PPAPI的插件,原本是能够使用JS与浏览器交互的,。这里还提供了一个JS与plugin交互的文档,但如今说不支持了。如今应该通过PPB_Messaging接口来完毕Plugin和浏览器的交互,详细參考这里。
我实验了一下。通了。
Messaging接口非常好。传递的消息能够自已定义。类型也无限制。非常方便。
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使用postMessage通信
Messaging接口与其他大多数接口一样,分PPB和PPP两側。
分开来说明一下要做的事情。
插件側
要做这么些事情:
- 实现PPP_Messaging接口。关键是void (*HandleMessage)(PP_Instance instance, struct PP_Var message)方法
- 在Get_Interface中返回名字是PPP_MESSAGING_INTERFACE的接口
- 在PPP_InitializeModule中获取 PPB_Messaging、PPB_Var、PPB_VarArray、PPB_VarDictionary等接口。 PPB_Messaging的PostMessage用于向浏览器发送消息。发送过去的消息,JS代码能够接收到。
- PPP_Messaging的HandleMessage处理浏览器的消息,假设须要。调用PPB_Messaging的PostMessage发送消息.
注意,插件側调用PPB_Var接口的VarFromUtf8时,传入的len不包含’\0’在内。PPAPI的ppb_var.h的凝视里的演示样例代码片段有误,调用时传递的长度是sizeof(hello_world)。应该减去一。
另一点,插件和浏览器交互的数据。都是数据的拷贝哦,调用接口会发生复制行为。
浏览器側
浏览器側能够使用JavaScript来监听插件发送的message事件,也能够使用插件元素的postMessage发送消息给插件。
基本上做以下几件事就可以:
- 实现处理消息的JS函数,其參数是MessageEvent。data成员为插件发过来的信息,能够当做JS对象来訪问。
- 监听插件的message事件
- 在合适的时候调用插件的postMessage(object)方法发送消息给插件
代码
分插件代码和HTML代码。
插件代码
代码是在一文演示样例代码的基础上改的。加入了消息处理的部分。仅仅贴相关的部分了。
获取消息相关接口的代码
在PPP_InitializeModule中加入了获取PPB_Messaging接口以及其他可能用到的PP_Var类型的接口。有Array和Dictionary。
g_var_interface = (const PPB_Var*)get_browser_interface(PPB_VAR_INTERFACE); g_dictionary_interface = (const PPB_VarDictionary*)get_browser_interface(PPB_VAR_DICTIONARY_INTERFACE); g_array_interface = (const PPB_VarArray*)get_browser_interface(PPB_VAR_ARRAY_INTERFACE); g_message_interface = (const PPB_Messaging*)get_browser_interface(PPB_MESSAGING_INTERFACE);
PPP_Messaging接口的实现
PPP_Messaging接口的实现代码例如以下:
void Plugin_HandleMessage(PP_Instance instance, struct PP_Var message){ char szLog[256] = { 0 }; sprintf_s(szLog, 256, "Plugin_HandleMessage, type = %d\r\n", message.type); OutputDebugStringA(szLog); if (message.type == PP_VARTYPE_DICTIONARY) { char command[] = "command"; struct PP_Var commandKey = g_var_interface->VarFromUtf8(command, sizeof(command) - 1); struct PP_Var commandVar = g_dictionary_interface->Get(message, commandKey); int len = 0; const char *strCommand = g_var_interface->VarToUtf8(commandVar, &len); g_var_interface->Release(commandKey); sprintf_s(szLog, 256, "Plugin_HandleMessage, dict, command = %s, len = %d\r\n", strCommand, len); OutputDebugStringA(szLog); if (len == 0) { OutputDebugString(_T("Tang_plugin, recv invalid command\r\n")); g_var_interface->Release(commandVar); return; } if (strncmp(strCommand, "joinConf", len) == 0) { char confIdKey[] = "confId"; char userNameKey[] = "userName"; char *szConfId = 0; char*szUserName = 0; struct PP_Var idKey = g_var_interface->VarFromUtf8(confIdKey, sizeof(confIdKey) - 1); struct PP_Var userKey = g_var_interface->VarFromUtf8(userNameKey, sizeof(userNameKey) - 1); struct PP_Var var = g_dictionary_interface->Get(message, idKey); const char *value = g_var_interface->VarToUtf8(var, &len); if (len > 0) { szConfId = malloc(len + 1); strncpy_s(szConfId, len+1, value, len); szConfId[len] = 0; } g_var_interface->Release(var); var = g_dictionary_interface->Get(message, userKey); value = g_var_interface->VarToUtf8(var, &len); if (len > 0) { szUserName = malloc(len + 1); strncpy_s(szUserName, len+1, value, len); szUserName[len] = 0; } g_var_interface->Release(var); sprintf_s(szLog, 256, "Plugin_HandleMessage, dict, command = joinConf, user = %s, confId = %s\r\n", szUserName, szConfId); OutputDebugStringA(szLog); if (szConfId && szUserName) { sprintf_s(szLog, 