KochView

KochView.cs

using System;

using Android.Content;
using Android.Graphics;
using Android.Views;

using TurtleGraphics.Library;

namespace TurtleGraphics
{
    public class KochView : View
    {
        private int nth;
        private const int MaxNth = 5;

        public KochView(Context context) : base (context)
        {
            Initialize();
        }

        private void Initialize()
        {
            this.nth = 1;
        }

        public override bool OnTouchEvent(MotionEvent e)
        {
            base.OnTouchEvent(e);

            if (e.Action == MotionEventActions.Down)
            {
                this.nth++;

                if (this.nth > MaxNth)
                {
                    this.nth = 1;
                }

                base.Invalidate();
            }

            return true;
        }

        protected override void OnDraw(Canvas canvas)
        {
            base.OnDraw(canvas);

            this.DrawBackground(canvas);
            this.DrawNumber(canvas);
            this.DrawKochCurve(canvas);
        }

        private void DrawBackground(Canvas canvas)
        {
            canvas.DrawColor(Color.White);
        }

        private void DrawNumber(Canvas canvas)
        {
            canvas.DrawText(nth.ToString(), 15, 15, new Paint { Color = Color.Black });
        }

        private void DrawKochCurve(Canvas canvas)
        {
            var startX = 0;
            var startY = this.Height / 2;
            var maxWidth = this.Width;
            var action = new Action<int, int, int, int>(
                  (x1, y1, x2, y2) => canvas.DrawLine(x1, y1, x2, y2, new Paint { Color = Color.CornflowerBlue }));

            KochCurve.Navigate(this.nth, startX, startY, maxWidth, action);
        }
    }
}