1QEventLoop(3qt) QEventLoop(3qt)
2
6 QEventLoop - Manages the event queue
7
9 #include <qeventloop.h>
10 Inherits QObject.
12 Inherited by QMotif.
14 Public Members
16 QEventLoop ( QObject * parent = 0, const char * name = 0 )
17 ~QEventLoop ()
18 enum ProcessEvents { AllEvents = 0x00, ExcludeUserInput = 0x01,
19 ExcludeSocketNotifiers = 0x02, WaitForMore = 0x04 }
20 typedef uint ProcessEventsFlags
21 void processEvents ( ProcessEventsFlags flags, int maxTime )
22 virtual bool processEvents ( ProcessEventsFlags flags )
23 virtual bool hasPendingEvents () const
24 virtual void registerSocketNotifier ( QSocketNotifier * notifier )
25 virtual void unregisterSocketNotifier ( QSocketNotifier * notifier )
26 void setSocketNotifierPending ( QSocketNotifier * notifier )
27 int activateSocketNotifiers ()
28 int activateTimers ()
29 int timeToWait () const
30 virtual int exec ()
31 virtual void exit ( int retcode = 0 )
32 virtual int enterLoop ()
33 virtual void exitLoop ()
34 virtual int loopLevel () const
35 virtual void wakeUp ()
36 Signals
38 void awake ()
39 void aboutToBlock ()
40
42 The QEventLoop class manages the event queue.
43 It receives events from the window system and other sources. It then
45 sends them to QApplication for processing and delivery.
46 QEventLoop allows the application programmer to have more control over
48 event delivery. Programs that perform long operations can call either
49 processOneEvent() or processEvents() with various ProcessEvent values
50 OR'ed together to control which events should be delivered.
51 QEventLoop also allows the integration of an external event loop with
53 the Qt event loop. The Motif Extension included with Qt includes a
54 reimplementation of QEventLoop for merging Qt and Motif events
55 together.
56 To use your own instance of QEventLoop or QEventLoop subclass create it
58 before you create the QApplication object.
59 See also Main Window and Related Classes and Event Classes.
61 Member Type Documentation
64 This enum controls the types of events processed by the processEvents()
65 functions.
66 QEventLoop::AllEvents - All events are processed
68 QEventLoop::ExcludeUserInput - Do not process user input events. (
70 ButtonPress, KeyPress, etc. )
71 QEventLoop::ExcludeSocketNotifiers - Do not process socket notifier
73 events.
74 QEventLoop::WaitForMore - Wait for events if no pending events are
76 available.
77 See also processEvents().
79
81 A typedef to allow various ProcessEvents values to be OR'ed together.
82 See also ProcessEvents.
84
87 Creates a QEventLoop object, this object becomes the global event loop
88 object. There can only be one event loop object. The QEventLoop is
89 usually constructed by calling QApplication::eventLoop(). To create
90 your own event loop object create it before you instantiate the
91 QApplication object.
92 The parent and name arguments are passed on to the QObject constructor.
94
96 Destructs the QEventLoop object.
97
99 This signal is emitted before the event loop calls a function that
100 could block.
101 See also awake().
103
105 Activates all pending socket notifiers and returns the number of socket
106 notifiers that were activated.
107
109 Activates all Qt timers and returns the number of timers that were
110 activated.
111 QEventLoop subclasses that do their own timer handling need to call
113 this after the time returned by timeToWait() has elapsed.
114 Note: This function is only useful on systems where select() is used to
116 block the eventloop. On Windows, this function always returns 0. On
117 MacOS X, this function always returns 0 when the GUI is enabled. On
118 MacOS X, this function returns the documented value when the GUI is
119 disabled.
120
122 This signal is emitted after the event loop returns from a function
123 that could block.
124 See also wakeUp() and aboutToBlock().
126
128 This function enters the main event loop (recursively). Do not call it
129 unless you really know what you are doing.
130
132 Enters the main event loop and waits until exit() is called, and
133 returns the value that was set to exit().
134 It is necessary to call this function to start event handling. The main
136 event loop receives events from the window system and dispatches these
137 to the application widgets.
138 Generally speaking, no user interaction can take place before calling
140 exec(). As a special case, modal widgets like QMessageBox can be used
141 before calling exec(), because modal widgets call exec() to start a
142 local event loop.
