Rudimentary MotionLayout collapsible toolbar

activity_test.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright ©  2019 Stelian Morariu. All rights reserved.
  -->
<androidx.constraintlayout.motion.widget.MotionLayout 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"
                                                      app:layoutDescription="@xml/collapsing_scene"
                                                      tools:context=".TestActivity"
                                                      tools:showPaths="true"
                                                      android:elevation="4dp">

    <FrameLayout android:id="@+id/drop_shadow_layout"
                 android:layout_width="match_parent"
                 android:background="@android:color/white"
                 android:layout_height="0dp"
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintTop_toTopOf="parent"
                 android:elevation="0dp"
                 android:clipToPadding="false"
                 app:layout_constraintBottom_toBottomOf="@+id/title"/>

    <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/recyclerview"
            android:layout_width="0dp"
            android:layout_height="0dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/title"/>

    <ImageView
            android:id="@+id/toolbar_image"
            android:layout_width="0dp"
            android:layout_height="200dp"
            android:adjustViewBounds="true"
            android:contentDescription="@null"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="@id/guideline2"
            android:fitsSystemWindows="true"
            android:src="@drawable/avd_antrics_loading"
    />


    <TextView
            android:id="@+id/title"
            android:layout_width="match_parent"
            android:layout_height="?actionBarSize"
            android:text="@string/app_name"
            android:textColor="?android:attr/textColorPrimary"
            android:textSize="32sp"
            android:textStyle="bold"
            android:gravity="center"
            android:padding="8dp"
            app:layout_constraintTop_toBottomOf="@id/toolbar_image"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"/>



    <androidx.constraintlayout.widget.Guideline android:layout_width="match_parent"
                                                android:layout_height="wrap_content"
                                                android:id="@+id/guideline2"
                                                app:layout_constraintGuide_percent="0.07"
                                                android:orientation="horizontal"/>

</androidx.constraintlayout.motion.widget.MotionLayout>

collapsing_scene.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  ~ Copyright ©  2019 Stelian Morariu. All rights reserved.
  -->

<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:app="http://schemas.android.com/apk/res-auto">

    <Transition
            app:constraintSetEnd="@id/collapsed"
            app:constraintSetStart="@id/expanded">

        <OnSwipe
                app:dragDirection="dragUp"
                app:touchAnchorId="@id/recyclerview"
                app:touchAnchorSide="top" />

    </Transition>

    <ConstraintSet android:id="@+id/expanded">
        <Constraint
                android:id="@id/toolbar_image"
                android:layout_height="200dp"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="@id/guideline2"
                android:elevation="4dp">
            <CustomAttribute
                    app:attributeName="imageAlpha"
                    app:customIntegerValue="255" />
        </Constraint>
        <Constraint
                android:id="@id/title"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="8dp"
                android:scaleX="1.0"
                android:scaleY="1.0"
                app:layout_constraintTop_toBottomOf="@id/toolbar_image"
                app:layout_constraintStart_toStartOf="parent" android:layout_marginEnd="8dp"
                app:layout_constraintEnd_toEndOf="parent" android:layout_marginTop="8dp">
        </Constraint>
        <Constraint  android:id="@id/drop_shadow_layout"
                     android:layout_width="match_parent"
                     android:background="@android:color/white"
                     android:layout_height="0dp"
                     app:layout_constraintStart_toStartOf="parent"
                     app:layout_constraintEnd_toEndOf="parent"
                     app:layout_constraintTop_toTopOf="parent"
                     android:elevation="0dp"
                     android:clipToPadding="false"
                     app:layout_constraintBottom_toBottomOf="@+id/title"/>
    </ConstraintSet>

    <ConstraintSet android:id="@+id/collapsed">
        <Constraint
                android:id="@id/toolbar_image"
                android:layout_height="?attr/actionBarSize"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                android:elevation="4dp"
                app:layout_constraintTop_toTopOf="parent">
            <CustomAttribute
                    app:attributeName="imageAlpha"
                    app:customIntegerValue="0" />
        </Constraint>
        <Constraint
                android:id="@id/title"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:scaleX="0.925"
                android:scaleY="0.925"
                android:elevation="4dp"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintEnd_toEndOf="parent" android:layout_marginTop="8dp"
                app:layout_constraintTop_toTopOf="parent">

        </Constraint>
        <Constraint  android:id="@id/drop_shadow_layout"
                     android:layout_width="match_parent"
                     android:background="@android:color/white"
                     android:layout_height="0dp"
                     app:layout_constraintStart_toStartOf="parent"
                     app:layout_constraintEnd_toEndOf="parent"
                     app:layout_constraintTop_toTopOf="parent"
                     android:elevation="4dp"
                     android:clipToPadding="false"
                     app:layout_constraintBottom_toBottomOf="@+id/title"/>

    </ConstraintSet>

</MotionScene>

TestActivity.kt

/*
 * Copyright ©  2019 Stelian Morariu. All rights reserved.
 */

package com.stelianmorariu.antrics

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class TestActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_test)
    }
}