Default to using hardware layer during fade transition.

Bug 17499864

When hasOverlappingRendering() is true, a layer is used to
to fade views because performance can be much worse then.
When hasOverlappingRendering() is false, the performance
is not hurt and a layer is not used.

Change-Id: If3fb1c23ffc8d0bef85c9d16df6c26ff4bbd49ac

1 files changed, 12 insertions, 0 deletions

diff --git a/core/java/android/transition/Fade.java b/core/java/android/transition/Fade.java
index 1f9d093..e7857c0 100644
--- a/core/java/android/transition/Fade.java
+++ b/core/java/android/transition/Fade.java
@@ -145,12 +145,21 @@ public class Fade extends Visibility {
         private final View mView;
         private boolean mCanceled = false;
         private float mPausedAlpha = -1;
+        private boolean mLayerTypeChanged = false;
 
         public FadeAnimatorListener(View view) {
             mView = view;
         }
 
         @Override
+        public void onAnimationStart(Animator animator) {
+            if (mView.hasOverlappingRendering() && mView.getLayerType() == View.LAYER_TYPE_NONE) {
+                mLayerTypeChanged = true;
+                mView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
+            }
+        }
+
+        @Override
         public void onAnimationCancel(Animator animator) {
             mCanceled = true;
             if (mPausedAlpha >= 0) {
@@ -163,6 +172,9 @@ public class Fade extends Visibility {
             if (!mCanceled) {
                 mView.setTransitionAlpha(1);
             }
+            if (mLayerTypeChanged) {
+                mView.setLayerType(View.LAYER_TYPE_NONE, null);
+            }
         }
 
         @Override