Fix SkTextBlob offset semantics.

src/utils/SkGatherPixelRefsAndRects.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkGatherPixelRefsAndRects_DEFINED
 #define SkGatherPixelRefsAndRects_DEFINED
 
@@ skipping 177 matching lines @@
         }
 
         SkScalar pad = (metrics.fBottom - metrics.fTop) / 2;
         bounds.fLeft -= pad;
         bounds.fRight += pad;
         bounds.offset(x, y);
 
         this->drawRect(draw, bounds, paint);
     }
     virtual void drawPosText(const SkDraw& draw, const void* text, size_t len,
-                             const SkScalar pos[], SkScalar constY,
-                             int scalarsPerPos, const SkPaint& paint) SK_OVERRIDE {
+                             const SkScalar pos[], int scalarsPerPos,
+                             const SkPoint& offset, const SkPaint& paint) SK_OVERRIDE {
         SkBitmap bitmap;
         if (!GetBitmapFromPaint(paint, &bitmap)) {
             return;
         }
 
         if (0 == len) {
             return;
         }
 
         // Similar to SkDraw asserts.
         SkASSERT(scalarsPerPos == 1 || scalarsPerPos == 2);
 
-        SkScalar y = scalarsPerPos == 1 ? constY : constY + pos[1];
-
-        SkPoint min, max;
-        min.set(pos[0], y);
-        max.set(pos[0], y);
+        SkPoint min = SkPoint::Make(offset.x() + pos[0],
+                                    offset.y() + (2 == scalarsPerPos ? pos[1] : 0));
+        SkPoint max = min;
 
         for (size_t i = 1; i < len; ++i) {
-            SkScalar x = pos[i * scalarsPerPos];
-            SkScalar y = constY;
-            if (2 == scalarsPerPos) {
-                y += pos[i * scalarsPerPos + 1];
-            }
+            SkScalar x = offset.x() + pos[i * scalarsPerPos];
+            SkScalar y = offset.y() + (2 == scalarsPerPos ? pos[i * 2 + 1] : 0);
 
             min.set(SkMinScalar(x, min.x()), SkMinScalar(y, min.y()));
             max.set(SkMaxScalar(x, max.x()), SkMaxScalar(y, max.y()));
         }
 
         SkRect bounds = SkRect::MakeLTRB(min.x(), min.y(), max.x(), max.y());
 
         // Math is borrowed from SkBBoxRecord
         SkPaint::FontMetrics metrics;
         paint.getFontMetrics(&metrics);
@@ skipping 83 matching lines @@
     static void NotSupported() {
         SkDEBUGFAIL("this method should never be called");
     }
 
     static void NothingToDo() {}
 
     typedef SkBaseDevice INHERITED;
 };
 
 #endif // SkGatherPixelRefsAndRects_DEFINED