Object order creation QT for C++ and QML - c++

Question

I'm developing an application in Qt/QML in a Linux environment. As the application grown bigger several issues appeared.
A particular issue is related to a C++ objecttranslator referred inside the QML sources. The project builds correctly and the translator object works for almost all the items in QML. However, in some places, I get the wrong text. Consider the following example:
Text{
x: 1036; y: 108
id: incomingLabel
text: qsTr("Weather") + translator.tr; // referred object
color: "white";
font.pixelSize: 34
}
In the case I got "WeatherUndefined" as text, all appended. My guess is that when this QML text element requires the text attribute, the translator object is not yet created and that causes the tr to be undefined.
This is how I register the C++ class in QML:
Translator translator(app.data(),":/translations");
viewer.rootContext()->setContextProperty("translator", &translator);
It should be noted that the problem does not appear on Windows but only in my Linux environment.
The complete code for the translator class is:
Yes translator.tr is a read only property. The translator code is:
#include "translator.h"
#include <QDebug>
Translator::Translator(QApplication *app, const QString &source, QObject *parent) :
QObject(parent),
m_app(app),
m_source(source)
{
addTranslation("DE", "lang_de_DE.qm");
addTranslation("ES", "lang_es_ES.qm");
addTranslation("FR", "lang_fr_FR.qm");
addTranslation("IT", "lang_it_IT.qm");
}
void Translator::addTranslation(const QString &name, const QString &file)
{
if (!m_translations.contains(name))
m_translations.insert(name, file);
}
QString Translator::tr()
{
return "";
}
void Translator::setSource(const QString &source)
{
m_source = source;
}
void Translator::translate(const QString &language)
{
if (language == "EN")
removeTranslation();
if (m_translations.contains(language))
{
QString langURL = m_translations.value(language).toString();
if (m_qtTranslator.load(langURL, m_source))
{
removeTranslation();
m_app->installTranslator(&m_qtTranslator);
emit languageChanged();
}
}
}
void Translator::removeTranslation()
{
m_app->removeTranslator(&m_qtTranslator);
emit languageChanged();
}
The header file:
#ifndef TRANSLATOR_H
#define TRANSLATOR_H
#include <QObject>
#include <QVariantMap>
#include <QtWidgets/QApplication>
#include <QTranslator>
class Translator : public QObject
{
Q_OBJECT
Q_PROPERTY(QString tr READ tr NOTIFY languageChanged)
public:
explicit Translator(QApplication *app, const QString &source, QObject *parent = 0);
void addTranslation(const QString &name, const QString &file);
void setSource(const QString &source);
Q_INVOKABLE void translate(const QString &language);
QString tr();
signals:
void languageChanged();
private:
QApplication *m_app;
QString m_source;
QVariantMap m_translations;
QTranslator m_qtTranslator;
void removeTranslation();
};
#endif // TRANSLATOR_H
Any ideas? Thank you in advance.

Answer 1

You need to check whether the problem lies in translator or tr.
If translator is not created yet, you will get this error in the console:
ReferenceError: translator is not defined.
And you won't see Weatherundefined in your Text object.
If translator exists but not tr, then translator.tr will return undefined, so you will get this output when calling qsTr("Weather") + translator.tr:
Weatherundefined
I suggest you call some console.log() to pinpoint the problem:
Text{
x: 1036; y: 108
id: incomingLabel
text: {
console.log(translator);
console.log(translator.tr);
return qsTr("Weather") + translator.tr(); // referred object
}
color: "white";
font.pixelSize: 34
}
Also I notice that your translator object is allocated on stack, that could cause problem too.