binary_messenger.h

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// Copyright 2013 The Flutter 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 FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_BINARY_MESSENGER_H_
#define FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_BINARY_MESSENGER_H_
 
#include <cstdint>
#include <functional>
#include <string>
 
namespace flutter {
 
// A binary message reply callback.
//
// Used for submitting a binary reply back to a Flutter message sender.
typedef std::function<void(const uint8_t* reply, size_t reply_size)>
    BinaryReply;
 
// A message handler callback.
//
// Used for receiving messages from Flutter and providing an asynchronous reply.
typedef std::function<
    void(const uint8_t* message, size_t message_size, BinaryReply reply)>
    BinaryMessageHandler;
 
// A protocol for a class that handles communication of binary data on named
// channels to and from the Flutter engine.
class BinaryMessenger {
 public:
  virtual ~BinaryMessenger() = default;
 
  // Sends a binary message to the Flutter engine on the specified channel.
  //
  // If |reply| is provided, it will be called back with the response from the
  // engine.
  virtual void Send(const std::string& channel,
                    const uint8_t* message,
                    size_t message_size,
                    BinaryReply reply = nullptr) const = 0;
 
  // Registers a message handler for incoming binary messages from the Flutter
  // side on the specified channel.
  //
  // Replaces any existing handler. Provide a null handler to unregister the
  // existing handler.
  virtual void SetMessageHandler(const std::string& channel,
                                 BinaryMessageHandler handler) = 0;
};
 
}  // namespace flutter
 
#endif  // FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_BINARY_MESSENGER_H_