To independently control the transluscency of the status and navigation bars on KitKat, you can simply use the window manager flags FLAG_TRANSLUSCENT_STATUS and FLAG_TRANSLUSCENT_NAVIGATION in the onCreate() method of your activity. However, on KitKat the system may draw a semi-opaque gradient scrim drawable over the status bar. This appears to be device-specific: on my KitKat device it's fully transparent, but on Android Studio emulator it shows a scrim.
On Lolliop or later you can instead set the status bar colour using the Window#setStatusBarColor(int) method together with the FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS window manager flag. Note that you clear the FLAG_TRANSLUSCENT_STATUS flag in this case. If you want the colour to be transparent, that implies that your application supports full screen mode and sets the system UI visibility, so it's down to your app to manage the status bar background colour.
Putting it all together would look something like this:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Window window = getWindow();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
window.setStatusBarColor(0x00000000); // transparent
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
int flags = WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;
window.addFlags(flags);
}
setContentView(R.layout.main);
window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
}
Example of layout used:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ff00ff00"
android:fitsSystemWindows="false"
tools:context=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="Hello World!"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true"
android:orientation="vertical">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay"/>
</LinearLayout>
</RelativeLayout>
Example screenshots.
Lollipop:
KitKat:
