StateListDrawable added.

Author: iammert

app/src/main/res/layout/activity_fab.xml

@@ -12,9 +12,9 @@
         android:layout_width="56dp"
         android:layout_height="56dp"
         android:layout_margin="16dp"
-        android:layout_alignParentBottom="true"
-        android:layout_alignParentRight="true"
+        android:layout_centerInParent="true"
         android:elevation="4dp"
+        android:foreground="@drawable/sl_state_drawable"
         app:radiusFactor="1">
 
         <RelativeLayout

scalinglib/src/main/res/drawable/sl_state_drawable.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item android:state_pressed="true">
+        <shape>
+            <solid android:color="#80ffffff" />
+        </shape>
+    </item>
+
+    <item>
+        <shape>
+            <solid android:color="#00ffffff" />
+        </shape>
+    </item>
+
+</selector>