在RichTextBox控件加入图片

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 = @"red0green0blue0";
   public const string Maroon = @"red128green0blue0";
   public const string Green = @"red0green128blue0";
   public const string Olive = @"red128green128blue0";
   public const string Navy = @"red0green0blue128";
   public const string Purple = @"red128green0blue128";
   public const string Teal = @"red0green128blue128";
   public const string Gray = @"red128green128blue128";
   public const string Silver = @"red192green192blue192";
   public const string Red = @"red255green0blue0";
   public const string Lime = @"red0green255blue0";
   public const string Yellow = @"red255green255blue0";
   public const string Blue = @"red0green0blue255";
   public const string Fuchsia = @"red255green0blue255";
   public const string Aqua = @"red0green255blue255";
   public const string White = @"red255green255blue255";
  }

  // 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;

  // Ensu