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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QObject Class Reference</h1>
33
34<p>The QObject class is the base class of all Qt objects.
35<a href="#details">More...</a>
36<p>All the functions in this class are <a href="threads.html#reentrant">reentrant</a> when Qt is built with thread support.</p>
37<p><tt>#include &lt;<a href="qobject-h.html">qobject.h</a>&gt;</tt>
38<p>Inherits <a href="qt.html">Qt</a>.
39<p>Inherited by <a href="qaccel.html">QAccel</a>, <a href="qaccessibleobject.html">QAccessibleObject</a>, <a href="qaction.html">QAction</a>, <a href="qapplication.html">QApplication</a>, <a href="qassistantclient.html">QAssistantClient</a>, <a href="qdatapump.html">QDataPump</a>, <a href="qaxobject.html">QAxObject</a>, <a href="qaxscript.html">QAxScript</a>, <a href="qaxscriptmanager.html">QAxScriptManager</a>, <a href="qwidget.html">QWidget</a>, <a href="qcanvas.html">QCanvas</a>, <a href="qstyle.html">QStyle</a>, <a href="qclipboard.html">QClipboard</a>, <a href="qcopchannel.html">QCopChannel</a>, <a href="qdns.html">QDns</a>, <a href="qlayout.html">QLayout</a>, <a href="qdragobject.html">QDragObject</a>, <a href="qeditorfactory.html">QEditorFactory</a>, <a href="qeventloop.html">QEventLoop</a>, <a href="qfileiconprovider.html">QFileIconProvider</a>, <a href="qnetworkprotocol.html">QNetworkProtocol</a>, <a href="qwskeyboardhandler.html">QWSKeyboardHandler</a>, <a href="qnetworkoperation.html">QNetworkOperation</a>, <a href="qnpinstance.html">QNPInstance</a>, <a href="qobjectcleanuphandler.html">QObjectCleanupHandler</a>, <a href="qprocess.html">QProcess</a>, <a href="qserversocket.html">QServerSocket</a>, <a href="qsessionmanager.html">QSessionManager</a>, <a href="qsignal.html">QSignal</a>, <a href="qsignalmapper.html">QSignalMapper</a>, <a href="qsocket.html">QSocket</a>, <a href="qsocketnotifier.html">QSocketNotifier</a>, <a href="qsound.html">QSound</a>, <a href="qsqldatabase.html">QSqlDatabase</a>, <a href="qsqldriver.html">QSqlDriver</a>, <a href="qsqlform.html">QSqlForm</a>, <a href="qstylesheet.html">QStyleSheet</a>, <a href="qtimer.html">QTimer</a>, <a href="qtooltipgroup.html">QToolTipGroup</a>, <a href="qtranslator.html">QTranslator</a>, <a href="qurloperator.html">QUrlOperator</a>, and <a href="qvalidator.html">QValidator</a>.
40<p><a href="qobject-members.html">List of all member functions.</a>
41<h2>Public Members</h2>
42<ul>
43<li class=fn><a href="#QObject"><b>QObject</b></a> ( QObject&nbsp;*&nbsp;parent = 0, const&nbsp;char&nbsp;*&nbsp;name = 0 )</li>
44<li class=fn>virtual <a href="#~QObject"><b>~QObject</b></a> ()</li>
45<li class=fn>virtual const char * <a href="#className"><b>className</b></a> () const</li>
46<li class=fn>virtual QMetaObject * <a href="#metaObject"><b>metaObject</b></a> () const</li>
47<li class=fn>virtual bool <a href="#event"><b>event</b></a> ( QEvent&nbsp;*&nbsp;e )</li>
48<li class=fn>virtual bool <a href="#eventFilter"><b>eventFilter</b></a> ( QObject&nbsp;*&nbsp;watched, QEvent&nbsp;*&nbsp;e )</li>
49<li class=fn>bool <a href="#isA"><b>isA</b></a> ( const&nbsp;char&nbsp;*&nbsp;clname ) const</li>
50<li class=fn>bool <a href="#inherits"><b>inherits</b></a> ( const&nbsp;char&nbsp;*&nbsp;clname ) const</li>
51<li class=fn>const char * <a href="#name"><b>name</b></a> () const</li>
52<li class=fn>const char * <a href="#name-2"><b>name</b></a> ( const&nbsp;char&nbsp;*&nbsp;defaultName ) const</li>
53<li class=fn>virtual void <a href="#setName"><b>setName</b></a> ( const&nbsp;char&nbsp;*&nbsp;name )</li>
54<li class=fn>bool <a href="#isWidgetType"><b>isWidgetType</b></a> () const</li>
55<li class=fn>bool <a href="#highPriority"><b>highPriority</b></a> () const</li>
56<li class=fn>bool <a href="#signalsBlocked"><b>signalsBlocked</b></a> () const</li>
57<li class=fn>void <a href="#blockSignals"><b>blockSignals</b></a> ( bool&nbsp;block )</li>
58<li class=fn>int <a href="#startTimer"><b>startTimer</b></a> ( int&nbsp;interval )</li>
59<li class=fn>void <a href="#killTimer"><b>killTimer</b></a> ( int&nbsp;id )</li>
60<li class=fn>void <a href="#killTimers"><b>killTimers</b></a> ()</li>
61<li class=fn>QObject * <a href="#child"><b>child</b></a> ( const&nbsp;char&nbsp;*&nbsp;objName, const&nbsp;char&nbsp;*&nbsp;inheritsClass = 0, bool&nbsp;recursiveSearch = TRUE )</li>
62<li class=fn>const QObjectList * <a href="#children"><b>children</b></a> () const</li>
63<li class=fn>QObjectList * <a href="#queryList"><b>queryList</b></a> ( const&nbsp;char&nbsp;*&nbsp;inheritsClass = 0, const&nbsp;char&nbsp;*&nbsp;objName = 0, bool&nbsp;regexpMatch = TRUE, bool&nbsp;recursiveSearch = TRUE ) const</li>
64<li class=fn>virtual void <a href="#insertChild"><b>insertChild</b></a> ( QObject&nbsp;*&nbsp;obj )</li>
65<li class=fn>virtual void <a href="#removeChild"><b>removeChild</b></a> ( QObject&nbsp;*&nbsp;obj )</li>
66<li class=fn>void <a href="#installEventFilter"><b>installEventFilter</b></a> ( const&nbsp;QObject&nbsp;*&nbsp;filterObj )</li>
67<li class=fn>void <a href="#removeEventFilter"><b>removeEventFilter</b></a> ( const&nbsp;QObject&nbsp;*&nbsp;obj )</li>
68<li class=fn>bool <a href="#connect-2"><b>connect</b></a> ( const&nbsp;QObject&nbsp;*&nbsp;sender, const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;char&nbsp;*&nbsp;member ) const</li>
69<li class=fn>bool <a href="#disconnect-2"><b>disconnect</b></a> ( const&nbsp;char&nbsp;*&nbsp;signal = 0, const&nbsp;QObject&nbsp;*&nbsp;receiver = 0, const&nbsp;char&nbsp;*&nbsp;member = 0 )</li>
70<li class=fn>bool <a href="#disconnect-3"><b>disconnect</b></a> ( const&nbsp;QObject&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member = 0 )</li>
71<li class=fn>void <a href="#dumpObjectTree"><b>dumpObjectTree</b></a> ()</li>
72<li class=fn>void <a href="#dumpObjectInfo"><b>dumpObjectInfo</b></a> ()</li>
73<li class=fn>virtual bool <a href="#setProperty"><b>setProperty</b></a> ( const&nbsp;char&nbsp;*&nbsp;name, const&nbsp;QVariant&nbsp;&amp;&nbsp;value )</li>
74<li class=fn>virtual QVariant <a href="#property"><b>property</b></a> ( const&nbsp;char&nbsp;*&nbsp;name ) const</li>
75<li class=fn>QObject * <a href="#parent"><b>parent</b></a> () const</li>
76</ul>
77<h2>Public Slots</h2>
78<ul>
79<li class=fn>void <a href="#deleteLater"><b>deleteLater</b></a> ()</li>
80</ul>
81<h2>Signals</h2>
82<ul>
83<li class=fn>void <a href="#destroyed"><b>destroyed</b></a> ()</li>
84<li class=fn>void <a href="#destroyed-2"><b>destroyed</b></a> ( QObject&nbsp;*&nbsp;obj )</li>
85</ul>
86<h2>Static Public Members</h2>
87<ul>
88<li class=fn>QString <a href="#tr"><b>tr</b></a> ( const&nbsp;char&nbsp;*&nbsp;sourceText, const&nbsp;char&nbsp;*&nbsp;comment )</li>
