Roll skia to 8cc209111876b7c78b5ec577c9221d8ed5e21024

skia/ext/refptr.h

-// Copyright 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SKIA_EXT_REFPTR_H_
-#define SKIA_EXT_REFPTR_H_
-
-#include "third_party/skia/include/core/SkRefCnt.h"
-
-namespace skia {
-
-// When creating/receiving a ref-counted pointer from Skia, wrap that pointer in
-// this class to avoid dealing with the ref-counting and prevent leaks/crashes
-// due to ref-counting bugs.
-//
-// Example of creating a new SkShader* and setting it on a SkPaint:
-//   skia::RefPtr<SkShader> shader = skia::AdoptRef(SkGradientShader::Create());
-//   paint.setShader(shader.get());
-//
-// When passing around a ref-counted pointer to methods outside of Skia, always
-// pass around the skia::RefPtr instead of the raw pointer. An example method
-// that takes a SkShader* parameter and saves the SkShader* in the class.
-//   void AMethodThatSavesAShader(const skia::RefPtr<SkShader>& shader) {
-//     member_refptr_ = shader;
-//   }
-//   skia::RefPtr<SkShader> member_refptr_;
-//
-// When returning a ref-counted pointer, also return the skia::RefPtr instead.
-// An example method that creates an SkShader* and returns it:
-//   skia::RefPtr<SkShader> MakeAShader() {
-//     return skia::AdoptRef(SkGradientShader::Create());
-//   }
-//
-// To take a scoped reference to an object whose references are all owned
-// by other objects (i.e. does not have one that needs to be adopted) use the
-// skia::SharePtr helper:
-//
-//   skia::RefPtr<SkShader> shader = skia::SharePtr(paint.getShader());
-//
-// Never call ref() or unref() on the underlying ref-counted pointer. If you
-// AdoptRef() the raw pointer immediately into a skia::RefPtr and always work
-// with skia::RefPtr instances instead, the ref-counting will be taken care of
-// for you.
-template<typename T>
-class RefPtr {
- public:
-  RefPtr() : ptr_(NULL) {}
-
-  RefPtr(const RefPtr& other)
-      : ptr_(other.get()) {
-    SkSafeRef(ptr_);
-  }
-
-  template<typename U>
-  RefPtr(const RefPtr<U>& other)
-      : ptr_(other.get()) {
-    SkSafeRef(ptr_);
-  }
-
-  ~RefPtr() {
-    clear();
-  }
-
-  RefPtr& operator=(const RefPtr& other) {
-    SkRefCnt_SafeAssign(ptr_, other.get());
-    return *this;
-  }
-
-  template<typename U>
-  RefPtr& operator=(const RefPtr<U>& other) {
-    SkRefCnt_SafeAssign(ptr_, other.get());
-    return *this;
-  }
-
-  void clear() {
-    T* to_unref = ptr_;
-    ptr_ = NULL;
-    SkSafeUnref(to_unref);
-  }
-
-  T* get() const { return ptr_; }
-  T& operator*() const { return *ptr_; }
-  T* operator->() const { return ptr_; }
-
-  typedef T* RefPtr::*unspecified_bool_type;
-  operator unspecified_bool_type() const {
-    return ptr_ ? &RefPtr::ptr_ : NULL;
-  }
-
- private:
-  T* ptr_;
-
-  // This function cannot be public because Skia starts its ref-counted
-  // objects at refcnt=1.  This makes it impossible to differentiate
-  // between a newly created object (that doesn't need to be ref'd) or an
-  // already existing object with one owner (that does need to be ref'd so that
-  // this RefPtr can also manage its lifetime).
-  explicit RefPtr(T* ptr) : ptr_(ptr) {}
-
-  template<typename U>
-  friend RefPtr<U> AdoptRef(U* ptr);
-
-  template<typename U>
-  friend RefPtr<U> SharePtr(U* ptr);
-};
-
-// For objects that have an unowned reference (such as newly created objects).
-template<typename T>
-RefPtr<T> AdoptRef(T* ptr) { return RefPtr<T>(ptr); }
-
-// For objects that are already owned. This doesn't take ownership of existing
-// references and adds a new one.
-template<typename T>
-RefPtr<T> SharePtr(T* ptr) { return RefPtr<T>(SkSafeRef(ptr)); }
-
-}  // namespace skia
-
-#endif  // SKIA_EXT_REFPTR_H_