Conservative SkTextBlob bounds.

include/core/SkTextBlob.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 SkTextBlob_DEFINED
 #define SkTextBlob_DEFINED
 
 #include "SkPaint.h"
 #include "SkRefCnt.h"
 #include "SkTArray.h"
 #include "SkTDArray.h"
 
 class SkReadBuffer;
 class SkWriteBuffer;
 
 /** \class SkTextBlob
 
     SkTextBlob combines multiple text runs into an immutable, ref-counted structure.
 */
 class SK_API SkTextBlob : public SkRefCnt {
 public:
     /**
-     *  Returns the blob bounding box.
+     *  Returns a conservative blob bounding box.
      */
     const SkRect& bounds() const { return fBounds; }
 
     /**
      *  Return a non-zero, unique value representing the text blob.
      */
     uint32_t uniqueID() const;
 
     /**
      *  Serialize to a buffer.
@@ skipping 144 matching lines @@
     const RunBuffer& allocRunPos(const SkPaint& font, int count, const SkRect* bounds = NULL);
 
 private:
     void reserve(size_t size);
     void allocInternal(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
                        int count, SkPoint offset, const SkRect* bounds);
     bool mergeRun(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
                   int count, SkPoint offset);
     void updateDeferredBounds();
 
+    static SkRect ConservativeRunBounds(const SkTextBlob::RunRecord&);
+    static SkRect TightRunBounds(const SkTextBlob::RunRecord&);
+
     SkAutoTMalloc<uint8_t> fStorage;
     size_t                 fStorageSize;
     size_t                 fStorageUsed;
 
     SkRect                 fBounds;
     int                    fRunCount;
     bool                   fDeferredBounds;
     size_t                 fLastRun; // index into fStorage
 
     RunBuffer              fCurrentRunBuffer;
 };
 
 #endif // SkTextBlob_DEFINED