WPF RichTextBox

FlowDocument RunFlowDoc = new FlowDocument();
Paragraph Runparagraph = new Paragraph();

RunFlowDoc.Blocks.Add(Runparagraph);
txtRichBox.Document = RunFlowDoc;

Run r = new Run(content);
if (type == 0)
r.Foreground = new SolidColorBrush(Color.FromArgb(255, 0, 0, 255));
else if (type == 1)
r.Foreground = new SolidColorBrush(Color.FromArgb(255, 0, 0, 0));
else
r.Foreground = new SolidColorBrush(Color.FromArgb(255, 255, 0, 0));
Runparagraph.Inlines.Add(r);
Runparagraph.Inlines.Add("\r");
txtRichBox.ScrollToEnd();

//行内追加

Run r = Runparagraph.Inlines.ElementAt(Runparagraph.Inlines.Count - 2) as Run;
r.Text += ">>正在上传";

//加入图片 
  BitmapImage bi = new BitmapImage(new Uri(@"F:\image\submit.png"));
                    Image image = new Image();
                    image.Source = bi;
                    InlineUIContainer container = new InlineUIContainer(image);
                    Paragraph paragraph = new Paragraph(container);