Multi theme in jetpack compose

DarkLightTheme.kt

// # Dark and light theme

// 01- Color
val colorBlue = Color(0xFF001E63)
val colorBlue1 = Color(0xFF000063)
val colorRed = Color(0xFF5A0000)
val colorGreen = Color(0xFF003A00)
val colorWhite = Color(0xFFFFFFFF)
val colorBlack = Color(0xE9000000)

// 02- Color Scheme
private val DarkColorScheme = darkColorScheme(
    primary = colorBlue,
    secondary = colorBlue1,
    background = colorBlack,
    onPrimary = colorWhite,
    onSecondary = colorWhite,
    onBackground = colorWhite
)

private val LightColorScheme = lightColorScheme(
    primary = colorRed,
    secondary = colorBlue1,
    background = colorWhite,
    onPrimary = colorWhite,
    onSecondary = colorWhite,
    onBackground = colorBlack
)

// 03- Enum Theme
enum class AppTheme {
    Light, Dark, Default
}

// 04- Theme
@Composable
fun MyApplicationTheme(
    appTheme: AppTheme,
    isDarkMode: Boolean = isSystemInDarkTheme(),
    content: @Composable () -> Unit
) {

    val colorScheme = when (appTheme) {
        AppTheme.Default -> {
            if (isDarkMode) {
                DarkColorScheme
            } else {
                LightColorScheme
            }
        }
        AppTheme.Light -> {
            LightColorScheme
        }
        AppTheme.Dark -> {
            DarkColorScheme
        }
    }

    MaterialTheme(
        colorScheme = colorScheme, 
        typography = Typography, 
        content = content
    )
}

// 05- Change theme programmatically
class MainViewModel: ViewModel() {

    var stateApp by mutableStateOf(MainState())

    fun onEvent(event: MainEvent) {
        when(event) {
            is MainEvent.ThemeChange -> {
                stateApp = stateApp.copy(theme = event.theme)
            }
        }
    }

}

sealed class MainEvent {
    data class ThemeChange(val theme: AppTheme): MainEvent()
}

data class MainState(
    val theme: AppTheme = AppPreferences.getTheme(),
)

// MainActivity
class MainActivity : ComponentActivity() {

    val viewModel: MainViewModel = MainViewModel()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApplicationTheme(appTheme = viewModel.stateApp.theme) {
                HomeScreen(viewModel)
            }
        }
    }
}

// Call event change theme
//Default 
AppPreferences.setTheme(AppTheme.Default)
mainViewModel.onEvent(MainEvent.ThemeChange(AppTheme.Default))

//Light
AppPreferences.setTheme(AppTheme.Light)
mainViewModel.onEvent(MainEvent.ThemeChange(AppTheme.Light))

//Dark
AppPreferences.setTheme(AppTheme.Dark)
mainViewModel.onEvent(MainEvent.ThemeChange(AppTheme.Dark))

// Save theme using pref

object AppPreferences {

    const val APP_THEME = "AppTheme"

    fun setTheme(theme: AppTheme) {
        Paper.book().write(APP_THEME, theme)
    }

    fun getTheme(): AppTheme {
        return Paper.book().read(APP_THEME, AppTheme.Default)!!
    }
}

MultiTheme.kt

// 01- Color

val colorBlue = Color(0xFF001E63)
val colorBlue1 = Color(0xFF000063)
val colorRed = Color(0xFF5A0000)
val colorGreen = Color(0xFF003A00)
val colorWhite = Color(0xFFFFFFFF)
val colorBlack = Color(0xE9000000)

// 02- Color Scheme
private val BlueColorScheme = lightColorScheme(
    primary = colorBlue,
    secondary = colorBlue1,
    background = colorWhite,
    onPrimary = colorWhite,
    onSecondary = colorWhite,
    onBackground = colorBlack
)


private val RedColorScheme = lightColorScheme(
    primary = colorRed,
    secondary = colorBlue1,
    background = colorWhite,
    onPrimary = colorWhite,
    onSecondary = colorWhite,
    onBackground = colorBlack
)


private val GreenColorScheme = lightColorScheme(
    primary = colorGreen,
    secondary = colorBlue1,
    background = colorWhite,
    onPrimary = colorWhite,
    onSecondary = colorWhite,
    onBackground = colorBlack
)

// 03- Enum Theme
enum class AppTheme {
    Blue, Red, Green
}

// 04- Theme

@Composable
fun MyApplicationTheme(
    appTheme: AppTheme,
    isDarkMode: Boolean = isSystemInDarkTheme(),
    content: @Composable () -> Unit
) {

    val colorScheme = when (appTheme) {
        AppTheme.Blue -> {
            BlueColorScheme
        }
        AppTheme.Red -> {
            RedColorScheme
        }
        AppTheme.Green -> {
            GreenColorScheme
        }
    }

    val systemUiController = rememberSystemUiController()
    SideEffect {
        systemUiController.setStatusBarColor(
            color = colorScheme.primary,
            darkIcons = false,
        )
    }
    MaterialTheme(
        colorScheme = colorScheme, typography = Typography, content = content
    )
}

// 05- Change theme programmatically
ViewModel

class MainViewModel: ViewModel() {
}
 
 // MainActivity
 
 class MainViewModel: ViewModel() {

    var stateApp by mutableStateOf(MainState())

    fun onEvent(event: MainEvent) {
        when(event) {
            is MainEvent.ThemeChange -> {
                stateApp = stateApp.copy(theme = event.theme)
            }
        }
    }

}

sealed class MainEvent {
    data class ThemeChange(val theme: AppTheme): MainEvent()
}

data class MainState(
    val theme: AppTheme = AppPreferences.getTheme(),
)


 val viewModel: MainViewModel = MainViewModel()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyApplicationTheme(appTheme = viewModel.stateApp.theme) {
                HomeScreen(viewModel)
            }
        }
    }
}


// Call event change theme

//Default 
AppPreferences.setTheme(AppTheme.Blue)
mainViewModel.onEvent(MainEvent.ThemeChange(AppTheme.Blue))

//Red
AppPreferences.setTheme(AppTheme.Red)
mainViewModel.onEvent(MainEvent.ThemeChange(AppTheme.Red))

//Default 
AppPreferences.setTheme(AppTheme.Green)
mainViewModel.onEvent(MainEvent.ThemeChange(AppTheme.Green))

// Save theme using pref

object AppPreferences {

    const val APP_THEME = "AppTheme"

    fun setTheme(theme: AppTheme) {
        Paper.book().write(APP_THEME, theme)
    }

    fun getTheme(): AppTheme {
        return Paper.book().read(APP_THEME, AppTheme.Blue)!!
    }
}


// # Finally

// In theme.xml add this line for don’t force night mode on Android 10 devices and above
  <style name="Theme.MultiTheme" parent="android:Theme.Material.Light.NoActionBar" >

        <item name="android:forceDarkAllowed" tools:targetApi="q">false</item>

    </style>