1 // Copyright 2014 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_CPP_MESSAGE_HANDLER_H_ 6 #define PPAPI_CPP_MESSAGE_HANDLER_H_ 7 8 namespace pp { 9 10 /// <code>MessageHandler</code> is an abstract base class that the plugin may 11 /// implement if it wants to receive messages from JavaScript on a background 12 /// thread when JavaScript invokes postMessage() or 13 /// postMessageAndAwaitResponse(). See pp::Instance::RegisterMessageHandler() 14 /// for usage. 15 class MessageHandler { 16 public: 17 virtual ~MessageHandler() {}; 18 19 /// Invoked as a result of JavaScript invoking postMessage() on the plugin's 20 /// DOM element. 21 /// 22 /// @param[in] instance An <code>InstanceHandle</code> identifying one 23 /// instance of a module. 24 /// @param[in] message_data A copy of the parameter that JavaScript provided 25 /// to postMessage(). 26 virtual void HandleMessage(pp::InstanceHandle instance, 27 const Var& message_data) = 0; 28 29 /// Invoked as a result of JavaScript invoking postMessageAndAwaitResponse() 30 /// on the plugin's DOM element. 31 /// 32 /// NOTE: JavaScript execution is blocked during the duration of this call. 33 /// Hence, the plugin should respond as quickly as possible. For this reason, 34 /// blocking completion callbacks are disallowed while handling a blocking 35 /// message. 36 /// 37 /// @param[in] instance An <code>InstanceHandle</code> identifying one 38 /// instance of a module. 39 /// @param[in] message_data A copy of the parameter that JavaScript provided 40 /// to postMessage(). 41 /// @return Returns a pp::Var that is then copied to a JavaScript object 42 /// which is returned as the result of JavaScript's call of 43 /// postMessageAndAwaitResponse(). 44 virtual pp::Var HandleBlockingMessage(pp::InstanceHandle instance, 45 const Var& message_data) = 0; 46 47 /// Invoked when this MessageHandler is no longer needed. After this, no more 48 /// calls will be made to this object. 49 /// 50 /// @param[in] instance An <code>InstanceHandle</code> identifying one 51 /// instance of a module. 52 virtual void WasUnregistered(pp::InstanceHandle instance) = 0; 53 }; 54 55 } // namespace pp 56 57 #endif // PPAPI_CPP_MESSAGE_HANDLER_H_ 58
