using System;
using System.Collections.Specialized;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;

namespace Khendys.Controls {

#region Public Enums

// Enum for possible RTF colors
 public enum RtfColor {
  Black, Maroon, Green, Olive, Navy, Purple, Teal, Gray, Silver,
  Red, Lime, Yellow, Blue, Fuchsia, Aqua, White
 }

#endregion

public class ExRichTextBox : System.Windows.Forms.RichTextBox {

#region My Enums

// Specifies the flags/options for the unmanaged call to the GDI+ method
  // Metafile.EmfToWmfBits().
  private enum EmfToWmfBitsFlags {

// Use the default conversion
EmfToWmfBitsFlagsDefault = 0x00000000,

// Embedded the source of the EMF metafiel within the resulting WMF
// metafile
EmfToWmfBitsFlagsEmbedEmf = 0x00000001,

// Place a 22-byte header in the resulting WMF file.  The header is
// required for the metafile to be considered placeable.
EmfToWmfBitsFlagsIncludePlaceable = 0x00000002,

// Don't simulate clipping by using the XOR operator.
EmfToWmfBitsFlagsNoXORClip = 0x00000004
  };

#endregion

#region My Structs

// Definitions for colors in an RTF document
  private struct RtfColorDef {
public const string Black = @"\red0\green0\blue0";
public const string Maroon = @"\red128\green0\blue0";
public const string Green = @"\red0\green128\blue0";
public const string Olive = @"\red128\green128\blue0";
public const string Navy = @"\red0\green0\blue128";
public const string Purple = @"\red128\green0\blue128";
public const string Teal = @"\red0\green128\blue128";
public const string Gray = @"\red128\green128\blue128";
public const string Silver = @"\red192\green192\blue192";
public const string Red = @"\red255\green0\blue0";
public const string Lime = @"\red0\green255\blue0";
public const string Yellow = @"\red255\green255\blue0";
public const string Blue = @"\red0\green0\blue255";
public const string Fuchsia = @"\red255\green0\blue255";
public const string Aqua = @"\red0\green255\blue255";
public const string White = @"\red255\green255\blue255";
  }

// Control words for RTF font families
  private struct RtfFontFamilyDef {
public const string Unknown = @"\fnil";
public const string Roman = @"\froman";
public const string Swiss = @"\fswiss";
public const string Modern = @"\fmodern";
public const string Script = @"\fscript";
public const string Decor = @"\fdecor";
public const string Technical = @"\ftech";
public const string BiDirect = @"\fbidi";
  }

#endregion

#region My Constants

// Not used in this application.  Descriptions can be found with documentation
  // of Windows GDI function SetMapMode
  private const int MM_TEXT = 1;
  private const int MM_LOMETRIC = 2;
  private const int MM_HIMETRIC = 3;
  private const int MM_LOENGLISH = 4;
  private const int MM_HIENGLISH = 5;
  private const int MM_TWIPS = 6;

// Ensures that the metafile maintains a 1:1 aspect ratio
  private const int MM_ISOTROPIC = 7;

// Allows the x-coordinates and y-coordinates of the metafile to be adjusted
  // independently
  private const int MM_ANISOTROPIC = 8;

// Represents an unknown font family
  private const string FF_UNKNOWN = "UNKNOWN";

// The number of hundredths of millimeters (0.01 mm) in an inch
  // For more information, see GetImagePrefix() method.
  private const int HMM_PER_INCH = 2540;

// The number of twips in an inch
  // For more information, see GetImagePrefix() method.
  private const int TWIPS_PER_INCH = 1440;

#endregion

#region My Privates

// The default text color
  private RtfColor textColor;

// The default text background color
  private RtfColor highlightColor;

// Dictionary that maps color enums to RTF color codes
  private HybridDictionary rtfColor;

// Dictionary that mapas Framework font families to RTF font families
  private HybridDictionary rtfFontFamily;

// The horizontal resolution at which the control is being displayed
  private float xDpi;

// The vertical resolution at which the control is being displayed
  private float yDpi;