256, "plugin got confId - %s, user - %s\r\n", szConfId, szUserName); OutputDebugStringA(szLog); joinConf(szConfId, szUserName); } else { OutputDebugString(_T("Invalid conference id or userName\r\n")); } if (szConfId) free(szConfId); if (szUserName) free(szUserName); g_var_interface->Release(idKey); g_var_interface->Release(userKey); /* fake attendees*/ char szMsgTypeValue[] = "userlist"; char szTypeKey[] = "type"; struct PP_Var typeKey = g_var_interface->VarFromUtf8(szTypeKey, sizeof(szTypeKey) - 1); struct PP_Var typeValue = g_var_interface->VarFromUtf8(szMsgTypeValue, sizeof(szMsgTypeValue) - 1); struct PP_Var attendee = g_dictionary_interface->Create(); g_dictionary_interface->Set(attendee, typeKey, typeValue); struct PP_Var userArray = g_array_interface->Create(); char szUser1[] = "ZhangSan"; char szUser2[] = "LiSi"; struct PP_Var user1 = g_var_interface->VarFromUtf8(szUser1, sizeof(szUser1) - 1); struct PP_Var user2 = g_var_interface->VarFromUtf8(szUser2, sizeof(szUser2) - 1); g_array_interface->Set(userArray, 0, user1); g_array_interface->Set(userArray, 1, user2); char szValueKey[] = "value"; struct PP_Var valueKey = g_var_interface->VarFromUtf8(szValueKey, sizeof(szValueKey) - 1); g_dictionary_interface->Set(attendee, valueKey, userArray); g_message_interface->PostMessage(instance, attendee); OutputDebugString(_T("Post attendee to browser")); g_var_interface->Release(typeKey); g_var_interface->Release(typeValue); g_var_interface->Release(user1); g_var_interface->Release(user2); g_var_interface->Release(valueKey); g_var_interface->Release(userArray); g_var_interface->Release(attendee); } else if (strncmp(strCommand, "viewVideo", len) == 0) { char userIdKey[] = "userId"; char *szUserId = 0; struct PP_Var idKey = g_var_interface->VarFromUtf8(userIdKey, sizeof(userIdKey) - 1); struct PP_Var var = g_dictionary_interface->Get(message, idKey); const char *value = g_var_interface->VarToUtf8(var, &len); if (len > 0) { szUserId = malloc(len + 1); strncpy_s(szUserId, len + 1, value, len); szUserId[len] = 0; } if (szUserId) { sprintf_s(szLog, 256, "plugin got userId - %s\r\n", szUserId); OutputDebugStringA(szLog); viewVideo(szUserId, g_child_window); } else { OutputDebugString(_T("Invalid viewVideo command without userId\r\n")); } if (szUserId) free(szUserId); g_var_interface->Release(var); g_var_interface->Release(idKey); } g_var_interface->Release(commandVar); } else if (message.type == PP_VARTYPE_STRING) { char hello_world[] = "Hello world!"; struct PP_Var var = g_var_interface->VarFromUtf8(hello_world, sizeof(hello_world) - 1); g_message_interface->PostMessage(instance, var); // var will be copyed g_var_interface->Release(var); }}static PPP_Messaging message_interface = { &Plugin_HandleMessage};
有点长,比較潦草。
返回PPP_Messaging的代码
完整的PPP_GetInterface函数例如以下:
PP_EXPORT const void* PPP_GetInterface(const char* interface_name) { if (strcmp(interface_name, PPP_INSTANCE_INTERFACE) == 0) { OutputDebugString(_T("PPP_GetInterface, instance_interface\r\n")); return &instance_interface; } else if (strcmp(interface_name, PPP_INPUT_EVENT_INTERFACE) == 0) { OutputDebugString(_T("PPP_GetInterface, input_interface\r\n")); return &input_interface; } else if (strcmp(interface_name, PPP_MESSAGING_INTERFACE) == 0) { OutputDebugString(_T("PPP_GetInterface, message_interface\r\n")); return &message_interface; } return NULL;}
网页代码
网页代码例如以下:
Tang in Plugin
contacts:
share video: