Fix bug in LayoutTransition that caused views to stay invisible

LayoutTransition side-effects the alpha property on View to fade views
in and out. This works fine if the layout transition is always used on
those views' container. But if you fade out a disappearing view and then
set the transition to null on the container and set that view to VISIBLE,
there is no transition logic to restore the alpha value to 1 (opaque).

The fix is to always restore alpha to its pre-animation value when fading
the view out.

Also, added extra info to alpha and the various View transform properties
to help hierarchyviewer debugging.

Issue #5958434: LayoutTransition temporary disablement may leave some views invisible

Change-Id: I3c21b0e7334dc29c10c5e372b589f0e2b59c2883

1 files changed, 16 insertions, 14 deletions

diff --git a/core/java/android/animation/LayoutTransition.java b/core/java/android/animation/LayoutTransition.java
index 274a9d5..634e4d8 100644
--- a/core/java/android/animation/LayoutTransition.java
+++ b/core/java/android/animation/LayoutTransition.java
@@ -960,17 +960,17 @@ public class LayoutTransition {
         if (anim instanceof ObjectAnimator) {
             ((ObjectAnimator) anim).setCurrentPlayTime(0);
         }
-        if (mListeners != null) {
-            anim.addListener(new AnimatorListenerAdapter() {
-                @Override
-                public void onAnimationEnd(Animator anim) {
-                    currentAppearingAnimations.remove(child);
+        anim.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationEnd(Animator anim) {
+                currentAppearingAnimations.remove(child);
+                if (mListeners != null) {
                     for (TransitionListener listener : mListeners) {
                         listener.endTransition(LayoutTransition.this, parent, child, APPEARING);
                     }
                 }
-            });
-        }
+            }
+        });
         currentAppearingAnimations.put(child, anim);
         anim.start();
     }
@@ -998,17 +998,19 @@ public class LayoutTransition {
         anim.setStartDelay(mDisappearingDelay);
         anim.setDuration(mDisappearingDuration);
         anim.setTarget(child);
-        if (mListeners != null) {
-            anim.addListener(new AnimatorListenerAdapter() {
-                @Override
-                public void onAnimationEnd(Animator anim) {
-                    currentDisappearingAnimations.remove(child);
+        final float preAnimAlpha = child.getAlpha();
+        anim.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationEnd(Animator anim) {
+                currentDisappearingAnimations.remove(child);
+                child.setAlpha(preAnimAlpha);
+                if (mListeners != null) {
                     for (TransitionListener listener : mListeners) {
                         listener.endTransition(LayoutTransition.this, parent, child, DISAPPEARING);
                     }
                 }
-            });
-        }
+            }
+        });
         if (anim instanceof ObjectAnimator) {
             ((ObjectAnimator) anim).setCurrentPlayTime(0);
         }