#endregion

#region Elements required to create an RTF document
  
  /* RTF HEADER
   * ----------
   *
   * \rtf[N]  - For text to be considered to be RTF, it must be enclosed in this tag.
   *   rtf1 is used because the RichTextBox conforms to RTF Specification
   *   version 1.
   * \ansi  - The character set.
   * \ansicpg[N] - Specifies that unicode characters might be embedded. ansicpg1252
   *   is the default used by Windows.
   * \deff[N]  - The default font. \deff0 means the default font is the first font
   *   found.
   * \deflang[N] - The default language. \deflang1033 specifies US English.
   * */
  private const string RTF_HEADER = @"{\rtf1\ansi\ansicpg1252\deff0\deflang1033";

/* RTF DOCUMENT AREA
   * -----------------
   *
   * \viewkind[N] - The type of view or zoom level.  \viewkind4 specifies normal view.
   * \uc[N]  - The number of bytes corresponding to a Unicode character.
   * \pard  - Resets to default paragraph properties
   * \cf[N]  - Foreground color.  \cf1 refers to the color at index 1 in
   *   the color table
   * \f[N]  - Font number. \f0 refers to the font at index 0 in the font
   *   table.
   * \fs[N]  - Font size in half-points.
   * */
  private const string RTF_DOCUMENT_PRE = @"\viewkind4\uc1\pard\cf1\f0\fs20";
  private const string RTF_DOCUMENT_POST = @"\cf0\fs17}";
  private string RTF_IMAGE_POST = @"}";

#endregion

#region Accessors

// TODO: This can be ommitted along with RemoveBadCharacters
  // Overrides the default implementation of RTF.  This is done because the control
  // was originally developed to run in an instant messenger that uses the
  // Jabber XML-based protocol.  The framework would throw an exception when the
  // XML contained the null character, so I filtered out.
  public new string Rtf {
get {return RemoveBadChars(base.Rtf);}
set {base.Rtf = value;}
  }

// The color of the text
  public RtfColor TextColor {
get {return textColor;}
set {textColor = value;}
  }

// The color of the highlight
  public RtfColor HiglightColor {
get {return highlightColor;}
set {highlightColor = value;}
  }

#endregion

#region Constructors

/// <summary>
  /// Initializes the text colors, creates dictionaries for RTF colors and
  /// font families, and stores the horizontal and vertical resolution of
  /// the RichTextBox's graphics context.
  /// </summary>
  public ExRichTextBox() : base() {

// Initialize default text and background colors
textColor = RtfColor.Black;
highlightColor = RtfColor.White;

// Initialize the dictionary mapping color codes to definitions
rtfColor = new HybridDictionary();
rtfColor.Add(RtfColor.Aqua, RtfColorDef.Aqua);
rtfColor.Add(RtfColor.Black, RtfColorDef.Black);
rtfColor.Add(RtfColor.Blue, RtfColorDef.Blue);
rtfColor.Add(RtfColor.Fuchsia, RtfColorDef.Fuchsia);
rtfColor.Add(RtfColor.Gray, RtfColorDef.Gray);
rtfColor.Add(RtfColor.Green, RtfColorDef.Green);
rtfColor.Add(RtfColor.Lime, RtfColorDef.Lime);
rtfColor.Add(RtfColor.Maroon, RtfColorDef.Maroon);
rtfColor.Add(RtfColor.Navy, RtfColorDef.Navy);
rtfColor.Add(RtfColor.Olive, RtfColorDef.Olive);
rtfColor.Add(RtfColor.Purple, RtfColorDef.Purple);
rtfColor.Add(RtfColor.Red, RtfColorDef.Red);
rtfColor.Add(RtfColor.Silver, RtfColorDef.Silver);
rtfColor.Add(RtfColor.Teal, RtfColorDef.Teal);
rtfColor.Add(RtfColor.White, RtfColorDef.White);
rtfColor.Add(RtfColor.Yellow, RtfColorDef.Yellow);

