Re: [gtk-vnc-devel] [PATCH 5/7] Use X window backing store for the VNC window 2008-11-24 Federico Mena Quintero <federico novell com>

[Anthony Liguori <anthony codemonkey ws>]

Federico Mena Quintero wrote:
> 	* src/vncdisplay.c (add_backing_store): New function; adds a
> 	backing_store of Always to our window.
> 	(realize): Add backing store (on the X-server side) to our window,
> 	so that it sends us as few expose events as possible.  Trick
> 	stolen from TightVNC.
>   

Is this just double buffering in GTK parlance?  If you avoid disabling 
double buffering, does that help?

Again, this will break the Windows build.

Regards,

Anthony Liguori

> Signed-off-by: Federico Mena Quintero <federico novell com>
> ---
>  ChangeLog        |    8 ++++++++
>  src/vncdisplay.c |   26 ++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+), 0 deletions(-)
>
> diff --git a/ChangeLog b/ChangeLog
> index a8cf656..a3d056b 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,11 @@
> +2008-11-24  Federico Mena Quintero  <federico novell com>
> +
> +	* src/vncdisplay.c (add_backing_store): New function; adds a
> +	backing_store of Always to our window.
> +	(realize): Add backing store (on the X-server side) to our window,
> +	so that it sends us as few expose events as possible.  Trick
> +	stolen from TightVNC.
> +
>  2008-11-20  Federico Mena Quintero  <federico novell com>
>  
>  	Do compression of motion events, like TightVNC does, so that the
> diff --git a/src/vncdisplay.c b/src/vncdisplay.c
> index fdec881..e9ba14e 100644
> --- a/src/vncdisplay.c
> +++ b/src/vncdisplay.c
> @@ -298,6 +298,25 @@ eat_pending_motion_events_filter_func (GdkXEvent *xevent,
>  }
>  
>  static void
> +add_backing_store(VncDisplay *obj)
> +{
> +	GdkWindow *window;
> +	Display *xdisplay;
> +	Window xwindow;
> +	XSetWindowAttributes attr;
> +	gulong value_mask;
> +
> +	window = gtk_widget_get_window (GTK_WIDGET (obj));
> +	xdisplay = gdk_x11_drawable_get_xdisplay (window);
> +	xwindow = GDK_WINDOW_XWINDOW (window);
> +
> +	attr.backing_store = Always;
> +	value_mask = CWBackingStore;
> +
> +	XChangeWindowAttributes (xdisplay, xwindow, value_mask, &attr);
> +}
> +
> +static void
>  realize (GtkWidget *widget)
>  {
>  	VncDisplay *obj = VNC_DISPLAY(widget);
> @@ -311,6 +330,13 @@ realize (GtkWidget *widget)
>  	 * motion events.
>  	 */
>  	gdk_window_add_filter (widget->window, eat_pending_motion_events_filter_func, widget);
> +
> +	/* TightVNC requests an X window backing_store of "Always".  We'll do
> +	 * the same, as this lets VNC viewers displayed on a remote X server
> +	 * (a common scenario, it seems) to minimize the number of expose events that
> +	 * get received.
> +	 */
> +	add_backing_store (obj);
>  }
>  
>  static gboolean expose_event(GtkWidget *widget, GdkEventExpose *expose)
>