Transparent Navigation in #Flutter App. 13th May 2019

MainActivity.java

import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.view.Window;

import io.flutter.app.FlutterActivity;
import io.flutter.plugins.GeneratedPluginRegistrant;


public class MainActivity extends FlutterActivity
{
	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		GeneratedPluginRegistrant.registerWith(this);
		drawUnderSystemUi();
	}

	@Override
	protected void onPostResume() {
		super.onPostResume();
		drawUnderSystemUi();
	}

	private void drawUnderSystemUi()
	{
		if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP){
			Window window = getWindow();
			window.setStatusBarColor(0x22000000);
			window.setNavigationBarColor(0x22000000);
			window.getDecorView()
				.setSystemUiVisibility(
					View.SYSTEM_UI_FLAG_LAYOUT_STABLE |
					View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN |
					View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);
		}
	}
}