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| 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_ |
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