On Sun, Feb 05, 2017 at 08:18:41PM -0500, Alan Corey wrote: > This probably isn't exactly the right list for this, but maybe > somebody lingering can answer. I'm trying to use xor to put a line on > the screen then erase it again when I want. With the XSetFunction() > to xor uncommented I get no line. If I comment it out I get a line, > but no erase. If I move it between the draws I get no erase. > > xor (exclusive or) should set every bit where there's one and only one > of the inputs true. If you xor something to the screen twice the 2nd > time erases what you wrote the first time. Except I'm doing something > wrong or there's something I didn't consider.
To get the "blackcolor" over "whitecolor" with GXxor, you should draw with "blackcolor^whitecolor". (because the result would be "whitecolor^(blackcolor^whitecolor)". In fact, on most displays blackcolor is an integer with the val- ue 0, therefore xor with just blackcolor does nothing. _______________________________________________ xorg@lists.x.org: X.Org support Archives: http://lists.freedesktop.org/archives/xorg Info: https://lists.x.org/mailman/listinfo/xorg Your subscription address: %(user_address)s
