[Qt-interest] Can't post a user event from compute thread to GUI thread

[Mihail Naydenov]

After just a quick look, why do you use an event filter, when you are sending events directly to that object?
Just reimplement event() in UpdateView and you will be ok.

Also note that your implementation of instance() is NOT thread safe. You can Q_GLOBAL_STATIC macro to help you out in that.
(no how to use it, look at QThreadPool or some other singleton in qt's src)

MihailNaydenov


>
>From: "Moinier, Pierre (UK)" <Pierre.Moinier at baesystems.com>
>To: qt-interest at trolltech.com
>Sent: Tue, November 10, 2009 1:14:03 PM
>Subject: [Qt-interest] Can't post a user event from compute thread to GUI thread
>
>
>Hi!
> 
>I am trying to 
>figure out how to send an event fom a thread to the main visualisation thread 
>using postEvent, installEventFilter and eventFilter.
>I am pasting parts 
>of the test code I am using, which compiles, but somehow, the event is probably 
>not reaching the filter, beause I am not geting any messages from 
>eventFilter.
> 
>Could anyone tell me 
>what I am doing wrong?
> 
>Regards,
> 
>    -Pierre.
> 
>-------------------------------------------------------------  Test 
>Code  
>------------------------------------------------------------------
>main.cpp:
> 
>#include 
><QApplication>
> 
>#include 
>"ComputeThread.h"
>#include <qpushbutton.h>
> 
>int main(int argc, 
>char* argv[])
>{
>  QApplication app(argc, argv);
>  
>ComputeThread thread;
>  thread.start();
> 
>  QPushButton 
>hello("Hello world!");
>  hello.resize(100, 30);
> 
>  
>hello.show();
>  return app.exec();
>}
>
>ComputeThread.cpp:
>  
>#include 
><iostream>
>#include <QApplication>
>#include 
><QEvent>
> 
>#include "ComputeThread.h"
>#include 
>"UpdateView.h"
> 
>void ComputeThread::run()
>{
>  for (int 
>i=0;i<100;i++)
>    {
>      
>sleep(1);
>      std::cout << "sending 
>Event...." << UpdateView::UPDATE_EV1 << 
>std::endl;
>      QEvent *e = new 
>QEvent(QEvent::User);
>      
>QApplication::postEvent(&UpdateView::instance(), 
>e);
>      //  
>QCoreApplication::postEvent(&UpdateView::instance(), new 
>QEvent(static_cast<QEvent::Type>(UpdateView::UPDATE_EV1)));
>    
>}
>}
>
>UpdateView.cpp:
>  
>#include 
><iostream>
>#include <QEvent>
> 
>#include 
>"UpdateView.h"
> 
>UpdateView::UpdateView()
>{
>  
>std::cout << "hello sailor" << std::endl;
>  
>installEventFilter(this);
>}
> 
>bool UpdateView::eventFilter(QObject *obj, QEvent 
>*event)
>{
>  std::cout << "hello" << std::endl;                                  
>!!! I should get Hello on the sceen.....
>  const Event 
>ev = static_cast<Event>(event->type());
>  
>switch(ev)
>    {
>    case 
>UPDATE_EV1:
>      std::cout << "Updating the 
>scene..." << std::endl;
>      
>break;
> 
>    
>default:
>      return false;
>    
>}
>  return true;
>}
>
>UpdateView.h:
> 
>#ifndef 
>UPDATEVIEW_H
>#define UPDATEVIEW_H
> 
>#include 
><QEvent>
>#include <QObject>
> 
>class UpdateView : 
>public QObject
>{
>  Q_OBJECT
>    public:
>  
>UpdateView(); 
>  static UpdateView& instance()
>    
>{
>      static UpdateView 
>theinstance;
>      return 
>theinstance;
>    }
> 
>  enum Event 
>{UPDATE_EV1 = 1000 , UPDATE_EV2 = 1001};
> 
>  bool 
>eventFilter(QObject *obj, QEvent *event);
> 
>};
> 
>#endif
> 
> 
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