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141 GtkSocket

Container for widgets from other processes

141.1 Overview

Together with <gtk-plug>, <gtk-socket> provides the ability to embed widgets from one process into another process in a fashion that is transparent to the user. One process creates a <gtk-socket> widget and, passes the that widget's window ID to the other process, which then creates a <gtk-plug> with that window ID. Any widgets contained in the <gtk-plug> then will appear inside the first applications window.

The socket's window ID is obtained by using gtk-socket-get-id. Before using this function, the socket must have been realized, and for hence, have been added to its parent.

     GtkWidget *socket = gtk_socket_new ();
     gtk_widget_show (socket);
     gtk_container_add (GTK_CONTAINER (parent), socket);
     /* The following call is only necessary if one of
      * the ancestors of the socket is not yet visible.
     gtk_widget_realize (socket);
     g_print ("The ID of the sockets window is %x\n",
              gtk_socket_get_id (socket));

Note that if you pass the window ID of the socket to another process that will create a plug in the socket, you must make sure that the socket widget is not destroyed until that plug is created. Violating this rule will cause unpredictable consequences, the most likely consequence being that the plug will appear as a separate toplevel window. You can check if the plug has been created by examining the field of the <gtk-socket> structure. If this field is non-‘#f’, then the plug has been successfully created inside of the socket.

When GTK+ is notified that the embedded window has been destroyed, then it will destroy the socket as well. You should always, therefore, be prepared for your sockets to be destroyed at any time when the main event loop is running.

The communication between a <gtk-socket> and a <gtk-plug> follows the XEmbed protocol. This protocol has also been implemented in other toolkits, e.g. , allowing the same level of integration when embedding a widget in GTK or vice versa.

A socket can also be used to swallow arbitrary pre-existing top-level windows using gtk-socket-steal, though the integration when this is done will not be as close as between a <gtk-plug> and a <gtk-socket>.

The <gtk-plug> and <gtk-socket> widgets are currently not available on all platforms supported by GTK+.

141.2 Usage

— Class: <gtk-socket>

Derives from <gtk-container>.

This class defines no direct slots.

— Signal on <gtk-socket>: plug-added

This signal is emitted when a client is successfully added to the socket.

— Signal on <gtk-socket>: plug-removed ⇒ <gboolean>

This signal is emitted when a client is removed from the socket. The default action is to destroy the <gtk-socket> widget, so if you want to reuse it you must add a signal handler that returns ‘#t’.

— Function: gtk-socket-new ⇒  (ret <gtk-widget>)

Create a new empty <gtk-socket>.

the new <gtk-socket>.
— Function: gtk-socket-add-id (self <gtk-socket>) (window_id unsigned-long)
— Method: add-id

Adds an XEMBED client, such as a <gtk-plug>, to the <gtk-socket>. The client may be in the same process or in a different process.

To embed a <gtk-plug> in a <gtk-socket>, you can either create the <gtk-plug> with ‘gtk_plug_new (0)’, call gtk-plug-get-id to get the window ID of the plug, and then pass that to the gtk-socket-add-id, or you can call gtk-socket-get-id to get the window ID for the socket, and call gtk-plug-new passing in that ID.

The <gtk-socket> must have already be added into a toplevel window before you can make this call.

a <gtk-socket>
the window ID of a client participating in the XEMBED protocol.
— Function: gtk-socket-get-id (self <gtk-socket>) ⇒  (ret unsigned-long)
— Method: get-id

Gets the window ID of a <gtk-socket> widget, which can then be used to create a client embedded inside the socket, for instance with gtk-plug-new.

The <gtk-socket> must have already be added into a toplevel window before you can make this call.

a <gtk-socket>.
the window ID for the socket