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

2 files changed, 32 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);
         }
diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index cf4cff9..7ba17b3 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -7312,6 +7312,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * 
      * @return The degrees of rotation.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getRotation() {
         return mTransformationInfo != null ? mTransformationInfo.mRotation : 0;
     }
@@ -7353,6 +7354,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * 
      * @return The degrees of Y rotation.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getRotationY() {
         return mTransformationInfo != null ? mTransformationInfo.mRotationY : 0;
     }
@@ -7399,6 +7401,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * 
      * @return The degrees of X rotation.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getRotationX() {
         return mTransformationInfo != null ? mTransformationInfo.mRotationX : 0;
     }
@@ -7446,6 +7449,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * @see #getPivotY()
      * @return The scaling factor.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getScaleX() {
         return mTransformationInfo != null ? mTransformationInfo.mScaleX : 1;
     }
@@ -7484,6 +7488,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * @see #getPivotY()
      * @return The scaling factor.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getScaleY() {
         return mTransformationInfo != null ? mTransformationInfo.mScaleY : 1;
     }
@@ -7522,6 +7527,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * @see #getPivotY()
      * @return The x location of the pivot point.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getPivotX() {
         return mTransformationInfo != null ? mTransformationInfo.mPivotX : 0;
     }
@@ -7566,6 +7572,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * @see #getPivotY()
      * @return The y location of the pivot point.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getPivotY() {
         return mTransformationInfo != null ? mTransformationInfo.mPivotY : 0;
     }
@@ -7606,6 +7613,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * <p>By default this is 1.0f.
      * @return The opacity of the view.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getAlpha() {
         return mTransformationInfo != null ? mTransformationInfo.mAlpha : 1;
     }
@@ -7619,6 +7627,10 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * equivalent to calling {@link #setLayerType(int, android.graphics.Paint)} and
      * setting a hardware layer.</p>
      *
+     * <p>Note that setting alpha to a translucent value (0 < alpha < 1) may have
+     * performance implications. It is generally best to use the alpha property sparingly and
+     * transiently, as in the case of fading animations.</p>
+     *
      * @param alpha The opacity of the view.
      *
      * @see #setLayerType(int, android.graphics.Paint)
@@ -7916,6 +7928,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      *
      * @return The visual x position of this view, in pixels.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getX() {
         return mLeft + (mTransformationInfo != null ? mTransformationInfo.mTranslationX : 0);
     }
@@ -7938,6 +7951,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      *
      * @return The visual y position of this view, in pixels.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getY() {
         return mTop + (mTransformationInfo != null ? mTransformationInfo.mTranslationY : 0);
     }
@@ -7961,6 +7975,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      *
      * @return The horizontal position of this view relative to its left position, in pixels.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getTranslationX() {
         return mTransformationInfo != null ? mTransformationInfo.mTranslationX : 0;
     }
@@ -7997,6 +8012,7 @@ public class View implements Drawable.Callback, Drawable.Callback2, KeyEvent.Cal
      * @return The vertical position of this view relative to its top position,
      * in pixels.
      */
+    @ViewDebug.ExportedProperty(category = "drawing")
     public float getTranslationY() {
         return mTransformationInfo != null ? mTransformationInfo.mTranslationY : 0;
     }