Fix flashing artifacts caused by invalidation bugs

Therea re 2 fixes here:
- We sometimes cleared a flag in ViewAncestor too soon that controlled
how invalidated areas were redrawn (related to whether the invalidates
happened on opaque views or not).
- TransitionDrawable was always setting/restoring alpha values on its
drawables every time it was drawn. setAlpha on BitmapDrawable causes
an invalidation, so essentially this was an infinite invalidation/redrawing
loop. The fix was to notice when the animation was done and to simply
draw the appropriate drawable[s].

Change-Id: I1849a5a909b0039a0e9bce0aa3cfc33c50f8f854

2 files changed, 18 insertions, 3 deletions

diff --git a/graphics/java/android/graphics/drawable/BitmapDrawable.java b/graphics/java/android/graphics/drawable/BitmapDrawable.java
index a4734ff..7e03e1c 100644
--- a/graphics/java/android/graphics/drawable/BitmapDrawable.java
+++ b/graphics/java/android/graphics/drawable/BitmapDrawable.java
@@ -405,8 +405,11 @@ public class BitmapDrawable extends Drawable {
 
     @Override
     public void setAlpha(int alpha) {
-        mBitmapState.mPaint.setAlpha(alpha);
-        invalidateSelf();
+        int oldAlpha = mBitmapState.mPaint.getAlpha();
+        if (alpha != oldAlpha) {
+            mBitmapState.mPaint.setAlpha(alpha);
+            invalidateSelf();
+        }
     }
 
     @Override
diff --git a/graphics/java/android/graphics/drawable/TransitionDrawable.java b/graphics/java/android/graphics/drawable/TransitionDrawable.java
index 9a3ca40..483fa56 100644
--- a/graphics/java/android/graphics/drawable/TransitionDrawable.java
+++ b/graphics/java/android/graphics/drawable/TransitionDrawable.java
@@ -187,8 +187,20 @@ public class TransitionDrawable extends LayerDrawable implements Drawable.Callba
         final int alpha = mAlpha;
         final boolean crossFade = mCrossFade;
         final ChildDrawable[] array = mLayerState.mChildren;
-        Drawable d;
 
+        if (done) {
+            // the setAlpha() calls below trigger invalidation and redraw. If we're done, just draw
+            // the appropriate drawable[s] and return
+            if (!crossFade || alpha == 0) {
+                array[0].mDrawable.draw(canvas);
+            }
+            if (alpha == 0xFF) {
+                array[1].mDrawable.draw(canvas);
+            }
+            return;
+        }
+
+        Drawable d;
         d = array[0].mDrawable;
         if (crossFade) {
             d.setAlpha(255 - alpha);