Add check for perspective matrix in quickRejectY

include/core/SkCanvas.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 470 matching lines @@
         that it is possible that if the method returns false, the band may still
         in fact be clipped out, but the converse is not true. If this method
         returns true, then the band is guaranteed to be clipped out.
         @param top  The top of the horizontal band to compare with the clip
         @param bottom The bottom of the horizontal and to compare with the clip
         @return true if the horizontal band is completely clipped out (i.e. does
                      not intersect the current clip)
     */
     bool quickRejectY(SkScalar top, SkScalar bottom) const {
         SkASSERT(top <= bottom);
+
+#ifndef SK_WILL_NEVER_DRAW_PERSPECTIVE_TEXT
+        // TODO: add a hasPerspective method similar to getLocalClipBounds. This
+        // would cache the SkMatrix::hasPerspective result. Alternatively, have
+        // the MC stack just set a hasPerspective boolean as it is updated.
+        if (this->getTotalMatrix().hasPerspective()) {
+            // TODO: consider implementing some half-plane test between the 
+            // two Y planes and the device-bounds (i.e., project the top and
+            // bottom Y planes and then determine if the clip bounds is completely
+            // outside either one).
+            return false;
+        }
+#endif
+
         const SkRect& clipR = this->getLocalClipBounds();
         // In the case where the clip is empty and we are provided with a
         // negative top and positive bottom parameter then this test will return
         // false even though it will be clipped. We have chosen to exclude that
         // check as it is rare and would result double the comparisons.
         return top >= clipR.fBottom || bottom <= clipR.fTop;
     }
 
     /** Return the bounds of the current clip (in local coordinates) in the
         bounds parameter, and return true if it is non-empty. This can be useful
@@ skipping 770 matching lines @@
     bool asROBitmap(SkBitmap*) const;
 
 private:
     SkBitmap    fBitmap;    // used if peekPixels() fails
     const void* fAddr;      // NULL on failure
     SkImageInfo fInfo;
     size_t      fRowBytes;
 };
 
 #endif