ppapi/c/ppb_messaging.h

   1 /* Copyright (c) 2012 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
   6 /* From ppb_messaging.idl modified Wed Sep 24 10:48:37 2014. */
   7
   8 #ifndef PPAPI_C_PPB_MESSAGING_H_
   9 #define PPAPI_C_PPB_MESSAGING_H_
  10
  11 #include "ppapi/c/pp_bool.h"
  12 #include "ppapi/c/pp_instance.h"
  13 #include "ppapi/c/pp_macros.h"
  14 #include "ppapi/c/pp_resource.h"
  15 #include "ppapi/c/pp_stdint.h"
  16 #include "ppapi/c/pp_var.h"
  17 #include "ppapi/c/ppp_message_handler.h"
  18
  19 #define PPB_MESSAGING_INTERFACE_1_0 "PPB_Messaging;1.0"
  20 #define PPB_MESSAGING_INTERFACE_1_2 "PPB_Messaging;1.2"
  21 #define PPB_MESSAGING_INTERFACE PPB_MESSAGING_INTERFACE_1_2
  22
  23 /**
  24  * @file
  25  * This file defines the <code>PPB_Messaging</code> interface implemented
  26  * by the browser for sending messages to DOM elements associated with a
  27  * specific module instance.
  28  */
  29
  30
  31 /**
  32  * @addtogroup Interfaces
  33  * @{
  34  */
  35 /**
  36  * The <code>PPB_Messaging</code> interface is implemented by the browser
  37  * and is related to sending messages to JavaScript message event listeners on
  38  * the DOM element associated with specific module instance.
  39  */
  40 struct PPB_Messaging_1_2 {
  41   /**
  42    * PostMessage() asynchronously invokes any listeners for message events on
  43    * the DOM element for the given module instance. A call to PostMessage()
  44    * will not block while the message is processed.
  45    *
  46    * @param[in] instance A <code>PP_Instance</code> identifying one instance
  47    * of a module.
  48    * @param[in] message A <code>PP_Var</code> containing the data to be sent to
  49    * JavaScript.
  50    * <code>message</code> can be any <code>PP_Var</code> type except
  51    * <code>PP_VARTYPE_OBJECT</code>. Array/Dictionary types are supported from
  52    * Chrome M29 onward. All var types are copied when passing them to
  53    * JavaScript.
  54    *
  55    * When passing array or dictionary <code>PP_Var</code>s, the entire reference
  56    * graph will be converted and transferred. If the reference graph has cycles,
  57    * the message will not be sent and an error will be logged to the console.
  58    *
  59    * Listeners for message events in JavaScript code will receive an object
  60    * conforming to the HTML 5 <code>MessageEvent</code> interface.
  61    * Specifically, the value of message will be contained as a property called
  62    *  data in the received <code>MessageEvent</code>.
  63    *
  64    * This messaging system is similar to the system used for listening for
  65    * messages from Web Workers. Refer to
  66    * <code>http://www.whatwg.org/specs/web-workers/current-work/</code> for
  67    * further information.
  68    *
  69    * <strong>Example:</strong>
  70    *
  71    * @code
  72    *
  73    * <body>
  74    *   <object id="plugin"
  75    *           type="application/x-ppapi-postMessage-example"/>
  76    *   <script type="text/javascript">
  77    *     var plugin = document.getElementById('plugin');
  78    *     plugin.addEventListener("message",
  79    *                             function(message) { alert(message.data); },
  80    *                             false);
  81    *   </script>
  82    * </body>
  83    *
  84    * @endcode
  85    *
  86    * The module instance then invokes PostMessage() as follows:
  87    *
  88    * @code
  89    *
  90    *  char hello_world[] = "Hello world!";
  91    *  PP_Var hello_var = ppb_var_interface->VarFromUtf8(instance,
  92    *                                                    hello_world,
  93    *                                                    sizeof(hello_world));
  94    *  ppb_messaging_interface->PostMessage(instance, hello_var); // Copies var.
  95    *  ppb_var_interface->Release(hello_var);
  96    *
  97    * @endcode
  98    *
  99    * The browser will pop-up an alert saying "Hello world!"
 100    */
 101   void (*PostMessage)(PP_Instance instance, struct PP_Var message);
 102   /**
 103    * Registers a handler for receiving messages from JavaScript. If a handler
 104    * is registered this way, it will replace PPP_Messaging, and all messages
 105    * sent from JavaScript via postMessage and postMessageAndAwaitResponse will
 106    * be dispatched to <code>handler</code>.
 107    *
 108    * The function calls will be dispatched via <code>message_loop</code>. This
 109    * means that the functions will be invoked on the thread to which
 110    * <code>message_loop</code> is attached, when <code>message_loop</code> is
 111    * run. It is illegal to pass the main thread message loop;
 112    * RegisterMessageHandler will return PP_ERROR_WRONG_THREAD in that case.
 113    * If you quit <code>message_loop</code> before calling Unregister(),
 114    * the browser will not be able to call functions in the plugin's message
 115    * handler any more. That could mean missing some messages or could cause a
 116    * leak if you depend on Destroy() to free hander data. So you should,
 117    * whenever possible, Unregister() the handler prior to quitting its event
 118    * loop.
 119    *
 120    * Attempting to register a message handler when one is already registered
 121    * will cause the current MessageHandler to be unregistered and replaced. In
 122    * that case, no messages will be sent to the "default" message handler
 123    * (PPP_Messaging). Messages will stop arriving at the prior message handler
 124    * and will begin to be dispatched at the new message handler.
 125    *
 126    * @param[in] instance A <code>PP_Instance</code> identifying one instance
 127    * of a module.
 128    * @param[in] user_data A pointer the plugin may choose to use when handling
 129    * calls to functions within PPP_MessageHandler. The browser will pass this
 130    * same pointer when invoking functions within PPP_MessageHandler.
 131    * @param[in] handler The plugin-provided set of functions for handling
 132    * messages.
 133    * @param[in] message_loop Represents the message loop on which
 134    * PPP_MessageHandler functions should be invoked.
 135    * @return PP_OK on success, or an error from pp_errors.h.
 136    */
 137   int32_t (*RegisterMessageHandler)(
 138       PP_Instance instance,
 139       void* user_data,
 140       const struct PPP_MessageHandler_0_2* handler,
 141       PP_Resource message_loop);
 142   /**
 143    * Unregisters the current message handler for <code>instance</code> if one
 144    * is registered. After this call, the message handler (if one was
 145    * registered) will have "Destroy" called on it and will receive no further
 146    * messages after that point. After that point, all messages sent from
 147    * JavaScript using postMessage() will be dispatched to PPP_Messaging (if
 148    * the plugin supports PPP_MESSAGING_INTERFACE). Attempts to call
 149    * postMessageAndAwaitResponse() from JavaScript will fail.
 150    *
 151    * Attempting to unregister a message handler when none is registered has no
 152    * effect.
 153    *
 154    * @param[in] instance A <code>PP_Instance</code> identifying one instance
 155    * of a module.
 156    */
 157   void (*UnregisterMessageHandler)(PP_Instance instance);
 158 };
 159
 160 typedef struct PPB_Messaging_1_2 PPB_Messaging;
 161
 162 struct PPB_Messaging_1_0 {
 163   void (*PostMessage)(PP_Instance instance, struct PP_Var message);
 164 };
 165 /**
 166  * @}
 167  */
 168
 169 #endif  /* PPAPI_C_PPB_MESSAGING_H_ */
 170