Dynamic Language Translation in Qt

[neel2818]

Hi All,

I have written one application in that application i have to do reboot the system then only after language translation applied.
What i want to change the language without reboot i mean at run time i have to change the all text in translated localized form.
In my sample application in main i have written following code.

@
QTranslator * translator;
translator = new QTranslator;
translator->load( "QM file path where the language file exist ");
app.installTranslator(translator);
@

From another file or form how can i know the language has changed and how to handle it ?
Can someone explain me how to do with this code ? or sample code or link will helped me a lot.

Thanks,
Neel

[Edit] Use @ for code

[Andreas]

You need to react on the language change event within your widgets. The change event is posted to all widgets if there is a change to the installed Qt translator.

"Dynamic translations":http://doc.qt.nokia.com/4.7/internationalization.html#dynamic-translation

example:
@ void MyWidget::MyWidget(QWidget* parent)
: QWidget(parent)
{
retranslate();
}

void MyWidget::changeEvent(QEvent* event)
{
if (event->type() == QEvent::LanguageChange)
{
// retranslate designer form
ui.retranslateUi(this);

       // retranslate other widgets which weren't added in designer
       retranslate();
   }
   
   // remember to call base class implementation
   QWidget::changeEvent(event);

}

void MyWidget::retranslate()
{
mylabel->setText(tr("Text"));
}
@

[AlterX]

Sorry for my intrusion...I've just located an entire desktop app, but I'm able to see translations just for my texts and not for ui generated texts.
shall I have to use dynamic translation to change ui texts?!

[Hareen Laks]

Some time ago I did it as follows;

First create actions for different languages and connect their triggered() SIGNALs with language specific SLOTs.

@
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
connect(ui->actionDanish, SIGNAL(triggered()), this, SLOT(changeLanguageToDanish()));
connect(ui->actionEnglish, SIGNAL(triggered()), this, SLOT(changeLanguageToEnglish()));
QApplication::instance()->installTranslator(&translator);

}@

Then from that SLOTs call to language change function.
@
void MainWindow::changeLanguageToEnglish()
{
changeLanguageTo(English_file_location);
}

void MainWindow::changeLanguageToDanish()
{
changeLanguageTo(Danish_file_location);
}@

Load the language file

@void MainWindow::changeLanguageTo(const QString &language_file_location)
{
translator.load(language_file_location);
}@

Call language change event

@void MainWindow::changeEvent(QEvent *e)
{
if(e->type() == QEvent::LanguageChange)
{
ui->retranslateUi(this);
}
QMainWindow::changeEvent(e);

}@

[AlterX]

So I have to do something to translate ui....I've tried to implement changeEvent for one ui file and now it is correctly located.
My question is: why my tr(text) in the code is automatically translated at runtime and ui generated tr did not?

[Hareen Laks]

@ AlterX ,

what do you mean by ui generated?

is it means the text of buttons, labels, menus etc?

[AlterX]

Yes,
it creates ui_xxxx.h with all localized code QApplication::translate(), but even they are present like my own code, ui form doesn't get translated at runtime like my code does!

[Hareen Laks]

generally I set the text of button as _[Click Me] _.
Then by using 'Qt Linguist' set the text in different languages for [Click me] .

And I'm not doing any other thing except my previous reply. ChangeEvent do the rest.

[AlterX]

Ok so changeEvent is necessary to translate uis...