[Interest] App crashing because of ImageProvider when exiting

[Martin Leutelt]

Hi Jean,



 From:   Nuno Santos <nunosantos at imaginando.pt> 
 To:   Jean-Michaël Celerier <jeanmichael.celerier at gmail.com> 
 Cc:   Qt Project MailingList <interest at qt-project.org> 
 Sent:   7/25/2018 12:59 PM 
 Subject:   Re: [Interest] App crashing because of ImageProvider when exiting 


Jean,


This is the main context. It will not get out until app.exec() terminates.


That’s why I’m connecting to aboutToQuit signal in order to remove the provider from the Qml engine. 


Since the engine takes ownership you don't need to remove the image provider in your case, since you're not adding/removing providers dynamically during runtime.







I had the provider instantiated inside the controller but I was having this problem already, therefore my efforts in getting it fixed.



QQmlApplicationEngine *e;


int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);


    Controller controller;


    QQmlApplicationEngine engine;


    e = &engine;


    engine.rootContext()->setContextProperty("controller", &controller);
    engine.load(QUrl(QStringLiteral("qrc:/qml/main.qml")));


    ImageProvider imageProvider;
    engine.addImageProvider("pictures", &imageProvider);


    QObject::connect(&app, &QGuiApplication::aboutToQuit, [=]()
    {
        e->removeImageProvider("pictures");
    });


    return app.exec();
}


Any ideas?


Regards,


Nuno



On 25 Jul 2018, at 11:30, Jean-Michaël Celerier <jeanmichael.celerier at gmail.com> wrote:


Shouldn't you allocate your ImageProvider on the heap or at least ensure that it survives during the whole execution ? here it will be deleted by the end of your function










-------Jean-Michaël Celerier
http://www.jcelerier.name 

On Wed, Jul 25, 2018 at 11:24 AM, Nuno Santos <nunosantos at imaginando.pt> wrote:

Hi,


Yesterday I have used for the first time a QQuickImageProvider but I’m having problems because now the app crashes when I terminate it.


Tried to do the following in order to avoid the crash but it is crashing anyway:



ImageProvider imageProvider;
engine.addImageProvider("pictures", &imageProvider);


QObject::connect(&app, &QGuiApplication::aboutToQuit, [=]()
{
    e->removeImageProvider("pictures");
});


The crash is always something like this:



malloc: *** error for object 0x7ffeef34e900: pointer being freed was not allocated


Does anyone knows how to fix this?


Thanks!


Regards,


Nuno


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