How to create QML object within a singleton?

I have defined a QML object under MyQMLObject.qml. This QML file looks like this:

import QtQuick 2.4

Item {
  id: rootItem
  implicitWidth: LayoutUtils.maxImplicitWidth(children)
  implicitHeight: LayoutUtils.maxImplicitHeight(children)

  Text {
    id: text1
  }
  Text {
    id: text2
  }
  // ...
  Text {
    id: textN
  }
}

The text is added dynamically when the application starts. For each language different text is added, there for the width of the rootItem varies by the chosen language. I would like to somehow create MyQMLObject only once at application startup without even visualizing it and save its actual width in a singleton for example so I can reuse that value throughout my code without creating MyQMLObject more then once. How could I achieve this?

Right now I have a singleton QML file, which holds a QtObject which contains some constant values. Can I somehow create an instance of MyQMLObject within this singleton QtObject?

My singleton Style.qml looks like this:

pragma Singleton

import QtQuick 2.4

QtObject {
  readonly property int maxWidth: 400
  // ...
}

Firstly, if possible, you could use a Column instead of manually calculating the maximum width:

MyQMLObject.qml

import QtQuick 2.4

Column {
    Text {
        text: "blah"
    }
    Text {
        text: "blahblah"
    }
}

You can use dynamic object creation to create the temporary Column item:

Style.qml

pragma Singleton

import QtQuick 2.4

QtObject {
    readonly property int maxWidth: {
        var component = Qt.createComponent("qrc:/MyQMLObject.qml");
        if (component.status === Component.Error) {
            console.error(component.errorString());
            return 0;
        }

        return component.createObject().width;
    }
}

main.qml

import QtQuick 2.5
import QtQuick.Window 2.2

import App 1.0

Window {
    visible: true

    Component.onCompleted: print(Style.maxWidth)
}

Then, register the singleton:

main.cpp

#include <QtGui>
#include <QtQml>

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

    qmlRegisterSingletonType(QUrl("qrc:///Style.qml"), "App", 1, 0, "Style");

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

However, note that this approach could be improved by calculating the maximum width from C++, eliminating the need to construct an item only to throw it away. Working off this example:

#include <QtGui>
#include <QtQml>

class Style : public QObject
{
    Q_OBJECT
    Q_PROPERTY(int maxWidth READ maxWidth CONSTANT)

public:
    Style(QObject* parent = 0) :
        QObject(parent),
        mMaxWidth(0)
    {
        QFontMetrics fontMetrics(qApp->font());
        // Here is where you'd fetch the text...
        QStringList dummyText;
        dummyText << "blah" << "blahblah";
        foreach (const QString &string, dummyText) {
            const int width = fontMetrics.boundingRect(string).width();
            if (width > mMaxWidth)
                mMaxWidth = width;
        }
    }

    int maxWidth() const
    {
        return mMaxWidth;
    }

private:
    int mMaxWidth;
};

static QObject *singletonTypeProvider(QQmlEngine *, QJSEngine *)
{

    Style *style = new Style();
    return style;
}

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

    qmlRegisterSingletonType<Style>("App", 1, 0, "Style", singletonTypeProvider);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

#include "main.moc"

It uses QFontMetrics to calculate the width.

main.qml remains unchanged.