[Helper] Changes to shiftLine

[discoleo]

Helper: Changes to shiftLine

• behaves now consistently: d = positive always shifts to the left or above the line;

### Shift Line
# d = distance to shift (translate);
#' @export
shiftLine = function(x, y, d=1, slope=NULL, scale=1) {
  if(is.null(slope)) {
    if(length(x) < 2 || length(y) < 2)
      stop("The base-line requires 2 points!");
    # TODO: handle if more than 2 points!
    slope = compute_slope(x,y);
  } else {
    if(missing(y)) {
      # both coordinates encoded using parameter x;
      y = x[2]; x = x[1];
    }
  }
  ### Vertical Line
  if(abs(slope) == Inf) {
    if(length(d) == 1) {
      r = data.frame(x = x - d, y = y);
    } else {
      r = lapply(seq(along=d), function(id) {
        data.frame(x = x - d[id], y = y, id=id);
      })
      r = do.call(rbind, r);
    }
    return(r)
  }
  ### Horizontal Line
  if(slope == 0) {
    d = d * scale;
    if(length(d) == 1) {
      r = data.frame(x = x, y = y + d);
    } else {
      r = lapply(seq(along=d), function(id) {
        data.frame(x = x, y = y + d[id], id=id);
      })
      r = do.call(rbind, r);
    }
    return(r)
  }
  ### Oblique Line
  sl.orto = - 1 / slope;
  sl2 = sqrt(sl.orto^2 + 1/scale^2);
  sl.orto = sl.orto * scale;
  # shift Start- & End-points:
  shift.f = function(x, y, id) {
    delta = d[id] / sl2;
    x.sh  = x - delta / scale;
    y.sh  = y - delta*sl.orto;
    data.frame(x=x.sh, y=y.sh, id=id);
  }
  rez = lapply(seq(length(d)), function(id) shift.f(x, y, id))
  rez = data.frame(do.call(rbind, rez));
  return(rez);
}

[DarianFlorianVoda]

Added