nanogui: nano-X and alha blending
Subject:
Re: nano-X and alha blending
From:
"Jordan Crouse" ####@####.####
Date:
30 Sep 2005 20:44:08 +0100
Message-Id: <20050930195911.GA30533@cosmic.amd.com>
On 30/09/05 09:05 -0600, Greg Haerr wrote:
> Yes, its possible, but getting the window drawing to alpha
> blend is going to be alot of work, since the only alpha blending
> is image support, and none of the window drawing uses that.
> All driver entry points would have to have to be modified to
> use the alpha channel in the color passed to alpha blend,
> which would be very slow without hardware support, or
> the whole window drawn offscreen first and then blitted.
> Both options currently would require big changes internally.
Yeah, you are right out of luck if you want the window decorations, even the
shaped windows. The best shot you have is hacking on the pixil window
manager, which uses images for the window decorations. If you hacked the
window manager info function (can't remember what its called right off the
bat) to include a alpha blend value, then you might be able to convince the
window manager to alpha blend the images.
But if you're not interested in the window decorations, then it might not be
too bad - you can keep your window in an offscreen, and then blit it on to
the screen with an BLENDCONSTANT rop. Then, to change the blending, blit in
the damaged parts of the background, and repeat.
Or better yet, do everything offscreen, and then blit in the whole screen.
You'll have to use more storage then you would if the window understood
blending directly, but its better then a poke in the eye with a sharp stick.
Jordan
--
Jordan Crouse
Senior Linux Engineer
AMD - Personal Connectivity Solutions Group
<www.amd.com/embeddedprocessors>
