Re: Mirrored Display?

[Antonino Daplas <adaplas@pol.net>]

On Mon, 2002-12-23 at 21:04, Michael Kaufmann wrote:
> Antonino has also answered to my question. And he said that there is nothing 
> i can do, because user apps will directly acces the framebuffer via read/write 
> or nmap. I can only patch the console and the show _logo to write the data 
> mirrored to the videobuffer (a lot of work).
> So my user apps (like nanoX or directfb/GTK+) must know about the mirrored 
> display and should write the picturedata mirrored in the framebuffer. 
> 
> I'm know a litte bit amazed about a rotation feature in next versions. Does 
> this mean, that the buffer where user apps (or also the console) are writing 
> there picture data is not directly the videobuffer anymore? Or how does this 
> rotation feature works?
I think the rotation hooks are console specific.  

> 
> I think it would be a good feature to have 'something' between the framebuffer 
> and the physical videobuffer to be able to manipulate the picture data (like 
That is the job of fb libraries.  You can use X (which already has
support for rotation, so mirroring should be easy to add), or modify
DirectFB.

> rotation, mirroring, etc.). But i don't know how this peace of software 
> should detect, changed data in the 'framebuffer' to e.g. mirror in the 
> videobuffer? Writing the whole buffers from time to time whould be a very
> bad solution (performance).
You can probably implement something similar to a shadow framebuffer. 
You expose this instead of the actual framebuffer (fix->smem_start, and
info->screen_base), then just refresh the contents of the actual
framebuffer, say during vsync.  You will have to set up a vsync
irq_handler or something similar.

Tony




-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf