From b37f089348f91a649613f40e91c56a2dea227fd1 Mon Sep 17 00:00:00 2001
From: Alexandre Pereira <alexandre.gomes2606@gmail.com>
Date: Wed, 21 Oct 2020 15:12:40 -0300
Subject: [PATCH 1/2] Create startLiftAnimation function

---
 app/src/main/res/layout/activity_main.xml | 28 +++++++++--------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index d25512f..36e4a6c 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -1,28 +1,22 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout 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"
+    android:orientation="vertical"
     tools:context=".MainActivity">
 
-    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/appBarLayout"
+    <androidx.appcompat.widget.Toolbar
+        android:id="@+id/toolbar"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:background="@android:color/white">
-
-        <androidx.appcompat.widget.Toolbar
-            android:id="@+id/toolbar"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            app:layout_constraintTop_toTopOf="parent"
-            app:navigationIcon="@null"
-            app:title="@string/app_name"
-            android:layout_margin="0dp"
-            app:titleTextAppearance="@style/Title.XLarge" />
-    </com.google.android.material.appbar.AppBarLayout>
-
+        android:layout_margin="0dp"
+        android:background="@android:color/white"
+        app:layout_constraintTop_toTopOf="parent"
+        app:navigationIcon="@null"
+        app:title="@string/app_name"
+        app:titleTextAppearance="@style/Title.XLarge" />
 
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/componentsRecycler"
@@ -34,4 +28,4 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/toolbar" />
 
-</androidx.coordinatorlayout.widget.CoordinatorLayout>
\ No newline at end of file
+</LinearLayout>
\ No newline at end of file

From 37276d36579aaf657b40d22d102ae0c5c29d50cf Mon Sep 17 00:00:00 2001
From: Alexandre Pereira <alexandre.gomes2606@gmail.com>
Date: Wed, 21 Oct 2020 15:12:58 -0300
Subject: [PATCH 2/2] Create startLiftAnimation function

---
 .../jerry/app/MainActivity.kt                 |  2 +-
 .../animation/ElevationSpringAnimation.kt     | 39 +++++++++++++++----
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/app/src/main/java/br/alexandregpereira/jerry/app/MainActivity.kt b/app/src/main/java/br/alexandregpereira/jerry/app/MainActivity.kt
index e035a4e..5a09e06 100644
--- a/app/src/main/java/br/alexandregpereira/jerry/app/MainActivity.kt
+++ b/app/src/main/java/br/alexandregpereira/jerry/app/MainActivity.kt
@@ -67,7 +67,7 @@ class MainActivity : AppCompatActivity(R.layout.activity_main) {
                 }
             }
         }
-        componentsRecycler.setupLiftViewOnScrollCompat(appBarLayout, 2f.dpToPx(resources))
+        componentsRecycler.setupLiftViewOnScrollCompat(toolbar, 2f.dpToPx(resources))
     }
 }
 
diff --git a/jerry/src/main/java/br/alexandregpereira/jerry/animation/ElevationSpringAnimation.kt b/jerry/src/main/java/br/alexandregpereira/jerry/animation/ElevationSpringAnimation.kt
index a163f6f..7c2c960 100644
--- a/jerry/src/main/java/br/alexandregpereira/jerry/animation/ElevationSpringAnimation.kt
+++ b/jerry/src/main/java/br/alexandregpereira/jerry/animation/ElevationSpringAnimation.kt
@@ -39,16 +39,41 @@ fun View.elevationSpring(
     targetValue = targetValue
 )
 
+@RequiresApi(21)
+fun RecyclerView.startLiftAnimation(liftView: View, elevation: Float) {
+    val layoutManager = this.layoutManager as? LinearLayoutManager ?: return
+    val adapter = this.adapter
+    val targetValue: Float = if (
+        adapter != null
+        && adapter.itemCount > 0
+        && layoutManager.findFirstCompletelyVisibleItemPosition() > 0
+    ) {
+        elevation
+    } else {
+        0f
+    }
+
+    if (liftView.elevation == targetValue) {
+        return
+    }
+
+    val animation = liftView.elevationSpring(targetValue = targetValue)
+    if (animation.targetValue == targetValue && animation.isRunning.not()) {
+        animation.start()
+    }
+}
+
+fun RecyclerView.startLiftAnimationCompat(liftView: View, elevation: Float) {
+    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
+        this.startLiftAnimation(liftView, elevation)
+    }
+}
+
 @RequiresApi(21)
 fun RecyclerView.setupLiftViewOnScroll(liftView: View, elevation: Float) {
-    val layoutManager = layoutManager as? LinearLayoutManager ?: return
+    if (layoutManager !is LinearLayoutManager) return
     addOnScrolled {
-        val animation = if (layoutManager.findFirstCompletelyVisibleItemPosition() != 0) {
-            liftView.elevationSpring(targetValue = elevation)
-        } else {
-            liftView.elevationSpring(targetValue = 0f)
-        }
-        animation.start()
+        this.startLiftAnimation(liftView, elevation)
     }
 }