What I am doing is that I am setting my Own Even Handle

I really do not understand what you want to do. Why would you want to paint whenever the event loop is empty?

I do understand a “paint after each event” or “paint x frames per second”, but why would you want to paint whenever the event queue is empty?

PS: How is ‘render whenever the event queue happens to be empty’ realtime?

Whent you are making an application like a video Game or a performace measuring tool, you need the application to update as fast as it can. That is why you draw after all events are processed.
It is a very standrad operation in all operating system and all GUIs I know.

A timer is a very, very bad Idea.

Try the aboutToBlock [doc.qt.nokia.com] signal.

I see that class QAbstractEventDispatcher seems to have what I look for,
but hwo do I use that class
I do not see a single example using a class like tha in the demos.

I tryed this

but all I get is a bunch of errors.

for what I can see thsi si too low level, It is asking me to impelmnet all thsi funtions

1> due to following members:
1> ‘bool QAbstractEventDispatcher::processEvents(QEventLoop::ProcessEventsFlags)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(71) : see declaration of ‘QAbstractEventDispatcher::processEvents’
1> ‘bool QAbstractEventDispatcher::hasPendingEvents(void)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(72) : see declaration of ‘QAbstractEventDispatcher::hasPendingEvents’
1> ‘void QAbstractEventDispatcher::registerSocketNotifier(QSocketNotifier *)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(74) : see declaration of ‘QAbstractEventDispatcher::registerSocketNotifier’
1> ‘void QAbstractEventDispatcher::unregisterSocketNotifier(QSocketNotifier *)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(75) : see declaration of ‘QAbstractEventDispatcher::unregisterSocketNotifier’
1> ‘void QAbstractEventDispatcher::registerTimer(int,int,QObject *)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(78) : see declaration of ‘QAbstractEventDispatcher::registerTimer’
1> ‘bool QAbstractEventDispatcher::unregisterTimer(int)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(79) : see declaration of ‘QAbstractEventDispatcher::unregisterTimer’
1> ‘bool QAbstractEventDispatcher::unregisterTimers(QObject *)’ : is abstract
1> c:\newton-dynamics_new\packages\thirdparty\qt\4.7.1\include\qtcore\../../src/corelib/kernel/qabstracteventdispatcher.h(80) : see declaration of ‘QAbstractEventDispatcher::unregisterTimers’
1> ‘QList<T> QAbstractEventDispatcher::registeredTimers(QObject *) const’ : is abstract
1> with

I am lost here, this is so eassy to do in Windows and WxWidget,
there has to be a way to do this eassy in Qt.
so far everything else has being very eassy.

From Qt’s documentation:
A QTimer with a timeout interval of 0 will time out as soon as all the events in the window system’s event queue have been processed.

I saw that but when I do this

kkrzewniak wrote:

From Qt’s documentation: A QTimer with a timeout interval of 0 will time out as soon as all the events in the window system’s event queue have been processed.

when I set it to this

It update as fast as it can, but still have the problem that if you click on en menu for example the timer still update send even and it should stops, because there are other events with higher priority.
Basically I need the updates if and only if when the system has nothing else to do.

To Bradley I see it is a signal, I read the explanation of that signal and it is no clear to me by I will experiment with that,
I see that there are other signals as well.

Bradley wrote:

1.  connect(QAbstractEventDispatcher::instance(), SIGNAL(aboutToBlock()), this, SLOT(onAboutToBlock())); @</blockquote>
2.  
3. That does part of what I want but still not exacty, because it does update as fas as it can  
4. however it still send the same sinal when I click on the menu.
5. I need tha teh signal to be the lowest possible priority of all signals.
6.  
7. Maybe I did it wrong, I implemenetd like this
8.  
9. @connect(QAbstractEventDispatcher::instance(), SIGNAL(aboutToBlock()), this, SLOT(OnIdle()));
10.  
11. ...
12.  
13.  
14. void newtonDemos::OnIdle()
15. {
16.  m_canvas->update();
17. }

is that how is supposet to be?

You are probably causing a cycle. The update() call will probably post an UpdateRequest event, and after it is processed (and any other events), the aboutToBlock signal will be sent again, which will cause another update() call.

so I though somethomg liek this shopuld do it, but it does not

what does “a funtion that coul block” means?
bq. This signal is emitted after the event loop returns from a function that could block.

For what I can see the only way I can do this is by having a bool that is toggled on each action/slot,
and that does not sound like an elegant or atractive solution.

I can not beleive this is not a trivial operation in Qt.
This is the default behavior in window

I can upload the two application to my server and post a link to it maybe some one can
take a look and tell me how to do what I want.
the window and the QT.

Well I could not find a clean way to do it, but it does no matter, I can acomplishe the same in diffrnet way
I end up doing this

and I set m_doVisualUpdates on and off on eh relvane Menu actions.
It is still better than using a timer, and I also learned a lot about trapping events wih Qt.
Thank every one for the help.