A bug was reported against xscreensaver in Debian (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=105372) which is really a deficiency in XFree. They asked me to forward my comments here...
Anyway, the original complaint is this: when xscreensaver is fading the whole screen to black, very bright colors don't fade (but less-than-fully-saturated colors do.) It looks pretty funny. This is because the new gamma interface in XFree 4 gives me insufficient control. There are three systems on which xscreensaver can fade the screen to black: - any X server running in PseudoColor mode (using colormap hackery) - the SGI server, in any depth (using gamma fade) - the XFree 4 server, in any depth (using gamma fade) It works great on the first two, and screws up on XFree 4. The reason gamma fade works fine on SGI is that their UI for setting the monitor's gamma lets me actually specify a *curve* for the gamma response of the monitor. So I do it by ramping all points on that curve down proportionally, until all colors/saturations are faded to black. The XFree interface only lets me specify a gamma value, not a curve. It generates a curve from that number in the traditional way, and the curve generated does not touch fully saturated colors. So only colors at low-to-medium saturation levels are faded properly. Furthermore, the XFree interface doesn't let me ramp all the way down to black: it signals an X error if you give it a gamma less than 0.1 (or something like that.) That means that it never fades all the way to black, and you see a slight jump at the very end. So, while it's nice that XFree finally gave us some control over gamma, they didn't give us enough control. Because of that, xscreensaver's fading looks kinda hokey on XFree (while it works great on SGIs, and in 8-bit mode.) So, please provide a gamma interface where I can specify the transfer map for each input value: something along the lines of, letting me give you an array of 255 values where I can map input intensity to output intensity. (The SGI interface uses three such maps, for R, G, and B.) -- Jamie Zawinski [EMAIL PROTECTED] http://www.jwz.org/ [EMAIL PROTECTED] http://www.dnalounge.com/ _______________________________________________ Xpert mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xpert
