rbd@lamont.ldgo.columbia.edu (roger davis) (01/13/90)
VERSION:
R4
CLIENT MACHINE and OPERATING SYSTEM:
Various Sun workstations running both 3.4 and 4.0.3
DISPLAY TYPE:
bwtwo0, cgtwo0, cgfour0
WINDOW MANAGER:
twm
AREA:
Xlib
SYNOPSIS:
XDrawLine
DESCRIPTION:
Drawing a horizontal line from right to left causes the drawn line
to be shifted one pixel too far to the right, i.e.,
XDrawLine(dpy, win, gc, x0, y, x1, y) and
XDrawLine(dpy, win, gc, x1, y, x0, y) do not draw the same line.
Drawing a vertical line from bottom to top causes the drawn line
to be shifted one pixel too far to the bottom.
Haven't had time to test lines which are both non-horizontal and
non-vertical, but someone probably should.
REPEAT BY:
black= BlackPixel(dpy, DefaultScreen(dpy));
white= WhitePixel(dpy, DefaultScreen(dpy));
gcv.function= GXcopy;
gcv.foreground= black;
gcv.background= white;
gc= XCreateGC(dpy, win, (GCFunction | GCForeground | GCBackground), &gcv);
x= y= 10;
XDrawLine(dpy, win, gc, x, y, x+10, y);
XDrawLine(dpy, win, gc, x+10, y+1, x, y+1);
This should draw two adjacent parallel horizontal lines which look like
XXXXXXXXXXX
XXXXXXXXXXX
but which turn out to be
XXXXXXXXXXX
XXXXXXXXXXX
--
Roger Davis
Lamont-Doherty Geological Observatory
rbd@lamont.ldgo.columbia.edu