3

我正在尝试使用 WPF RichTextEditor 实现基本语法高亮。为此，我想以不同的颜色显示 {} gropus。

这是应该将 RichTextBox 的内容分成不同组的代码：

    List<Tag> SplitIntoParts(TextRange textRange, int level)
    {
        if (textRange==null||textRange.IsEmpty)
        {
            return new List<Tag>();
        }
        string text = textRange.Text;
        if (text.Length==0)
        {
            return new List<Tag>();
        }
        int startPos=-1, counter = 0;
        List<Tag> result=new List<Tag>();
        for (int i = 0; i < text.Length; i++)
        {
            if (text[i]=='{')
            {
                if (counter==0)
                {
                    startPos = i;
                }
                counter++;
            }
            if (text[i]=='}')
            {
                if (counter==1)
                {
                    Tag t = new Tag()
                                {
                                    StartPosition = textRange.Start.GetPositionAtOffset(startPos), 
                                    EndPosition = textRange.Start.GetPositionAtOffset(i+1), 
                                    Level = level,
                                    Word = text.Substring(startPos,i+1-startPos)
                                };
                    result.Add(t);
                    var tr=new TextRange(textRange.Start.GetPositionAtOffset(startPos + 1), textRange.Start.GetPositionAtOffset(i));
                    result.AddRange(SplitIntoParts(tr, level + 1));
                }
                counter--;
            }
        }
        if (counter>0)//some open branches still left
        {
            var i = text.Length;
            Tag t = new Tag()
            {
                StartPosition = textRange.Start.GetPositionAtOffset(startPos),
                EndPosition = textRange.End,
                Level = level,
                Word = text.Substring(startPos, i - startPos)
            };
            result.Add(t);
            result.AddRange(SplitIntoParts(new TextRange(textRange.Start.GetPositionAtOffset(startPos + 1), textRange.Start.GetPositionAtOffset(i - 1)), level + 1));
        }

        return result;
    }

在这段代码中，我发现 textRange.Start.GetPositionAtOffset(startPos + 1) 的行为很奇怪：

假设，代码找到了以下组：

{test|try}

并使用以下代码选择它：

var t=new Tag()
                                {
                                    StartPosition = textRange.Start.GetPositionAtOffset(startPos), 
                                    EndPosition = textRange.Start.GetPositionAtOffset(i+1), 
                                    Level = level,
                                    Word = text.Substring(startPos,i+1-startPos)
                                };

(egtWord=='{test|try}')

当我尝试通过传递递归地做同样的事情时

var tr=new TextRange(textRange.Start.GetPositionAtOffset(startPos + 1), textRange.Start.GetPositionAtOffset(i));
result.AddRange(SplitIntoParts(tr, level + 1));

而不是“test|try”，tr.Text =="{test"

为什么我会出现这种行为，我应该如何处理？

4

2 回答 2

3

GetPositionAtOffset不只计算（可见）字符。幸运的是，我最近遇到了同样的问题，所以我做了一个方法来获取TextPointer指定偏移量（仅计算可见字符的偏移量）。首先，它可能看起来有点复杂，但实际上并非如此:-)。

作为参数，它需要内联（从富文本框中，例如RichTextBox.Document.Blocks.FirstBlock.Inlines，这分别仅获取 rtb 中第一段的内联，如果有的话......）；第二个参数是偏移量本身。

建议给出第三个参数，TextPointer表示内容的开始。如果指定了 inlines，则从第一个 inline 开始确定开始位置，但如果没有 inline，则会引发异常，为避免这种情况，请将 content start 参数设置为RichTextBox.Document.ContentStart。方法如下：

    /// <summary>
    /// Returns the position of the specified offset in the text specified by the inlines.
    /// </summary>
    /// <param name="inlines">The inlines which specifies the text.</param>
    /// <param name="offset">The offset within the text to get the position of.</param>
    /// <param name="contentStartPosition">The position where the content starts. If null, the position before the start of the first inline will be used. If null and there are no inlines, an exception is thrown.</param>
    /// <returns>A <see cref="TextPointer"/> indicating the position of the specified offset.</returns>
    public static TextPointer GetPositionAtOffset(this InlineCollection inlines, int offset, TextPointer contentStartPosition = null)
    {
        if (inlines == null)
            throw new ArgumentNullException(nameof(inlines));
        if (!inlines.Any() && contentStartPosition == null)//if no inlines, can't determine start of content
            throw new ArgumentException("A content start position has to be specified if the inlines collection is empty.", nameof(contentStartPosition));

        if (contentStartPosition == null)
            contentStartPosition = inlines.First().ContentStart.DocumentStart;//if no content start specified, gets it
        int offsetWithInlineBorders = 0;//collects the value of offset (with inline borders)
        foreach (var inline in inlines)
        {
            int inlineLength = (inline as Run)?.Text.Length ?? (inline is LineBreak ? 1 : 0);//gets the length of the inline (length of a Run is the lengts of its text, length of a LineBreak is 1, other types are ignored)

            if (inlineLength < offset)//if position specified by the offset is beyond this inline...
                offsetWithInlineBorders += inlineLength + 2;//...then the whole length is added with the two borders
            else if (inlineLength == offset)//if position specified by the offset is at the end of this inline...
                offsetWithInlineBorders += inlineLength + 1;//...then the whole length is added with only the opening border
            else //inlineLength > value, if the position specified by the offset is within this inline
            {
                offsetWithInlineBorders += offset + 1;//...then adds the remaining length (the offset itself), plus the opening border
                break;//the inlines beyond are not needed
            }
            offset -= inlineLength;//substracts the added inline length
        }

        return contentStartPosition.GetPositionAtOffset(
            Math.Min(Math.Max(offsetWithInlineBorders, 0), contentStartPosition.GetOffsetToPosition(contentStartPosition.DocumentEnd)));//if the value is not within the boundaries of the text, returns the start or the end of the text
    }

祝你好运

于 2017-02-20T22:26:18.513 回答
0

GetPositionAtOffset计数符号，可能超过文本插入位置。见MSDN：

将一个 TextPointer 返回到由当前 TextPointer 开头的指定偏移量（以符号表示）的位置。

于 2013-04-05T16:12:52.877 回答