Cairo.Context.ArcNegative C# (CSharp) Метод

        public void ArcNegative(double xc, double yc, double radius, double angle1, double angle2)
        {
            CheckDisposed ();
            NativeMethods.cairo_arc_negative (handle, xc, yc, radius, angle1, angle2);
        }

    static void draw(Cairo.Context gr, int width, int height)
    {
        double xc     = 0.5;
        double yc     = 0.5;
        double radius = 0.4;
        double angle1 = 45.0 * (M_PI / 180.0);         /* angles are specified */
        double angle2 = 180.0 * (M_PI / 180.0);        /* in radians           */

        gr.Scale(width, height);
        gr.LineWidth = 0.04;

        gr.ArcNegative(xc, yc, radius, angle1, angle2);
        gr.Stroke();

        /* draw helping lines */
        gr.Color = new Color(1, 0.2, 0.2, 0.6);
        gr.Arc(xc, yc, 0.05, 0, 2 * M_PI);
        gr.Fill();
        gr.LineWidth = 0.03;
        gr.Arc(xc, yc, radius, angle1, angle1);
        gr.LineTo(new PointD(xc, yc));
        gr.Arc(xc, yc, radius, angle2, angle2);
        gr.LineTo(new PointD(xc, yc));
        gr.Stroke();
    }