Compute GradientDrawable's opacity correctly

The current implementation of GradientDrawable always assumes the shape needs
to be blended. This causes all windows to be considered translucent by default.
This change recomputes the opacity as needed to ensure windows are marked
opaque when they should.

Change-Id: Iaf291d889a6c5122ab00c9f5781df3e7f61547fa

graphics/java/android/graphics/drawable/DrawableContainer.java

@@ -444,7 +444,6 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
         int         mConstantMinimumWidth;
         int         mConstantMinimumHeight;
 
-        boolean     mHaveOpacity = false;
         int         mOpacity;
 
         boolean     mHaveStateful = false;
@@ -493,7 +492,6 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
                 mConstantWidth = orig.mConstantWidth;
                 mConstantHeight = orig.mConstantHeight;
                 
-                mHaveOpacity = orig.mHaveOpacity;
                 mOpacity = orig.mOpacity;
                 mHaveStateful = orig.mHaveStateful;
                 mStateful = orig.mStateful;
@@ -528,7 +526,6 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
             mDrawables[pos] = dr;
             mNumChildren++;
             mChildrenChangingConfigurations |= dr.getChangingConfigurations();
-            mHaveOpacity = false;
             mHaveStateful = false;
 
             mConstantPadding = null;
@@ -656,10 +653,6 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
         }
 
         public final int getOpacity() {
-            if (mHaveOpacity) {
-                return mOpacity;
-            }
-
             final int N = getChildCount();
             final Drawable[] drawables = mDrawables;
             int op = N > 0 ? drawables[0].getOpacity() : PixelFormat.TRANSPARENT;
@@ -667,7 +660,6 @@ public class DrawableContainer extends Drawable implements Drawable.Callback {
                 op = Drawable.resolveOpacity(op, drawables[i].getOpacity());
             }
             mOpacity = op;
-            mHaveOpacity = true;
             return op;
         }