blob: df884e15f08eb2328a3d122d50079b0412c9486f [file] [log] [blame]
/*
* Copyright 2020 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrRefCnt_DEFINED
#define GrRefCnt_DEFINED
#include "include/core/SkRefCnt.h"
#include "include/private/base/SkAssert.h"
#include "include/private/base/SkDebug.h"
#include <cstddef>
#include <type_traits>
// We have to use auto for the function pointers here because if the actual functions live on the
// base class of T we need the function here to be a pointer to a function of the base class and not
// a function on T. Thus we can't have something like void(T::*Ref)() since we may need T or we may
// need some base class of T.
template <typename T, auto Ref, auto Unref> class gr_sp {
private:
static inline T* SafeRef(T* obj) {
if (obj) {
(obj->*Ref)();
}
return obj;
}
static inline void SafeUnref(T* obj) {
if (obj) {
(obj->*Unref)();
}
}
public:
using element_type = T;
constexpr gr_sp() : fPtr(nullptr) {}
constexpr gr_sp(std::nullptr_t) : fPtr(nullptr) {}
/**
* Shares the underlying object by calling Ref(), so that both the argument and the newly
* created gr_sp both have a reference to it.
*/
gr_sp(const gr_sp<T, Ref, Unref>& that) : fPtr(SafeRef(that.get())) {}
template <typename U,
typename = typename std::enable_if<std::is_convertible<U*, T*>::value>::type>
gr_sp(const gr_sp<U, Ref, Unref>& that) : fPtr(SafeRef(that.get())) {}
gr_sp(const sk_sp<T>& that) : fPtr(SafeRef(that.get())) {}
/**
* Move the underlying object from the argument to the newly created gr_sp. Afterwards only the
* new gr_sp will have a reference to the object, and the argument will point to null.
* No call to Ref() or Unref() will be made.
*/
gr_sp(gr_sp<T, Ref, Unref>&& that) : fPtr(that.release()) {}
/**
* Copies the underlying object pointer from the argument to the gr_sp. It will then call
* Ref() on the new object.
*/
gr_sp(sk_sp<T>&& that) : fPtr(SafeRef(that.get())) {}
/**
* Adopt the bare pointer into the newly created gr_sp.
* No call to Ref() or Unref() will be made.
*/
explicit gr_sp(T* obj) : fPtr(obj) {}
/**
* Calls Unref() on the underlying object pointer.
*/
~gr_sp() {
SafeUnref(fPtr);
SkDEBUGCODE(fPtr = nullptr);
}
gr_sp& operator=(std::nullptr_t) {
this->reset();
return *this;
}
/**
* Shares the underlying object referenced by the argument by calling Ref() on it. If this gr_sp
* previously had a reference to an object (i.e. not null) it will call Unref() on that object.
*/
gr_sp& operator=(const gr_sp<T, Ref, Unref>& that) {
if (this != &that) {
this->reset(SafeRef(that.get()));
}
return *this;
}
/**
* Copies the underlying object pointer from the argument to the gr_sp. If the gr_sp previously
* held a reference to another object, Unref() will be called on that object. It will then call
* Ref() on the new object.
*/
gr_sp& operator=(const sk_sp<T>& that) {
this->reset(SafeRef(that.get()));
return *this;
}
/**
* Move the underlying object from the argument to the gr_sp. If the gr_sp previously held
* a reference to another object, Unref() will be called on that object. No call to Ref() will
* be made.
*/
gr_sp& operator=(gr_sp<T, Ref, Unref>&& that) {
this->reset(that.release());
return *this;
}
/**
* Copies the underlying object pointer from the argument to the gr_sp. If the gr_sp previously
* held a reference to another object, Unref() will be called on that object. It will then call
* Ref() on the new object.
*/
gr_sp& operator=(sk_sp<T>&& that) {
this->reset(SafeRef(that.get()));
return *this;
}
T& operator*() const {
SkASSERT(this->get() != nullptr);
return *this->get();
}
explicit operator bool() const { return this->get() != nullptr; }
T* get() const { return fPtr; }
T* operator->() const { return fPtr; }
/**
* Adopt the new bare pointer, and call Unref() on any previously held object (if not null).
* No call to Ref() will be made.
*/
void reset(T* ptr = nullptr) {
T* oldPtr = fPtr;
fPtr = ptr;
SafeUnref(oldPtr);
}
private:
/**
* Return the bare pointer, and set the internal object pointer to nullptr.
* The caller must assume ownership of the object, and manage its reference count directly.
* No call to Unref() will be made.
*/
[[nodiscard]] T* release() {
T* ptr = fPtr;
fPtr = nullptr;
return ptr;
}
T* fPtr;
};
////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Shared pointer class to wrap classes that support a refCommandBuffer() and unrefCommandBuffer()
* interface.
*
* This class supports copying, moving, and assigning an sk_sp into it. In general these commands do
* not modify the sk_sp at all but just call refCommandBuffer() on the underlying object.
*
* This class is designed to be used by GrGpuResources/graphite::Resources that need to track when
* they are in use on gpu (usually via a command buffer) separately from tracking if there are any
* current logical usages in Skia. This allows for a scratch resources to be reused for new draw
* calls even if it is in use on the GPU.
*/
template <typename T>
using gr_cb = gr_sp<T, &T::refCommandBuffer, &T::unrefCommandBuffer>;
////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* This class mimics sk_sp but instead of calling unref it calls recycle instead.
*/
template <typename T> using gr_rp = gr_sp<T, &T::ref, &T::recycle>;
/**
* Returns a gr_rp wrapping the provided ptr AND calls ref on it (if not null).
*
* This is different than the semantics of the constructor for gr_rp, which just wraps the ptr,
* effectively "adopting" it.
*/
template <typename T> gr_rp<T> gr_ref_rp(T* obj) { return gr_rp<T>(SkSafeRef(obj)); }
template <typename T> gr_rp<T> gr_ref_rp(const T* obj) {
return gr_rp<T>(const_cast<T*>(SkSafeRef(obj)));
}
#endif