Subject: Re: determining greyscale vs. color with wsdisplay framework
To: David P. Reese Jr. <>
From: Bill Studenmund <>
List: current-users
Date: 01/06/2004 16:46:17
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On Mon, Jan 05, 2004 at 11:37:08AM -0800, David P. Reese Jr. wrote:
> I'm curious if you can determine if a frame buffer is running in greyscale
> versus color by giving an ioctl on /dev/ttyE0.  My scenario involves a
> mac68k with internal video.  Using the WSDISPLAYIO_GINFO ioctl I can
> determine the bit depth of the frame buffer, but I don't know if it's
> running in greyscale.
> Should this be determined using the WSDISPLAYIO_GTYPE ioctl and having it
> return a different display type for greyscale versus color?

I don't think so. While the difference is quite clear to end users, from=20
the point of view of the graphics system, they are the same. The only=20
difference is that the color pallete is rather restricted. So for indirect=
color setups (256 and fewer colors) it makes sense to use a pallete that=20
has shades of grey, not different colors.

It strikes me that greyscale is more of a behavior. You definitely want it
if the monitor is greyscale, but you can use it even if you have a "color"=
monitor. So I'd think it's more an attribute of the monitor, not a=20
different type.

Take care,


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