Re: [AL] Color problems with X11

[De M. <bjo...@pa...>]

> Date: Sat, 26 Oct 2002 13:00:30 +0200 (MEST)
> From: Henrik Schmidt <hb...@ks...>
> Subject: Re: [AL] Color problems with X11
> Reply-To: al...@ca...
> On Sat, 26 Oct 2002, Eric Botcazou wrote:
> 
> The code does work perfectly on windows. I'm pretty sure it would
> even work on linux. My guess is thats the big endianess of the
> sparc processor which makes RGB working like BGR in some circumstances.
> 
> The code is pretty straightforward.
> 
> set depth
> set gfx mode
> make text colors
> load images
> 
> I'm working with a 24bit X11 server.
> 

X11R6 has a known issue with endianess for 24 bits colour 
depths. I don't know the details of it, but IIRC 24 bits
coulour is a nonstandard extension to X. AFAIK, the X 
standard colour sepths are 1, 8, 16 and 32 bits, and all 
the rest are vendor-specific extensions. Someone please 
correct me if I am mistaken here.

I think you'll find more about it on the pages of xfree.org
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From: Eric Botcazou <ebo...@li...>
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> Now its even worse. At 16 bit its the same (ok images, wrong text
> color) but at the image colors are still broken but now the text is als=
o
> wrong. Lots of red and black instead of yellow and green.
>
> Note that the wrong image colors do appear in either pcx or bmp images.
> Its not only bmp releated.

The patch is not meant to fix the 16-bit problem, only the 24-bit one. Wh=
at =20
happens now in 24-bit mode ? Same thing with PCX images ?

--=20
Eric Botcazou
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From: Grzegorz Adam Hankiewicz <gr...@te...>
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On Mon, Oct 28, 2002 at 09:40:43AM +0100, Eric Botcazou wrote:
> The problem is the 3rd item, all color formats reset to the default
> order (RGB), which makes Allegro "forget" the order for 24-bit. The
> short-term fix is to disable the code: comment out lines 660-670
> in src/graphics.c (below the /* restore default truecolor pixel
> format */ comment).

Hmmm... couldn't Allegro use internally one of those whatever_virgin
variables to hold the byte order? Say, once a graphic mode is set,
it's unlikely that this ordering will change for that color depth,
so Allegro could 'remember' it instead of resetting it.
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Date: Tue, 29 Oct 2002 04:12:51 +0800
To: al...@ca...
From: Scott DC <be...@ii...>
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Subject: [AL] Using a graphics tablet
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Has anyone tried using a graphics tablet with Allegro?

I'll be acquiring one soon and was wondering if it is possible for allegro 
or other library to drive the tablet.

Thanks
Scott DC

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