Added background color for selected subscribe button

app/src/main/java/me/vadik/knigopis/user/UserActivity.kt

@@ -49,7 +49,9 @@ class UserActivity : AppCompatActivity() {
         toolbarImage.setElevationRes(R.dimen.image_view_elevation)
         setSupportActionBar(toolbar)
         fab.setOnClickListener { view ->
-            fab.hideScale()
+            fab.isSelected = true
+            fab.setImageResource(R.drawable.ic_done)
+            fab.setOnClickListener(null)
             interactor.subscribe(userId)
                 .subscribe({
                     view.snackbar(R.string.users_info_subscribed)

app/src/main/res/drawable/subscribe_button_background.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android" android:color="#000000">
+    <item android:color="@color/colorSuccessAccent" android:state_selected="true" />
+    <item android:color="@color/colorAccent" />
+</selector>

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

@@ -86,6 +86,7 @@
         android:layout_margin="16dp"
         android:tint="@color/white"
         android:visibility="gone"
+        app:backgroundTint="@drawable/subscribe_button_background"
         app:layout_anchor="@id/app_bar"
         app:layout_anchorGravity="bottom|end"
         app:srcCompat="@drawable/ic_person_add" />

app/src/main/res/values/colors.xml

@@ -8,6 +8,7 @@
     <color name="colorPrimary100">#D1C4E9</color>
     <color name="colorPrimary50">#EDE7F6</color>
     <color name="colorAccent">#FF3D00</color>
+    <color name="colorSuccessAccent">#00E676</color>
     <color name="white">#FFFFFF</color>
     <color name="white_12">#1FFFFFFF</color>
     <color name="white_38">#61FFFFFF</color>