在流文档中创建 RTF 运行

Create RTF run in flowdocument

谁能帮我理解RTF?我有一个 inputStream 由一些字符串

填充
inputStream = new MemoryStream(Encoding.ASCII.GetBytes((myObject.someStr)));

然后这个流传递给flowdocument

FlowDocument fldoc = new FlowDocument();
TextRange tr = new TextRange(
    fldoc.ContentStart, fldoc.ContentEnd);
tr.Load(inputStream, DataFormats.Rtf);

之后我创建自定义文本框来处理 myObject 的 属性

Block curBlock = fldoc.Blocks.FirstBlock;
Inline curInline = (currentBlock as Paragraph).Inlines.FirstInline;
Run curRun = (currentInline as Span).Inlines.FirstInline as Run;
return new CustomTextBox(tr, currentRun.ContentStart, myObject)

一旦失去焦点,我的自定义文本框就会

TextPointer ptr = CurrentRun.ContentStart;
ptr.DeleteTextInRun(ptr.GetTextRunLength(LogicalDirection.Forward));
ptr.InsertTextInRun(mainTextbox.Text);
using (MemoryStream ms = new MemoryStream())
{
    tr.Save(ms, DataFormats.Rtf);
    myObject.someStr = ASCIIEncoding.Default.GetString(ms.ToArray());
}

现在的问题是:如果 myObject.someStr == "",那么 curBlock == null,我无法实例化 CustomTextBox。我正在努力

Paragraph p = new Paragraph();
Span s = new Span();
Run r = new Run(tr.Text);
s.Inlines.Add(r);
p.Inlines.Add(s);
fldoc.Blocks.Add(new Paragraph());
return new CustomTextBox(tr, r.ContentStart, myObject)

,但 tr 无论如何都是空的。我该如何处理?

fldoc = new FlowDocument(p);

有帮助