Underline Page Indicator 
This indicator will underline each tab text, morphing its size while scrolling
How to use
Add JitPack repository to your build.gradle file
allprojects {
repositories {
...
maven { url 'https://jitpack.io' }
}
}Add the Dependency
dependencies {
implementation "com.github.dcampogiani:underlinepageindicator:0.0.2"
}Add TabLayout and UnderlinePageIndicator to XML:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
tools:context=".MainActivity">
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabIndicatorHeight="0dp"
app:tabMode="fixed" />
<com.danielecampogiani.underlinepageindicator.UnderlinePageIndicator
android:id="@+id/indicator"
android:layout_width="match_parent"
android:layout_height="2dp" />
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>Style TabLayout with app:tabIndicatorHeight="0dp" and app:tabMode="fixed"
Setup with ViewPager
pager.adapter = Adapter(...)
indicator.setTabLayoutAndViewPager(tabs, pager)Checkout the app project for an example.