WebKit2WebExtensionWebExtension

Represents an extension of the WebProcess.

WebKitWebExtension is a loadable module for the WebProcess. It allows you to execute code in the WebProcess and being able to use the DOM API, to change any request or to inject custom JavaScript code, for example.

To create a WebKitWebExtension you should write a module with an initialization function that could be either webkit_web_extension_initialize() with prototype WebKitWebExtensionInitializeFunction or webkit_web_extension_initialize_with_user_data() with prototype WebKitWebExtensionInitializeWithUserDataFunction. This function has to be public and it has to use the #G_MODULE_EXPORT macro. It is called when the web process is initialized.

static void
web_page_created_callback (WebKitWebExtension *extension,
                           WebKitWebPage      *web_page,
                           gpointer            user_data)
{
    g_print ("Page %d created for %s\n",
             webkit_web_page_get_id (web_page),
             webkit_web_page_get_uri (web_page));
}

G_MODULE_EXPORT void
webkit_web_extension_initialize (WebKitWebExtension *extension)
{
    g_signal_connect (extension, "page-created",
                      G_CALLBACK (web_page_created_callback),
                      NULL);
}

The previous piece of code shows a trivial example of an extension that notifies when a WebKitWebPage is created.

WebKit has to know where it can find the created WebKitWebExtension. To do so you should use the webkit_web_context_set_web_extensions_directory() function. The signal WebKitWebContext::initialize-web-extensions is the recommended place to call it.

To provide the initialization data used by the webkit_web_extension_initialize_with_user_data() function, you have to call webkit_web_context_set_web_extensions_initialization_user_data() with the desired data as parameter. You can see an example of this in the following piece of code:

#define WEB_EXTENSIONS_DIRECTORY // ...

static void
initialize_web_extensions (WebKitWebContext *context,
                           gpointer          user_data)
{
  // Web Extensions get a different ID for each Web Process
  static guint32 unique_id = 0;

  webkit_web_context_set_web_extensions_directory (
     context, WEB_EXTENSIONS_DIRECTORY);
  webkit_web_context_set_web_extensions_initialization_user_data (
     context, g_variant_new_uint32 (unique_id++));
}

int main (int argc, char **argv)
{
  g_signal_connect (webkit_web_context_get_default (),
                   "initialize-web-extensions",
                    G_CALLBACK (initialize_web_extensions),
                    NULL);

  GtkWidget *view = webkit_web_view_new ();

  // ...
}