Crash in Qml destkop application.

**anda_skoa** · 15th December 2016, 17:35

Are those viewmanager instances available through out the program or do they get creates/deleted on demand?

Do you have any Q_INVOKABLE methods that return instances of QObject derived classes?

Cheers,
_

**JanW** · 16th December 2016, 08:28

Hi,

they are available through the entire lifetime of the application (the tabs are stored per layout in a QList<std::shared_ptr>. I have one Q_INVOKABLE method that returns a pointer to the tab.

Qt Code:

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Q_INVOKABLE ViewManagerTabQMLInterface* getTab(int index);
 
//--------------------------------------------------------------------------------------
/// Returns the tab model from the given index.
//--------------------------------------------------------------------------------------
 
ViewManagerTabQMLInterface* ViewManagerQMLInterface::getTab(int index)
{
	if(index >= 0 && index < (int)_tabsList.size())
	{
		return _tabsList[index].get();
	}
	return NULL;
}

Q_INVOKABLE ViewManagerTabQMLInterface* getTab(int index);

//--------------------------------------------------------------------------------------
/// Returns the tab model from the given index.
//--------------------------------------------------------------------------------------

ViewManagerTabQMLInterface* ViewManagerQMLInterface::getTab(int index)
{
	if(index >= 0 && index < (int)_tabsList.size())
	{
		return _tabsList[index].get();
	}
	return NULL;
}

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I see that at one point the destructor of the ViewManagerTabQMLInterface is called after a QDeleteDefferedEvent (just reading from the call stack).

Qt Code:

Switch view

MeshingMaster.exe!ViewManagerTabQMLInterface::~ViewManagerTabQMLInterface() Line 69	C++
 	[External Code]	
 	Qt5Cored.dll!qDeleteInEventHandler(QObject * o) Line 4482	C++
>	Qt5Cored.dll!QObject::event(QEvent * e) Line 1255	C++
 	Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e) Line 3799	C++
 	Qt5Widgetsd.dll!QApplication::notify(QObject * receiver, QEvent * e) Line 3159	C++
 	Qt5Cored.dll!QCoreApplication::notifyInternal2(QObject * receiver, QEvent * event) Line 988	C++
 	Qt5Cored.dll!QCoreApplication::sendEvent(QObject * receiver, QEvent * event) Line 231	C++
 	Qt5Cored.dll!QCoreApplicationPrivate::sendPostedEvents(QObject * receiver, int event_type, QThreadData * data) Line 1649	C++
 	Qt5Cored.dll!QEventDispatcherWin32::sendPostedEvents() Line 1295	C++
 	qwindowsd.dll!QWindowsGuiEventDispatcher::sendPostedEvents() Line 82	C++
 	Qt5Cored.dll!qt_internal_proc(HWND__ * hwnd, unsigned int message, unsigned __int64 wp, __int64 lp) Line 445	C++
 	[External Code]	
 	Qt5Cored.dll!QEventDispatcherWin32::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 845	C++
 	qwindowsd.dll!QWindowsGuiEventDispatcher::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 74	C++
 	Qt5Cored.dll!QEventLoop::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 135	C++
 	Qt5Cored.dll!QEventLoop::exec(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 210	C++
 	Qt5Cored.dll!QCoreApplication::exec() Line 1261	C++

MeshingMaster.exe!ViewManagerTabQMLInterface::~ViewManagerTabQMLInterface() Line 69	C++
 	[External Code]	
 	Qt5Cored.dll!qDeleteInEventHandler(QObject * o) Line 4482	C++
>	Qt5Cored.dll!QObject::event(QEvent * e) Line 1255	C++
 	Qt5Widgetsd.dll!QApplicationPrivate::notify_helper(QObject * receiver, QEvent * e) Line 3799	C++
 	Qt5Widgetsd.dll!QApplication::notify(QObject * receiver, QEvent * e) Line 3159	C++
 	Qt5Cored.dll!QCoreApplication::notifyInternal2(QObject * receiver, QEvent * event) Line 988	C++
 	Qt5Cored.dll!QCoreApplication::sendEvent(QObject * receiver, QEvent * event) Line 231	C++
 	Qt5Cored.dll!QCoreApplicationPrivate::sendPostedEvents(QObject * receiver, int event_type, QThreadData * data) Line 1649	C++
 	Qt5Cored.dll!QEventDispatcherWin32::sendPostedEvents() Line 1295	C++
 	qwindowsd.dll!QWindowsGuiEventDispatcher::sendPostedEvents() Line 82	C++
 	Qt5Cored.dll!qt_internal_proc(HWND__ * hwnd, unsigned int message, unsigned __int64 wp, __int64 lp) Line 445	C++
 	[External Code]	
 	Qt5Cored.dll!QEventDispatcherWin32::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 845	C++
 	qwindowsd.dll!QWindowsGuiEventDispatcher::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 74	C++
 	Qt5Cored.dll!QEventLoop::processEvents(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 135	C++
 	Qt5Cored.dll!QEventLoop::exec(QFlags<enum QEventLoop::ProcessEventsFlag> flags) Line 210	C++
 	Qt5Cored.dll!QCoreApplication::exec() Line 1261	C++

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Any idea?

**anda_skoa** · 16th December 2016, 10:10

Originally Posted by JanW

they are available through the entire lifetime of the application (the tabs are stored per layout in a QList<std::shared_ptr>. I have one Q_INVOKABLE method that returns a pointer to the tab.

Do those objects have a QObject parent?
Or, alternatively, have they been marked as owned by C++ using QQmlEngine::setObjectOwnership()?

Cheers,
_

**JanW** · 16th December 2016, 11:01

Yes, they have a qobject parent, and yes, at one point they get deleted. I removed the passing of those objects via qml to my other class and now they stay alive.
Thanks you very much for the tips!!!!
Regards,

Jan