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Cannot modify Qml propriety from Cpp

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  • M Offline
    M Offline
    mikecurl91
    wrote on last edited by
    #3

    Hi, thanks for the answer.
    I've changed the code:
    @int main(int argc, char *argv[])
    {
    QGuiApplication app(argc, argv); //preparo l'applicazione
    QQmlApplicationEngine engine(QUrl("qml/main.qml")); //carico l'interfaccia
    QObject *radice = engine.rootObjects().value(0); //identifico la radice
    QQuickWindow *applicationwindow = qobject_cast<QQuickWindow *>(radice); //acquisisco in C++ l'ogg QML ApplicationWindow
    if ( !applicationwindow )
    {
    qWarning("Error: Your root item has to be a Window.");
    return -1;
    }
    applicationwindow->show();
    return app.exec();

    QObject *button = radice->findChild<QObject*>("buttonOpenCloseCom",Qt::FindChildrenRecursively);
    if (button)
    {
        button->setProperty("text", "Open");
        qDebug()<<"found!";
    }
    else
    {
        button->setProperty("text", "Open");
        qDebug()<<"not found!";
    }
    

    }@

    but there is no output.
    The problem persists!

    I've also tried to change the buttonComText in ApplicationWindows, but the result is the same.

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    • W Offline
      W Offline
      wspilot
      wrote on last edited by
      #4

      Try this:
      objectName: "buttonOpenCloseCom"

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      • M Offline
        M Offline
        mikecurl91
        wrote on last edited by
        #5

        There is yet the objectName proprety.
        I've tried this solution... but doesn't work.
        [quote author="wspilot" date="1376930837"]Try this:
        objectName: "buttonOpenCloseCom"[/quote]

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        • W Offline
          W Offline
          wspilot
          wrote on last edited by
          #6

          In your code it is still an identifier/var or whatever, but not a string
          objectName: buttonOpenCloseCom
          not
          objectName: “buttonOpenCloseCom”

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          • M Offline
            M Offline
            mikecurl91
            wrote on last edited by
            #7

            Excuseme but in the code:
            @
            Button
            {
            id: buttonOpenCloseCom
            objectName: buttonOpenCloseCom
            text:applicationwindow.buttonComText
            enabled: true
            }
            @

            objectName: “buttonOpenCloseCom” there is![/quote]

            what is the problem you talk about?!

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            • sierdzioS Offline
              sierdzioS Offline
              sierdzio
              Moderators
              wrote on last edited by
              #8

              Put it in quotes: ". Not just string but "string".

              (Z(:^

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              • W Offline
                W Offline
                wspilot
                wrote on last edited by
                #9

                @ Button
                {
                id: buttonOpenCloseCom
                objectName: "buttonOpenCloseCom"
                text:applicationwindow.buttonComText
                enabled: true
                }@

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                • M Offline
                  M Offline
                  mikecurl91
                  wrote on last edited by
                  #10

                  I've understand what you mean, and I've tried with the correction, but the result is the same as before.
                  Debugging i've see that the root object is correctly the "applicationwindow",
                  but when I try to find the child, it fails and return a null pointer...
                  in "this":http://qt-project.org/doc/qt-5.1/qtqml/qtqml-cppintegration-interactqmlfromcpp.html#loading-qml-objects-from-c reference it used QQuickView, and not QQuickWindow to handle the root object...
                  Could it be a problem?
                  If yes, how can I resolve it? any suggestions?

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                  • mranger90M Offline
                    mranger90M Offline
                    mranger90
                    wrote on last edited by
                    #11

                    The problem is that you make the change after the return() statement.
                    Nothing after that will be executed.

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                    • M Offline
                      M Offline
                      mikecurl91
                      wrote on last edited by
                      #12

                      I've modified the code:
                      @int main(int argc, char *argv[])
                      {
                      QGuiApplication app(argc, argv); //preparo l'applicazione
                      QQmlApplicationEngine engine(QUrl("qml/main.qml")); //carico l'interfaccia
                      QObject *radice = engine.rootObjects().value(0); //identifico la radice
                      QQuickWindow *applicationwindow = qobject_cast<QQuickWindow *>(radice); //acquisisco in C++ l'ogg QML ApplicationWindow
                      if ( !applicationwindow )
                      {
                      qWarning("Error: Your root item has to be a Window.");
                      return -1;
                      }
                      QObject button = radice->findChild<QObject>("buttonOpenCloseCom",Qt::FindChildrenRecursively);
                      if (button)
                      {
                      button->setProperty("text", "Open");
                      qDebug()<<"found!";
                      }
                      else
                      {
                      button->setProperty("text", "Open");
                      qDebug()<<"not found!";
                      }

                      applicationwindow->show();
                      return app.exec();
                      

                      }@

                      but is the same as before...
                      [quote author="mranger90" date="1376947874"]The problem is that you make the change after the return() statement.
                      Nothing after that will be executed.[/quote]

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                      0
                      • sierdzioS Offline
                        sierdzioS Offline
                        sierdzio
                        Moderators
                        wrote on last edited by
                        #13

                        One drawback of QML is that it's mightily hard to explain certain things... In order for this to work (IMO) you need to do that property manipulation outside of "main.cpp":https://github.com/sierdzio/closecombatfree/blob/master/src/ccfmain.cpp so for example in a QObject that gets initialised somewhere later. Same as with QWidgets or console apps in Qt: you need to have a working event loop for moc to work.

                        One possible alternative would be to modify the property using Qt::QueuedConnection, or the infamous singleshot QTimer.

                        (Z(:^

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