Method d2

renderers/agg/include/agg_span_gradient.h:76–76

        const ColorF& color_function() const { return *m_color_function; }
        double d1() const { return double(m_d1) / gradient_subpixel_scale; }
        double d2() const { return double(m_d2) / gradient_subpixel_scale; }

        //--------------------------------------------------------------------
        void interpolator(interpolator_type& i) { m_interpolator = &i; }