inline void _dla_changebrightness(rgb_color_p from,
				  rgb_color_p to, float br)
{
  if ( br > 1.0 ) br = 1.0;
  /* linear... Maybe something more complex could give better look */
  to->red = br * (float)from->red;
  to->green = br * (float)from->green;
  to->blue = br * (float)from->blue;
}

#define plot_(X,Y,D) do{ rgb_color f_;				\
  f_.red = r; f_.green = g; f_.blue = b;			\
  _dla_plot(img, (X), (Y), &f_, (D)) ; }while(0)

inline void _dla_plot(image img, int x, int y, rgb_color_p col, float br)
{
  rgb_color oc;
  _dla_changebrightness(col, &oc, br);
  put_pixel_clip(img, x, y, oc.red, oc.green, oc.blue);
}

#define ipart_(X) ((int)(X))
#define round_(X) ((int)(((double)(X))+0.5))
#define fpart_(X) (((double)(X))-(double)ipart_(X))
#define rfpart_(X) (1.0-fpart_(X))

#define swap_(a, b) do{ __typeof__(a) tmp;  tmp = a; a = b; b = tmp; }while(0)
void draw_line_antialias(
  image img,
  unsigned int x1, unsigned int y1,
  unsigned int x2, unsigned int y2,
  color_component r,
  color_component g,
  color_component b )
{
  double dx = (double)x2 - (double)x1;
  double dy = (double)y2 - (double)y1;
  if ( fabs(dx) > fabs(dy) ) {
    if ( x2 < x1 ) {
      swap_(x1, x2);
      swap_(y1, y2);
    }
    double gradient = dy / dx;
    double xend = round_(x1);
    double yend = y1 + gradient*(xend - x1);
    double xgap = rfpart_(x1 + 0.5);
    int xpxl1 = xend;
    int ypxl1 = ipart_(yend);
    plot_(xpxl1, ypxl1, rfpart_(yend)*xgap);
    plot_(xpxl1, ypxl1+1, fpart_(yend)*xgap);
    double intery = yend + gradient;

    xend = round_(x2);
    yend = y2 + gradient*(xend - x2);
    xgap = fpart_(x2+0.5);
    int xpxl2 = xend;
    int ypxl2 = ipart_(yend);
    plot_(xpxl2, ypxl2, rfpart_(yend) * xgap);
    plot_(xpxl2, ypxl2 + 1, fpart_(yend) * xgap);

    int x;
    for(x=xpxl1+1; x < xpxl2; x++) {
      plot_(x, ipart_(intery), rfpart_(intery));
      plot_(x, ipart_(intery) + 1, fpart_(intery));
      intery += gradient;
    }
  } else {
    if ( y2 < y1 ) {
      swap_(x1, x2);
      swap_(y1, y2);
    }
    double gradient = dx / dy;
    double yend = round_(y1);
    double xend = x1 + gradient*(yend - y1);
    double ygap = rfpart_(y1 + 0.5);
    int ypxl1 = yend;
    int xpxl1 = ipart_(xend);
    plot_(xpxl1, ypxl1, rfpart_(xend)*ygap);
    plot_(xpxl1 + 1, ypxl1, fpart_(xend)*ygap);
    double interx = xend + gradient;

    yend = round_(y2);
    xend = x2 + gradient*(yend - y2);
    ygap = fpart_(y2+0.5);
    int ypxl2 = yend;
    int xpxl2 = ipart_(xend);
    plot_(xpxl2, ypxl2, rfpart_(xend) * ygap);
    plot_(xpxl2 + 1, ypxl2, fpart_(xend) * ygap);

    int y;
    for(y=ypxl1+1; y < ypxl2; y++) {
      plot_(ipart_(interx), y, rfpart_(interx));
      plot_(ipart_(interx) + 1, y, fpart_(interx));
      interx += gradient;
    }
  }
}
#undef swap_
#undef plot_
#undef ipart_
#undef fpart_
#undef round_
#undef rfpart_