Transparent Activity background unusally going grey in recents apps menu

Question

I'm developing an Android application with a transparent background. It works fine, but in the recents view, the activity turns grey instead of retaining its transparency. I've tried several approaches but haven't been able to resolve the issue.

Here is my MainActivity.kt

package b.os.calculator



import android.os.Bundle

import android.view.View

import androidx.activity.ComponentActivity

import androidx.activity.compose.setContent

import androidx.activity.enableEdgeToEdge

import androidx.compose.foundation.background

import androidx.compose.foundation.layout.Box

import androidx.compose.foundation.layout.fillMaxSize

import androidx.compose.foundation.layout.padding

import androidx.compose.material3.Scaffold

import androidx.compose.material3.Text

import androidx.compose.runtime.Composable

import androidx.compose.ui.Modifier

import androidx.compose.ui.graphics.Color

import androidx.compose.ui.tooling.preview.Preview

import b.os.calculator.ui.theme.CalculatorTheme

import android.view.Window;

import android.view.WindowManager;

import androidx.compose.material3.MaterialTheme



class MainActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {

        setTheme(R.style.Theme_Calculator)

        super.onCreate(savedInstanceState)



        enableEdgeToEdge()

        window.setBackgroundDrawableResource(android.R.color.transparent)

        setBlurEffect()

        enableEdgeToEdge()

        setContent {

            CalculatorTheme {

                TransparentBackgroundContent()



            }



        }

    }



    private fun setBlurEffect() {

        window.setBackgroundBlurRadius(169) // Adjust the radius as needed

    }

}





@Composable

public fun TransparentBackgroundContent() {

    val transparency = 0.9f



    // Define your primary Material color (e.g., Primary color)

    val primaryColor = MaterialTheme.colorScheme.background // Replace with your actual primary color



    // Create a Color with the desired transparency and tint

    val transparentPrimaryColor = primaryColor.copy(alpha = transparency)

    Box(

        modifier = Modifier

            .fillMaxSize()

            .background(color = transparentPrimaryColor)

    ) {

        // Add other UI elements but now removed for simplicity

    }

}

@Preview(showBackground = false)

@Composable

fun TransparentBackgroundContentPreview() {

    CalculatorTheme {

        TransparentBackgroundContent()

    }

}

I've added a blur effect and set the window background to transparent. The activity displays correctly while in use, but the transparency effect doesn't carry over to the recents view.I also tried to integrate a function to safely set the task description, but the app crashes when I do this:

private fun setTaskDescriptionSafely() {

    try {

        val taskDescription = ActivityManager.TaskDescription.Builder()

            .setLabel(null) // Use default app label

            .setIcon(null) // Use default app icon

            .setPrimaryColor(ContextCompat.getColor(this, android.R.color.transparent)) // Set background color to transparent

            .build()



        setTaskDescription(taskDescription)

    } catch (e: Exception) {

        e.printStackTrace() // Handle any potential exceptions

    }

}

Screenshots:

Normal view: When my app runs normally

Recents view: When the app goes in the recents

I've been searching for a solution but haven't had any luck. How can I ensure that the activity maintains its transparency in the recents view?

BTW I AM USING API 34 (Android 14) And using a Pixel 7a vitual device running Android 15 Api 35

Thanks in advance for your help!