Graph::SetStroke PHP Method

    protected function SetStroke(&$attr, $line_join = null)
    {
        if ($this->stroke_width > 0) {
            $attr['stroke'] = $this->stroke_colour;
            $attr['stroke-width'] = $this->stroke_width;
            if (!is_null($line_join)) {
                $attr['stroke-linejoin'] = $line_join;
            }
        }
    }