nanogui: exposure event
Subject:
Re: [nanogui] exposure event
From:
"Greg Haerr" ####@####.####
Date:
13 Jul 2007 21:16:41 +0100
Message-Id: <1a2201c7c58a$bb3e00b0$0300a8c0@RDP>
: what is the difference between an exposure event and an update event. When
: is the exposure event generated???
An exposure event is sent when the server uncovers a portion
of a window that requires redrawing by the owner application,
so the screen contents are correct.
An update event is sent when window information, such as mapping,
position, etc are changed. This is used by the window manager
nanowm so it can reparent a top level window and draw
the title bar, for instance.
Both events are only sent if the application registers the events
using GrSelectEvent with the proper window id. An application
can register for events for any window, even those it hasn't created.
This is how the window manager receives update events, for instance.
The server will usually draw the window background color before
sending an expose event to the registered list of applications requesting
expose events. If no application has registered an expose event,
then the window contents won't be redrawn, except for the background
color.
Regards,
Greg
