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

[Louai Al-Khanji]

Hi again,

Here's a slightly cleaner version.

-- Louai

On Tue, Nov 10, 2009 at 5:43 PM, Louai Al-Khanji <louai.khanji at gmail.com> wrote:
> Hi
>
> The attached works for me.
>
> -- Louai
>
> On Tue, Nov 10, 2009 at 8:48 AM, Moinier, Pierre (UK)
> <Pierre.Moinier at baesystems.com> wrote:
>> Hi!
>>
>> I have done what you suggested, but the behaviour is the same. Nothing seems
>> to go to event()...
>>
>> So I commented out the call to installEventFilter and to evenFilter and here
>> is my reimplementation of event():
>>
>>  bool UpdateView::event(QEvent *event)
>>  {
>>        std::cout << "hello" << std::endl;
>>      if (event->type() == QEvent::User) {
>>        std::cout << "hello ... found the event!" << std::endl;
>>              return true;
>>          }
>>
>>      else
>>        return false;
>>  }
>> If it is easier, I could tar up the couple of files and send it to you...
>>
>> Regards,
>>
>>     -Pierre.
>> ________________________________
>> From: Mihail Naydenov [mailto:mlists at ymail.com]
>> Sent: 10 November 2009 12:35
>> To: Moinier, Pierre (UK); qt-interest at trolltech.com
>> Subject: Re: [Qt-interest] Can't post a user event from compute thread to
>> GUI thread
>>
>>                     *** WARNING ***
>>
>>   This message has originated outside your organisation,
>>   either from an external partner or the Global Internet.
>>       Keep this in mind if you answer this message.
>>
>> 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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>
>
>
> --
> - Louai Al-Khanji
>



-- 
- Louai Al-Khanji
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