How can I get the application QmlEngine ?

J.Hilk

@kmarconi what @KroMignon described was the way you had to go before Qt 5.10

you can take a look at this blog post, I think its rather good:

https://retifrav.github.io/blog/2017/01/04/translating-qml-app/

kmarconi

@J-Hilk Yeah I've seen this post but it's kinda dirty way to retranslate the whole app I think ... I still will try it but I hope to find a way to use the retranslate function properly.

J.Hilk

@kmarconi
what would you consider a proper retranslate functionality ?

You can either,

call retranslate() on the QQmlEngine,
update the strings via the empty string property workaround
reload the qml file entirely

there are not other ways, at least that I know of

kmarconi

@J-Hilk Calling retranslate for me is the cleanest way. No need to add "+trans.emptyString" on each of my qsTr object and I have a lot. I need to figure out how to solve this infinite binding loop. Is reloading the whole qml a heavy task for the system ?

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

I still will try it but I hope to find a way to use the retranslate function properly.

I can not figure out what your problem is.
@J-Hilk have give you all information you need to do it.

If you are using Qt 5.10 and upper (which is not my case) simply follow documentation
That's not so complicated to follow, you could create a class which handle the locales, for example let it call LocalHandler, when you have install the new translator with QCoreApplication::installTranslator() then emit a signal for example called translationUpated().
Then in your main.cpp:

LocalHandler loc;

QObject::connect(&loc, &LocalHandler::translationUpated, engine, &QQmlEngine::retranslate);

Alternatively you can use a app->installEventFilter() to catch QEvent::LanguageChange and then trigger QQmlEngine::retranslate().

For prior version, you have to do more work ==> https://retifrav.github.io/blog/2017/01/04/translating-qml-app/

kmarconi

@KroMignon I already done everything you told me but thank you ;) I was just saying that if I could not use the emptyString trick it could be interesting for me. Why I'm saying this is because with the trick , I have the error " ListElement: cannot use script for property value" . Is is because I cannot use the trick in a ListElement object ?

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

I have the error "ListElement: cannot use script for property value"

AFAIK, ListElement cannot be changed dynamically ==> cf QTBUG-16289

edit

You have to use QT_TR_NOOP() and qsTr() on the delegate, like this (extract from QTBUG-16289):

ListModel {
    id: myModel

    ListElement {
        desc: QT_TR_NOOP("Example")
    }
}

ListView {
    model: myModel

    delegate: Text {
        text: qsTr(desc)
    }
}

kmarconi

@KroMignon Yeah just seen it on a stackoverflow post (https://stackoverflow.com/questions/7659442/listelement-fields-as-properties) but I canno't change my qml part because the way it is designed is fixed so I need to find a way to use the retranslate function without having this binding loop.

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

I need to find a way to use the retranslate function without having this binding loop.

Take a look at the QTBUG-16289, the way they propose is to use QT_TR_NOOP() on ListElement to add string in translation file, and to use qsTr() in the delegate to do translation.

kmarconi

@KroMignon Damn it is so hard to debug a binding loop with QT. Will keep you updated if I finally found out what's going on with my program.

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

Damn it is so hard to debug a binding loop with QT.

Yes, binding loops are the hell!
Which Qt Version are you using? For Qt 5.10 and upper you can enable tracing to help you to find bindings problems with QT_LOGGING_RULES.
For example in your main.cpp:

    qputenv("QT_LOGGING_RULES", "qt.qml.binding.removal.info=true");

Take look at this https://www.kdab.com/new-qt-5-10-diagnostics-breaking-qml-bindings/ for more details.

kmarconi

@KroMignon I'm on QT 5.12.3 so that could save me. Will tell you, thanks !

kmarconi

@KroMignon My binding loop error hasn't changed at all even with "qputenv("QT_LOGGING_RULES", "qt.qml.binding.removal.info=true");" in my main.cpp file .. Am I condemned to live in this infinite binding loop ? haha

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

Am I condemned to live in this infinite binding loop ?

Can you show the QML code which is not working well?

kmarconi

@kmarconi said in How can I get the application QmlEngine ?:

Here is my main.qml file :

Item {
id:root
visible: true
width: 640
height: 480
property var mainMenu: Menu{rootStack: root}

StackView {
    anchors.fill: parent
    id: menuStack

    property var button: hmiclass.button
    initialItem: mainMenu

    onButtonChanged: {
        mainMenu.onButtonPushed(button)
    }
}
}

EDIT: I need to find where that loop is coming from.. Or to find a patch to refresh only the bindings which are in the translation file.

This is the one

KroMignon

@kmarconi And what is the binding loop error message? I can't see any obvious error on this code extract.

kmarconi

@KroMignon Sorry, the error is : QML StackView: Binding loop detected for property "button"

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

the error is : QML StackView: Binding loop detected for property "button"

According to your code, it looks like mainMenu.onButtunPushed() will change hmiclass.button content, which will recall mainMenu.onButtunPushed()...

kmarconi

@KroMignon Yeah that's what I tought but why this error is only showing on retranslate and not on the app boot too ?

KroMignon

@kmarconi said in How can I get the application QmlEngine ?:

Yeah that's what I tought but why this error is only showing on retranslate and not on the app boot too ?

Because there have to be a first change to start the loop!
I don't know what is changing hmiclass.button?

I suppose hmiclass is a C++ class instance and button is a property of this class.
In some way the attached signal to this property is emitted, which will start the loop.

That is just an hypothesis, I don't have a clue about your code.