Make the file chooser use PP_ArrayOutput

ppapi/proxy/proxy_array_output.h

+// Copyright (c) 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 PPAPI_PROXY_PROXY_ARRAY_OUTPUT_H_
+#define PPAPI_PROXY_PROXY_ARRAY_OUTPUT_H_
+
+#include <vector>
+
+#include "base/logging.h"
+#include "base/memory/ref_counted.h"
+#include "ppapi/c/pp_array_output.h"
+
+// Like ppapi/cpp/array_output.h file in the C++ wrappers but for use in the
+// proxy where we can't link to the C++ wrappers. This also adds a refcounted
+// version.
+//
+// Use ArrayOutputAdapter when calling a function that synchronously returns
+// an array of data. Use RefCountedArrayOutputAdapterWithStorage for
+// asynchronous returns:
+//
+// void OnCallbackComplete(
+//     int32_t result,
+//     scoped_refptr<RefCountedArrayOutputAdapter<PP_Resource> > output) {
+//   // Vector is in output->output().
+// }
+//
+// void ScheduleCallback() {
+//   base::scoped_refptr<RefCountedArrayOutputAdapter<PP_Resource> > output;
+//
+//   callback = factory.NewOptionalCallback(&OnCallbackComplete, output);
+//   DoSomethingAsynchronously(output->pp_array_output(),
+//                             callback.PP_CompletionCallback());
+//   ...
+namespace ppapi {
+namespace proxy {
+
+// Non-templatized base class for the array output conversion. It provides the
+// C implementation of a PP_ArrayOutput whose callback function is implemented
+// as a virtual call on a derived class. Do not use directly, use one of the
+// derived classes below.
+class ArrayOutputAdapterBase {
+ public:
+  ArrayOutputAdapterBase() {
+    pp_array_output_.GetDataBuffer =
+        &ArrayOutputAdapterBase::GetDataBufferThunk;
+    pp_array_output_.user_data = this;
+  }
+  virtual ~ArrayOutputAdapterBase() {}
+
+  const PP_ArrayOutput& pp_array_output() { return pp_array_output_; }
+
+ protected:
+  virtual void* GetDataBuffer(uint32_t element_count,
+                              uint32_t element_size) = 0;
+
+ private:
+  static void* GetDataBufferThunk(void* user_data,
+                                  uint32_t element_count,
+                                  uint32_t element_size);
+
+  PP_ArrayOutput pp_array_output_;
+
+  // Disallow copying and assignment. This will do the wrong thing for most
+  // subclasses.
+  ArrayOutputAdapterBase(const ArrayOutputAdapterBase&);
+  ArrayOutputAdapterBase& operator=(const ArrayOutputAdapterBase&);
+};
+
+// This adapter provides functionality for implementing a PP_ArrayOutput
+// structure as writing to a given vector object.
+//
+// This is generally used internally in the C++ wrapper objects to
+// write into an output parameter supplied by the plugin. If the element size
+// that the browser is writing does not match the size of the type we're using
+// this will assert and return NULL (which will cause the browser to fail the
+// call).
+//
+// Example that allows the browser to write into a given vector:
+//   void DoFoo(std::vector<int>* results) {
+//     ArrayOutputAdapter<int> adapter(results);
+//     ppb_foo->DoFoo(adapter.pp_array_output());
+//   }
+template<typename T>
+class ArrayOutputAdapter : public ArrayOutputAdapterBase {
+ public:
+  ArrayOutputAdapter(std::vector<T>* output) : output_(output) {}
+
+ protected:
+  // Two-step init for the "with storage" version below.
+  ArrayOutputAdapter() : output_(NULL) {}
+  void set_output(std::vector<T>* output) { output_ = output; }
+
+  // ArrayOutputAdapterBase implementation.
+  virtual void* GetDataBuffer(uint32_t element_count, uint32_t element_size) {
+    DCHECK(element_size == sizeof(T));
+    if (element_count == 0 || element_size != sizeof(T))
+      return NULL;
+    output_->resize(element_count);
+    return &(*output_)[0];
+  }
+
+ private:
+  std::vector<T>* output_;
+};
+
+template<typename T>
+class ArrayOutputAdapterWithStorage : public ArrayOutputAdapter<T> {
+ public:
+  ArrayOutputAdapterWithStorage() {
+    // Note: "this->" is required due to two-phase name lookup where it isn't
+    // allowed to look in the base class during parsing.
+    this->set_output(&output_storage_);
+  }
+
+  std::vector<T>& output() { return output_storage_; }
+
+ private:
+  std::vector<T> output_storage_;
+};
+
+// A reference counted version of ArrayOutputAdapterWithStorage. Since it
+// doesn't make much sense to heap-allocate one without storage, we don't
+// call it "with storage" to keep the name length under control.
+template<typename T>
+class RefCountedArrayOutputAdapter
+    : public ArrayOutputAdapterWithStorage<T>,
+      public base::RefCounted<RefCountedArrayOutputAdapter<T> > {
+ public:
+  RefCountedArrayOutputAdapter()
+      : ArrayOutputAdapterWithStorage<T>() {
+  }
+};
+
+}  // namespace proxy
+}  // namespace ppapi
+
+#endif  // PPAPI_PROXY_PROXY_ARRAY_OUTPUT_H_