fb_cmap and transparency

fb_cmap and transparency

[Geert Uytterhoeven]

If a colormap contains no transparency information, fb_set_cmap() calls
fb_setcolreg() with trans = 0. This causes all CLUT entries to be fully
transparent on hardware that does have transparency information in the CLUT
registers.

The following patch solves this problem by changing the default transparency
from 0 (full transparent) to 0xffff (full opaque).

The patch applies to both 2.4.20 and 2.5.65.

--- linux/drivers/video/fbcmap.c.orig	Mon Mar  5 09:29:30 2001
+++ linux/drivers/video/fbcmap.c	Mon Mar 17 17:39:59 2003
@@ -271,7 +271,7 @@
 	    hred = *red;
 	    hgreen = *green;
 	    hblue = *blue;
-	    htransp = transp ? *transp : 0;
+	    htransp = transp ? *transp : 0xffff;
 	} else {
 	    get_user(hred, red);
 	    get_user(hgreen, green);
@@ -279,7 +279,7 @@
 	    if (transp)
 		get_user(htransp, transp);
 	    else
-		htransp = 0;
+		htransp = 0xffff;
 	}
 	red++;
 	green++;

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds



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Re: fb_cmap and transparency

[James Simmons]

Applied.


On Tue, 18 Mar 2003, Geert Uytterhoeven wrote:

> 
> If a colormap contains no transparency information, fb_set_cmap() calls
> fb_setcolreg() with trans = 0. This causes all CLUT entries to be fully
> transparent on hardware that does have transparency information in the CLUT
> registers.
> 
> The following patch solves this problem by changing the default transparency
> from 0 (full transparent) to 0xffff (full opaque).
> 
> The patch applies to both 2.4.20 and 2.5.65.
> 
> --- linux/drivers/video/fbcmap.c.orig	Mon Mar  5 09:29:30 2001
> +++ linux/drivers/video/fbcmap.c	Mon Mar 17 17:39:59 2003
> @@ -271,7 +271,7 @@
>  	    hred = *red;
>  	    hgreen = *green;
>  	    hblue = *blue;
> -	    htransp = transp ? *transp : 0;
> +	    htransp = transp ? *transp : 0xffff;
>  	} else {
>  	    get_user(hred, red);
>  	    get_user(hgreen, green);
> @@ -279,7 +279,7 @@
>  	    if (transp)
>  		get_user(htransp, transp);
>  	    else
> -		htransp = 0;
> +		htransp = 0xffff;
>  	}
>  	red++;
>  	green++;
> 
> Gr{oetje,eeting}s,
> 
> 						Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> 							    -- Linus Torvalds
> 
> 



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Programmers documetnation on framebuffer console?

[Kendall Bennett]

Hi Guys,

Can someone point me at programmer's documentation on how to use the 
framebuffer console subsystem on Linux? I have been to linux-fbdev.org 
and a few other places, but all of the linux to what would appear to be 
useful documentation or libraries are all dead. I need something that 
talks about the ioctl()'s that an application uses to get mode 
information, set modes and use the acceleration functions from the 
framebuffer console driver.

Thanks!

---
Kendall Bennett
Chief Executive Officer
SciTech Software, Inc.
Phone: (530) 894 8400
http://www.scitechsoft.com

~ SciTech SNAP - The future of device driver technology! ~



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Re: Programmers documetnation on framebuffer console?

[Richard Drummond]

Hi Kendal

Since nobody else has replied to you yet, I'll stop lurking and attempt a 
reply. ;-b)

On Tuesday 18 March 2003 16:58, Kendall Bennett wrote:
> Can someone point me at programmer's documentation on how to use the
> framebuffer console subsystem on Linux? I have been to linux-fbdev.org
> and a few other places, but all of the linux to what would appear to be
> useful documentation or libraries are all dead.

There seems to be precious little documentation around on actually how to use 
the fbdev API. Alas, the only real sources of information seem to be the code 
of the projects that actually use fbdev - for example, LibSDL, DirectFB (see 
http://www.directfb.org), and tools such as fbset, fbi, etc. Luckily, the API 
is very simple.

> I need something that
> talks about the ioctl()'s that an application uses to get mode
> information, set modes and use the acceleration functions from the
> framebuffer console driver.

The kernel source code is of course the definitive source of info here. Look 
in drivers/video/fbmem.c to see the ioctl()s that fbdev supports. As far as 
acceleration goes, this is useable only from the kernel space and is designed 
for accelerating text consoles (the accelerated functions are called by 
various functions in drivers/video/fbcon.c).

Cheers,
Rich




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