Application.md

Window - application APIs

Every Aurora-powered application needs an auroraApplication block that wraps it.

This block creates an AuroraApplicationScope that extends the base Compose ApplicationScope, as well as Aurora's own AuroraLocaleScope.

The definition of AuroraLocaleScope is:

interface AuroraLocaleScope {
    var applicationLocale: Locale
}

Setting application locale

The default value for application locale is set to Locale.getDefault(). Applications that expose locale switching can persist their currently selected locale on application exit and use that saved value on next application startup:

fun main() = auroraApplication {
    // Hard coded here, but can be read from persisted
    // value and constructed dynamically
    applicationLocale = Locale("iw", "IL")

    AuroraWindow(...) {
        // Content
    }
}

Working with resource bundles

Use the combination of applicationLocale and Compose's derivedStateOf to load your localized strings.

First, create your derived ResourceBundle:

val resourceBundle = derivedStateOf {
    ResourceBundle.getBundle(
      "org.pushingpixels.aurora.demo.Resources",
      applicationLocale)
}

Now you can use this resource bundle to configure strings in your UI:

CommandButtonProjection(
    contentModel = Command(
        text = resourceBundle.value.getString("Control.button.toggle"),
        icon = computer(),
        ...
    ),
    presentationModel = CommandButtonPresentationModel(
      ...
    )
).project()

Switching locale at runtime

The applicationLocale in AuroraLocaleScope is a var, which means that you can wire your application logic not only to retrieve localized strings for your UI, but also to change locale at runtime and have all relevant pieces recompose to reflect the newly set locale.

Here is sample code on how this can be achieved. We first start with two commands, one to set locale to en_US (English) and one to set locale to iw_IL (Hebrew):

val englishLocale = Command(
  text = resourceBundle.value.getString("Language.english"),
  icon = us(),
  action = {
    applicationLocale = Locale("en", "US")
    // Only necessary for embedded Swing content
    for (window in Window.getWindows()) {
      window.applyComponentOrientation(
        ComponentOrientation.getOrientation(applicationLocale)
      )
    }
  }
)
val hebrewLocale = Command(
  text = resourceBundle.value.getString("Language.hebrew"),
  icon = il(),
  action = {
    applicationLocale = Locale("iw", "IL")
    // Only necessary for embedded Swing content
    for (window in Window.getWindows()) {
      window.applyComponentOrientation(
        ComponentOrientation.getOrientation(applicationLocale)
      )
    }
  }
)

Now we create a command with a secondary content model and project it, which ends up emitting what is otherwise known as a popup button:

val localeCommand = Command(
  text = resourceBundle.value.getString("Language.select"),
  icon = preferences_desktop_locale_2(),
  secondaryContentModel = CommandMenuContentModel(
    group = CommandGroup(
      commands = arrayListOf(englishLocale, hebrewLocale)
    )
  )
)
CommandButtonProjection(
  contentModel = localeCommand,
  presentationModel = CommandButtonPresentationModel(
    presentationState = CommandButtonPresentationState.Medium
  )
).project()

Here is how this popup looks like:

If your resource bundle is constructed as a derivedStateOf using the applicationLocale from the AuroraApplicationScope, the action lambda in each one of these two commands that changes the value of applicationLocale will also end up recomposing your UI with strings fetched from the new resource bundle. In addition, Aurora will also apply the matching layout direction (left-to-right or right-to-left) based on the new application locale.