143 To make your application perform idle processing, i.e. executing a
145 special function whenever there are no pending events, use a QTimer
146 with 0 timeout. More advanced idle processing schemes can be achieved
147 using processEvents().
148 See also QApplication::quit(), exit(), and processEvents().
150
152 Tells the event loop to exit with a return code.
153 After this function has been called, the event loop returns from the
155 call to exec(). The exec() function returns retcode.
156 By convention, a retcode of 0 means success, and any non-zero value
158 indicates an error.
159 Note that unlike the C library function of the same name, this function
161 does return to the caller -- it is event processing that stops.
162 See also QApplication::quit() and exec().
164
166 This function exits from a recursive call to the main event loop. Do
167 not call it unless you really know what you are doing.
168
170 Returns TRUE if there is an event waiting, otherwise it returns FALSE.
171
173 Returns the current loop level.
174
176 Process pending events that match flags for a maximum of maxTime
177 milliseconds, or until there are no more events to process, which ever
178 is shorter.
179 This function is especially useful if you have a long running operation
181 and want to show its progress without allowing user input, i.e. by
182 using the ExcludeUserInput flag.
183 NOTE: This function will not process events continuously; it returns
185 after all available events are processed.
186 NOTE: Specifying the WaitForMore flag makes no sense and will be
188 ignored.
189
191 This is an overloaded member function, provided for convenience. It
192 behaves essentially like the above function.
193 Processes pending events that match flags until there are no more
195 events to process.
196 This function is especially useful if you have a long running operation
198 and want to show its progress without allowing user input, i.e. by
199 using the ExcludeUserInput flag.
200 If the WaitForMore flag is set in flags, the behavior of this function
202 is as follows:
203 If events are available, this function returns after processing them.
205 If no events are available, this function will wait until more are
207 available and return after processing newly available events.
208 If the WaitForMore flag is not set in flags, and no events are
210 available, this function will return immediately.
211 NOTE: This function will not process events continuously; it returns
213 after all available events are processed.
214 This function returns TRUE if an event was processed; otherwise it
216 returns FALSE.
217 See also ProcessEvents and hasPendingEvents().
219
221 [virtual]
222 Registers notifier with the event loop. Subclasses need to reimplement
223 this method to tie a socket notifier into another event loop.
224 Reimplementations MUST call the base implementation.
225
227 Marks notifier as pending. The socket notifier will be activated the
228 next time activateSocketNotifiers() is called.
229
231 Returns the number of milliseconds that Qt needs to handle its timers
232 or -1 if there are no timers running.
233 QEventLoop subclasses that do their own timer handling need to use this
235 to make sure that Qt's timers continue to work.
236 Note: This function is only useful on systems where select() is used to
238 block the eventloop. On Windows, this function always returns -1. On
239 MacOS X, this function always returns -1 when the GUI is enabled. On
240 MacOS X, this function returns the documented value when the GUI is
241 disabled.
242
244 [virtual]
245 Unregisters notifier from the event loop. Subclasses need to
246 reimplement this method to tie a socket notifier into another event
247 loop. Reimplementations MUST call the base implementation.
248
250 Note: This function is thread-safe when Qt is built withthread
251 support.</p>
252 Wakes up the event loop.
254 See also awake().
256
259 http://doc.trolltech.com/qeventloop.html
260 http://www.trolltech.com/faq/tech.html
261
263 Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
264 license file included in the distribution for a complete license
265 statement.
266
268 Generated automatically from the source code.
269
271 If you find a bug in Qt, please report it as described in
272 http://doc.trolltech.com/bughowto.html. Good bug reports help us to
273 help you. Thank you.
274 The definitive Qt documentation is provided in HTML format; it is
276 located at $QTDIR/doc/html and can be read using Qt Assistant or with a
277 web browser. This man page is provided as a convenience for those users
278 who prefer man pages, although this format is not officially supported
279 by Trolltech.
280 If you find errors in this manual page, please report them to qt-
282 bugs@trolltech.com. Please include the name of the manual page
283 (qeventloop.3qt) and the Qt version (3.3.8).
284Trolltech AS 2 February 2007 QEventLoop(3qt)