piepiecs.cs

private void DrawGeometry(StreamGeometryContext context)
        {
            Point startPoint = new Point(CenterX, CenterY);

            Point innerArcStartPoint =
                Utils.CartesianCoordinate(RotationAngle, InnerRadius);
            innerArcStartPoint.Offset(CenterX, CenterY);

            Point innerArcEndPoint =
                Utils.CartesianCoordinate(RotationAngle + WedgeAngle, InnerRadius);
            innerArcEndPoint.Offset(CenterX, CenterY);

            Point outerArcStartPoint =
                Utils.CartesianCoordinate(RotationAngle, Radius);
            outerArcStartPoint.Offset(CenterX, CenterY);

            Point outerArcEndPoint =
                Utils.CartesianCoordinate(RotationAngle + WedgeAngle, Radius);
            outerArcEndPoint.Offset(CenterX, CenterY);

            bool largeArc = WedgeAngle > 180.0;

            Size outerArcSize = new Size(Radius, Radius);
            Size innerArcSize = new Size(InnerRadius, InnerRadius);

            context.BeginFigure(outerArcStartPoint, true, true);
            context.ArcTo(outerArcEndPoint, outerArcSize, 0, largeArc, SweepDirection.Clockwise, true, true);
            context.LineTo(innerArcEndPoint, true, true);
            context.ArcTo(innerArcStartPoint, innerArcSize, 0, largeArc, SweepDirection.Counterclockwise, true, true);

            context.Close();
        }
        
        public static Point CartesianCoordinate(double angle, double radius)
        {
            double angleRad = ToRadians(angle);
            double x = radius * Math.Cos(angle);
            double y = radius * Math.Sin(angle);
            return new Point(x,y);
        }

        private static double ToRadians(double rotationAngleDegrees)
        {
            return rotationAngleDegrees * Math.PI / 180;
        }