如何使用TextRange替换运行的字母？

Question

我对FlowDocuments完全陌生，似乎在任何地方都找不到这个。

我创建了一个TextBlock，其中每个内联都是一个运行，只包含一个单词。(内联是用代码创建的)。然后，我使用TextRange替换运行中的一些字母。但是， TextRange似乎没有替换运行的字符，而是清空运行，并将字母追加到上一次运行。

(重要的是保留原始的TextBlock结构和原始的Run对象，因为我将事件绑定到它们。)

我做错了什么？TextRange.Text =文本实际上在做什么？

任何帮助都是非常感谢的。

示例

  ---Before textrange--
<Run>
6||perrla
</Run>
<Run>
1||                       **NOTE THIS IS A SPACE IN THE RUN
</Run>
<Run>
5||nc/at
</Run>

--After textrange --- 
<Run>           **NOTE THE EMPTY RUN
</Run>
<Run>
5|| test    **NOTE HOW TEST IS APPENDED TO THE SPACE OF THE PREVIOUS RUN
</Run>
<Run>
5||nc/at
</Run>

产生上述结果的代码：

            string text = nw.Replace("\0", string.Empty);

            TextPointer s = StartInlineElement.GetInsertionPosition(LogicalDirection.Forward);
            TextPointer start = s.GetPositionAtOffset(StartIndex);
            TextPointer end = start.GetPositionAtOffset(Text.Length);

            var y = start.GetAdjacentElement(LogicalDirection.Backward);
            if (y != null)
            {
                do
                {
                    GetXaml((TextElement)y);
                    y = (y as Run).PreviousInline;
                } while (y != null);
            }

            THIS IS WRONG -- IT EMPTIES THE RUN AND APPENDS TO THE RUN
            BEFORE IT.
            TextRange tr = new TextRange(start, end);
            tr.Text = text;

            y = start.GetAdjacentElement(LogicalDirection.Forward);
            if (y != null)
            {
                do
                {
                    GetXaml((TextElement)y);
                    y = (y as Run).PreviousInline;
                } while (y != null);
            }
        }

GetXaml来自微软(https://msdn.microsoft.com/en-us/library/system.windows.documents.textpointercontext(v=vs.110).aspx )，我轻描淡写地修改到：

     void GetXaml(TextElement element)
    {
        // Position a "navigator" pointer before the opening tag of the element.
        TextPointer navigator = element.ElementStart;

        while (navigator.CompareTo(element.ElementEnd) < 0)
        {
            switch (navigator.GetPointerContext(LogicalDirection.Forward))
            {
                case TextPointerContext.ElementStart:
                    // Output opening tag of a TextElement
                    Console.WriteLine(String.Format("<{0}>", navigator.GetAdjacentElement(LogicalDirection.Forward).GetType().Name));
                    break;
                case TextPointerContext.ElementEnd:
                    // Output closing tag of a TextElement
                    Console.WriteLine(String.Format("</{0}>", navigator.GetAdjacentElement(LogicalDirection.Forward).GetType().Name));
                    break;
                case TextPointerContext.EmbeddedElement:
                    // Output simple tag for embedded element
                    Console.WriteLine(String.Format("<{0}>", navigator.GetAdjacentElement(LogicalDirection.Forward).GetType().Name));
                    break;
                case TextPointerContext.Text:
                    // Output the text content of this text run
                    Console.WriteLine(String.Format("{0}||{1}", navigator.GetTextRunLength(LogicalDirection.Forward),
                        navigator.GetTextInRun(LogicalDirection.Forward)));
                    break;
            }

            // Advance the naviagtor to the next context position.
            navigator = navigator.GetNextContextPosition(LogicalDirection.Forward);

        } 
    } 

Answer 1

这似乎是因为TextRange.Start总是有一个LogicalDirection或向后。因此，它将文本放在前面的元素中。

也许我对我的特殊情况的修正可以帮助你解决你自己的问题：

if (this.Selection.Start.GetPointerContext(LogicalDirection.Backward) == TextPointerContext.ElementStart &&
    this.Selection.End.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.ElementEnd &&
    this.Selection.Start.Parent == this.Selection.End.Parent && this.Selection.Start.Parent is Run)
{
     ((Run)this.Selection.Start.Parent).Text = "NewText";
}