using System;

using System.Drawing;

using System.Drawing.Imaging;

using System.Collections.Generic;

namespace Assistance {

	public class Canvas {

		public static readonly int initialSize = 100;

		public static readonly double incrementScale = 1.2;

		private System.Drawing.Point offset = new System.Drawing.Point(-initialSize/2, -initialSize/2);

		private Bitmap bitmap = new Bitmap(initialSize, initialSize);

		public void draw(Graphics g) {

			g.DrawImageUnscaled(bitmap, offset);

		}

		public void expand(Rectangle rect) {

			System.Drawing.Point lt = offset;

			System.Drawing.Point rb = lt + bitmap.Size;

		    System.Drawing.Rectangle recti = rect.toInt();

		    int incX = (int)Math.Ceiling(bitmap.Width*incrementScale);

		    int incY = (int)Math.Ceiling(bitmap.Height*incrementScale);

		    if (recti.Left   < lt.X) lt.X = recti.Left   - incX;

		    if (recti.Top    < lt.Y) lt.Y = recti.Top    - incY;

		    if (recti.Right  > rb.X) rb.X = recti.Right  + incX;

		    if (recti.Bottom > rb.Y) rb.Y = recti.Bottom + incY;

		    Size size = new Size(rb.X - lt.X, rb.Y - lt.Y);

		    if (lt != offset || size != bitmap.Size) {

				Bitmap newBitmap = new Bitmap(size.Width, size.Height);

				Graphics g = Graphics.FromImage(newBitmap);

				g.DrawImageUnscaled(bitmap, new System.Drawing.Point(offset.X - lt.X, offset.Y - lt.Y));

				g.Flush();

				offset = lt;

				bitmap = newBitmap;

			}

		}

		private Graphics getGraphics() {

			Graphics g = Graphics.FromImage(bitmap);

			g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

			g.TranslateTransform(-offset.X, -offset.Y);

			return g;

		}

		public void paintTrack(Track track) {

			expand(track.getBounds());

			Graphics g = getGraphics();

			track.draw(g);

			g.Flush();

		}

	}

}