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

1 files changed, 12 insertions, 3 deletions

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index febd2e2efdac..7d823b1c100d 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 (!keepBoundsClear && !hasCustomKeepClearRects) {
+            return Collections.emptyList();
+        } else if (keepBoundsClear && !hasCustomKeepClearRects) {
+            return Collections.singletonList(new Rect(0, 0, getWidth(), getHeight()));
+        }
 
-        if ((info != null && info.mPreferKeepClear) || mPreferKeepClearForFocus) {
+        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);
         }