From 5112cdd30b62009545d6bfd43b2ccd11abd9cdf7 Mon Sep 17 00:00:00 2001
From: Tony Wickham <twickham@google.com>
Date: Fri, 12 Jun 2020 14:23:46 -0500
Subject: [PATCH] Skip fling anim if it is a no-op, to save a frame of
 aniamtion

Bug: 158701272
Change-Id: Id2bc502d1caaeefeca339d5e5ad355ad8ba6d7ec
---
 src/com/android/launcher3/anim/FlingSpringAnim.java | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/com/android/launcher3/anim/FlingSpringAnim.java b/src/com/android/launcher3/anim/FlingSpringAnim.java
index 06d0f1c463..6ea38ec8ab 100644
--- a/src/com/android/launcher3/anim/FlingSpringAnim.java
+++ b/src/com/android/launcher3/anim/FlingSpringAnim.java
@@ -35,6 +35,7 @@ public class FlingSpringAnim {
 
     private final FlingAnimation mFlingAnim;
     private SpringAnimation mSpringAnim;
+    private final boolean mSkipFlingAnim;
 
     private float mTargetPosition;
 
@@ -57,6 +58,10 @@ public class FlingSpringAnim {
                 .setMaxValue(maxValue);
         mTargetPosition = targetPosition;
 
+        // We are already past the fling target, so skip it to avoid losing a frame of the spring.
+        mSkipFlingAnim = startPosition <= minValue && startVelocity < 0
+                || startPosition >= maxValue && startVelocity > 0;
+
         mFlingAnim.addEndListener(((animation, canceled, value, velocity) -> {
             mSpringAnim = new SpringAnimation(object, property)
                     .setStartValue(value)
@@ -84,6 +89,9 @@ public class FlingSpringAnim {
 
     public void start() {
         mFlingAnim.start();
+        if (mSkipFlingAnim) {
+            mFlingAnim.cancel();
+        }
     }
 
     public void end() {