4 files changed, 41 insertions, 1 deletions
diff --git a/core/java/android/view/ViewGroup.java b/core/java/android/view/ViewGroup.java
index 92a8ce7..6f90971 100644
--- a/core/java/android/view/ViewGroup.java
+++ b/core/java/android/view/ViewGroup.java
@@ -2854,7 +2854,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
             // display lists to render, force an invalidate to allow the animation to
             // continue drawing another frame
             invalidate(true);
-            if (a instanceof AlphaAnimation) {
+            if (a.hasAlpha()) {
                 // alpha animations should cause the child to recreate its display list
                 child.invalidate(true);
             }
diff --git a/core/java/android/view/animation/AlphaAnimation.java b/core/java/android/view/animation/AlphaAnimation.java
index 651fe45..c4d9afc 100644
--- a/core/java/android/view/animation/AlphaAnimation.java
+++ b/core/java/android/view/animation/AlphaAnimation.java
@@ -78,4 +78,12 @@ public class AlphaAnimation extends Animation {
     public boolean willChangeBounds() {
         return false;
     }
+
+    /**
+     * @hide
+     */
+    @Override
+    public boolean hasAlpha() {
+        return true;
+    }
 }
diff --git a/core/java/android/view/animation/Animation.java b/core/java/android/view/animation/Animation.java
index 87c759c..b7dfabc 100644
--- a/core/java/android/view/animation/Animation.java
+++ b/core/java/android/view/animation/Animation.java
@@ -1001,6 +1001,15 @@ public abstract class Animation implements Cloneable {
     }
 
     /**
+     * Return true if this animation changes the view's alpha property.
+     * 
+     * @hide
+     */
+    public boolean hasAlpha() {
+        return false;
+    }
+
+    /**
      * Utility class to parse a string description of a size.
      */
     protected static class Description {
diff --git a/core/java/android/view/animation/AnimationSet.java b/core/java/android/view/animation/AnimationSet.java
index 873ce53..5c0b3af 100644
--- a/core/java/android/view/animation/AnimationSet.java
+++ b/core/java/android/view/animation/AnimationSet.java
@@ -43,6 +43,8 @@ public class AnimationSet extends Animation {
     private static final int PROPERTY_CHANGE_BOUNDS_MASK      = 0x80;
 
     private int mFlags = 0;
+    private boolean mDirty;
+    private boolean mHasAlpha;
 
     private ArrayList<Animation> mAnimations = new ArrayList<Animation>();
 
@@ -137,6 +139,25 @@ public class AnimationSet extends Animation {
         super.setStartOffset(startOffset);
     }
 
+    @Override
+    public boolean hasAlpha() {
+        if (mDirty) {
+            mDirty = mHasAlpha = false;
+
+            final int count = mAnimations.size();
+            final ArrayList<Animation> animations = mAnimations;
+
+            for (int i = 0; i < count; i++) {
+                if (animations.get(i).hasAlpha()) {
+                    mHasAlpha = true;
+                    break;
+                }
+            }
+        }
+
+        return mHasAlpha;
+    }
+
     /**
      * <p>Sets the duration of every child animation.</p>
      *
@@ -175,6 +196,8 @@ public class AnimationSet extends Animation {
             mLastEnd = Math.max(mLastEnd, a.getStartOffset() + a.getDuration());
             mDuration = mLastEnd - mStartOffset;
         }
+
+        mDirty = true;
     }
     
     /**