// Initialize the dictionary mapping default Framework font families to
// RTF font families
rtfFontFamily = new HybridDictionary();
rtfFontFamily.Add(FontFamily.GenericMonospace.Name, RtfFontFamilyDef.Modern);
rtfFontFamily.Add(FontFamily.GenericSansSerif, RtfFontFamilyDef.Swiss);
rtfFontFamily.Add(FontFamily.GenericSerif, RtfFontFamilyDef.Roman);
rtfFontFamily.Add(FF_UNKNOWN, RtfFontFamilyDef.Unknown);

// Get the horizontal and vertical resolutions at which the object is
// being displayed
using(Graphics _graphics = this.CreateGraphics()) {
 xDpi = _graphics.DpiX;
 yDpi = _graphics.DpiY;
}
  }

/// <summary>
  /// Calls the default constructor then sets the text color.
  /// </summary>
  /// <param name="_textColor"></param>
  public ExRichTextBox(RtfColor _textColor) : this() {
textColor = _textColor;
  }

/// <summary>
  /// Calls the default constructor then sets te text and highlight colors.
  /// </summary>
  /// <param name="_textColor"></param>
  /// <param name="_highlightColor"></param>
  public ExRichTextBox(RtfColor _textColor, RtfColor _highlightColor) : this() {
textColor = _textColor;
highlightColor = _highlightColor;
  }

#endregion

#region Append RTF or Text to RichTextBox Contents

/// <summary>
  /// Assumes the string passed as a paramter is valid RTF text and attempts
  /// to append it as RTF to the content of the control.
  /// </summary>
  /// <param name="_rtf"></param>
  public void AppendRtf(string _rtf) {

// Move caret to the end of the text
this.Select(this.TextLength, 0);

// Since SelectedRtf is null, this will append the string to the
// end of the existing RTF
this.SelectedRtf = _rtf;
  }

/// <summary>
  /// Assumes that the string passed as a parameter is valid RTF text and
  /// attempts to insert it as RTF into the content of the control.
  /// </summary>
  /// <remarks>
  /// NOTE: The text is inserted wherever the caret is at the time of the call,
  /// and if any text is selected, that text is replaced.
  /// </remarks>
  /// <param name="_rtf"></param>
  public void InsertRtf(string _rtf) {
this.SelectedRtf = _rtf;
  }

/// <summary>
  /// Appends the text using the current font, text, and highlight colors.
  /// </summary>
  /// <param name="_text"></param>
  public void AppendTextAsRtf(string _text) {
AppendTextAsRtf(_text, this.Font);
  }

/// <summary>
  /// Appends the text using the given font, and current text and highlight
  /// colors.
  /// </summary>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  public void AppendTextAsRtf(string _text, Font _font) {
AppendTextAsRtf(_text, _font, textColor);
  }
  
  /// <summary>
  /// Appends the text using the given font and text color, and the current
  /// highlight color.
  /// </summary>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  /// <param name="_color"></param>
  public void AppendTextAsRtf(string _text, Font _font, RtfColor _textColor) {
AppendTextAsRtf(_text, _font, _textColor, highlightColor);
  }

/// <summary>
  /// Appends the text using the given font, text, and highlight colors.  Simply
  /// moves the caret to the end of the RichTextBox's text and makes a call to
  /// insert.
  /// </summary>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  /// <param name="_textColor"></param>
  /// <param name="_backColor"></param>
  public void AppendTextAsRtf(string _text, Font _font, RtfColor _textColor, RtfColor _backColor) {
// Move carret to the end of the text
this.Select(this.TextLength, 0);

InsertTextAsRtf(_text, _font, _textColor, _backColor);
  }

#endregion

#region Insert Plain Text

/// <summary>
  /// Inserts the text using the current font, text, and highlight colors.
  /// </summary>
  /// <param name="_text"></param>
  public void InsertTextAsRtf(string _text) {
InsertTextAsRtf(_text, this.Font);
  }

/// <summary>
  /// Inserts the text using the given font, and current text and highlight
  /// colors.
  /// </summary>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  public void InsertTextAsRtf(string _text, Font _font) {
InsertTextAsRtf(_text, _font, textColor);
  }
  
  /// <summary>
  /// Inserts the text using the given font and text color, and the current
  /// highlight color.
  /// </summary>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  /// <param name="_color"></param>
  public void InsertTextAsRtf(string _text, Font _font, RtfColor _textColor) {
InsertTextAsRtf(_text, _font, _textColor, highlightColor);
  }