89<li class=fn>QString <a href="#trUtf8"><b>trUtf8</b></a> ( const&nbsp;char&nbsp;*&nbsp;sourceText, const&nbsp;char&nbsp;*&nbsp;comment )</li>
90<li class=fn>const QObjectList * <a href="#objectTrees"><b>objectTrees</b></a> ()</li>
91<li class=fn>bool <a href="#connect"><b>connect</b></a> ( const&nbsp;QObject&nbsp;*&nbsp;sender, const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;QObject&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member )</li>
92<li class=fn>bool <a href="#disconnect"><b>disconnect</b></a> ( const&nbsp;QObject&nbsp;*&nbsp;sender, const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;QObject&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member )</li>
93</ul>
94<h2>Properties</h2>
95<ul>
96<li class=fn>QCString <a href="#name-prop"><b>name</b></a>&nbsp;- the name of this object</li>
97</ul>
98<h2>Protected Members</h2>
99<ul>
100<li class=fn>const QObject * <a href="#sender"><b>sender</b></a> ()</li>
101<li class=fn>virtual void <a href="#timerEvent"><b>timerEvent</b></a> ( QTimerEvent * )</li>
102<li class=fn>virtual void <a href="#childEvent"><b>childEvent</b></a> ( QChildEvent * )</li>
103<li class=fn>virtual void <a href="#customEvent"><b>customEvent</b></a> ( QCustomEvent * )</li>
104<li class=fn>virtual void <a href="#connectNotify"><b>connectNotify</b></a> ( const&nbsp;char&nbsp;*&nbsp;signal )</li>
105<li class=fn>virtual void <a href="#disconnectNotify"><b>disconnectNotify</b></a> ( const&nbsp;char&nbsp;*&nbsp;signal )</li>
106<li class=fn>virtual bool <a href="#checkConnectArgs"><b>checkConnectArgs</b></a> ( const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;QObject&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member )</li>
107</ul>
108<h2>Static Protected Members</h2>
109<ul>
110<li class=fn>QCString <a href="#normalizeSignalSlot"><b>normalizeSignalSlot</b></a> ( const&nbsp;char&nbsp;*&nbsp;signalSlot )</li>
111</ul>
112<h2>Related Functions</h2>
113<ul>
114<li class=fn>void * <a href="#qt_find_obj_child"><b>qt_find_obj_child</b></a> ( QObject&nbsp;*&nbsp;parent, const&nbsp;char&nbsp;*&nbsp;type, const&nbsp;char&nbsp;*&nbsp;name )</li>
115</ul>
116<hr><a name="details"></a><h2>Detailed Description</h2>
117
118
119The QObject class is the base class of all Qt objects.
120<p>
121
122
123<p> QObject is the heart of the <a href="object.html">Qt object model.</a> The central feature in this model is a very powerful
124mechanism for seamless object communication called <a href="signalsandslots.html">signals and slots</a>. You can
125connect a signal to a slot with <a href="#connect">connect</a>() and destroy the
126connection with <a href="#disconnect">disconnect</a>(). To avoid never ending notification
127loops you can temporarily block signals with <a href="#blockSignals">blockSignals</a>(). The
128protected functions <a href="#connectNotify">connectNotify</a>() and <a href="#disconnectNotify">disconnectNotify</a>() make it
129possible to track connections.
130<p> QObjects organize themselves in object trees. When you create a
131QObject with another object as parent, the object will
132automatically do an <a href="#insertChild">insertChild</a>() on the parent and thus show up
133in the parent's <a href="#children">children</a>() list. The parent takes ownership of the
134object i.e. it will automatically delete its children in its
135destructor. You can look for an object by name and optionally type
136using <a href="#child">child</a>() or <a href="#queryList">queryList</a>(), and get the list of tree roots using
137<a href="#objectTrees">objectTrees</a>().
138<p> Every object has an object <a href="#name">name</a>() and can report its <a href="#className">className</a>()
139and whether it <a href="#inherits">inherits</a>() another class in the QObject inheritance
140hierarchy.
141<p> When an object is deleted, it emits a <a href="#destroyed">destroyed</a>() signal. You can
142catch this signal to avoid dangling references to QObjects. The
143<a href="qguardedptr.html">QGuardedPtr</a> class provides an elegant way to use this feature.
144<p> QObjects can receive events through <a href="#event">event</a>() and filter the events
145of other objects. See <a href="#installEventFilter">installEventFilter</a>() and <a href="#eventFilter">eventFilter</a>() for
146details. A convenience handler, <a href="#childEvent">childEvent</a>(), can be reimplemented
147to catch child events.
148<p> Last but not least, QObject provides the basic timer support in
149Qt; see <a href="qtimer.html">QTimer</a> for high-level support for timers.
150<p> Notice that the <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a> macro is mandatory for any object that
151implements signals, slots or properties. You also need to run the
152<a href="moc.html">moc program (Meta Object Compiler)</a> on the
153source file. We strongly recommend the use of this macro in <em>all</em>
154subclasses of QObject regardless of whether or not they actually
155use signals, slots and properties, since failure to do so may lead
156certain functions to exhibit undefined behaviour.
157<p> All Qt widgets inherit QObject. The convenience function
158<a href="#isWidgetType">isWidgetType</a>() returns whether an object is actually a widget. It
159is much faster than <a href="#inherits">inherits</a>( "QWidget" ).
160<p> Some QObject functions, e.g. <a href="#children">children</a>(), <a href="#objectTrees">objectTrees</a>() and
161<a href="#queryList">queryList</a>() return a <a href="qobjectlist.html">QObjectList</a>. A QObjectList is a <a href="qptrlist.html">QPtrList</a> of
162QObjects. QObjectLists support the same operations as QPtrLists
163and have an iterator class, QObjectListIt.
164<p>See also <a href="objectmodel.html">Object Model</a>.
165
166<hr><h2>Member Function Documentation</h2>
167<h3 class=fn><a name="QObject"></a>QObject::QObject ( <a href="qobject.html">QObject</a>&nbsp;*&nbsp;parent = 0, const&nbsp;char&nbsp;*&nbsp;name = 0 )
168</h3>
169Constructs an object called <em>name</em> with parent object, <em>parent</em>.
170<p> The parent of an object may be viewed as the object's owner. For
171instance, a <a href="qdialog.html">dialog box</a> is the parent of the
172"OK" and "Cancel" buttons it contains.
173<p> The destructor of a parent object destroys all child objects.
174<p> Setting <em>parent</em> to 0 constructs an object with no parent. If the
175object is a widget, it will become a top-level window.
176<p> The object name is some text that can be used to identify a
177QObject. It's particularly useful in conjunction with <a href="designer-manual.html"><i>Qt Designer</i></a>. You can find an
178object by name (and type) using <a href="#child">child</a>(). To find several objects
179use <a href="#queryList">queryList</a>().
