Set background color for whole app. Android, Jetpack Compose

Question

I need to set background color for whole app. In xml, we use android:background tag in fragment || activity.

What analog Compose has? Surface argument for theme colorPalette doesn't help (background color doesn't changes). Where in code I need to set the background? Look for your solutions.

Answer 1

You can place your app inside a Box with needed background:

setContent {
    YourTheme {
        Box(
            modifier = Modifier
                .fillMaxSize()
                .background(Color.Yellow)
        ) {
            YourApp()
        }
    }
}

Answer 2

Put a window background color from your theme, which will set the background of your whole app, and also remove the white flicker while the app is loading (which looks quite odd if you have a color background in your app):

res/values/themes/themes.xml

<style name="Theme.YourThemeName" 
    parent="Theme.MaterialComponents.DayNight.DarkActionBar">
        ...
        <item name="android:windowBackground">@color/purple_700</item>
</style>