/// <summary>
  /// Inserts the text using the given font, text, and highlight colors.  The
  /// text is wrapped in RTF codes so that the specified formatting is kept.
  /// You can only assign valid RTF to the RichTextBox.Rtf property, else
  /// an exception is thrown.  The RTF string should follow this format ...
  ///
  /// {\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{[FONTS]}{\colortbl ;[COLORS]}}
  /// \viewkind4\uc1\pard\cf1\f0\fs20 [DOCUMENT AREA] }
  ///
  /// </summary>
  /// <remarks>
  /// NOTE: The text is inserted wherever the caret is at the time of the call,
  /// and if any text is selected, that text is replaced.
  /// </remarks>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  /// <param name="_color"></param>
  /// <param name="_color"></param>
  public void InsertTextAsRtf(string _text, Font _font, RtfColor _textColor, RtfColor _backColor) {

StringBuilder _rtf = new StringBuilder();

// Append the RTF header
_rtf.Append(RTF_HEADER);

// Create the font table from the font passed in and append it to the
// RTF string
_rtf.Append(GetFontTable(_font));

// Create the color table from the colors passed in and append it to the
// RTF string
_rtf.Append(GetColorTable(_textColor, _backColor));

// Create the document area from the text to be added as RTF and append
// it to the RTF string.
_rtf.Append(GetDocumentArea(_text, _font));

this.SelectedRtf = _rtf.ToString();
  }

/// <summary>
  /// Creates the Document Area of the RTF being inserted. The document area
  /// (in this case) consists of the text being added as RTF and all the
  /// formatting specified in the Font object passed in. This should have the
  /// form ...
  ///
  /// \viewkind4\uc1\pard\cf1\f0\fs20 [DOCUMENT AREA] }
  ///
  /// </summary>
  /// <param name="_text"></param>
  /// <param name="_font"></param>
  /// <returns>
  /// The document area as a string.
  /// </returns>
  private string GetDocumentArea(string _text, Font _font) {

StringBuilder _doc = new StringBuilder();

// Append the standard RTF document area control string
_doc.Append(RTF_DOCUMENT_PRE);

// Set the highlight color (the color behind the text) to the
// third color in the color table.  See GetColorTable for more details.
_doc.Append(@"\highlight2");

// If the font is bold, attach corresponding tag
if (_font.Bold)
 _doc.Append(@"\b");

// If the font is italic, attach corresponding tag
if (_font.Italic)
 _doc.Append(@"\i");

// If the font is strikeout, attach corresponding tag
if (_font.Strikeout)
 _doc.Append(@"\strike");

// If the font is underlined, attach corresponding tag
if (_font.Underline)
 _doc.Append(@"\ul");

// Set the font to the first font in the font table.
// See GetFontTable for more details.
_doc.Append(@"\f0");

// Set the size of the font.  In RTF, font size is measured in
// half-points, so the font size is twice the value obtained from
// Font.SizeInPoints
_doc.Append(@"\fs");
_doc.Append((int)Math.Round((2 * _font.SizeInPoints)));

// Apppend a space before starting actual text (for clarity)
_doc.Append(@" ");

// Append actual text, however, replace newlines with RTF \par.
// Any other special text should be handled here (e.g.) tabs, etc.
_doc.Append(_text.Replace("\n", @"\par "));

// RTF isn't strict when it comes to closing control words, but what the
// heck ...

