Re: Transparency Support and/or Big-endian Framebuffer

[email protected] Fri, 24 Feb 2006 17:42:55 +0000
Newsgroups gmane.linux.fbdev.user
Message-ID <022420061742.1446.43FF459F0005F4CD000005A62200748184079A0D00@comcast.net>
Just a quick note, the latest FBUI deals with transparency
to an extent. Although not yet implemented, the goal is to 
eventually use overlays to have semi-transparent windows. 
Right now transparency is handled in drawing.
See here: http://fbui.org

Zack Smith

-------------- Original message -------------- 
From: "Mike Bourgeous" <[email protected]> 

> I'm working on a framebuffer driver for a high-definition tuner 
> card's OSD, and I have two equally bad options for pixel format. 
> I can choose 24-bit pixels, with every FOUR bytes in reverse 
> order (even though pixels are three bytes long - that makes for 
> some interesting pictures when it's not set up right), or 32-bit 
> pixels, with mandatory transparency. 
> 
> When I try the 24-bit route, I get video, but it looks kind of like 
> someone took the color columns of an LCD screen and mixed 
> them up, so the red of one pixel will be before the green of the 
> pixel to its left or something. 
> 
> When I do 32-bit, it seems that no programs pay attention to 
> the transparency field of fb_var_screeninfo. fbi, for example, 
> clears the screen to 0x00000000 before drawing its image 
> data, leaving the screen black. If I manually set all of the 
> alpha bytes to 0x7f (full opacity), the fbi image is displayed, 
> but as soon as fbi updates the display everything's black 
> again. 
> 
> Is it possible, without modifying userland software, to either 
> 1. byte-swap every four bytes with three-byte wide pixels 
> or 
> 2. force the transparency byte of all 32-bit pixels to 0x7f 
> ?? 
> 
> I have a modified version of libfbx (u4x.sf.net/projects/libfbx) 
> that sets the transparency value correctly, which I used to 
> test the framebuffer driver, but I'd really prefer to have this 
> work without too much work in userspace. My main goal is 
> to get X to display on the framebuffer. 
> 
> Any help or suggestions would be greatly appreciated. 
> 
> My framebuffer driver uses the following driver as a backend: 
> 
> http://myhd.sf.net/ 
> 
> Mike Bourgeous 
> 
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