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handle.h
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1 //
2 // Copyright 2020 Pixar
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5 // with the following modification; you may not use this file except in
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24 #ifndef PXR_IMAGING_HGI_HANDLE_H
25 #define PXR_IMAGING_HGI_HANDLE_H
26 
27 #include "pxr/pxr.h"
28 #include "pxr/imaging/hgi/api.h"
29 
30 #include <stdint.h>
31 
33 
34 /// \class HgiHandle
35 ///
36 /// Handle that contains a hgi object and unique id.
37 ///
38 /// The unique id is used to compare two handles to gaurd against pointer
39 /// aliasing, where the same memory address is used to create a similar object,
40 /// but it is not actually the same object.
41 ///
42 /// Handle is not a shared or weak_ptr and destruction of the contained object
43 /// should be explicitely managed by the client via the HgiDestroy*** functions.
44 ///
45 /// If shared/weak ptr functionality is desired, the client creating Hgi objects
46 /// can wrap the returned handle in a shared_ptr.
47 ///
48 template<class T>
49 class HgiHandle
50 {
51 public:
52  HgiHandle() : _ptr(nullptr), _id(0) {}
53  HgiHandle(T* obj, uint64_t id) : _ptr(obj), _id(id) {}
54 
55  T*
56  Get() const {
57  return _ptr;
58  }
59 
60  // Note this only checks if a ptr is set, it does not offer weak_ptr safety.
61  explicit operator bool() const {return _ptr!=nullptr;}
62 
63  // Pointer access operator
64  T* operator ->() const {return _ptr;}
65 
66  bool operator==(const HgiHandle& other) const {
67  return _id == other._id;
68  }
69 
70  bool operator!=(const HgiHandle& other) const {
71  return !(*this == other);
72  }
73 
74 private:
75 
76  // Destruction of objects should only happen via the HgiDestroy*** function.
77  // This function is in-accessible by clients using this handle, but
78  // accessible by the Hgi friend class that created the handle.
79  friend class Hgi;
80 
81  T* _ptr;
82  uint64_t _id;
83 };
84 
85 
87 
88 #endif
bool operator!=(const HgiHandle &other) const
Definition: handle.h:70
T * operator->() const
Definition: handle.h:64
GLhandleARB obj
Definition: glew.h:6236
T * Get() const
Definition: handle.h:56
HgiHandle(T *obj, uint64_t id)
Definition: handle.h:53
Definition: hgi.h:106
PXR_NAMESPACE_CLOSE_SCOPE PXR_NAMESPACE_OPEN_SCOPE
Definition: path.h:1346
#define PXR_NAMESPACE_CLOSE_SCOPE
Definition: pxr.h:91
HgiHandle()
Definition: handle.h:52
bool operator==(const HgiHandle &other) const
Definition: handle.h:66