[Interest] QML MenuBar : works with PySide2 but not c++ ?

[Fabrice Mousset | GEOCEPT GmbH]

I think you also have to load QML module in PRO file:
MenuBar.pro
===========
QT += quick qml

Best regards

Fabrice Mousset

Von: Interest <interest-bounces at qt-project.org> Im Auftrag von Nicholas Yue
Gesendet: Donnerstag, 3. Juni 2021 06:09
An: Tony Rietwyk <tony at rightsoft.com.au>
Cc: interest at qt-project.org
Betreff: Re: [Interest] QML MenuBar : works with PySide2 but not c++ ?

I copied the qml loading code from another working example, I was just testing a change in the QML content.

I'd have to dig further about the lambda

MenuBar.pro
===========
QT += quick

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Refer to the documentation for the
# deprecated API to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
        main.cpp

RESOURCES += main.qrc

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =

# Additional import path used to resolve QML modules just for Qt Quick Designer
QML_DESIGNER_IMPORT_PATH =

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

main.qrc
=======
<RCC>
    <qresource prefix="/">
        <file>MenuBar.qml</file>
    </qresource>
</RCC>

On Wed, 2 Jun 2021 at 20:36, Tony Rietwyk <tony at rightsoft.com.au<mailto:tony at rightsoft.com.au>> wrote:

Hi Nicholas,

The short answer is because your C++ is doing completely different things to the python code.  :O)

I'm not sure about using QML.  Have you included the qml file as a resource correctly to access via qrc:?  You aren't checking the result of the engine.load.  Also, why is the lambda exiting the application when the objectCreated matches the url?

Have run the Qt QML examples?  How is your C++ code different to those?

Hope that helps, Tony


On 3/06/2021 11:33 am, Nicholas Yue wrote:
Hi,

  I am learning about QML.

  I would like to find out why the PySide2 loading of the QML file results in a visible window but the C++ one does not. The compiled application runs but no window is displayed.

MenuBar.qml
===========
import QtQuick 2.4
import QtQuick.Controls 2.13

ApplicationWindow {
    visible: true
    width: 720
    height: 480
    title: "simple window"

    menuBar: MenuBar{
        Menu{
            title: "Menu1"
        }

        Menu{
            title: "Menu2"
        }

        Menu{
            title: "&Menu3"
        }
    }
}

main.cpp
========
#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/MenuBar.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

main.py
=======
import sys
from PySide2 import QtCore, QtGui, QtQml

if __name__ == '__main__':

    QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
    app = QtGui.QGuiApplication(sys.argv)

    engine = QtQml.QQmlApplicationEngine()

    url = QtCore.QUrl.fromLocalFile('MenuBar.qml')
    engine.load(url)
    if not engine.rootObjects():
        sys.exit(-1)

    sys.exit(app.exec_())

--
Nicholas Yue
Graphics - Arnold, Alembic, RenderMan, OpenGL, HDF5
Custom Dev - C++ porting, OSX, Linux, Windows
http://au.linkedin.com/in/nicholasyue
https://vimeo.com/channels/naiadtools


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--
Nicholas Yue
Graphics - Arnold, Alembic, RenderMan, OpenGL, HDF5
Custom Dev - C++ porting, OSX, Linux, Windows
http://au.linkedin.com/in/nicholasyue
https://vimeo.com/channels/naiadtools
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