180<p> <p>See also <a href="#parent">parent</a>(), <a href="#name-prop">name</a>, <a href="#child">child</a>(), and <a href="#queryList">queryList</a>().
181
182<h3 class=fn><a name="~QObject"></a>QObject::~QObject ()<tt> [virtual]</tt>
183</h3>
184Destroys the object, deleting all its child objects.
185<p> All signals to and from the object are automatically disconnected.
186<p> <b>Warning:</b> All child objects are deleted. If any of these objects
187are on the stack or global, sooner or later your program will
188crash. We do not recommend holding pointers to child objects from
189outside the parent. If you still do, the <a href="#destroyed">QObject::destroyed</a>()
190signal gives you an opportunity to detect when an object is
191destroyed.
192<p> <b>Warning:</b> Deleting a QObject while pending events are waiting to be
193delivered can cause a crash. You must not delete the QObject
194directly from a thread that is not the GUI thread. Use the
195<a href="#deleteLater">QObject::deleteLater</a>() method instead, which will cause the event
196loop to delete the object after all pending events have been
197delivered to the object.
198
199<h3 class=fn>void <a name="blockSignals"></a>QObject::blockSignals ( bool&nbsp;block )
200</h3>
201Blocks signals if <em>block</em> is TRUE, or unblocks signals if <em>block</em> is FALSE.
202<p> Emitted signals disappear into hyperspace if signals are blocked.
203Note that the <a href="#destroyed">destroyed</a>() signals will be emitted even if the signals
204for this object have been blocked.
205
206<p>Examples: <a href="rot-example.html#x1371">rot13/rot13.cpp</a> and <a href="qaxserver-example-simple.html#x2525">simple/main.cpp</a>.
207<h3 class=fn>bool <a name="checkConnectArgs"></a>QObject::checkConnectArgs ( const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member )<tt> [virtual protected]</tt>
208</h3>
209
210<p> Returns TRUE if the <em>signal</em> and the <em>member</em> arguments are
211compatible; otherwise returns FALSE. (The <em>receiver</em> argument is
212currently ignored.)
213<p> <b>Warning:</b> We recommend that you use the default implementation and
214do not reimplement this function.
215<p>
216
217<h3 class=fn><a href="qobject.html">QObject</a>&nbsp;* <a name="child"></a>QObject::child ( const&nbsp;char&nbsp;*&nbsp;objName, const&nbsp;char&nbsp;*&nbsp;inheritsClass = 0, bool&nbsp;recursiveSearch = TRUE )
218</h3>
219Searches the children and optionally grandchildren of this object,
220and returns a child that is called <em>objName</em> that inherits <em>inheritsClass</em>. If <em>inheritsClass</em> is 0 (the default), any class
221matches.
222<p> If <em>recursiveSearch</em> is TRUE (the default), <a href="#child">child</a>() performs a
223depth-first search of the object's children.
224<p> If there is no such object, this function returns 0. If there are
225more than one, the first one found is retured; if you need all of
226them, use <a href="#queryList">queryList</a>().
227
228<h3 class=fn>void <a name="childEvent"></a>QObject::childEvent ( <a href="qchildevent.html">QChildEvent</a>&nbsp;* )<tt> [virtual protected]</tt>
229</h3>
230This event handler can be reimplemented in a subclass to receive
231child events.
232<p> Child events are sent to objects when children are inserted or
233removed.
234<p> Note that events with <a href="qevent.html#type">QEvent::type</a>() <a href="qevent.html#Type-enum">QEvent::ChildInserted</a> are
235posted (with <a href="qapplication.html#postEvent">QApplication::postEvent</a>()) to make sure that the
236child's construction is completed before this function is called.
237<p> If a child is removed immediately after it is inserted, the <tt>ChildInserted</tt> event may be suppressed, but the <tt>ChildRemoved</tt>
238event will always be sent. In such cases it is possible that there
239will be a <tt>ChildRemoved</tt> event without a corresponding <tt>ChildInserted</tt> event.
240<p> If you change state based on <tt>ChildInserted</tt> events, call
241<a href="qwidget.html#constPolish">QWidget::constPolish</a>(), or do
242<pre>
243 QApplication::<a href="qapplication.html#sendPostedEvents">sendPostedEvents</a>( this, QEvent::ChildInserted );
244 </pre>
245
246in functions that depend on the state. One notable example is
247<a href="qwidget.html#sizeHint">QWidget::sizeHint</a>().
248<p> <p>See also <a href="#event">event</a>() and <a href="qchildevent.html">QChildEvent</a>.
249
250<p>Reimplemented in <a href="qmainwindow.html#childEvent">QMainWindow</a> and <a href="qsplitter.html#childEvent">QSplitter</a>.
251<h3 class=fn>const&nbsp;<a href="qobjectlist.html">QObjectList</a>&nbsp;* <a name="children"></a>QObject::children () const
252</h3>
253
254<p> Returns a list of child objects, or 0 if this object has no
255children.
256<p> The <a href="qobjectlist.html">QObjectList</a> class is defined in the <a href="qobjectlist-h.html">qobjectlist.h</a> header
257file.
258<p> The first child added is the <a href="qptrlist.html#first">first</a>
259object in the list and the last child added is the <a href="qptrlist.html#last">last</a> object in the list, i.e. new
260children are appended at the end.
261<p> Note that the list order changes when <a href="qwidget.html">QWidget</a> children are <a href="qwidget.html#raise">raised</a> or <a href="qwidget.html#lower">lowered.</a> A widget that is raised becomes the last object
262in the list, and a widget that is lowered becomes the first object
263in the list.
264<p> <p>See also <a href="#child">child</a>(), <a href="#queryList">queryList</a>(), <a href="#parent">parent</a>(), <a href="#insertChild">insertChild</a>(), and <a href="#removeChild">removeChild</a>().
265
266<h3 class=fn>const char * <a name="className"></a>QObject::className () const<tt> [virtual]</tt>
267</h3>
268
269<p> Returns the class name of this object.
270<p> This function is generated by the <a href="metaobjects.html">Meta
271 Object Compiler.</a>
272<p> <b>Warning:</b> This function will return the wrong name if the class
273definition lacks the <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a> macro.
274<p> <p>See also <a href="#name-prop">name</a>, <a href="#inherits">inherits</a>(), <a href="#isA">isA</a>(), and <a href="#isWidgetType">isWidgetType</a>().
275
276<p>Example: <a href="sql.html#x2235">sql/overview/custom1/main.cpp</a>.
277<h3 class=fn>bool <a name="connect"></a>QObject::connect ( const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;sender, const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member )<tt> [static]</tt>
278</h3>
279Connects <em>signal</em> from the <em>sender</em> object to <em>member</em> in object
280<em>receiver</em>, and returns TRUE if the connection succeeds; otherwise
281returns FALSE.
282<p> You must use the SIGNAL() and SLOT() macros when specifying the <em>signal</em>
283and the <em>member</em>, for example:
284<pre>
285 <a href="qlabel.html">QLabel</a> *label = new <a href="qlabel.html">QLabel</a>;
286 <a href="qscrollbar.html">QScrollBar</a> *scroll = new <a href="qscrollbar.html">QScrollBar</a>;
287 QObject::<a href="#connect">connect</a>( scroll, SIGNAL(<a href="qscrollbar.html#valueChanged">valueChanged</a>(int)),
288 label, SLOT(<a href="qlabel.html#setNum">setNum</a>(int)) );
289 </pre>
290
291<p> This example ensures that the label always displays the current
292scroll bar value. Note that the signal and slots parameters must not
293contain any variable names, only the type. E.g. the following would
294not work and return FALSE:
295<a href="#connect">QObject::connect</a>( scroll, SIGNAL(valueChanged(int v)),
296label, SLOT(setNum(int v)) );
297<p> A signal can also be connected to another signal:
298<p> <pre>
299 class MyWidget : public <a href="qwidget.html">QWidget</a>
300 {
301 <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
302 public:
303 MyWidget();
304
305 signals:
306 void myUsefulSignal();
307
308 private:
309 <a href="qpushbutton.html">QPushButton</a> *aButton;
310 };
311
312 MyWidget::MyWidget()
313 {
314 aButton = new <a href="qpushbutton.html">QPushButton</a>( this );
315 <a href="#connect">connect</a>( aButton, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), SIGNAL(myUsefulSignal()) );
316 }
317 </pre>
318
319<p> In this example, the MyWidget constructor relays a signal from a
320private member variable, and makes it available under a name that
321relates to MyWidget.
