From e10a3513f4831fcb47c641215438c9316835ef87 Mon Sep 17 00:00:00 2001
From: Robert Horvath <robhor@google.com>
Date: Wed, 23 Mar 2022 15:21:10 +0100
Subject: [PATCH] Prevent ArrayList allocation for prefer keep clear areas

This avoids creating an ArrayList if there are no keep clear areas,
returning early with an empty or singleton list where possible.

Bug: 222567277
Test: android.view.ViewShowHidePerfTest#testVisibleToInvisible
Change-Id: Id718a37ea8aa4fcf4edbaade532cea826b15adf0
---
 core/java/android/view/View.java | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index febd2e2efdacf..7d823b1c100d2 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -11939,13 +11939,22 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
     @NonNull
     List<Rect> collectPreferKeepClearRects() {
         ListenerInfo info = mListenerInfo;
-        final List<Rect> list = new ArrayList<>();
+        boolean keepBoundsClear =
+                (info != null && info.mPreferKeepClear) || mPreferKeepClearForFocus;
+        boolean hasCustomKeepClearRects = info != null && info.mKeepClearRects != null;
 
-        if ((info != null && info.mPreferKeepClear) || mPreferKeepClearForFocus) {
+        if (!keepBoundsClear && !hasCustomKeepClearRects) {
+            return Collections.emptyList();
+        } else if (keepBoundsClear && !hasCustomKeepClearRects) {
+            return Collections.singletonList(new Rect(0, 0, getWidth(), getHeight()));
+        }
+
+        final List<Rect> list = new ArrayList<>();
+        if (keepBoundsClear) {
             list.add(new Rect(0, 0, getWidth(), getHeight()));
         }
 
-        if (info != null && info.mKeepClearRects != null) {
+        if (hasCustomKeepClearRects) {
             list.addAll(info.mKeepClearRects);
         }