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// 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 an 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 ponter, 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());
// }
//
// 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_;
explicit RefPtr(T* ptr) : ptr_(ptr) {}
template<typename U>
friend RefPtr<U> AdoptRef(U* ptr);
};
template<typename T>
RefPtr<T> AdoptRef(T* ptr) { return RefPtr<T>(ptr); }
} // namespace skia
#endif // SKIA_EXT_REFPTR_H_
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