322<p> A signal can be connected to many slots and signals. Many signals
323can be connected to one slot.
324<p> If a signal is connected to several slots, the slots are activated
325in an arbitrary order when the signal is emitted.
326<p> The function returns TRUE if it successfully connects the signal
327to the slot. It will return FALSE if it cannot create the
328connection, for example, if QObject is unable to verify the
329existence of either <em>signal</em> or <em>member</em>, or if their signatures
330aren't compatible.
331<p> A signal is emitted for <em>every</em> connection you make, so if you
332duplicate a connection, two signals will be emitted. You can
333always break a connection using <a href="#disconnect">disconnect</a>().
334<p> <p>See also <a href="#disconnect">disconnect</a>().
335
336<p>Examples: <a href="qaction-application-example.html#x1179">action/main.cpp</a>, <a href="simple-application-example.html#x1599">application/main.cpp</a>, <a href="extension-dialog-example.html#x2868">extension/main.cpp</a>, <a href="iconview-example.html#x1460">iconview/main.cpp</a>, <a href="archivesearch-example.html#x489">network/archivesearch/main.cpp</a>, <a href="regexptester-example.html#x2512">regexptester/main.cpp</a>, and <a href="tutorial1-02.html#x2291">t2/main.cpp</a>.
337<h3 class=fn>bool <a name="connect-2"></a>QObject::connect ( const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;sender, const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;char&nbsp;*&nbsp;member ) const
338</h3>
339This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
340<p> Connects <em>signal</em> from the <em>sender</em> object to this object's <em>member</em>.
341<p> Equivalent to: <tt>QObject::connect(sender, signal, this, member)</tt>.
342<p> <p>See also <a href="#disconnect">disconnect</a>().
343
344<h3 class=fn>void <a name="connectNotify"></a>QObject::connectNotify ( const&nbsp;char&nbsp;*&nbsp;signal )<tt> [virtual protected]</tt>
345</h3>
346
347<p> This virtual function is called when something has been connected
348to <em>signal</em> in this object.
349<p> <b>Warning:</b> This function violates the object-oriented principle of
350modularity. However, it might be useful when you need to perform
351expensive initialization only if something is connected to a
352signal.
353<p> <p>See also <a href="#connect">connect</a>() and <a href="#disconnectNotify">disconnectNotify</a>().
354
355<h3 class=fn>void <a name="customEvent"></a>QObject::customEvent ( <a href="qcustomevent.html">QCustomEvent</a>&nbsp;* )<tt> [virtual protected]</tt>
356</h3>
357This event handler can be reimplemented in a subclass to receive
358custom events. Custom events are user-defined events with a type
359value at least as large as the "User" item of the <a href="qevent.html#Type-enum">QEvent::Type</a>
360enum, and is typically a <a href="qcustomevent.html">QCustomEvent</a> or QCustomEvent subclass.
361<p> <p>See also <a href="#event">event</a>() and <a href="qcustomevent.html">QCustomEvent</a>.
362
363<h3 class=fn>void <a name="deleteLater"></a>QObject::deleteLater ()<tt> [slot]</tt>
364</h3>
365Performs a deferred deletion of this object.
366<p> Instead of an immediate deletion this function schedules a
367deferred delete event for processing when Qt returns to the main
368event loop.
369
370<p>Example: <a href="bigtable-example.html#x1290">table/bigtable/main.cpp</a>.
371<h3 class=fn>void <a name="destroyed"></a>QObject::destroyed ()<tt> [signal]</tt>
372</h3>
373
374<p> This signal is emitted when the object is being destroyed.
375<p> Note that the signal is emitted by the QObject destructor, so
376the object's virtual table is already degenerated at this point,
377and it is not safe to call any functions on the object emitting
378the signal. This signal can not be blocked.
379<p> All the objects's children are destroyed immediately after this
380signal is emitted.
381
382<h3 class=fn>void <a name="destroyed-2"></a>QObject::destroyed ( <a href="qobject.html">QObject</a>&nbsp;*&nbsp;obj )<tt> [signal]</tt>
383</h3>
384This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
385<p> This signal is emitted immediately before the object <em>obj</em> is
386destroyed, and can not be blocked.
387<p> All the objects's children are destroyed immediately after this
388signal is emitted.
389
390<h3 class=fn>bool <a name="disconnect"></a>QObject::disconnect ( const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;sender, const&nbsp;char&nbsp;*&nbsp;signal, const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member )<tt> [static]</tt>
391</h3>
392Disconnects <em>signal</em> in object <em>sender</em> from <em>member</em> in object
393<em>receiver</em>.
394<p> A signal-slot connection is removed when either of the objects
395involved are destroyed.
396<p> <a href="#disconnect">disconnect</a>() is typically used in three ways, as the following
397examples demonstrate.
398<ol type=1>
399<li> Disconnect everything connected to an object's signals:
400<pre>
401 <a href="#disconnect">disconnect</a>( myObject, 0, 0, 0 );
402 </pre>
403
404equivalent to the non-static overloaded function
405<pre>
406 myObject-&gt;disconnect();
407 </pre>
408
409<li> Disconnect everything connected to a specific signal:
410<pre>
411 <a href="#disconnect">disconnect</a>( myObject, SIGNAL(mySignal()), 0, 0 );
412 </pre>
413
414equivalent to the non-static overloaded function
415<pre>
416 myObject-&gt;disconnect( SIGNAL(mySignal()) );
417 </pre>
418
419<li> Disconnect a specific receiver:
420<pre>
421 <a href="#disconnect">disconnect</a>( myObject, 0, myReceiver, 0 );
422 </pre>
423
424equivalent to the non-static overloaded function
425<pre>
426 myObject-&gt;disconnect( myReceiver );
427 </pre>
428
429</ol>
430<p> 0 may be used as a wildcard, meaning "any signal", "any receiving
431object", or "any slot in the receiving object", respectively.
432<p> The <em>sender</em> may never be 0. (You cannot disconnect signals from
433more than one object in a single call.)
434<p> If <em>signal</em> is 0, it disconnects <em>receiver</em> and <em>member</em> from
435any signal. If not, only the specified signal is disconnected.
436<p> If <em>receiver</em> is 0, it disconnects anything connected to <em>signal</em>. If not, slots in objects other than <em>receiver</em> are not
437disconnected.
438<p> If <em>member</em> is 0, it disconnects anything that is connected to <em>receiver</em>. If not, only slots named <em>member</em> will be disconnected,
439and all other slots are left alone. The <em>member</em> must be 0 if <em>receiver</em> is left out, so you cannot disconnect a
440specifically-named slot on all objects.
441<p> <p>See also <a href="#connect">connect</a>().
442
443<h3 class=fn>bool <a name="disconnect-2"></a>QObject::disconnect ( const&nbsp;char&nbsp;*&nbsp;signal = 0, const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;receiver = 0, const&nbsp;char&nbsp;*&nbsp;member = 0 )
444</h3>
445This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
446<p> Disconnects <em>signal</em> from <em>member</em> of <em>receiver</em>.
