January 19, 2011

sasibu sasibu
Lab Rat
4 posts

QApplication error in exec()

 

Hi all,

I have a weird problem when my applicarion tries to execute

  1. app.exec() //QApplication object in main.cpp

I’m trying to integrate an Ogre widget and a VTK widget on my application. All goes good if I use only one of them, but I get that error:

  1. Unhandled exception at 0x00a1fd88 in QtApp.exe: 0xC0000005: Access violation reading location 0x0672faf0

I followed the error and it seems to crash on the Qt Core, when processing events in file “qapplicarion_win.cpp”

  1. bool QGuiEventDispatcherWin32::processEvents(QEventLoop::ProcessEventsFlags flags)
  2. {
  3.     if (!QEventDispatcherWin32::processEvents(flags))  //HERE CRASHES!!!!
  4.         return false;
  5.  
  6.     if (configRequests)                        // any pending configs?
  7.         qWinProcessConfigRequests();
  8.  
  9.     return true;
  10. }

I’m using Qt 4.7 under Windows 7.
Have somebody any clue?

Thanks a lot!

6 replies

January 19, 2011

Andre Andre
Area 51 Engineer
6076 posts
  • Certified Specialist
  • Qt DevNet Moderator

I think you need to show some of your actual code before anyone can help you.

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January 19, 2011

sasibu sasibu
Lab Rat
4 posts

Here it goes.

The ‘main.cpp’:

  1. //Main
  2. int main(int argc, char *argv[])
  3. {
  4.      QApplication app(argc, argv);
  5.  MainWindow *mainWin = new MainWindow();
  6.  mainWin->show();
  7.  
  8.  return app.exec();
  9.  //while (true){}
  10. }

‘MainWindow.h’:

  1. #ifndef MAINWINDOW_H
  2. #define MAINWINDOW_H
  3.  
  4. //Qt
  5. #include <QMainWindow>
  6.  
  7. #include "VTKWidget.h"
  8. #include "OgreWidget.h"
  9.  
  10.  
  11. namespace Ui {
  12.     class MainWindow;
  13. }
  14.  
  15. class MainWindow : public QMainWindow
  16. {
  17.     Q_OBJECT
  18.  
  19. public:
  20.  explicit MainWindow(QWidget *parent = 0);//, QtOgre::GameLogic* gameLogic = 0);
  21.      ~MainWindow();
  22.  
  23. private:
  24.  //Class Members
  25.      Ui::MainWindow *ui;
  26.  
  27.  //Widgets
  28.  VTKWidget *mVTKWidget;
  29.  OgreWidget *mOgreWidget;
  30. };
  31.  
  32. #endif // MAINWINDOW_H

And the constructor of ‘MainWindow’ in ‘MainWindow.cpp’:

  1. MainWindow::MainWindow(QWidget *parent):
  2.  QMainWindow(parent),
  3.  ui(new Ui::MainWindow)
  4. {
  5.  ui->setupUi(this);
  6.  
  7.  //Create Ogre Widget
  8.  mOgreWidget = new OgreWidget( ui->widgetVis );
  9.  mOgreWidget->resize(800, 600);
  10.  
  11.  ui->verticalLayoutWidgetVis->addWidget(mOgreWidget);
  12.  ui->verticalLayoutWidgetVis->update();
  13.  
  14.  mOgreWidget->show();
  15.  
  16.  //Create VTK Widget
  17.  //vtkRenderWindow* renWin = vtkRenderWindow::New();
  18.  mVTKWidget = new VTKWidget(this);
  19.  //mVTKWidget->SetRenderWindow(renWin);
  20.  //mVTKWidget->createScene();
  21.  //mVTKWidget->show();
  22.  
  23.  ui->verticalLayoutWidgetSmallVis->addWidget(mVTKWidget);
  24.  ui->verticalLayoutWidgetSmallVis->update();
  25.  
  26. }

I’m using the QVTKWidget from VTK source, and the Ogre widget like the defined here [ogre3d.org]

Thanks

January 19, 2011

sasibu sasibu
Lab Rat
4 posts

It seems that the problem is in the QVTKWidget provided. Concretly in the paintEvent().

I have overloaded the function in my class and now all is working, so the problem is in the painting…

January 19, 2011

Andre Andre
Area 51 Engineer
6076 posts
  • Certified Specialist
  • Qt DevNet Moderator

I don’t know anything about QVTKWidget. Perhaps VTK has a forum or mailinglist you can use for support on that?

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January 20, 2011

sasibu sasibu
Lab Rat
4 posts
Andre wrote:
I don’t know anything about QVTKWidget. Perhaps VTK has a forum or mailinglist you can use for support on that?

It seems more an event queue problem of Qt, but maybe it’s a VTK issue.

Thanks!

January 20, 2011

Andre Andre
Area 51 Engineer
6076 posts
  • Certified Specialist
  • Qt DevNet Moderator

Well, it could be that QVTKWidget tries to do some magic with Qt’s eventloop, and that that causes the issue. But again: I really don’t

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