QX11EmbedWidget Class Reference

Detailed Description

The QX11EmbedWidget class provides an XEmbed client widget.

XEmbed is an X11 protocol that supports the embedding of a widget from one application into another application.

An XEmbed client widget is a window that is embedded into a container. A container is the graphical location that embeds (or swallows) an external application.

QX11EmbedWidget is a widget used for writing XEmbed applets or plugins. When it has been embedded and the container receives tab focus, focus is passed on to the widget. When the widget reaches the end of its focus chain, focus is passed back to the container. Window activation, accelerator support, modality and drag and drop (XDND) are also handled.

The widget and container can both initiate the embedding. If the widget is the initiator, the X11 window ID of the container that it wants to embed itself into must be passed to embedInto().

If the container initiates the embedding, the window ID of the embedded widget must be known. The container calls embed(), passing the window ID.

This example shows an application that embeds a QX11EmbedWidget subclass into the window whose ID is passed as a command-line argument:

 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);

     if (app.arguments().count() != 2) {
         qFatal("Error - expected window id as argument");
         return 1;
     }

     QString windowId(app.arguments()[1]);
     EmbedWidget window;
     window.embedInto(windowId.toULong());
     window.show();

     return app.exec();
 }

The problem of obtaining the window IDs is often solved by the container invoking the application that provides the widget as a separate process (as a panel invokes a docked applet), passing its window ID to the new process as a command-line argument. The new process can then call embedInto() with the container's window ID, as shown in the example code above. Similarly, the new process can report its window ID to the container through IPC, in which case the container can embed the widget.

When the widget has been embedded, it emits the signal embedded(). If it is closed by the container, the widget emits containerClosed(). If an error occurs when embedding, error() is emitted.

There are XEmbed widgets available for KDE and GTK+. The GTK+ equivalent of QX11EmbedWidget is GtkPlug. The corresponding KDE 3 widget is called QXEmbed.