FlowDocument Converter - To create a bitmap from a RichTextBox document

FlowDocumentConverter.cs

public class FlowDocumentConverter
{

  /// <summary>
  /// Converts a FlowDocument to a bitmap you can save or print
  /// </summary>
  /// <remarks>
  /// No longer used
  /// </remarks>
  /// <param name="document"></param>
  /// <param name="size"></param>
  /// <returns></returns>
  public Bitmap FlowDocumentToBitmap(FlowDocument document, System.Windows.Size size)
  {
      // Clone document first
      var clonedDocument = new FlowDocument();
      {
          var sourceRange = new TextRange(document.ContentStart, document.ContentEnd);
          var targetRange = new TextRange(clonedDocument.ContentStart, clonedDocument.ContentEnd);

          using (var stream = new MemoryStream())
          {
              sourceRange.Save(stream, DataFormats.XamlPackage);
              targetRange.Load(stream, DataFormats.XamlPackage);
          }
      }

      DocumentPaginator paginator = ((IDocumentPaginatorSource)clonedDocument).DocumentPaginator;
      paginator.PageSize = size;
      paginator.ComputePageCount();

      var container = new DrawingVisual();
      using (var drawingContext = container.RenderOpen())
      {
          // Draw white background
          drawingContext.DrawRectangle(Brushes.White, null, new Rect(0, 0, size.Width, size.Height * paginator.PageCount));

          for (int i = 0; i < paginator.PageCount; i++)
          {
              var visual = paginator.GetPage(i).Visual;

              var tempBitmap = new RenderTargetBitmap((int)size.Width, (int)size.Height * paginator.PageCount,
                  96, 96, PixelFormats.Pbgra32);
              tempBitmap.Render(visual);

              // Don't even ask, the way DrawingContext works is weird to me as I'm not used to do graphics like this
              const int lineHeightFix = 36;
              drawingContext.DrawImage(tempBitmap, new Rect(0, (size.Height * i) - (i != 0 ? (lineHeightFix * i) : 0), size.Width, size.Height * paginator.PageCount));
          }
      }

      // Create RenderTargetBitmap
      var bitmapTargetBitmap = new RenderTargetBitmap((int)size.Width, (int)size.Height * paginator.PageCount,
          96, 96, PixelFormats.Pbgra32);
      bitmapTargetBitmap.Render(container);

      // Convert it into something we can use
      Bitmap bitmap;
      using (MemoryStream outStream = new MemoryStream())
      {
          BitmapEncoder enc = new BmpBitmapEncoder();
          enc.Frames.Add(BitmapFrame.Create(bitmapTargetBitmap));
          enc.Save(outStream);

          var tmpBitmap = (new System.Drawing.Bitmap(outStream));
          bitmap = tmpBitmap.Clone(new System.Drawing.Rectangle(0, 0, tmpBitmap.Width, tmpBitmap.Height), System.Drawing.Imaging.PixelFormat.Format32bppArgb); ;
      }

      return bitmap;
  }

  /// Usage example
  public Bitmap GenerateScreenshot()
  {
      return FlowDocumentToBitmap(richTextBox.Document, new System.Windows.Size(richTextBox.ActualWidth, richTextBox.ActualHeight));
  }
}