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

[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.

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)
-- 
1.5.6