RenderFile.cs

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace charposition
{
    static class RenderFile
    {
        static internal Bitmap Draw(string text)
        {
            Size maxTextSize = GetTextSizeInLinesAndCols(text);

            Font codeFont = new Font("Consolas", 14.0f);
            Size codeTextSize = TextRenderer.MeasureText("Z", codeFont);

            int xSpace = codeTextSize.Width + 2;
            int ySpace = codeTextSize.Height + 10;

            int xInitialMargin = xSpace;
            int yInitialMargin = ySpace;

            var bitmap = new Bitmap(
                maxTextSize.Width * xSpace + xInitialMargin +1 ,
                maxTextSize.Height * ySpace + yInitialMargin + 1,
                PixelFormat.Format32bppArgb);

            var g = Graphics.FromImage(bitmap);

            g.SmoothingMode = SmoothingMode.AntiAlias;
            g.TextRenderingHint = TextRenderingHint.AntiAlias;

            RenderNumbers numbers = new RenderNumbers();
            numbers.RenderColumns(g, maxTextSize.Width, xSpace, xInitialMargin);
            numbers.RenderLines(g, maxTextSize.Height, ySpace, yInitialMargin);

            Font numberFont = new Font("Consolas", 7.0f);
            Font eolFont = new Font("Consolas", 11.0f);

            var eolBrush = new SolidBrush(Color.Gray);

            var brush = new SolidBrush(Color.Navy);
            var pen = new Pen(brush);

            var linePen = new Pen(new SolidBrush(Color.Gray));

            Size numberTextSize = TextRenderer.MeasureText("Z", numberFont);

            int x = xInitialMargin;
            int y = yInitialMargin;

            for (int pos = 0; pos < text.Length; ++pos)
            {
                string charToDraw = text[pos].ToString();

                Font currentFont = codeFont;
                Brush currentBrush = brush;

                if (text[pos] == '\r')
                {
                    charToDraw = "\\r";
                    currentFont = eolFont;
                    currentBrush = eolBrush;
                }

                if (text[pos] == '\n')
                {
                    charToDraw = "\\n";
                    currentFont = eolFont;
                    currentBrush = eolBrush;
                }

                g.DrawString(charToDraw, currentFont, currentBrush, new PointF(x, y));

                g.DrawRectangle(linePen, new Rectangle(
                    x, y,
                    xSpace,
                    ySpace));

                string posString = pos.ToString();

                g.DrawString(posString, numberFont, eolBrush,
                    new PointF(
                        x + xSpace - TextRenderer.MeasureText(posString, numberFont).Width,
                        y + ySpace - numberTextSize.Height));

                x += xSpace;

                if (text[pos] == '\n')
                {
                    y += ySpace;
                    x = xInitialMargin;
                }
            }

            return bitmap;
        }

        static Size GetTextSizeInLinesAndCols(string text)
        {
            int lines = 1;
            int maxCols = 0;

            int lineWidth = 0;

            for (int i = 0; i < text.Length; ++i)
            {
                ++lineWidth;

                if (text[i] == '\n')
                {
                    ++lines;

                    if (maxCols < lineWidth)
                        maxCols = lineWidth;

                    lineWidth = 0;
                }
            }

            return new Size(maxCols, lines);
        }

        class RenderNumbers
        {
            internal void RenderColumns(
                Graphics g,
                int columns,
                int xSpace,
                int xInitialMargin)
            {
                int x = xInitialMargin;
                int y = 10;

                for (int i = 1; i <= columns; ++i)
                {
                    Size numberTextSize = TextRenderer.MeasureText(i.ToString(), mNumberFont);

                    g.DrawString(i.ToString(), mNumberFont, mGrayBrush,
                        new PointF(
                            x + xSpace / 2 - (numberTextSize.Width / 2),
                            y)
                    );

                    x += xSpace;
                }
            }

            internal void RenderLines(
                Graphics g,
                int lines,
                int ySpace,
                int yInitialMargin)
            {
                int x = 5;
                int y = yInitialMargin;

                for (int i = 1; i <= lines; ++i)
                {
                    Size numberTextSize = TextRenderer.MeasureText(i.ToString(), mNumberFont);

                    g.DrawString(i.ToString(), mNumberFont, mGrayBrush,
                        new PointF(
                            x,
                            y + ySpace / 2 - (numberTextSize.Height / 2))
                    );

                    y += ySpace;
                }
            }

            Font mNumberFont = new Font("Consolas", 9.0f);
            Brush mGrayBrush = new SolidBrush(Color.Gray);
        }
    }
}