WPF FlowDocument - 绝对字符位置

Question

我有一个WPF RichTextBox,我正在键入一些文本,然后解析整个文本进行处理.在这个解析过程中,我有每个单词开头和结尾的绝对字符位置.

我想使用这些字符位置将格式应用于某些单词.但是,我发现FlowDocument使用TextPointer实例来标记文档中的位置.

我发现我可以通过使用开始和结束指针构造TextRange来创建它.一旦我有TextRange,我可以轻松地将格式应用于其中的文本.我一直在使用GetPositionAtOffset为我的角色偏移量获取TextPointer,但怀疑它的偏移量与我的不同,因为所选文本的位置与我的预期略有不同.

我的问题是,如何准确地将绝对字符位置转换为TextPointer？

Answer 1

我没有找到将绝对字符位置转换为TextPosition实例的可靠方法.

我的替代解决方案是修改原始解析以处理单个运行而不是捕获RichTextBox的整个文本.使用与特定Run实例相关的字符位置对我来说是可靠的.我认为将我的思维方式更多地转向WPF的思维方式有所帮助.

我采用以下方法在FlowDocument中导航运行(受http://blogs.msdn.com/prajakta/archive/2006/10/12/customize-richtextbox-to-allow-only-plain-text-input的启发. aspx):

// Get starting pointer
TextPointer navigator = flowDocument.ContentStart;

// While we are not at end of document
while (navigator.CompareTo(flowDocument.ContentEnd) < 0)
{
    // Get text pointer context
    TextPointerContext context = navigator.GetPointerContext(LogicalDirection.Backward);

    // Get parent as run
    Run run = navigator.Parent as Run;

    // If start of text element within run
    if (context == TextPointerContext.ElementStart && run != null)
    {
        // Get text of run
        string runText = run.Text;

        // ToDo: Parse run text
    }

    // Get next text pointer
    navigator = navigator.GetNextContextPosition(LogicalDirection.Forward);
}

Answer 2

我也有这个问题,并最终得到了以下RichTextBox扩展方法.在我的背景下,它完美无瑕!

/// <summary>
/// Gets the text pointer at the given character offset.
/// Each line break will count as 2 chars.
/// </summary>
/// <param name="richTextBox">The rich text box.</param>
/// <param name="offset">The offset.</param>
/// <returns>The TextPointer at the given character offset</returns>
public static TextPointer GetTextPointerAtOffset(this RichTextBox richTextBox, int offset)
{
    var navigator = richTextBox.Document.ContentStart;
    int cnt = 0;

    while (navigator.CompareTo(richTextBox.Document.ContentEnd) < 0)
    {
        switch (navigator.GetPointerContext(LogicalDirection.Forward))
        {
            case TextPointerContext.ElementStart:
                break;
            case TextPointerContext.ElementEnd:
                if (navigator.GetAdjacentElement(LogicalDirection.Forward) is Paragraph)
                    cnt += 2;
                break;
            case TextPointerContext.EmbeddedElement:
                // TODO: Find out what to do here?
                cnt++;
                break;
            case TextPointerContext.Text:
                int runLength = navigator.GetTextRunLength(LogicalDirection.Forward);

                if (runLength > 0 && runLength + cnt < offset)
                {
                    cnt += runLength;
                    navigator = navigator.GetPositionAtOffset(runLength);
                    if (cnt > offset)
                        break;
                    continue;
                }
                cnt++;
                break;
        }

        if (cnt > offset)
            break;

        navigator = navigator.GetPositionAtOffset(1, LogicalDirection.Forward);

    } // End while.

    return navigator;
}