private void Search_Click(object sender, RoutedEventArgs e)//查询定位文本{    List
     
       textRanges = FindWordFromPosition(richTextBox1.Document.ContentStart, txtSearch.Text);    foreach (var range in textRanges)    {        range.ApplyPropertyValue(TextElement.ForegroundProperty, new SolidColorBrush(Colors.Red));        //range.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);        //range.ApplyPropertyValue(TextElement.BackgroundProperty, new SolidColorBrush(Colors.PowderBlue));    }}
     

 

List
     
       FindWordFromPosition(TextPointer position, string word){    List
      
        matchingText = new List
       
        ();    while (position != null)    {        if (position.GetPointerContext(LogicalDirection.Forward) == TextPointerContext.Text)        {            //带有内容的文本            string textRun = position.GetTextInRun(LogicalDirection.Forward);            //查找关键字在这文本中的位置            int indexInRun = textRun.IndexOf(word);            int indexHistory = 0;            while (indexInRun >= 0)            {                TextPointer start = position.GetPositionAtOffset(indexInRun + indexHistory);                TextPointer end = start.GetPositionAtOffset(word.Length);                matchingText.Add(new TextRange(start, end));                indexHistory = indexHistory + indexInRun + word.Length;                textRun = textRun.Substring(indexInRun + word.Length);//去掉已经采集过的内容                indexInRun = textRun.IndexOf(word);//重新判断新的字符串是否还有关键字            }        }        position = position.GetNextContextPosition(LogicalDirection.Forward);    }    return matchingText;}