// Remove the highlight
_doc.Append(@"\highlight0");

// If font is bold, close tag
if (_font.Bold)
 _doc.Append(@"\b0");

// If font is italic, close tag
if (_font.Italic)
 _doc.Append(@"\i0");

// If font is strikeout, close tag
if (_font.Strikeout)
 _doc.Append(@"\strike0");

// If font is underlined, cloes tag
if (_font.Underline)
 _doc.Append(@"\ulnone");

// Revert back to default font and size
_doc.Append(@"\f0");
_doc.Append(@"\fs20");

// Close the document area control string
_doc.Append(RTF_DOCUMENT_POST);

return _doc.ToString();
  }

#endregion

#region Insert Image

/// <summary>
  /// Inserts an image into the RichTextBox.  The image is wrapped in a Windows
  /// Format Metafile, because although Microsoft discourages the use of a WMF,
  /// the RichTextBox (and even MS Word), wraps an image in a WMF before inserting
  /// the image into a document.  The WMF is attached in HEX format (a string of
  /// HEX numbers).
  ///
  /// The RTF Specification v1.6 says that you should be able to insert bitmaps,
  /// .jpegs, .gifs, .pngs, and Enhanced Metafiles (.emf) directly into an RTF
  /// document without the WMF wrapper. This works fine with MS Word,
  /// however, when you don't wrap images in a WMF, WordPad and
  /// RichTextBoxes simply ignore them.  Both use the riched20.dll or msfted.dll.
  /// </summary>
  /// <remarks>
  /// NOTE: The image is inserted wherever the caret is at the time of the call,
  /// and if any text is selected, that text is replaced.
  /// </remarks>
  /// <param name="_image"></param>
  public void InsertImage(Image _image) {

StringBuilder _rtf = new StringBuilder();

// Append the RTF header
_rtf.Append(RTF_HEADER);

// Create the font table using the RichTextBox's current font and append
// it to the RTF string
_rtf.Append(GetFontTable(this.Font));

// Create the image control string and append it to the RTF string
_rtf.Append(GetImagePrefix(_image));

// Create the Windows Metafile and append its bytes in HEX format
_rtf.Append(GetRtfImage(_image));

// Close the RTF image control string
_rtf.Append(RTF_IMAGE_POST);

this.SelectedRtf = _rtf.ToString();
  }

/// <summary>
  /// Creates the RTF control string that describes the image being inserted.
  /// This description (in this case) specifies that the image is an
  /// MM_ANISOTROPIC metafile, meaning that both X and Y axes can be scaled
  /// independently.  The control string also gives the images current dimensions,
  /// and its target dimensions, so if you want to control the size of the
  /// image being inserted, this would be the place to do it. The prefix should
  /// have the form ...
  ///
  /// {\pict\wmetafile8\picw[A]\pich[B]\picwgoal[C]\pichgoal[D]
  ///
  /// where ...
  ///
  /// A = current width of the metafile in hundredths of millimeters (0.01mm)
  ///  = Image Width in Inches * Number of (0.01mm) per inch
  ///  = (Image Width in Pixels / Graphics Context's Horizontal Resolution) * 2540
  ///  = (Image Width in Pixels / Graphics.DpiX) * 2540
  ///
  /// B = current height of the metafile in hundredths of millimeters (0.01mm)
  ///  = Image Height in Inches * Number of (0.01mm) per inch
  ///  = (Image Height in Pixels / Graphics Context's Vertical Resolution) * 2540
  ///  = (Image Height in Pixels / Graphics.DpiX) * 2540
  ///
  /// C = target width of the metafile in twips
  ///  = Image Width in Inches * Number of twips per inch
  ///  = (Image Width in Pixels / Graphics Context's Horizontal Resolution) * 1440
  ///  = (Image Width in Pixels / Graphics.DpiX) * 1440
  ///
  /// D = target height of the metafile in twips
  ///  = Image Height in Inches * Number of twips per inch
  ///  = (Image Height in Pixels / Graphics Context's Horizontal Resolution) * 1440
  ///  = (Image Height in Pixels / Graphics.DpiX) * 1440
  /// 
  /// </summary>
  /// <remarks>
  /// The Graphics Context's resolution is simply the current resolution at which
  /// windows is being displayed.  Normally it's 96 dpi, but instead of assuming
  /// I just added the code.
  ///
  /// According to Ken Howe at pbdr.com, "Twips are screen-independent units
  /// used to ensure that the placement and proportion of screen elements in
  /// your screen application are the same on all display systems."
  ///
  /// Units Used
  /// ----------
  /// 1 Twip = 1/20 Point
  /// 1 Point = 1/72 Inch
  /// 1 Twip = 1/1440 Inch
  ///
  /// 1 Inch = 2.54 cm
  /// 1 Inch = 25.4 mm
  /// 1 Inch = 2540 (0.01)mm
  /// </remarks>
  /// <param name="_image"></param>
  /// <returns></returns>
  private string GetImagePrefix(Image _image) {

