SkTCopyOnFirstWrite-based SkPaintFilterCanvas API

include/core/SkTLazy.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTLazy_DEFINED
 #define SkTLazy_DEFINED
 
@@ skipping 113 matching lines @@
  *    thing.writable()->changeMe(); // makes a copy of constThing if we didn't call modifyMe()
  * }
  *
  * consume_a_thing(thing); // could be constThing or a modified copy.
  */
 template <typename T>
 class SkTCopyOnFirstWrite {
 public:
     SkTCopyOnFirstWrite(const T& initial) : fObj(&initial) {}
 
+    SkTCopyOnFirstWrite(const T* initial) : fObj(initial) {}
+
     // Constructor for delayed initialization.
     SkTCopyOnFirstWrite() : fObj(NULL) {}
 
     // Should only be called once, and only if the default constructor was used.
     void init(const T& initial) {
         SkASSERT(NULL == fObj);
         SkASSERT(!fLazy.isValid());
         fObj = &initial;
     }
 
@@ skipping 18 matching lines @@
     operator const T*() const { return fObj; }
 
     const T& operator *() const { return *fObj; }
 
 private:
     const T*    fObj;
     SkTLazy<T>  fLazy;
 };
 
 #endif