Re: [Linux-fbdev-devel] video overlay in fbdev, take 3, plus fbcon question

[<dol...@cl...>]

> have we functionality to do rectangle lists, as X does ?

No, the only hardware accel in 2.2/2.4 is character drawing and
rectangle erase (in character unit).

> Could this be usefull ?

Not for fbcon, maybe for other app.

> You need something similar if you want to add clipping support to video
> overlay. Well at least for complexe clipping, i guess that for most fb
> apps, you would clipp out only a rectangular region, and nothing more
> complex.

Not if you rely on the app to properly fill the main screen with either
an alpha or a color key. it's done only once in a while, so doing it by
software shouldn't be too much of a problem.

The problem is when fbcon step on your toes by cleaning the alpha
channel...

> Clipping is currently done by writting a value to the alpha channel for
> each pixel that will show (or not show) the overlay. Then we can do alpha
> keyed overlay on them.

YOu can do the same in FB, only the app mustr handle it. It ain't
difficult : the app must mmap() the whole FB area anyway, and the
GET_VARINFO IOCTL give the size & offset of the alpha channel. You just
have to fill it by software. my pm3fb_setoverlay do that and it works
fine, even if the initial filling of the alpha channel is slow. But
after that, as long as noone touch your alpha channel, you only need to
fill the offscreen buffer.

-- 
DOLBEAU Romain               |
ENS Cachan / Ker Lann        | l'histoire est entierement vraie, puisque
Thesard IRISA / CAPS         |     je l'ai imaginee d'un bout a l'autre
dol...@cl...    |           -- Boris Vian