using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public struct triple
        {
            public int r;
            public int g;
            public int b;
        };
        public int distance(triple a, triple b)
        {
            return (a.r - b.r) * (a.r - b.r) + (a.g - b.g) * (a.g - b.g) + (a.b - b.b) * (a.b - b.b);
        }
        public Form1()
        {
            InitializeComponent();
        }
        Bitmap pic1;
        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog open_dialog = new OpenFileDialog();
            open_dialog.Title = "Open Picture";
            open_dialog.Filter = "Bitmap Files (*.bmp)|*.bmp";
            if (open_dialog.ShowDialog() == DialogResult.OK)
            {
                pic1 = new Bitmap(open_dialog.FileName);
                pictureBox1.Image = pic1;
            }
            open_dialog.Dispose();
        }
        private void button2_Click(object sender, EventArgs e)
        {
            this.Cursor = Cursors.WaitCursor;
            //int[,] par = new int[pic1.Width, pic1.Height];
            int num_colors = Convert.ToInt32(textBox1.Text);
            List<triple> colors = new List<triple>();
            Bitmap pic2 = new Bitmap(pic1);
            for (int i = 0; i < pic1.Width; i++)
                for (int j = 0; j < pic1.Height; j++)
                {
                    Color color1 = pic1.GetPixel(i, j);
                    triple cur;
                    cur.r = color1.R;
                    cur.g = color1.G;
                    cur.b = color1.B;
                    colors.Add(cur);
                }
            colors = colors.Distinct().ToList();
			if( colors.Count() <= num_colors )
			{
				pictureBox2.Image = pic2;
				this.Cursor = Cursors.Default;
				return;
			}
			triple[] means = new triple[num_colors];
            bool[] used = new bool[colors.Count()];
			Random r = new Random();
            for (int i = 0; i < num_colors; i++)
            {
				int random_index;
				while( true )
				{
					random_index = r.Next(0,colors.Count());
					if( used[random_index] == true )
						continue;
					break;
				}
                means[i] = colors[random_index];
            }
            int[] par = new int[colors.Count()];
            for (int i = 0; i < colors.Count(); i++)
            {
                int cur_dis = distance(colors[i], means[0]);
                par[i] = 0;
                for (int k = 1; k < num_colors; k++)
                {
                    int temp = distance(colors[i], means[k]);
                    if (temp < cur_dis)
                    {
                        cur_dis = temp;
                        par[i] = k;
                    }
                }
            }
            bool change = true;
            int sepid = 10;
            triple[] sum = new triple[num_colors];
            int[] cnt = new int[num_colors];
            while( change && (--sepid != 0) )
            {
                change = false;
                //creating new means
                for( int i = 0; i < num_colors; i++ )
                    sum[i].r = sum[i].g = sum[i].b = cnt[i] = 0;
                for (int i = 0; i < colors.Count(); i++)
                {
                    sum[par[i]].r += colors[i].r;
                    sum[par[i]].g += colors[i].g;
                    sum[par[i]].b += colors[i].b;
                    cnt[par[i]]++;
                }
                for (int i = 0; i < num_colors; i++)
                {
                    if (cnt[i] == 0)
                    {
                        int someoneelse = r.Next(0, colors.Count());
                        means[i].r = colors[someoneelse].r;
                        means[i].g = colors[someoneelse].g;
                        means[i].b = colors[someoneelse].b;
                        continue;
                    }
                    means[i].r = sum[i].r / cnt[i];
                    means[i].g = sum[i].g / cnt[i];
                    means[i].b = sum[i].b / cnt[i];
                }
                //recalculating the clusters
                for (int i = 0; i < colors.Count(); i++)
                {
                    int cur_dis = distance(colors[i], means[0]);
                    for (int k = 1; k < num_colors; k++)
                    {
                        int temp = distance(colors[i], means[k]);
                        if (temp < cur_dis)
                        {
                            cur_dis = temp;
                            if (par[i] != k)
                            {
                                par[i] = k;
                                change = true;
                            }
                        }
                    }
                }
            }
            Dictionary <triple, triple> convert = new Dictionary<triple,triple>();
            for (int i = 0; i < colors.Count(); i++)
            {
                try
                {
                    convert.Add(colors[i], means[par[i]]);
                }
                catch { };
            }
            for( int i = 0; i < pic2.Width; i++ )
                for (int j = 0; j < pic2.Height; j++)
                {
                    Color color1 = pic1.GetPixel(i, j);
                    triple cur;
                    cur.r = color1.R;
                    cur.g = color1.G;
                    cur.b = color1.B;
                    cur = convert[cur];
                    color1 = Color.FromArgb(cur.r, cur.g, cur.b);
                    pic2.SetPixel(i, j, color1);
                }
            pictureBox2.Image = pic2;
            this.Cursor = Cursors.Default;
        }
    }
}