447<p> A signal-slot connection is removed when either of the objects
448involved are destroyed.
449
450<h3 class=fn>bool <a name="disconnect-3"></a>QObject::disconnect ( const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;receiver, const&nbsp;char&nbsp;*&nbsp;member = 0 )
451</h3>
452This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
453<p> Disconnects all signals in this object from <em>receiver</em>'s <em>member</em>.
454<p> A signal-slot connection is removed when either of the objects
455involved are destroyed.
456
457<h3 class=fn>void <a name="disconnectNotify"></a>QObject::disconnectNotify ( const&nbsp;char&nbsp;*&nbsp;signal )<tt> [virtual protected]</tt>
458</h3>
459
460<p> This virtual function is called when something has been
461disconnected from <em>signal</em> in this object.
462<p> <b>Warning:</b> This function violates the object-oriented principle of
463modularity. However, it might be useful for optimizing access to
464expensive resources.
465<p> <p>See also <a href="#disconnect">disconnect</a>() and <a href="#connectNotify">connectNotify</a>().
466
467<h3 class=fn>void <a name="dumpObjectInfo"></a>QObject::dumpObjectInfo ()
468</h3>
469Dumps information about signal connections, etc. for this object
470to the debug output.
471<p> This function is useful for debugging, but does nothing if the
472library has been compiled in release mode (i.e. without debugging
473information).
474
475<h3 class=fn>void <a name="dumpObjectTree"></a>QObject::dumpObjectTree ()
476</h3>
477Dumps a tree of children to the debug output.
478<p> This function is useful for debugging, but does nothing if the
479library has been compiled in release mode (i.e. without debugging
480information).
481
482<h3 class=fn>bool <a name="event"></a>QObject::event ( <a href="qevent.html">QEvent</a>&nbsp;*&nbsp;e )<tt> [virtual]</tt>
483</h3>
484This virtual function receives events to an object and should
485return TRUE if the event <em>e</em> was recognized and processed.
486<p> The <a href="#event">event</a>() function can be reimplemented to customize the
487behavior of an object.
488<p> <p>See also <a href="#installEventFilter">installEventFilter</a>(), <a href="#timerEvent">timerEvent</a>(), <a href="qapplication.html#sendEvent">QApplication::sendEvent</a>(), <a href="qapplication.html#postEvent">QApplication::postEvent</a>(), and <a href="qwidget.html#event">QWidget::event</a>().
489
490<p>Reimplemented in <a href="qwidget.html#event">QWidget</a>.
491<h3 class=fn>bool <a name="eventFilter"></a>QObject::eventFilter ( <a href="qobject.html">QObject</a>&nbsp;*&nbsp;watched, <a href="qevent.html">QEvent</a>&nbsp;*&nbsp;e )<tt> [virtual]</tt>
492</h3>
493Filters events if this object has been installed as an event
494filter for the <em>watched</em> object.
495<p> In your reimplementation of this function, if you want to filter
496the event <em>e</em>, out, i.e. stop it being handled further, return
497TRUE; otherwise return FALSE.
498<p> Example:
499<pre>
500 class MyMainWindow : public <a href="qmainwindow.html">QMainWindow</a>
501 {
502 public:
503 MyMainWindow( <a href="qwidget.html">QWidget</a> *parent = 0, const char *name = 0 );
504
505 protected:
506 bool eventFilter( QObject *obj, QEvent *ev );
507
508 private:
509 <a href="qtextedit.html">QTextEdit</a> *textEdit;
510 };
511
512 MyMainWindow::MyMainWindow( <a href="qwidget.html">QWidget</a> *parent, const char *name )
513 : <a href="qmainwindow.html">QMainWindow</a>( parent, name )
514 {
515 textEdit = new <a href="qtextedit.html">QTextEdit</a>( this );
516 <a href="qmainwindow.html#setCentralWidget">setCentralWidget</a>( textEdit );
517 textEdit-&gt;<a href="#installEventFilter">installEventFilter</a>( this );
518 }
519
520 bool MyMainWindow::<a href="#eventFilter">eventFilter</a>( QObject *obj, QEvent *ev )
521 {
522 if ( obj == textEdit ) {
523 if ( e-&gt;type() == QEvent::KeyPress ) {
524 <a href="qkeyevent.html">QKeyEvent</a> *k = (QKeyEvent*)ev;
525 <a href="qapplication.html#qDebug">qDebug</a>( "Ate key press %d", k-&gt;<a href="qkeyevent.html#key">key</a>() );
526 return TRUE;
527 } else {
528 return FALSE;
529 }
530 } else {
531 // pass the event on to the parent class
532 return QMainWindow::eventFilter( obj, ev );
533 }
534 }
535 </pre>
536
537<p> Notice in the example above that unhandled events are passed to
538the base class's <a href="#eventFilter">eventFilter</a>() function, since the base class
539might have reimplemented eventFilter() for its own internal
540purposes.
541<p> <b>Warning:</b> If you delete the receiver object in this function, be
542sure to return TRUE. Otherwise, Qt will forward the event to the
543deleted object and the program might crash.
544<p> <p>See also <a href="#installEventFilter">installEventFilter</a>().
545
546<p>Reimplemented in <a href="qaccel.html#eventFilter">QAccel</a>, <a href="qscrollview.html#eventFilter">QScrollView</a>, and <a href="qspinbox.html#eventFilter">QSpinBox</a>.
547<h3 class=fn>bool <a name="highPriority"></a>QObject::highPriority () const
548</h3>
549
550<p> Returns TRUE if the object is a high-priority object, or FALSE if
551it is a standard-priority object.
552<p> High-priority objects are placed first in QObject's list of
553children on the assumption that they will be referenced very
554often.
555
556<h3 class=fn>bool <a name="inherits"></a>QObject::inherits ( const&nbsp;char&nbsp;*&nbsp;clname ) const
557</h3>
558Returns TRUE if this object is an instance of a class that
559inherits <em>clname</em>, and <em>clname</em> inherits QObject; otherwise
560returns FALSE.
561<p> A class is considered to inherit itself.
562<p> Example:
563<pre>
564 <a href="qtimer.html">QTimer</a> *t = new <a href="qtimer.html">QTimer</a>; // QTimer inherits QObject
565 t-&gt;<a href="#inherits">inherits</a>( "QTimer" ); // returns TRUE
566 t-&gt;<a href="#inherits">inherits</a>( "QObject" ); // returns TRUE
567 t-&gt;<a href="#inherits">inherits</a>( "QButton" ); // returns FALSE
568
569 // QScrollBar inherits QWidget and QRangeControl
570 <a href="qscrollbar.html">QScrollBar</a> *s = new <a href="qscrollbar.html">QScrollBar</a>( 0 );
571 s-&gt;<a href="#inherits">inherits</a>( "QWidget" ); // returns TRUE
572 s-&gt;<a href="#inherits">inherits</a>( "QRangeControl" ); // returns FALSE
573 </pre>
574
575<p> (<a href="qrangecontrol.html">QRangeControl</a> is not a QObject.)
576<p> <p>See also <a href="#isA">isA</a>() and <a href="#metaObject">metaObject</a>().
577
578<p>Examples: <a href="statistics-example.html#x2783">table/statistics/statistics.cpp</a>, <a href="themes-example.html#x282">themes/metal.cpp</a>, and <a href="themes-example.html#x211">themes/wood.cpp</a>.
579<h3 class=fn>void <a name="insertChild"></a>QObject::insertChild ( <a href="qobject.html">QObject</a>&nbsp;*&nbsp;obj )<tt> [virtual]</tt>
580</h3>
581Inserts an object <em>obj</em> into the list of child objects.
582<p> <b>Warning:</b> This function cannot be used to make one widget the child
583widget of another widget. Child widgets can only be created by
584setting the parent widget in the constructor or by calling
585<a href="qwidget.html#reparent">QWidget::reparent</a>().
