Optimization of alpha with DisplayList properties

Some views (such as ImageView and TextView) handle non-opaque alpha
values directly. This was originally an optimization, but we can handle it faster
in many cases without this optimization when DisplayList properties are enabled.
Basically, if a view has non-overlapping rendering, we set the alpha value directly
on the renderer (the equivalent of setting it on the Paint object) and draw each
primitive with that alpha value. Doing it this way avoids re-creating DisplayLists
while getting the same speedup that onSetAlpha() used to get pre-DisplayList properties.

Change-Id: I0f7827f075d3b35093a882d4adbb300a1063c288

1 files changed, 4 insertions, 0 deletions

diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index b651904..ab137cc 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -85,6 +85,10 @@ public:
     virtual int saveLayerAlpha(float left, float top, float right, float bottom,
             int alpha, int flags);
 
+    virtual void setAlpha(float alpha) {
+        mSnapshot->alpha = alpha;
+    }
+
     virtual void translate(float dx, float dy);
     virtual void rotate(float degrees);
     virtual void scale(float sx, float sy);