Proper way for adding 2nd language

masa4

I added all my text label in english in my project. But now i want to add 2nd language to project. I created a combobox for language selection.

I watched a tutorial, created a .ts file, translated some texts with qlinguist, created .qm file from it. Added it to my project as resource and i tried to load it. Loading returns true but texts are not changing.

QTranslator t;
qDebug() << t.load(":/i18n/lang_2nd.qm");

Any clean resource about this? Are what can be problem here? And also, i need to create a qm file for original language(english) and load it when selected in combobox, rgiht?

Christian Ehrlicher

As described in the documentation you also have to install the translator (and make sure it's alive during the program lifetime).

masa4

@Christian-Ehrlicher said in Proper way for adding 2nd language:

As described in the documentation you also have to install the translator (and make sure it's alive during the program lifetime).

I moved QTranslator t to header. and added qDebug() << QCoreApplication::installTranslator(&t); after load method. It returns true but still language is not changing. Note that, i didnt changed all translatable words in ts file, just some of them to test it.I dont know if that make any difference.

Christian Ehrlicher

@masa4 said in Proper way for adding 2nd language:

It returns true but still language is not changing.

Please read my comment:

and make sure it's alive during the program lifetime

masa4

@Christian-Ehrlicher Yes object t is alive for program lifetime. I created it in Settings.h and I am just creating one instance from Settings class at program startup in mainwidget. And not deleting it anywhere.

JonB

@masa4
You are wanting to change language at runtime, is that right? Because https://doc.qt.io/qt-6/qtranslator.html#details tells you

Note that the translator must be created before the application's widgets.

If you want to change after that I think you have to cause all your tr()s to re-translate, e.g. Change language at runtime? But I have never used it so I stand to be corrected....

ollarch

If your UI is designed on QDesigner you can call "retranslateUi" on your ui. Look at "ui_yourGUIClass.h" generated by UIC compiler.
If you add GUI elements dynamically you need to set its text again using the "tr".

masa4

@JonB Yes in runtime, when user change language setting in combobox, i want to change language. I have multiple ui, so i need call changeEvent for all of my ui class?
And I didnt understand ReUiSetText part. For example I have:

QMessageBox msgBox(QMessageBox::Information, "PROCESS", "Process done.");

in one of slot. How will I change its text in ReUiSetText across 2 languages?

masa4

@ollarch I created ui's with design ui and all widgets are checked as translatable and they appeared in my ts file when i used lupdate. And yes some part is created dynamically lie QMessageBox etc.
But its not working right now, since runtime language changing is need additional steps what i understand from above post

edit: I read your post again, i will check it

JonB

@masa4
I think you have to do as @ollarch says. Call retranslateUi() on each instance of classes designed in Designer, plus re-execute any dynamically created widgets' tr() statements.

QMessageBox msgBox(QMessageBox::Information, "PROCESS", "Process done.");

This won't translate as there is no translation marked on it. Why aren't you using a tr() here?

masa4

@JonB Thnik this as :

QMessageBox msgBox(QMessageBox::Information, tr("PROCESS"), tr("Process done."));

And I have 2 .qm files as resources, lang_en.qm, lang_de.qm. After i change langauge setting in combobox english to german, I will call retranslateUi(), i understand that part. But how will i change dynamically created widget's texts like this messagebox? Will it change automatically or will i do something in ReUiSetText method?

JonB

@masa4
Because you recreate the message box whenever it is to be shown its tr() will take into account the current language each time.

ollarch

@masa4 As you have translator loaded, every call to "tr" will automatically translate the text. So, in the case of your QMessageBox you only have to add "tr" as @JonB suggested.
For your GUI widgets thar are created dynamically you have a pointer to it, so you have to set all the texts again with "tr". If you have own designed widgets it's a good idea to have a method like "retranslateUi" like UIC does.

Christian Ehrlicher

@masa4 said in Proper way for adding 2nd language:

But how will i change dynamically created widget's texts like this messagebox?

Since you can't show a MessageBox and change the language simulatneously this shouldn't be a problem since the next time you call the message box you text is properly translated due to the tr() call.
If you changed a text in your ui after setupUi() you have to do the same manually after the language change event. See the documentation.