C# 如何将选定文本的开始索引和结束索引转换为精确的TextRange？

我可以在RichTextBox中获得所选文本的确切开始和结束索引，但如何实现相反的操作？使用实际的开始和结束索引（字符位置）再次选择文本作为一个范围，对其执行一些格式化，如突出显示背景

示例-使用鼠标选择的文本与应用的高光不重叠

编辑：

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我只能处理由highlightFromSelection（）方法确定的绝对字符位置。

可能重复的@Harsh请删除重复标志，这是winforms，这是wpf您尝试过这个解决方案吗？我想这里已经回答了：@Harsh我想这是我能找到的最接近的

private void textBox_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    if(this.textBox.Selection.Text.Length > 0)
        highlightFromSelection(this.textBox, new SolidColorBrush(Colors.Yellow));
}

public void highlightFromSelection(RichTextBox textBox, SolidColorBrush color)
{
    TextPointer docStart = textBox.Document.ContentStart;

    TextPointer selectionStart = textBox.Selection.Start;
    TextPointer selectionEnd = textBox.Selection.End;

    TextRange start = new TextRange(docStart, selectionStart);
    TextRange end = new TextRange(docStart, selectionEnd);

    int indexStart = start.Text.Length;
    int indexEnd = end.Text.Length;

    MessageBox.Show("start: " + indexStart + " end: " + indexEnd);

    ApplyHighlight(textBox, indexStart, indexEnd, color);
}

public void ApplyHighlight(RichTextBox textBox, int startIndex, int endIndex, SolidColorBrush color)
{
    TextPointer docStart = textBox.Document.ContentStart;

    //This code highlights the wrong part of text - its the closest I could get 
    //i.e. the highlighting does not overlap exactly with the original selection made

    //TextPointer startPointer = docStart.GetPositionAtOffset(startIndex, LogicalDirection.Forward);
    //TextPointer endPointer = docStart.GetPositionAtOffset(endIndex, LogicalDirection.Backward);
    //TextRange range = new TextRange(startPointer, endPointer);
    //range.ApplyPropertyValue(TextElement.BackgroundProperty, new SolidColorBrush(Colors.Yellow));
}