if ($xr - $xl > $yb - $yt) {
                    // width is greater than height -> use x-dimension for steps
                    $steps = $xr - $xl;
                    $delta = $xr >= $xl ? 1 : -1;
                    $this->GetColArray($from_color, $to_color, $steps * 2, $colors, $this->numcolors);