Draft of a PPAPI interface for ArrayBuffer and typed arrays.

ppapi/cpp/dev/var_array_buffer_dev.h

+// Copyright (c) 2011 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_CPP_DEV_VAR_ARRAY_BUFFER_DEV_H_
+#define PPAPI_CPP_DEV_VAR_ARRAY_BUFFER_DEV_H_
+
+#include "ppapi/cpp/var.h"
+
+/// @file
+/// This file defines the API for interacting with an ArrayBuffer.
+
+namespace pp {
+
+class Instance;
+
+/// VarArrayBuffer_Dev provides a way to interact with JavaScript ArrayBuffers,
+/// which represent a contiguous sequence of bytes. Note that
+/// VarArrayBuffer_Devs are not part of the embedding page's DOM, and can only
+/// be shared with JavaScript via pp::Instance's PostMessage and HandleMessage
+/// functions.
+class VarArrayBuffer_Dev : public Var {
+ public:
+  /// Contruct a VarArrayBuffer_Dev given a var for which is_array_buffer() is
+  /// true. This will refer to the same buffer as var, but allows you to access
+  /// methods specific to VarArrayBuffer_Dev.
+  ///
+  /// @param[in] var An array buffer Var.
+  explicit VarArrayBuffer_Dev(const Var& var);

[dmichael (off chromium), 2011/12/02 18:53:52]

This is basically down-casting the 'var handle'. There are other ways to do
this, but this way seemed fairly simple to implement and use.

+
+  VarArrayBuffer_Dev(const VarArrayBuffer_Dev& buffer) : Var(buffer) {}
+
+  /// Construct a new VarArrayBuffer_Dev which is size_in_bytes bytes long and
+  /// initialized to zero.
+  ///
+  /// @param[in] instance The Instance which is creating the VarArrayBuffer_Dev.
+  /// @param[in] size_in_bytes The size of the constructed array in bytes.
+  VarArrayBuffer_Dev(const Instance& instance, uint32_t size_in_bytes);
+
+  /// Return the length of the VarArrayBuffer_Dev in bytes.
+  ///
+  /// @return The length of the VarArrayBuffer_Dev in bytes.
+  uint32_t ByteLength() const;
+
+  /// Return a pointer to the buffer associated with this VarArrayBuffer_Dev.
+  ///
+  /// @return A pointer to the buffer associated with this VarArrayBuffer_Dev.
+  void* Map();
+  const void* Map() const;
+
+  virtual ~VarArrayBuffer_Dev() {}
+
+ private:
+  // We cache the buffer so that repeated calls to Map() are quick.
+  void* buffer_;
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_DEV_VAR_ARRAY_BUFFER_DEV_H_