Change color of Nine-Patch that's set as the background of a ConstraintLayout

Question

Very mad question:

I'm trying to change the color of a Nine-Patch that's set as the background of a ConstraintLayout. android:backgroundTint in the XML works fine, but this is only supported by Android 5.0+. Using app:backgroundTint instead of android:backgroundTint doesn't change the color.

My XML:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    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="29dp"
    android:background="@drawable/round"

    android:backgroundTint="@android:color/darker_gray">
</android.support.constraint.ConstraintLayout>

Does anyone know another way to change the color? Any help is appreciated.

Answer 1

I've just found the answer:

in the onCreate() method:

View line = findViewById(R.id.line);
ColorStateList tint = ColorStateList.valueOf(ContextCompat.getColor(this, android.R.color.holo_blue_light));
ViewCompat.setBackgroundTintList(line, tint);

Thanks to @azizbekian for the suggestion.