The following contains an example that will add a green circle with a black border to a canvas. The blue lines represent the x and y axes, and show through since an alpha value of 0.9 is used.
Circle drawn by example code below
Circle::pointer example_circle(bool fill, bool outline) { // Create a circle with a radius of 50 Papyrus::Circle::pointer circle = Papyrus::Circle::create( 50 ); // Set the fill color to green, with an alpha value of 0.9 if (fill) circle->set_fill( Cairo::SolidPattern::create_rgba(0.0, 1.0, 0.0, 0.9) ); // And the outline color to black if (outline) circle->set_outline( Cairo::SolidPattern::create_rgba(0.0, 0.0, 0.0, 0.9) ); return circle; }