the_application(agg::pix_format_e format, bool flip_y) :
     agg::platform_support(format, flip_y),
     m_alpha(2,  2,  200, 30,  6, !flip_y)
 {
     m_alpha.value(0, 1.0);
     m_alpha.value(1, 1.0);
     m_alpha.value(2, 1.0);
     m_alpha.value(3, 0.5);
     m_alpha.value(4, 0.5);
     m_alpha.value(5, 1.0);
     m_alpha.update_spline();
     add_ctrl(m_alpha);
 }
    the_application(agg::pix_format_e format, bool flip_y) :
        agg::platform_support(format, flip_y),
        m_idx(-1),
        m_alpha(2,  2,  200, 30,  6, !flip_y)
    {
        m_x[0] = 257;    m_y[0] = 60;
        m_x[1] = 369;   m_y[1] = 170;
        m_x[2] = 143;   m_y[2] = 310;

        m_alpha.point(0, 0.0,     0.0);
        m_alpha.point(1, 1.0/5.0, 1.0 - 4.0/5.0);
        m_alpha.point(2, 2.0/5.0, 1.0 - 3.0/5.0);
        m_alpha.point(3, 3.0/5.0, 1.0 - 2.0/5.0);
        m_alpha.point(4, 4.0/5.0, 1.0 - 1.0/5.0);
        m_alpha.point(5, 1.0,     1.0);
        m_alpha.update_spline();
        add_ctrl(m_alpha);
    }