586<p> <p>See also <a href="#removeChild">removeChild</a>() and <a href="qwidget.html#reparent">QWidget::reparent</a>().
587
588<h3 class=fn>void <a name="installEventFilter"></a>QObject::installEventFilter ( const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;filterObj )
589</h3>
590
591<p> Installs an event filter <em>filterObj</em> on this object. For example:
592<pre>
593 monitoredObj-&gt;installEventFilter( filterObj );
594 </pre>
595
596<p> An event filter is an object that receives all events that are
597sent to this object. The filter can either stop the event or
598forward it to this object. The event filter <em>filterObj</em> receives
599events via its <a href="#eventFilter">eventFilter</a>() function. The eventFilter() function
600must return TRUE if the event should be filtered, (i.e. stopped);
601otherwise it must return FALSE.
602<p> If multiple event filters are installed on a single object, the
603filter that was installed last is activated first.
604<p> Here's a <tt>KeyPressEater</tt> class that eats the key presses of its
605monitored objects:
606<pre>
607 class KeyPressEater : public QObject
608 {
609 ...
610 protected:
611 bool eventFilter( QObject *o, QEvent *e );
612 };
613
614 bool KeyPressEater::<a href="#eventFilter">eventFilter</a>( QObject *o, QEvent *e )
615 {
616 if ( e-&gt;type() == QEvent::KeyPress ) {
617 // special processing for key press
618 <a href="qkeyevent.html">QKeyEvent</a> *k = (QKeyEvent *)e;
619 <a href="qapplication.html#qDebug">qDebug</a>( "Ate key press %d", k-&gt;<a href="qkeyevent.html#key">key</a>() );
620 return TRUE; // eat event
621 } else {
622 // standard event processing
623 return FALSE;
624 }
625 }
626 </pre>
627
628<p> And here's how to install it on two widgets:
629<pre>
630 KeyPressEater *keyPressEater = new KeyPressEater( this );
631 <a href="qpushbutton.html">QPushButton</a> *pushButton = new <a href="qpushbutton.html">QPushButton</a>( this );
632 <a href="qlistview.html">QListView</a> *listView = new <a href="qlistview.html">QListView</a>( this );
633
634 pushButton-&gt;<a href="#installEventFilter">installEventFilter</a>( keyPressEater );
635 listView-&gt;<a href="#installEventFilter">installEventFilter</a>( keyPressEater );
636 </pre>
637
638<p> The <a href="qaccel.html">QAccel</a> class, for example, uses this technique to intercept
639accelerator key presses.
640<p> <b>Warning:</b> If you delete the receiver object in your <a href="#eventFilter">eventFilter</a>()
641function, be sure to return TRUE. If you return FALSE, Qt sends
642the event to the deleted object and the program will crash.
643<p> <p>See also <a href="#removeEventFilter">removeEventFilter</a>(), <a href="#eventFilter">eventFilter</a>(), and <a href="#event">event</a>().
644
645<h3 class=fn>bool <a name="isA"></a>QObject::isA ( const&nbsp;char&nbsp;*&nbsp;clname ) const
646</h3>
647Returns TRUE if this object is an instance of the class <em>clname</em>;
648otherwise returns FALSE.
649<p> Example:
650<pre>
651 <a href="qtimer.html">QTimer</a> *t = new <a href="qtimer.html">QTimer</a>; // QTimer inherits QObject
652 t-&gt;<a href="#isA">isA</a>( "QTimer" ); // returns TRUE
653 t-&gt;<a href="#isA">isA</a>( "QObject" ); // returns FALSE
654 </pre>
655
656<p> <p>See also <a href="#inherits">inherits</a>() and <a href="#metaObject">metaObject</a>().
657
658<h3 class=fn>bool <a name="isWidgetType"></a>QObject::isWidgetType () const
659</h3>
660
661<p> Returns TRUE if the object is a widget; otherwise returns FALSE.
662<p> Calling this function is equivalent to calling
663<a href="#inherits">inherits</a>("QWidget"), except that it is much faster.
664
665<h3 class=fn>void <a name="killTimer"></a>QObject::killTimer ( int&nbsp;id )
666</h3>
667Kills the timer with timer identifier, <em>id</em>.
668<p> The timer identifier is returned by <a href="#startTimer">startTimer</a>() when a timer
669event is started.
670<p> <p>See also <a href="#timerEvent">timerEvent</a>(), <a href="#startTimer">startTimer</a>(), and <a href="#killTimers">killTimers</a>().
671
672<h3 class=fn>void <a name="killTimers"></a>QObject::killTimers ()
673</h3>
674Kills all timers that this object has started.
675<p> <b>Warning:</b> Using this function can cause hard-to-find bugs: it kills
676timers started by sub- and superclasses as well as those started
677by you, which is often not what you want. We recommend using a
678<a href="qtimer.html">QTimer</a> or perhaps <a href="#killTimer">killTimer</a>().
679<p> <p>See also <a href="#timerEvent">timerEvent</a>(), <a href="#startTimer">startTimer</a>(), and <a href="#killTimer">killTimer</a>().
680
681<h3 class=fn><a href="qmetaobject.html">QMetaObject</a>&nbsp;* <a name="metaObject"></a>QObject::metaObject () const<tt> [virtual]</tt>
682</h3>
683
684<p> Returns a pointer to the <a href="metaobjects.html#meta-object">meta object</a> of this object.
685<p> A meta object contains information about a class that inherits
686QObject, e.g. class name, superclass name, properties, signals and
687slots. Every class that contains the <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a> macro will also have
688a meta object.
689<p> The meta object information is required by the signal/slot
690connection mechanism and the property system. The functions <a href="#isA">isA</a>()
691and <a href="#inherits">inherits</a>() also make use of the meta object.
692
693<h3 class=fn>const char * <a name="name"></a>QObject::name () const
694</h3><p>Returns the name of this object.
695See the <a href="qobject.html#name-prop">"name"</a> property for details.
696<h3 class=fn>const char * <a name="name-2"></a>QObject::name ( const&nbsp;char&nbsp;*&nbsp;defaultName ) const
697</h3>
698This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
699<p> Returns the name of this object, or <em>defaultName</em> if the object
700does not have a name.
701
702<h3 class=fn><a href="qcstring.html">QCString</a> <a name="normalizeSignalSlot"></a>QObject::normalizeSignalSlot ( const&nbsp;char&nbsp;*&nbsp;signalSlot )<tt> [static protected]</tt>
703</h3>
704Normlizes the signal or slot definition <em>signalSlot</em> by removing
705unnecessary whitespace.
706
707<h3 class=fn>const&nbsp;<a href="qobjectlist.html">QObjectList</a>&nbsp;* <a name="objectTrees"></a>QObject::objectTrees ()<tt> [static]</tt>
708</h3>
709Returns a pointer to the list of all object trees (their root
710objects), or 0 if there are no objects.
711<p> The <a href="qobjectlist.html">QObjectList</a> class is defined in the <a href="qobjectlist-h.html">qobjectlist.h</a> header
712file.
713<p> The most recent root object created is the <a href="qptrlist.html#first">first</a> object in the list and the first root object added
714is the <a href="qptrlist.html#last">last</a> object in the list.
715<p> <p>See also <a href="#children">children</a>(), <a href="#parent">parent</a>(), <a href="#insertChild">insertChild</a>(), and <a href="#removeChild">removeChild</a>().
716
717<h3 class=fn><a href="qobject.html">QObject</a>&nbsp;* <a name="parent"></a>QObject::parent () const
718</h3>
719
720<p> Returns a pointer to the parent object.
721<p> <p>See also <a href="#children">children</a>().
