I’m working on a Compose app that lets users switch between dark, light and system default themes. C...

# compose

[Jorge Domínguez]

I’m working on a Compose app that lets users switch between dark, light and system default themes. Currently I’m having a problem where if the user selects the dark theme, the resources I have in the drawable-night resource set are not used, and instead the regular drawable resources are used, which leads to a very weird-looking UI. I know I can inform the system of the selected theme by doing either UiModeManager.setApplicationNightMode() or AppCompatDelegate.setDefaultNightMode(), and it seems to work, but for some reason it breaks the theme change when the users selects the system default option. Are there additional considerations for doing this in Compose that I’m missing?

[Alex Vanyo]

Which type of base Activity is your Compose app using? If you are using AppCompatDelegate, you will need to use AppCompatActivity to get all of the backporting in behavior that AppCompatDelegate applies.

[Jorge Domínguez]

I’m using ComponentActivity as base, and I’m only using AppCompatDelegate if the API is lower than 31

[Alex Vanyo]

For API levels lower than 31, I would expect needing to use AppCompatActivity to get the right behavior

[Jorge Domínguez]

I see, but even so I’m noticing the behavior on a Pixel 6a running Android 14

[Alex Vanyo]

Hmm that is surprising. When the user selects the “system default” option, you’re then setting the application night mode back to the AUTO mode?

[Jorge Domínguez]

Not really, I’m using whatever isSystemInDarkTheme() returns to set MODE_NIGHT_YES or MODE_NIGHT_NO respectively.

[Alex Vanyo]

Ah, I’d try to use https://developer.android.com/reference/android/app/UiModeManager#MODE_NIGHT_AUTO for UiModeManager or https://developer.android.com/reference/androidx/appcompat/app/AppCompatDelegate#MODE_NIGHT_FOLLOW_SYSTEM() for AppCompatDelegate

[Jorge Domínguez]

I’ll try that, thanks. I guess it’s also worth mentioning that I’m also using android:configChanges="uiMode" in my manifest, and noticed that the onConfigurationChanged callback is not giving me the right UI_MODE value when I change it in the device’s settings

[Jorge Domínguez]

oh wow, your suggestion seems to work

[Alex Vanyo]

Nice! If you only set UiModeManager or AppCompatDelegate to “yes” or “no”, you won’t be following the system as that changes, you have to explicity switch back to the setting which follows the system

[Jorge Domínguez]

got it, thanks a lot!