Per-app language settings support on macOS

[sikmir]

I wonder if it's possible to support additional languages for Qt app on macOS:

[tumic0]

I think this feature will be somehow based on the standard "lproj" files used by native OS X apps. Qt uses its own mechanism so the answer is IMHO no. But I can not give you any authoritative answer as I do not even have access to a Mac where such setting would be possible.

[sikmir]

VirtualBox is just an example of such Qt app that supports language settings:

$ find /Applications/VirtualBox.app -name "*cs*"
/Applications/VirtualBox.app/Contents/MacOS/nls/VirtualBox_cs.qm
/Applications/VirtualBox.app/Contents/MacOS/nls/qt_cs.qm
/Applications/VirtualBox.app/Contents/Resources/cs.lproj

/Applications/VirtualBox.app/Contents/Resources/cs.lproj/ is empty, there is no *.strings files in it.

https://www.virtualbox.org/browser/vbox/trunk/src/VBox/Frontends/VirtualBox/Makefile.kmk#L1931
https://www.virtualbox.org/browser/vbox/trunk/src/VBox/Frontends/VirtualBox/src/platform/darwin/VBoxUtils-darwin.cpp#L193

[sikmir]

Another example (more simple) is https://github.com/openorienteering/mapper, it also supports language settings:

$ find /Applications/Mapper.app -name "*cs.*"
/Applications/Mapper.app/Contents/Resources/cs.lproj
/Applications/Mapper.app/Contents/Resources/translations/map_symbols_cs.qm
/Applications/Mapper.app/Contents/Resources/translations/qt_help_cs.qm
/Applications/Mapper.app/Contents/Resources/translations/assistant_cs.qm
/Applications/Mapper.app/Contents/Resources/translations/OpenOrienteering_cs.qm
/Applications/Mapper.app/Contents/Resources/translations/qt_cs.qm
$ ls /Applications/Mapper.app/Contents/Resources/cs.lproj
locversion.plist
$ cat /Applications/Mapper.app/Contents/Resources/cs.lproj/locversion.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>LprojCompatibleVersion</key>
    <string>123</string>
    <key>LprojLocale</key>
    <string>cs</string>
    <key>LprojRevisionLevel</key>
    <string>1</string>
    <key>LprojVersion</key>
    <string>123</string>
</dict>
</plist>

[tumic0]

I have added the lproj stuff to the Resources directory in the latest OS X builds, does that help?

[sikmir]

I have added the lproj stuff to the Resources directory in the latest OS X builds, does that help?

Now it's possible to select a language:

But it doesn't applied yet, GPXSee still uses system language. Seems like one more trick is required somewhere, at least we have https://github.com/openorienteering/mapper as an example, where it works properly.

[tumic0]

I have extended the Info.plist which may have some impact. If that didn't help, please try to delete the "empty.lproj" file generated by qmake/macdeployqt from Resources and see if that has any effect.

[sikmir]

I have extended the Info.plist which may have some impact. If that didn't help, please try to delete the "empty.lproj" file generated by qmake/macdeployqt from Resources and see if that has any effect.

No, it doesn't work, the same with deleted "empty.lproj".

[tumic0]

Thanks for testing it. I have switched to CFBundleLocalizations in the Info.plist instead of separate lproj directories (2549204) as this is a better way how to "promote" the translations in cases where a non-native translation mechanism is used, but that will most probably also have no effect. The problem will be in the way how Qt gets the locale. I suppose there is a special API for that in newer OS X versions.

I have looked into the OpenOrienteering Mapper sources but there is IMHO no magic there. They seem to also use QLocale::system under the hood. But I have noticed, that they have their own application-specific language setting so maybe you have set it to the desired language and it may look like what is set in the OS X per-app settings works, but in reality it is just coincidence?

[sikmir]

But I have noticed, that they have their own application-specific language setting so maybe you have set it to the desired language and it may look like what is set in the OS X per-app settings works, but in reality it is just coincidence?

No, what I've tried:

$ defaults delete org.openorienteering.Mapper
$ open /Applications/Mapper.app

System default language (Finnish) is used.

$ defaults read org.openorienteering.Mapper
{
    AppleLanguages =     (
        fi
    );
    ...
}

Set Čeština for Mapper via macOS settings.

$ open /Applications/Mapper.app
$ defaults read org.openorienteering.Mapper
{
    AppleLanguages =     (
        cs
    );
    ...
}

Čeština is used.
Set Svenska via Mapper's application-specific language setting.

$ defaults read org.openorienteering.Mapper
{
    AppleLanguages =     (
        sv
    );
    ...
    language = sv;
    ...
}

macOS language settings is not used anymore after that.

[sikmir]

I have extended the Info.plist which may have some impact. If that didn't help, please try to delete the "empty.lproj" file generated by qmake/macdeployqt from Resources and see if that has any effect.

But macos dialogs (open file, etc) are properly translated now.

[tumic0]

I have investigated the problem a little bit more and it turns out, that the per-app language settings work by macOS putting a special configuration entry with the key "AppleLanguages" into the program preferences plist. So what looks like OpenOrienteeringMapper reading its own settings is in reality reading the entry set by the OS. There is QTBUG-51386 with the Qt-related info that is sadly closed as "Out of scope". So everyone who wants to enable per-app language settings has to "hack" the preferences plist and duplicate the selection from the languages list.

So it can be done, but it requires some ugly hack. Either by fiddling with the settings (there is AFAIK no official documentation from Apple - you shall access the locale by their API functions) or by using some Core Foundation platform specific code. The biggest problem for me is however that I have no access to a system where I could test my assumptions, implement the hack and test the result.

Given the low priority of the issue, my actual decision is to let the issue open until I get access to some recent mac machine.

[acrostich]

GPXSee 3.11 is not using the macOS (Sonoma 14.1.1) system default that is set to English for my system. The language it is using is set in macOS as my second preferred language (out of three).

I tried adding GPXSee in the Applications section at the bottom of Language & Region tab in System Settings, however I can't add it with the System Default - English (UK). I can only add it if I select another language, which is obviously not what I want.

[tumic0]

That's IMHO another Qt bug - QTBUG-86179. You can try the Qt6 Mac build from Github Actions and see if it works there, but be aware that the build may not work at all as I have no HW where I can test it. It's all the same story - unless GPXSee users start to support the project financially, the support for the Mac platform will only get worse through time and soon or later there will be no Mac builds at all.

[acrostich]

@tumic0 That Qt bug does indeed describe exactly what I'm experiencing. I've tried a Qt6 build from Github Actions and that is in English so solves that issue. Thank you.

As for the problem of financial support to the project and long term support of macOS, it may be useful to open a separate issue to raise the profile of these difficulties for everyone looking at the tracker and interested in macOS.

[tumic0]

As for the problem of financial support to the project and long term support of macOS, it may be useful to open a separate issue to raise the profile of these difficulties for everyone looking at the tracker and interested in macOS.

I doubt that this would have any effect. You have a "Sponsor this project" section on the GitHub project main page, a "GPXSee needs your financial help. Become a sponsor" section on the GPXSee web and yet the funding is practically nonexistent. Let's look at you as an example - you now know GPXSee macOS support is dying, you use GPXSee on Mac and you even ask the developers for help. But your name is still not on the list of the sponsors of the project...