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.