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] 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)
     }
 }