void Draw::DrawArcOp(const Rect& rc, Point start, Point end, int width, Color color)
{
DrawLock __;
XGCValues gcv, gcv_old;
XGetGCValues(Xdisplay, GetGC(), GCForeground, &gcv_old);
Point offset = GetOffset();
gcv.foreground = GetXPixel(color);
XChangeGC(Xdisplay, GetGC(), GCForeground, &gcv);
Point centre = rc.CenterPoint();
int angle1 = fround(360 * 64 / (2 * M_PI) *
atan2(centre.y - start.y, start.x - centre.x));
int angle2 = fround(360 * 64 / (2 * M_PI) *
atan2(centre.y - end.y, end.x - centre.x));
if(angle2 <= angle1)
angle2 += 360 * 64;
angle2 -= angle1;
XDrawArc(Xdisplay, GetDrawable(), GetGC(), rc.left + offset.x, rc.top + offset.y,
rc.Width(), rc.Height(), angle1, angle2);
XChangeGC(Xdisplay, GetGC(), GCForeground, &gcv_old);
}