PseudoColor and DirectColor visuals (was Re: Documentation?)

Glynn Clements glynn at
Thu Apr 9 12:33:53 PDT 2009

Patrick O'Donnell wrote:

> >So much stuff breaks with a DirectColor visual that no-one ever uses
> >one.
> By this, I presume you mean that many clients fail to support
> DirectColor correctly, (or fail to match visuals correctly) so they
> break?  Or are you referring to server support for DirectColor failing
> often?

Clients. Either they print a "not supported" error message, or just
assume that the default colourmap has full-scale monotonic ramps and
treat it as TrueColor. If you're really lucky, they'll allocate a
private colourmap, set linear ramps, then treat it as TrueColor.

The number of programs which break with a DirectColor visual suggests
that they're essentially a theoretical concept which doesn't occur in

Glynn Clements <glynn at>

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