722
723<h3 class=fn><a href="qvariant.html">QVariant</a> <a name="property"></a>QObject::property ( const&nbsp;char&nbsp;*&nbsp;name ) const<tt> [virtual]</tt>
724</h3>
725Returns the value of the object's <em>name</em> property.
726<p> If no such property exists, the returned variant is invalid.
727<p> Information about all available properties are provided through
728the <a href="#metaObject">metaObject</a>().
729<p> <p>See also <a href="#setProperty">setProperty</a>(), <a href="qvariant.html#isValid">QVariant::isValid</a>(), <a href="#metaObject">metaObject</a>(), <a href="qmetaobject.html#propertyNames">QMetaObject::propertyNames</a>(), and <a href="qmetaobject.html#property">QMetaObject::property</a>().
730
731<p>Example: <a href="qaxcontainer-example-qutlook.html#x2729">qutlook/centralwidget.cpp</a>.
732<h3 class=fn><a href="qobjectlist.html">QObjectList</a>&nbsp;* <a name="queryList"></a>QObject::queryList ( const&nbsp;char&nbsp;*&nbsp;inheritsClass = 0, const&nbsp;char&nbsp;*&nbsp;objName = 0, bool&nbsp;regexpMatch = TRUE, bool&nbsp;recursiveSearch = TRUE ) const
733</h3>
734Searches the children and optionally grandchildren of this object,
735and returns a list of those objects that are named or that match
736<em>objName</em> and inherit <em>inheritsClass</em>. If <em>inheritsClass</em> is 0
737(the default), all classes match. If <em>objName</em> is 0 (the
738default), all object names match.
739<p> If <em>regexpMatch</em> is TRUE (the default), <em>objName</em> is a <a href="qregexp.html#regular-expression">regular expression</a> that the objects's names must match. The syntax is that
740of a <a href="qregexp.html">QRegExp</a>. If <em>regexpMatch</em> is FALSE, <em>objName</em> is a string
741and object names must match it exactly.
742<p> Note that <em>inheritsClass</em> uses single inheritance from QObject,
743the way <a href="#inherits">inherits</a>() does. According to inherits(), <a href="qmenubar.html">QMenuBar</a>
744inherits <a href="qwidget.html">QWidget</a> but not <a href="qmenudata.html">QMenuData</a>. This does not quite match
745reality, but is the best that can be done on the wide variety of
746compilers Qt supports.
747<p> Finally, if <em>recursiveSearch</em> is TRUE (the default), <a href="#queryList">queryList</a>()
748searches <em>n</em>th-generation as well as first-generation children.
749<p> If all this seems a bit complex for your needs, the simpler
750<a href="#child">child</a>() function may be what you want.
751<p> This somewhat contrived example disables all the buttons in this
752window:
753<pre>
754 <a href="qobjectlist.html">QObjectList</a> *l = topLevelWidget()-&gt;queryList( "QButton" );
755 QObjectListIt it( *l ); // iterate over the buttons
756 QObject *obj;
757
758 while ( (obj = it.current()) != 0 ) {
759 // for each found object...
760 ++it;
761 ((QButton*)obj)-&gt;setEnabled( FALSE );
762 }
763 delete l; // delete the list, not the objects
764 </pre>
765
766<p> The <a href="qobjectlist.html">QObjectList</a> class is defined in the <a href="qobjectlist-h.html">qobjectlist.h</a> header
767file.
768<p> <b>Warning:</b> Delete the list as soon you have finished using it. The
769list contains pointers that may become invalid at almost any time
770without notice (as soon as the user closes a window you may have
771dangling pointers, for example).
772<p> <p>See also <a href="#child">child</a>(), <a href="#children">children</a>(), <a href="#parent">parent</a>(), <a href="#inherits">inherits</a>(), <a href="#name-prop">name</a>, and <a href="qregexp.html">QRegExp</a>.
773
774<h3 class=fn>void <a name="removeChild"></a>QObject::removeChild ( <a href="qobject.html">QObject</a>&nbsp;*&nbsp;obj )<tt> [virtual]</tt>
775</h3>
776Removes the child object <em>obj</em> from the list of children.
777<p> <b>Warning:</b> This function will not remove a child widget from the
778screen. It will only remove it from the parent widget's list of
779children.
780<p> <p>See also <a href="#insertChild">insertChild</a>() and <a href="qwidget.html#reparent">QWidget::reparent</a>().
781
782<h3 class=fn>void <a name="removeEventFilter"></a>QObject::removeEventFilter ( const&nbsp;<a href="qobject.html">QObject</a>&nbsp;*&nbsp;obj )
783</h3>
784Removes an event filter object <em>obj</em> from this object. The
785request is ignored if such an event filter has not been installed.
786<p> All event filters for this object are automatically removed when
787this object is destroyed.
788<p> It is always safe to remove an event filter, even during event
789filter activation (i.e. from the <a href="#eventFilter">eventFilter</a>() function).
790<p> <p>See also <a href="#installEventFilter">installEventFilter</a>(), <a href="#eventFilter">eventFilter</a>(), and <a href="#event">event</a>().
791
792<h3 class=fn>const&nbsp;<a href="qobject.html">QObject</a>&nbsp;* <a name="sender"></a>QObject::sender ()<tt> [protected]</tt>
793</h3>
794Returns a pointer to the object that sent the signal, if called in
795a slot activated by a signal; otherwise it returns 0. The pointer
796is valid only during the execution of the slot that calls this
797function.
798<p> The pointer returned by this function becomes invalid if the
799sender is destroyed, or if the slot is disconnected from the
800sender's signal.
801<p> <b>Warning:</b> This function violates the object-oriented principle of
802modularity. However, getting access to the sender might be useful
803when many signals are connected to a single slot. The sender is
804undefined if the slot is called as a normal C++ function.
805
806<h3 class=fn>void <a name="setName"></a>QObject::setName ( const&nbsp;char&nbsp;*&nbsp;name )<tt> [virtual]</tt>
807</h3>
808Sets the object's name to <em>name</em>.
809
810<h3 class=fn>bool <a name="setProperty"></a>QObject::setProperty ( const&nbsp;char&nbsp;*&nbsp;name, const&nbsp;<a href="qvariant.html">QVariant</a>&nbsp;&amp;&nbsp;value )<tt> [virtual]</tt>
811</h3>
812Sets the value of the object's <em>name</em> property to <em>value</em>.
813<p> Returns TRUE if the operation was successful; otherwise returns
814FALSE.
815<p> Information about all available properties is provided through the
816<a href="#metaObject">metaObject</a>().
817<p> <p>See also <a href="#property">property</a>(), <a href="#metaObject">metaObject</a>(), <a href="qmetaobject.html#propertyNames">QMetaObject::propertyNames</a>(), and <a href="qmetaobject.html#property">QMetaObject::property</a>().
818
819<p>Example: <a href="qaxcontainer-example-qutlook.html#x2730">qutlook/centralwidget.cpp</a>.
820<h3 class=fn>bool <a name="signalsBlocked"></a>QObject::signalsBlocked () const
821</h3>
822
823<p> Returns TRUE if signals are blocked; otherwise returns FALSE.
824<p> Signals are not blocked by default.
825<p> <p>See also <a href="#blockSignals">blockSignals</a>().
826
827<h3 class=fn>int <a name="startTimer"></a>QObject::startTimer ( int&nbsp;interval )
828</h3>
829Starts a timer and returns a timer identifier, or returns zero if
830it could not start a timer.
831<p> A timer event will occur every <em>interval</em> milliseconds until
832<a href="#killTimer">killTimer</a>() or <a href="#killTimers">killTimers</a>() is called. If <em>interval</em> is 0, then
833the timer event occurs once every time there are no more window
834system events to process.