StringBuilder _rtf = new StringBuilder();

// Calculate the current width of the image in (0.01)mm
int picw = (int)Math.Round((_image.Width / xDpi) * HMM_PER_INCH);

// Calculate the current height of the image in (0.01)mm
int pich = (int)Math.Round((_image.Height / yDpi) * HMM_PER_INCH);

// Calculate the target width of the image in twips
int picwgoal = (int)Math.Round((_image.Width / xDpi) * TWIPS_PER_INCH);

// Calculate the target height of the image in twips
int pichgoal = (int)Math.Round((_image.Height / yDpi) * TWIPS_PER_INCH);

// Append values to RTF string
_rtf.Append(@"{\pict\wmetafile8");
_rtf.Append(@"\picw");
_rtf.Append(picw);
_rtf.Append(@"\pich");
_rtf.Append(pich);
_rtf.Append(@"\picwgoal");
_rtf.Append(picwgoal);
_rtf.Append(@"\pichgoal");
_rtf.Append(pichgoal);
_rtf.Append(" ");

return _rtf.ToString();
  }

/// <summary>
  /// Use the EmfToWmfBits function in the GDI+ specification to convert a
  /// Enhanced Metafile to a Windows Metafile
  /// </summary>
  /// <param name="_hEmf">
  /// A handle to the Enhanced Metafile to be converted
  /// </param>
  /// <param name="_bufferSize">
  /// The size of the buffer used to store the Windows Metafile bits returned
  /// </param>
  /// <param name="_buffer">
  /// An array of bytes used to hold the Windows Metafile bits returned
  /// </param>
  /// <param name="_mappingMode">
  /// The mapping mode of the image.  This control uses MM_ANISOTROPIC.
  /// </param>
  /// <param name="_flags">
  /// Flags used to specify the format of the Windows Metafile returned
  /// </param>
  [DllImportAttribute("gdiplus.dll")]
  private static extern uint GdipEmfToWmfBits (IntPtr _hEmf, uint _bufferSize,
byte[] _buffer, int _mappingMode, EmfToWmfBitsFlags _flags);

/// <summary>
  /// Wraps the image in an Enhanced Metafile by drawing the image onto the
  /// graphics context, then converts the Enhanced Metafile to a Windows
  /// Metafile, and finally appends the bits of the Windows Metafile in HEX
  /// to a string and returns the string.
  /// </summary>
  /// <param name="_image"></param>
  /// <returns>
  /// A string containing the bits of a Windows Metafile in HEX
  /// </returns>
  private string GetRtfImage(Image _image) {

StringBuilder _rtf = null;

// Used to store the enhanced metafile
MemoryStream _stream = null;

// Used to create the metafile and draw the image
Graphics _graphics = null;

// The enhanced metafile
Metafile _metaFile = null;

// Handle to the device context used to create the metafile
IntPtr _hdc;

try {
 _rtf = new StringBuilder();
 _stream = new MemoryStream();

// Get a graphics context from the RichTextBox
 using(_graphics = this.CreateGraphics()) {

// Get the device context from the graphics context
  _hdc = _graphics.GetHdc();

// Create a new Enhanced Metafile from the device context
  _metaFile = new Metafile(_stream, _hdc);

// Release the device context
  _graphics.ReleaseHdc(_hdc);
 }

// Get a graphics context from the Enhanced Metafile
 using(_graphics = Graphics.FromImage(_metaFile)) {

// Draw the image on the Enhanced Metafile
  _graphics.DrawImage(_image, new Rectangle(0, 0, _image.Width, _image.Height));

}

// Get the handle of the Enhanced Metafile
 IntPtr _hEmf = _metaFile.GetHenhmetafile();

