add isRect() check to AAClip, to detect if a soft-clip is really just an irect

src/core/SkRasterClip.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkRasterClip_DEFINED
 #define SkRasterClip_DEFINED
 
@@ skipping 71 matching lines @@
     bool        fIsBW;
     // these 2 are caches based on querying the right obj based on fIsBW
     bool        fIsEmpty;
     bool        fIsRect;
 
     bool computeIsEmpty() const {
         return fIsBW ? fBW.isEmpty() : fAA.isEmpty();
     }
 
     bool computeIsRect() const {
-        return fIsBW ? fBW.isRect() : false;
+        return fIsBW ? fBW.isRect() : fAA.isRect();
     }
 
-    bool updateCacheAndReturnNonEmpty() {
+    bool updateCacheAndReturnNonEmpty(bool detectAARect = true) {
         fIsEmpty = this->computeIsEmpty();
+
+        // detect that our computed AA is really just a (hard-edged) rect
+        if (detectAARect && !fIsEmpty && !fIsBW && fAA.isRect()) {
+            fBW.setRect(fAA.getBounds());
+            fAA.setEmpty(); // don't need this guy anymore
+            fIsBW = true;
+        }
+
         fIsRect = this->computeIsRect();
         return !fIsEmpty;
     }
 
     void convertToAA();
 };
 
 class SkAutoRasterClipValidate : SkNoncopyable {
 public:
     SkAutoRasterClipValidate(const SkRasterClip& rc) : fRC(rc) {
@@ skipping 47 matching lines @@
 
 private:
     SkRegion        fBWRgn;
     SkAAClipBlitter fAABlitter;
     // what we return
     const SkRegion* fClipRgn;
     SkBlitter* fBlitter;
 };
 
 #endif