re drawing lines inverse xor in article apr alf uib no singg alf uib no kurt george gjerde writes in article apr news media mit edu dyoung media mit edu david young writes xsetfunction mydisplay gc gxxor xsetforeground mydisplay gc drawindex then to draw i do xdrawline mydisplay xtwindow drawingarea gc x y x y xflush mydisplay and when i m all done to return things to normal i do xsetfunction mydisplay gc gxcopy what i d like to happen is for the lines i draw to be the inverse of whatever i m drawing over instead what happens is i get white lines if the lines are over a white background nothing shows up if the lines are over a black area nothing shows up it s very strange but the gxxor function seems right since if i do a rubber banding box it erases and redraws itself correctly ie not disturbing the underlying image any suggestions what i m doing wrong david try change the gxxor to gxequiv i have to do this for programs that are to run on ncd terminals on sun terminals i have to change it back to gxxor there is a small section in the o reilly xlib books that describes the right thing to do the key is to set the plane mask in the gc to the or of the foreground and background pixel values douglas s rand drand osf org osf motif dev snail cambridge center cambridge ma disclaimer i don t know if osf agrees with me let s vote on it amateur radio kc kj