// A call to EmfToWmfBits with a null buffer return the size of the
 // buffer need to store the WMF bits.  Use this to get the buffer
 // size.
 uint _bufferSize = GdipEmfToWmfBits(_hEmf, 0, null, MM_ANISOTROPIC,
  EmfToWmfBitsFlags.EmfToWmfBitsFlagsDefault);

// Create an array to hold the bits
 byte[] _buffer = new byte[_bufferSize];

// A call to EmfToWmfBits with a valid buffer copies the bits into the
 // buffer an returns the number of bits in the WMF. 
 uint _convertedSize = GdipEmfToWmfBits(_hEmf, _bufferSize, _buffer, MM_ANISOTROPIC,
  EmfToWmfBitsFlags.EmfToWmfBitsFlagsDefault);

// Append the bits to the RTF string
 for(int i = 0; i < _buffer.Length; ++i) {
  _rtf.Append(String.Format("{0:X2}", _buffer[i]));
 }

return _rtf.ToString();
}
finally {
 if(_graphics != null)
  _graphics.Dispose();
 if(_metaFile != null)
  _metaFile.Dispose();
 if(_stream != null)
  _stream.Close();
}
  }
  
  #endregion

#region RTF Helpers

/// <summary>
  /// Creates a font table from a font object.  When an Insert or Append
  /// operation is performed a font is either specified or the default font
  /// is used.  In any case, on any Insert or Append, only one font is used,
  /// thus the font table will always contain a single font.  The font table
  /// should have the form ...
  ///
  /// {\fonttbl{\f0\[FAMILY]\fcharset0 [FONT_NAME];}
  /// </summary>
  /// <param name="_font"></param>
  /// <returns></returns>
  private string GetFontTable(Font _font) {

StringBuilder _fontTable = new StringBuilder();

// Append table control string
_fontTable.Append(@"{\fonttbl{\f0");
_fontTable.Append(@"\");

// If the font's family corresponds to an RTF family, append the
// RTF family name, else, append the RTF for unknown font family.
if (rtfFontFamily.Contains(_font.FontFamily.Name))
 _fontTable.Append(rtfFontFamily[_font.FontFamily.Name]);
else
 _fontTable.Append(rtfFontFamily[FF_UNKNOWN]);

// \fcharset specifies the character set of a font in the font table.
// 0 is for ANSI.
_fontTable.Append(@"\fcharset0 ");

// Append the name of the font
_fontTable.Append(_font.Name);

// Close control string
_fontTable.Append(@";}}");

return _fontTable.ToString();
  }

/// <summary>
  /// Creates a font table from the RtfColor structure.  When an Insert or Append
  /// operation is performed, _textColor and _backColor are either specified
  /// or the default is used.  In any case, on any Insert or Append, only three
  /// colors are used.  The default color of the RichTextBox (signified by a
  /// semicolon (;) without a definition), is always the first color (index 0) in
  /// the color table.  The second color is always the text color, and the third
  /// is always the highlight color (color behind the text).  The color table
  /// should have the form ...
  ///
  /// {\colortbl ;[TEXT_COLOR];[HIGHLIGHT_COLOR];}
  ///
  /// </summary>
  /// <param name="_textColor"></param>
  /// <param name="_backColor"></param>
  /// <returns></returns>
  private string GetColorTable(RtfColor _textColor, RtfColor _backColor) {

StringBuilder _colorTable = new StringBuilder();

// Append color table control string and default font (;)
_colorTable.Append(@"{\colortbl ;");

// Append the text color
_colorTable.Append(rtfColor[_textColor]);
_colorTable.Append(@";");

// Append the highlight color
_colorTable.Append(rtfColor[_backColor]);
_colorTable.Append(@";}\n");
  
return _colorTable.ToString();
  }

/// <summary>
  /// Called by overrided RichTextBox.Rtf accessor.
  /// Removes the null character from the RTF.  This is residue from developing
  /// the control for a specific instant messaging protocol and can be ommitted.
  /// </summary>
  /// <param name="_originalRtf"></param>
  /// <returns>RTF without null character</returns>
  private string RemoveBadChars(string _originalRtf) {
return _originalRtf.Replace("\0", "");
  }

#endregion
 }
}