AppLocale

Additional

Language
Kotlin
Version
2.0.3 (Sep 18, 2020)
Created
Jan 20, 2020
Updated
Sep 18, 2020
Owner
Benedikt Löbbecke (B3nedikt)
Contributor
Benedikt Löbbecke (B3nedikt)
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Blurb

App Locale 2.0.3

AppLocale is a android library to update the app language dynamically.

1. Add dependency

// Manages the Locale used by the app
implementation 'dev.b3nedikt.applocale:applocale:2.0.3'

2. Initialize

Initialize AppLocale in your Application class:

// The languages supported by our app, normally the ones we have strings.xml files for
// in the resources. If you dont set this, it will be assumed the app supports every language
// set programmatically using this lib.
AppLocale.supportedLocales = listOf(Locale.ENGLISH, Locale.French)

// Optional: Persist changes to the desiredLocale to sharedPreferences
AppLocale.appLocaleRepository = SharedPrefsAppLocaleRepository(this)

2. Add to the base activity

If the app has a base activity, this can go there, otherwise it needs to be added to every activity:

abstract class BaseActivity : AppCompatActivity() {

    override fun attachBaseContext(newBase: Context) {
        super.attachBaseContext(AppLocale.wrap(newBase))
    }

    override fun getResources(): Resources {
        return AppLocale.wrap(baseContext).resources
    }
}

3. Update the app language

Now we can just set the desiredLocale to the Locale we want our app to use:

AppLocale.desiredLocale = Locale.FRENCH

When the activity gets restarted, all texts will be localized using the new Locale.

Update the app language without restarting the activity

If you want to change the apps Locale without restarting the activity, you need to add the following additional dependencies:

// Needed to intercept view inflation
implementation 'dev.b3nedikt.viewpump:viewpump:3.0.1'

// Allows to update the text of views at runtime without recreating the activity
implementation 'dev.b3nedikt.reword:reword:2.0.0'

Initialize ViewPump & Reword in the application class:

// To dynamically update views we need to intercept view inflation and update
// the text of each view. The libraries ViewPump and reword do exactly that when setup
// like this:
ViewPump.init(ViewPump.builder()
        .addInterceptor(RewordInterceptor)
        .build())

To use ViewPump we need to additionally wrap the context with ViewPump in our base activity:

abstract class BaseActivity : AppCompatActivity() {

    override fun attachBaseContext(newBase: Context) {
        super.attachBaseContext(ViewPumpContextWrapper.wrap(AppLocale.wrap(newBase)))
    }

    override fun getResources(): Resources {
        return AppLocale.wrap(baseContext).resources
    }
}

If you use fragments add this to your base fragment:

abstract class BaseFragment : Fragment() {

    override fun onResume() {
        super.onResume()

        ViewPump.setOverwriteContext(AppLocale.wrap(requireContext()))
    }

    override fun onGetLayoutInflater(savedInstanceState: Bundle?): LayoutInflater {
        val wrappedContext = ViewPumpContextWrapper.wrap(AppLocale.wrap(requireContext()))
        return wrappedContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
    }
}

After setting the new locale you need to call reword to update all views which have been inflated from xml:

// If we want to update the app language without restarting the activity,
// we need to perform the update of the texts manually:
val rootView = window.decorView.findViewById<ContentFrameLayout>(android.R.id.content)
Reword.reword(rootView)

If you have changed the texts of views in code, you need to update these texts manually of course. Also should you use the application context somewhere to retrieve strings and inject it with a DI tool like koin or dagger, I would recommend wrapping it in your application class.

App Bundle support

If you use the new android app bundle (aab) format to distribute your app, android will strip out all languages which are not the users devices default language. To disable this add this to your build.gradle:

android {
    bundle {
        language {
            // We want to be able to switch the locale at runtime using AppLocale!
            enableSplit = false
        }
    }
}

Alternatively load the languages dynamically using the playcore library as described in its Documentation.

License

Copyright 2020 applocale Contributors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.