On Mon, 23 Sep 2002, Steve Kirkendall wrote: > but stopped when I came to a problem that can't easily be resolved in > the server or Xlib. > > The problem is that if the programmer assumed that displays would always > be 8-bit PseudoColor, then there's a pretty good chance that the program > does too -- that it simply uses the default Visual, and *assumes* it is > an 8-bit PseudoColor Visual. I know the old "quake" game did that. > But there's no good way for the server or Xlib to know that when some > applications ask for the default Visual, they really want a PseudoColor > Visual. > > I think the best way to handle this would be to put the PseudoColor > emulation code into something like Xnest -- a server which merely passes > the requests on to a real X server after translating the colors. The > legacy applications would run on the Xnest-like display, while modern > applications talk directly to the real X server.
You are right to think about this problem, we have already hit it with the 8+24 overlays, provided by the mga and a few other drivers, where we have both visuals in hardware. There we have solved it by making PseudoColor the default visual. This is a pain in many circumstances, so can be overridded with the "-cc n" command line option, or the "keyword "Visual" in the display subsections of the config file. (Although I'm having problems with the "Visual" keyword being ignored). xnest is probably a good enough solution when the visual is emulated. However I'm pleased to hear that Jim thinks we can go further, and emulate the visuals in the server, so that xnest only needs to change the default visual. ----- Keith is worried about the performance of a pseudocolor visual emulated on truecolour. Most legacy apps (other than games) aren't going to be changing the colour maps a lot, and if they do we probably have more cpu than they were expecting anyway, so I wouldn't be worried about. I don't appear to have a card which supports TrueColor but not DirectColor; are they common enough to worry about ? -- Dr. Andrew C. Aitchison Computer Officer, DPMMS, Cambridge [EMAIL PROTECTED] http://www.dpmms.cam.ac.uk/~werdna _______________________________________________ Xpert mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xpert
