nanogui: Screen update methods
Subject:
Re: [nanogui] Re: Screen update methods
From:
"Greg Haerr" ####@####.####
Date:
28 May 2007 18:53:38 +0100
Message-Id: <044a01c7a151$0ba73980$2f01a8c0@HaydenLake>
> My question is if I'm drawing to the "mirror" frame buffer, should the
> server be writing to the actual framebuffer for any reason? I expect no
> activity to the actual framebuffer until I do a copy from the pixmap to
> that memory. If the latter is true, then drawing horiz lines on the pixmap
> shouldn't have any effect on the actural framebuffer unless they are one
> and the same. Not so?
You're using the terms mirror framebuffer and pixmap, which is
a bit confusing to me. Nano-X knows nothing about mirrors
and alternate framebuffers. It handles pixmaps and the framebuffer,
which in my earlier email showed are the same structure,
just a different memory address.
Nano-X draws under two circumstances: when it receives
an API call to draw (in your case only to a pixmap), and
when events occur (like mouse or window z-order change),
which cause an expose event requiring
a window to be redrawn. In this latter case, two things happen:
an expose event is packaged up for each application which
manages any window being exposed (for it to send re-draw
calls to), and the server may immediately clear the window
background, if the background clear bit is set for the
window being exposed. This background clear will use the
horz line draw to fill to the background color.
Regards,
Greg
