Translation not working in Qt - c++

Question

I have been all day long googling for a solution and changing my code, but no luck.
Basically, I have added translation to my app. It is working fine except here:
QString MainWindow::getMessage(Messages msg) {
static const char* const messages[] = {
QT_TR_NOOP("Setting power on"),
QT_TR_NOOP("Reading ID..."),
QT_TR_NOOP("Programming..."),
QT_TR_NOOP("Setting write-protect"),
QT_TR_NOOP("Finished ok"),
QT_TR_NOOP("PROGRAMMED OK"),
QT_TR_NOOP("ERROR!"),
QT_TR_NOOP("OK"),
QT_TR_NOOP("The programmer is not connected.\nPlease check the connection."),
QT_TR_NOOP("Disconnect the board, it is in short!!"),
QT_TR_NOOP("ERROR: Supply voltage too low (1 Volt is required, Measured: 0.0 Volt)."),
QT_TR_NOOP("Board is already programmed and write protected."),
QT_TR_NOOP("Check device connection or there is short."),
QT_TR_NOOP("Unknown error.")
};
return tr(messages[msg]);
}
However, I don't get the translation. The files for translation seems to be ok, the UI translations are applied fine.
I also tried this:
static const char* const messages[] = {
QT_TRANSLATE_NOOP("test", "Setting power on"),
QT_TRANSLATE_NOOP("test", "Reading ID..."),
QT_TRANSLATE_NOOP("test", "Programming..."),
QT_TRANSLATE_NOOP("test", "Setting write-protect"),
QT_TRANSLATE_NOOP("test", "Finished ok"),
QT_TRANSLATE_NOOP("test", "PROGRAMMED OK"),
QT_TRANSLATE_NOOP("test", "ERROR!"),
QT_TRANSLATE_NOOP("test", "OK"),
QT_TRANSLATE_NOOP("test", "The programmer is not connected.\nPlease check the connection."),
QT_TRANSLATE_NOOP("test", "Disconnect the board, it is in short!!"),
QT_TRANSLATE_NOOP("test", "ERROR: Supply voltage too low (1 Volt is required, Measured: 0.0 Volt)."),
QT_TRANSLATE_NOOP("test", "Board is already programmed and write protected."),
QT_TRANSLATE_NOOP("test", "Check device connection or there is short."),
QT_TRANSLATE_NOOP("test", "Unknown error.")
};
Then, I have a method to get the message:
QString MainWindow::getMessage(Messages msg) {
return qApp->translate("test", messages[msg]);
}
But it doesn't work either.
Any tips or suggestions?

Answer 1

I have found the real issue here.
Usually translators are installed at main.cpp, so the translator object remains in memory.
However, in my case, I was switching the translator after the user changes the language at settings dialog, using a local variable but void QCoreApplication::installTranslator ( QTranslator * translationFile ) [static] needs a pointer. That local variable is removed as soon as the function exits.
So, I declared a QTranslator object on my class, so it keeps in memory.

Answer 2

Maybe not applicable in this situation, but often people forget to place the Q_OBJECT macro in the class declaration. Resulting in (amongst others) tr() not working.

Answer 3

I was preparing a simpler source to upload here but now it is working fine! I rebooted my PC yesterday, you know, sometimes a reboot fixes everything (?).
Anyway, here is some source as it was requested. And by the way, I'm doing the translation on the fly, and by letting the user to choose the language (not by detecting locales):
This is main.cpp (nothing was added by me):
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
This is mainwindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDir>
#include <QTranslator>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QDir d(":/translations/");
QStringList files = d.entryList(QStringList("*.qm"));
qDebug("There are %d files for translation", files.count());
// Now let's fill the combobox
this->ui->comboBox->clear();
for (int i = 0; i < files.count(); ++i) {
QTranslator translator;
translator.load(files[i], ":/translations/");
QString language = translator.translate("MainWindow",
"English");
this->ui->comboBox->addItem(language);
}
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_comboBox_currentIndexChanged(int index)
{
// Now, based on the new itemindex, let's change the translator
QString selectedLang = this->ui->comboBox->itemText(index);
QString language;
QDir d(":/translations/");
QStringList files = d.entryList(QStringList("*.qm"));
for (int i = 0; i < files.count(); ++i) {
QTranslator translator;
translator.load(files[i], ":/translations/");
language = translator.translate("MainWindow",
"English");
if (language == selectedLang) {
if (!qApp->installTranslator(&translator)) {
qDebug("ERROR INSTALLING TRANSLATOR !!!");
}
this->uiTranslate();
break;
}
}
}
/// This function translates all the UI texts:
void MainWindow::uiTranslate(void) {
this->setWindowTitle(tr("MainWindow"));
// Just for testing, also show all the messages
for (int i = 0; i < MSG_LAST; ++i) {
this->ui->textBrowser->append(this->getMessage((Messages)i));
}
}
QString MainWindow::getMessage(Messages idx) {
static const char* const messagesText[MSG_LAST] = {
QT_TR_NOOP("Hello!"),
QT_TR_NOOP("Bye bye"),
QT_TR_NOOP("Nice to meet you")
};
return (tr(messagesText[idx]));
}
in this test app, the UI just has a combobox and a text browser.
The combobox is filled with the languages included on the resource file.
When I change the combobox, the mainwindow title is changed and the messages are printed in the right language.
Thanks anyway!
Best regards,