1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef PPAPI_PROXY_PROXY_ARRAY_OUTPUT_H_ 6 #define PPAPI_PROXY_PROXY_ARRAY_OUTPUT_H_ 7 8 #include <vector> 9 10 #include "base/logging.h" 11 #include "base/memory/ref_counted.h" 12 #include "ppapi/c/pp_array_output.h" 13 14 // Like ppapi/cpp/array_output.h file in the C++ wrappers but for use in the 15 // proxy where we can't link to the C++ wrappers. This also adds a refcounted 16 // version. 17 // 18 // Use ArrayOutputAdapter when calling a function that synchronously returns 19 // an array of data. Use RefCountedArrayOutputAdapterWithStorage for 20 // asynchronous returns: 21 // 22 // void OnCallbackComplete( 23 // int32_t result, 24 // scoped_refptr<RefCountedArrayOutputAdapter<PP_Resource> > output) { 25 // // Vector is in output->output(). 26 // } 27 // 28 // void ScheduleCallback() { 29 // base::scoped_refptr<RefCountedArrayOutputAdapter<PP_Resource> > output; 30 // 31 // callback = factory.NewOptionalCallback(&OnCallbackComplete, output); 32 // DoSomethingAsynchronously(output->pp_array_output(), 33 // callback.pp_completion_callback()); 34 // ... 35 namespace ppapi { 36 namespace proxy { 37 38 // Non-templatized base class for the array output conversion. It provides the 39 // C implementation of a PP_ArrayOutput whose callback function is implemented 40 // as a virtual call on a derived class. Do not use directly, use one of the 41 // derived classes below. 42 class ArrayOutputAdapterBase { 43 public: ArrayOutputAdapterBase()44 ArrayOutputAdapterBase() { 45 pp_array_output_.GetDataBuffer = 46 &ArrayOutputAdapterBase::GetDataBufferThunk; 47 pp_array_output_.user_data = this; 48 } ~ArrayOutputAdapterBase()49 virtual ~ArrayOutputAdapterBase() {} 50 pp_array_output()51 const PP_ArrayOutput& pp_array_output() { return pp_array_output_; } 52 53 protected: 54 virtual void* GetDataBuffer(uint32_t element_count, 55 uint32_t element_size) = 0; 56 57 private: 58 static void* GetDataBufferThunk(void* user_data, 59 uint32_t element_count, 60 uint32_t element_size); 61 62 PP_ArrayOutput pp_array_output_; 63 64 // Disallow copying and assignment. This will do the wrong thing for most 65 // subclasses. 66 ArrayOutputAdapterBase(const ArrayOutputAdapterBase&); 67 ArrayOutputAdapterBase& operator=(const ArrayOutputAdapterBase&); 68 }; 69 70 // This adapter provides functionality for implementing a PP_ArrayOutput 71 // structure as writing to a given vector object. 72 // 73 // This is generally used internally in the C++ wrapper objects to 74 // write into an output parameter supplied by the plugin. If the element size 75 // that the browser is writing does not match the size of the type we're using 76 // this will assert and return NULL (which will cause the browser to fail the 77 // call). 78 // 79 // Example that allows the browser to write into a given vector: 80 // void DoFoo(std::vector<int>* results) { 81 // ArrayOutputAdapter<int> adapter(results); 82 // ppb_foo->DoFoo(adapter.pp_array_output()); 83 // } 84 template<typename T> 85 class ArrayOutputAdapter : public ArrayOutputAdapterBase { 86 public: ArrayOutputAdapter(std::vector<T> * output)87 ArrayOutputAdapter(std::vector<T>* output) : output_(output) {} 88 89 protected: 90 // Two-step init for the "with storage" version below. ArrayOutputAdapter()91 ArrayOutputAdapter() : output_(NULL) {} set_output(std::vector<T> * output)92 void set_output(std::vector<T>* output) { output_ = output; } 93 94 // ArrayOutputAdapterBase implementation. GetDataBuffer(uint32_t element_count,uint32_t element_size)95 virtual void* GetDataBuffer(uint32_t element_count, uint32_t element_size) { 96 DCHECK(element_size == sizeof(T)); 97 if (element_count == 0 || element_size != sizeof(T)) 98 return NULL; 99 output_->resize(element_count); 100 return &(*output_)[0]; 101 } 102 103 private: 104 std::vector<T>* output_; 105 }; 106 107 template<typename T> 108 class ArrayOutputAdapterWithStorage : public ArrayOutputAdapter<T> { 109 public: ArrayOutputAdapterWithStorage()110 ArrayOutputAdapterWithStorage() { 111 // Note: "this->" is required due to two-phase name lookup where it isn't 112 // allowed to look in the base class during parsing. 113 this->set_output(&output_storage_); 114 } 115 output()116 std::vector<T>& output() { return output_storage_; } 117 118 private: 119 std::vector<T> output_storage_; 120 }; 121 122 // A reference counted version of ArrayOutputAdapterWithStorage. Since it 123 // doesn't make much sense to heap-allocate one without storage, we don't 124 // call it "with storage" to keep the name length under control. 125 template<typename T> 126 class RefCountedArrayOutputAdapter 127 : public ArrayOutputAdapterWithStorage<T>, 128 public base::RefCounted<RefCountedArrayOutputAdapter<T> > { 129 public: RefCountedArrayOutputAdapter()130 RefCountedArrayOutputAdapter() 131 : ArrayOutputAdapterWithStorage<T>() { 132 } 133 }; 134 135 } // namespace proxy 136 } // namespace ppapi 137 138 #endif // PPAPI_PROXY_PROXY_ARRAY_OUTPUT_H_ 139