at $QTDIR/doc/html and can be read using Qt Assistant or with a
990 web browser. This man page is provided as a convenience for those users
991 who prefer man pages, although this format is not officially supported
992 by Trolltech.
993 If you find errors in this manual page, please report them to qt-
995 bugs@trolltech.com. Please include the name of the manual page
996 (qobject.3qt) and the Qt version (3.3.8).
997Trolltech AS 2 February 2007 QObject(3qt)