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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            int[] palette = new int[]{Color.Black.ToArgb(), Color.Red.ToArgb(), Color.Blue.ToArgb(), Color.Yellow.ToArgb()};
            int[] pixels = new int[128 * 128];
            var chrData = File.ReadAllBytes(@"C:\gangstreet\ascii.chr");


            var nesTileDrawing = new NesTileDrawing(chrData, palette, pixels, 128);

            for (int y = 0; y < 16; y++)
            {
                for (int x = 0; x < 16; x++)
                {
                    nesTileDrawing.DrawTile(x * 8, y * 8, x + y * 16);
                }
            }
            Bitmap bmp = new Bitmap(128,128,  System.Drawing.Imaging.PixelFormat.Format32bppRgb);
            var bits = bmp.LockBits(new Rectangle(0, 0, 128, 128), System.Drawing.Imaging.ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
            Marshal.Copy(pixels, 0, bits.Scan0, pixels.Length);
            bmp.UnlockBits(bits);
            this.BackgroundImage = bmp;
            this.BackgroundImageLayout = ImageLayout.None;
        }

        class NesTileDrawing
        {
            byte[] chrData;
            int[] palette;
            int[] pixels;
            int imageWidth;

            public NesTileDrawing(byte[] chrData, int[] palette, int[] pixels, int imageWidth)
            {
                this.chrData = chrData;
                this.palette = palette;
                this.pixels = pixels;
                this.imageWidth = imageWidth;
            }

            public void DrawTile(int x0, int y0, int tileNumber)
            {
                for (int y = 0; y < 8; y++)
                {
                    int imageY = y0 + y;
                    int mask = 0x80;
                    byte b = chrData[tileNumber * 16 + y];
                    byte b2 = chrData[tileNumber * 16 + 8 + y];
                    int imageOffset = imageY * imageWidth;

                    for (int x = 0; x < 8; x++)
                    {
                        int imageX = x0 + x;
                        int c = 0;
                        if (0 != (mask & b)) c += 1;
                        if (0 != (mask & b2)) c += 2;
                        c = palette[c];
                        pixels[imageOffset + imageX] = c;
                        mask >>= 1;
                    }
                }
            }
        }
    }
}