Printer Text Writer

PrinterWriter.cs

using System.Drawing;
using System.Drawing.Printing;
using System.IO;
using System.Text;
using System.Threading.Tasks;

namespace Printing
{
    public class PrinterWriter : TextWriter
    {
        private readonly PrintDocument _document;
        private readonly Font _font;

        private int _currentIndex;
        private int _linesPerPage;
        private readonly StringBuilder _text;
        private string _contents;

        public PrinterWriter()
            : this(new Font("Consolas", 10), "Untitled")
        {
        }

        public PrinterWriter(Font font, string documentName, PrinterSettings settings)
        {
            _text = new StringBuilder();
            _font = font;
            _document = new PrintDocument();
            _document.PrintPage += DocumentOnPrintPage;
            _document.DocumentName = documentName;
            _document.PrinterSettings = settings;
        }

        public PrinterWriter(Font font, string documentName)
        {
            _text = new StringBuilder();
            _font = font;
            _document = new PrintDocument();
            _document.DocumentName = documentName;
            _document.PrintPage += DocumentOnPrintPage;
        }

        private void DocumentOnPrintPage(object sender, PrintPageEventArgs e)
        {
            _linesPerPage = e.PageBounds.Height / _font.Height;

            int nextPage = GetNextPageIndex(_contents, _linesPerPage);

            e.Graphics.DrawString(_contents.Substring(_currentIndex, nextPage - _currentIndex), _font, Brushes.Black, e.MarginBounds, new StringFormat(StringFormatFlags.NoWrap));

            e.HasMorePages = nextPage != _contents.Length;

            _currentIndex = nextPage;
        }

        private int GetNextPageIndex(string contents, int linesPerPage)
        {
            int count = linesPerPage;
            for (int i = _currentIndex; i < _contents.Length; i++)
            {
                if (contents[i] == '\r')
                {
                    --count;
                    if (count == 0)
                        return i;
                }
            }
            return _contents.Length;
        }

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);
            Close();
        }

        public override void Close()
        {
            _contents = _text.ToString();
            _document.Print();
        }

        public override Encoding Encoding
        {
            get { return Encoding.Unicode; }
        }

        public override void Write(char value)
        {
            _text.Append(value);
        }

        public override async Task WriteAsync(char value)
        {
            await Task.Factory.StartNew(() => _text.Append(value));
        }
    }
}