Communication between browser process and render process in CEF

Https://bitbucket.org/chromiumembedded/cef/wiki/GeneralUsage mentioned several mechanisms that CEF provides for communication between the browser and browser processes, and I experimented with the process Runtime messages this way, using Cefprocessmessage and Cefbrowser::sendprocessmessage ().

I was in the CEF in the JS and C + + interactive article on the basis of the completion, we say the basic steps, the side gives the key code.

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• 1. Send Message

Send a message using Cefbrowser::sendprocessmessage (), sendprocessmessage the first parameter is Cefprocessid, send to BROWSER process, use Pid_browser, Send to the render process, using Pid_renderer.

My code for sending messages in the render process is as follows (within the Execute method of Clientv8handler):

CefRefPtr<CefProcessMessage> msg = CefProcessMessage::Create("login_msg");

        // Retrieve the argument list object.
        CefRefPtr<CefListValue> args = msg->GetArgumentList();

        // Populate the argument values.
        args->SetSize(2);
        args->SetString(0, strUser);
        args->SetString(1, strPassword);

        // Send the process message to the browser process.
        CefV8Context::GetCurrentContext()->GetBrowser()->SendProcessMessage(PID_BROWSER, msg);

I sent the login message (the render process) received in that Cef_js_integration example to the browser process.

• 1. Processing messages

Browser process side, rewrite cefclient::onprocessmessagereceived () This method to handle cross-process messages.

In Cef_js_integration, for example, the Onprocessmessagereceived method is overridden in ClientHandler:

bool ClientHandler::OnProcessMessageReceived(CefRefPtr<CefBrowser> browser,
    CefProcessId source_process,
    CefRefPtr<CefProcessMessage> message)
{
    const std::string& messageName = message->GetName();
    if (messageName == "login_msg") 
    {   
        // extract message
        CefRefPtr<CefListValue> args = message->GetArgumentList();
        CefString strUser = args->GetString(0);
        CefString strPassword = args->GetString(1);
        TCHAR szLog[256] = { 0 };
        _stprintf_s(szLog, 256, _T("BrowserProcess, user - %s, password - %s\r\n"), strUser.c_str(), strPassword.c_str());
        OutputDebugString(szLog);

        //send reply to render process
        CefRefPtr<CefProcessMessage> outMsg = CefProcessMessage::Create("login_reply");

        // Retrieve the argument list object.
        CefRefPtr<CefListValue> replyArgs = outMsg->GetArgumentList();

        // Populate the argument values.
        replyArgs->SetSize(1);
        replyArgs->SetInt(0, 0);

        // Send the process message to the renderer process.
        browser->SendProcessMessage(PID_RENDERER, outMsg);

        return true;
    }
    return false;
}

As you can see, the above code sends a message to the render process.

The render process side, overriding the Cefrenderprocesshandler::onprocessmessagereceived () method to handle messages from the browser process, in the Clientapprender class:

bool ClientAppRenderer::OnProcessMessageReceived(CefRefPtr<CefBrowser> browser,
    CefProcessId source_process,
    CefRefPtr<CefProcessMessage> message)
{
    const std::string& messageName = message->GetName();
    if (messageName == "login_reply")
    {
        // extract message
        CefRefPtr<CefListValue> args = message->GetArgumentList();
        int status = args->GetInt(0);
        OutputDebugString(status == 0 ? _T("Renderer process, login ok\r\n") : _T("Renderer process, login failed\r\n"));
        CefRefPtr<CefFrame> frame = browser->GetMainFrame();
        frame->ExecuteJavaScript("alert(‘Got Login Reply from Browser process‘)", frame->GetURL(), 0);
        return true;
    }
    return false;
}

Well, that's the whole process.

Other reference articles:

• CEF Windows Development Environment Setup
• CEF Load Ppapi Plugin
• VS2013 compiling the simplest Ppapi plugin
• Understanding the design of PPAPI
• Ppapi plugin-to-browser interaction process
• Windows compiled from the source CEF
• Media_stream_video Example of compiling PPAPI
• PPAPI plug-in drawing and input event handling
• Creating a local window in the PPAPI plug-in
• PPAPI plug-in communication with the browser
• Skia compiled from source under Windows
• Using Skia drawing in the Ppapi plug-in
• Load a picture resource in a DLL to generate a Skbitmap object in Skia
• Ppapi+skia implementation of Graffiti Board
• 3D graphics interface using chromium in PPAPI
• Using OpenGL ES drawing in Ppapi
• JS in CEF interacts with C + +

Communication between browser process and render process in CEF