835<p> The virtual <a href="#timerEvent">timerEvent</a>() function is called with the <a href="qtimerevent.html">QTimerEvent</a>
836event parameter class when a timer event occurs. Reimplement this
837function to get timer events.
838<p> If multiple timers are running, the <a href="qtimerevent.html#timerId">QTimerEvent::timerId</a>() can be
839used to find out which timer was activated.
840<p> Example:
841<pre>
842 class MyObject : public QObject
843 {
844 Q_OBJECT
845 public:
846 MyObject( QObject *parent = 0, const char *name = 0 );
847
848 protected:
849 void timerEvent( <a href="qtimerevent.html">QTimerEvent</a> * );
850 };
851
852 MyObject::MyObject( QObject *parent, const char *name )
853 : QObject( parent, name )
854 {
855 <a href="#startTimer">startTimer</a>( 50 ); // 50-millisecond timer
856 <a href="#startTimer">startTimer</a>( 1000 ); // 1-second timer
857 <a href="#startTimer">startTimer</a>( 60000 ); // 1-minute timer
858 }
859
860 void MyObject::<a href="#timerEvent">timerEvent</a>( <a href="qtimerevent.html">QTimerEvent</a> *e )
861 {
862 <a href="qapplication.html#qDebug">qDebug</a>( "timer event, id %d", e-&gt;<a href="qtimerevent.html#timerId">timerId</a>() );
863 }
864 </pre>
865
866<p> Note that <a href="qtimer.html">QTimer</a>'s accuracy depends on the underlying operating
867system and hardware. Most platforms support an accuracy of 20 ms;
868some provide more. If Qt is unable to deliver the requested
869number of timer clicks, it will silently discard some.
870<p> The QTimer class provides a high-level programming interface with
871one-shot timers and timer signals instead of events.
872<p> <p>See also <a href="#timerEvent">timerEvent</a>(), <a href="#killTimer">killTimer</a>(), <a href="#killTimers">killTimers</a>(), <a href="qeventloop.html#awake">QEventLoop::awake</a>(), and <a href="qeventloop.html#aboutToBlock">QEventLoop::aboutToBlock</a>().
873
874<h3 class=fn>void <a name="timerEvent"></a>QObject::timerEvent ( <a href="qtimerevent.html">QTimerEvent</a>&nbsp;* )<tt> [virtual protected]</tt>
875</h3>
876This event handler can be reimplemented in a subclass to receive
877timer events for the object.
878<p> <a href="qtimer.html">QTimer</a> provides a higher-level interface to the timer
879functionality, and also more general information about timers.
880<p> <p>See also <a href="#startTimer">startTimer</a>(), <a href="#killTimer">killTimer</a>(), <a href="#killTimers">killTimers</a>(), and <a href="#event">event</a>().
881
882<p>Examples: <a href="biff-example.html#x1959">biff/biff.cpp</a>, <a href="dclock-example.html#x1102">dclock/dclock.cpp</a>, <a href="forever-example.html#x1048">forever/forever.cpp</a>, <a href="grapher-nsplugin-example.html#x2755">grapher/grapher.cpp</a>, <a href="qmag-example.html#x1781">qmag/qmag.cpp</a>, and <a href="xform-example.html#x1232">xform/xform.cpp</a>.
883<h3 class=fn><a href="qstring.html">QString</a> <a name="tr"></a>QObject::tr ( const&nbsp;char&nbsp;*&nbsp;sourceText, const&nbsp;char&nbsp;*&nbsp;comment )<tt> [static]</tt>
884</h3>
885
886
887<p> Returns a translated version of <em>sourceText</em>, or <em>sourceText</em>
888itself if there is no appropriate translated version. The
889translation context is QObject with <em>comment</em> (0 by default).
890All QObject subclasses using the <a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a> macro automatically have
891a reimplementation of this function with the subclass name as
892context.
893<p> <b>Warning:</b> This method is reentrant only if all translators are
894installed <em>before</em> calling this method. Installing or removing
895translators while performing translations is not supported. Doing
896so will probably result in crashes or other undesirable behavior.
897<p> <p>See also <a href="#trUtf8">trUtf8</a>(), <a href="qapplication.html#translate">QApplication::translate</a>(), and <a href="i18n.html">Internationalization with Qt</a>.
898
899<p>Example: <a href="qdialog.html#x2130">network/networkprotocol/view.cpp</a>.
900<h3 class=fn><a href="qstring.html">QString</a> <a name="trUtf8"></a>QObject::trUtf8 ( const&nbsp;char&nbsp;*&nbsp;sourceText, const&nbsp;char&nbsp;*&nbsp;comment )<tt> [static]</tt>
901</h3>
902
903
904<p> Returns a translated version of <em>sourceText</em>, or
905<a href="qstring.html#fromUtf8">QString::fromUtf8</a>(<em>sourceText</em>) if there is no appropriate
906version. It is otherwise identical to <a href="#tr">tr</a>(<em>sourceText</em>, <em>comment</em>).
907<p> <b>Warning:</b> This method is reentrant only if all translators are
908installed <em>before</em> calling this method. Installing or removing
909translators while performing translations is not supported. Doing
910so will probably result in crashes or other undesirable behavior.
911<p> <p>See also <a href="#tr">tr</a>() and <a href="qapplication.html#translate">QApplication::translate</a>().
912
913<hr><h2>Property Documentation</h2>
914<h3 class=fn><a href="qcstring.html">QCString</a> <a name="name-prop"></a>name</h3>
915<p>This property holds the name of this object.
916<p>You can find an object by name (and type) using <a href="#child">child</a>(). You can
917find a set of objects with <a href="#queryList">queryList</a>().
918<p> The object name is set by the constructor or by the <a href="#setName">setName</a>()
919function. The object name is not very useful in the current
920version of Qt, but will become increasingly important in the
921future.
922<p> If the object does not have a name, the <a href="#name">name</a>() function returns
923"unnamed", so printf() (used in <a href="qapplication.html#qDebug">qDebug</a>()) will not be asked to
924output a null pointer. If you want a null pointer to be returned
925for unnamed objects, you can call name( 0 ).
926<p> <pre>
927 <a href="qapplication.html#qDebug">qDebug</a>( "MyClass::setPrecision(): (%s) invalid precision %f",
928 <a href="#name">name</a>(), newPrecision );
929 </pre>
930
931<p> <p>See also <a href="#className">className</a>(), <a href="#child">child</a>(), and <a href="#queryList">queryList</a>().
932
933<p>Set this property's value with <a href="#setName">setName</a>() and get this property's value with <a href="#name">name</a>().
934<hr><h2>Related Functions</h2>
935<h3 class=fn>void * <a name="qt_find_obj_child"></a>qt_find_obj_child ( <a href="qobject.html">QObject</a>&nbsp;*&nbsp;parent, const&nbsp;char&nbsp;*&nbsp;type, const&nbsp;char&nbsp;*&nbsp;name )
936</h3>
937
938<p> Returns a pointer to the object named <em>name</em> that inherits <em>type</em> and with a given <em>parent</em>.
939<p> Returns 0 if there is no such child.
940<p> <pre>
941 <a href="qlistbox.html">QListBox</a> *c = (QListBox *) <a href="#qt_find_obj_child">qt_find_obj_child</a>( myWidget, "QListBox",
942 "my list box" );
943 if ( c )
944 c-&gt;<a href="qlistbox.html#insertItem">insertItem</a>( "another string" );
945 </pre>
946
947
948<!-- eof -->
949<hr><p>
950This file is part of the <a href="index.html">Qt toolkit</a>.
951Copyright &copy; 1995-2007
952<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
953<table width=100% cellspacing=0 border=0><tr>
954<td>Copyright &copy; 2007
955<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
956<td align=right><div align=right>Qt 3.3.8</div>
957</table></div></address></body>
958</html>
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