Properly initialize WebEngineView

[S0ulM1ke]

I've decided to add YouTube video playback feature in my app (in QML), so I choose WebEngineView

As I watched the documentation I do this in main.cpp :

    QCoreApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
    QtWebEngineQuick::initialize();

Before initializing QCoreApplication.

And in my view i use this:

import QtWebEngine 1.10
...
                        WebEngineView {
                            width: 600
                            height: 300
                            Component.onCompleted: {
                                url = model.gameVideoUrl
                            }
                        }
...

This works but I have this message in output (happens when item initializes):

QWebEngineFileSystemAccessRequest is neither a QObject, nor default- and copy-constructible. You should not use it as a QML type.
QWebEngineCertificateError is neither a QObject, nor default- and copy-constructible. You should not use it as a QML type.
QWebEngineFullScreenRequest is neither a QObject, nor default- and copy-constructible. You should not use it as a QML type.
QWebEngineLoadingInfo is neither a QObject, nor default- and copy-constructible. You should not use it as a QML type.

What am I doing wrong?

[Drazz]

Does anyone know why this warnings appear?

[JonB]

@Drazz
Seemingly same as https://github.com/OmixVisualization/qtjambi/issues/94#issuecomment-1290511207 ?
I don't know whether QCoreApplication (rather than QApplication) is enough for your purposes, but what happens if you do it before the QtWebEngineQuick::initialize();?
Otherwise is it a harmless warning which should just be ignored, because of the order of initialization?

[Drazz]

Thanks for your answer.

In my case, I've tested WebEngine Quick Nano Browser example using Qt 6.4.3. It uses QGuiApplication and QtWebEngineQuick::initialize is called before creating the application instance.

If I move QtWebEngine::initialize() below QGuiApplication, I not only get the same warnings but also an additional message:

QtWebEngineQuick::initialize() called with QCoreApplication object already created and should be called before. This is deprecated and may fail in the future.

I like to take care of warnings whenever possible, as they can indicate potential issues. Is there any official explanation for these specific warnings?