Gst::XOverlay Class Reference
[gstreamermm Interfaces]

XOverlay - Interface for setting/getting a Window on elements supporting it. More...

#include <xoverlay.h>

Inheritance diagram for Gst::XOverlay:

Gst::XImageSink Gst::XvImageSink

List of all members.

Public Member Functions

virtual ~XOverlay ()
GstXOverlay* gobj ()
 Provides access to the underlying C GObject.
const GstXOverlay* gobj () const
 Provides access to the underlying C GObject.
void set_xwindow_id (gulong xwindow_id)
 This will call the video overlay's set_xwindow_id method.
void got_xwindow_id (gulong xwindow_id)
 This will post a "have-xwindow-id" element message on the bus.
void prepare_xwindow_id ()
 This will post a "prepare-xwindow-id" element message on the bus to give applications an opportunity to call gst_x_overlay_set_xwindow_id() before a plugin creates its own window.
void expose ()
 Tell an overlay that it has been exposed.
void handle_events (bool handle_events)
 Tell an overlay that it should handle events from the window system.
virtual void set_xwindow_id_vfunc (gulong xwindow_id)
 Virtual method to configure the XWindow id.
virtual void expose_vfunc ()
 Virtual method to handle expose events.
virtual void handle_events_vfunc (bool handle_events)
 Virtual method to handle events.

Static Public Member Functions

static void add_interface (GType gtype_implementer)

Related Functions

(Note that these are not member functions.)

Glib::RefPtr<Gst::XOverlaywrap (GstXOverlay* object, bool take_copy=false)
 A Glib::wrap() method for this object.


Detailed Description

XOverlay - Interface for setting/getting a Window on elements supporting it.

The XOverlay interface is used for 2 main purposes :

Using the Window created by the video sink is probably the simplest scenario, in some cases, though, it might not be flexible enough for application developers if they need to catch events such as mouse moves and button clicks.

Setting a specific Window identifier on the video sink element is the most flexible solution but it has some issues. Indeed the application needs to set its Window identifier at the right time to avoid internal Window creation from the video sink element. To solve this issue a Message is posted on the bus to inform the application that it should set the Window identifier immediately. Here is an example on how to do that correctly:

 #include <gdk/gdkx.h>
 ...
 void PlayerWindow::on_bus_message_sync(
     const Glib::RefPtr<Gst::Message>& message)
 {
   // ignore anything but 'prepare-xwindow-id' element messages
   if(message->get_message_type() != Gst::MESSAGE_ELEMENT)
    return;

   if(!message->get_structure().has_name("prepare-xwindow-id"))
      return;

   Glib::RefPtr<Gst::Element> element =
       Glib::RefPtr<Gst::Element>::cast_dynamic(message->get_source());

   Glib::RefPtr< Gst::ElementInterfaced<Gst::XOverlay> > xoverlay =
       Gst::Interface::cast <Gst::XOverlay>(element);

   if(xoverlay)
   {
     const gulong xWindowId =
     GDK_WINDOW_XID(widget->get_window()->gobj());
     xoverlay->set_xwindow_id(xWindowId);
   }
 }
 ...
 int main (int argc, char *argv[])
 {
   ...
   // Get the bus from the pipeline:
   Glib::RefPtr<Gst::Bus> bus = pipeline->get_bus();
 
  // Enable synchronous message emission:
  bus->enable_sync_message_emission();

  // Connect to bus's synchronous message signal:
  bus->signal_sync_message().connect(
    sigc::mem_fun(*this, &PlayerWindow::on_bus_message_sync));
   ...
 }

Constructor & Destructor Documentation

virtual Gst::XOverlay::~XOverlay (  )  [virtual]


Member Function Documentation

static void Gst::XOverlay::add_interface ( GType  gtype_implementer  )  [static]

GstXOverlay* Gst::XOverlay::gobj (  )  [inline]

Provides access to the underlying C GObject.

Reimplemented in Gst::XImageSink, and Gst::XvImageSink.

const GstXOverlay* Gst::XOverlay::gobj (  )  const [inline]

Provides access to the underlying C GObject.

Reimplemented in Gst::XImageSink, and Gst::XvImageSink.

void Gst::XOverlay::set_xwindow_id ( gulong  xwindow_id  ) 

This will call the video overlay's set_xwindow_id method.

You should use this method to tell to a XOverlay to display video output to a specific XWindow. Passing 0 as the xwindow_id will tell the overlay to stop using that window and create an internal one.

Parameters:
xwindow_id A X::ID referencing the XWindow.

void Gst::XOverlay::got_xwindow_id ( gulong  xwindow_id  ) 

This will post a "have-xwindow-id" element message on the bus.

This function should only be used by video overlay plugin developers.

Parameters:
xwindow_id A X::ID referencing the XWindow.

void Gst::XOverlay::prepare_xwindow_id (  ) 

This will post a "prepare-xwindow-id" element message on the bus to give applications an opportunity to call gst_x_overlay_set_xwindow_id() before a plugin creates its own window.

This function should only be used by video overlay plugin developers.

void Gst::XOverlay::expose (  ) 

Tell an overlay that it has been exposed.

This will redraw the current frame in the drawable even if the pipeline is PAUSED.

void Gst::XOverlay::handle_events ( bool  handle_events  ) 

Tell an overlay that it should handle events from the window system.

These events are forwared upstream as navigation events. In some window system, events are not propagated in the window hierarchy if a client is listening for them. This method allows you to disable events handling completely from the XOverlay.

Parameters:
handle_events A bool indicating if events should be handled or not.

virtual void Gst::XOverlay::set_xwindow_id_vfunc ( gulong  xwindow_id  )  [virtual]

Virtual method to configure the XWindow id.

virtual void Gst::XOverlay::expose_vfunc (  )  [virtual]

Virtual method to handle expose events.

virtual void Gst::XOverlay::handle_events_vfunc ( bool  handle_events  )  [virtual]

Virtual method to handle events.


Friends And Related Function Documentation

Glib::RefPtr<Gst::XOverlay> wrap ( GstXOverlay *  object,
bool  take_copy = false 
) [related]

A Glib::wrap() method for this object.

Parameters:
object The C instance.
take_copy False if the result should take ownership of the C instance. True if it should take a new copy or ref.
Returns:
A C++ instance that wraps this C instance.


The documentation for this class was generated from the following file:

Generated on Wed May 20 14:43:52 2009 for gstreamermm by  doxygen 1.5.6