The following contains an example that will add a yellow arc 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.
Arc drawn by example code below
Arc::pointer example_arc(bool fill, bool outline) { // Create an arc with a radius of 50 that will start at 45' and stop at 315' Papyrus::Arc::pointer arc = Papyrus::Arc::create(50, M_PI_4, 3.0*M_PI_2+M_PI_4); // Set the fill color with an alpha value of 0.9 if (fill) arc->set_fill( Cairo::SolidPattern::create_rgba(1.0, 1.0, 0.0, 0.9) ); // And set the outline color if (outline) arc->set_outline( Cairo::SolidPattern::create_rgba(0.0, 0.0, 0.0, 0.9) ); return arc; }