Flutter如何将文本处理成小说阅读格式

在Flutter中将文本处理成小说阅读格式，主要涉及文本分页、样式设置和翻页交互。以下是核心实现方法：

1. 文本分页核心代码

class TextPagination {
  static List<String> paginateText(String text, double pageWidth, double pageHeight, TextStyle style) {
    List<String> pages = [];
    String currentPage = '';
    
    TextPainter painter = TextPainter(
      textDirection: TextDirection.ltr,
      text: TextSpan(text: '', style: style),
    );
    
    List<String> paragraphs = text.split('\n');
    
    for (String paragraph in paragraphs) {
      if (paragraph.isEmpty) {
        currentPage += '\n';
        continue;
      }
      
      String remainingText = paragraph;
      
      while (remainingText.isNotEmpty) {
        painter.text = TextSpan(text: currentPage + remainingText, style: style);
        painter.layout(maxWidth: pageWidth);
        
        if (painter.didExceedMaxLines || painter.height > pageHeight) {
          // 查找合适的断点
          int breakIndex = _findBreakIndex(currentPage + remainingText, painter, pageHeight);
          
          if (breakIndex > currentPage.length) {
            pages.add(currentPage);
            currentPage = remainingText.substring(breakIndex - currentPage.length);
            remainingText = '';
          } else {
            String line = remainingText;
            int lineBreak = _findLineBreak(line);
            
            if (lineBreak > 0) {
              currentPage += line.substring(0, lineBreak) + '\n';
              remainingText = line.substring(lineBreak);
            } else {
              pages.add(currentPage);
              currentPage = '';
              remainingText = line;
            }
          }
        } else {
          currentPage += remainingText + '\n';
          remainingText = '';
        }
      }
    }
    
    if (currentPage.isNotEmpty) {
      pages.add(currentPage);
    }
    
    return pages;
  }
  
  static int _findBreakIndex(String text, TextPainter painter, double maxHeight) {
    int start = 0;
    int end = text.length;
    
    while (start < end) {
      int mid = (start + end) ~/ 2;
      painter.text = TextSpan(text: text.substring(0, mid), style: painter.text!.style);
      painter.layout();
      
      if (painter.height <= maxHeight) {
        start = mid + 1;
      } else {
        end = mid;
      }
    }
    
    return start - 1;
  }
  
  static int _findLineBreak(String text) {
    // 优先在标点符号后断行
    List<String> breakChars = ['。', '！', '？', ';', '；', '.', '!', '?'];
    for (int i = 0; i < text.length; i++) {
      if (breakChars.contains(text[i])) {
        return i + 1;
      }
    }
    
    // 其次在空格处断行
    int spaceIndex = text.indexOf(' ');
    if (spaceIndex != -1) {
      return spaceIndex + 1;
    }
    
    return -1;
  }
}

2. 阅读器界面实现

class NovelReader extends StatefulWidget {
  final String novelText;
  
  const NovelReader({super.key, required this.novelText});
  
  @override
  _NovelReaderState createState() => _NovelReaderState();
}

class _NovelReaderState extends State<NovelReader> {
  late List<String> pages;
  int currentPage = 0;
  late double pageWidth;
  late double pageHeight;
  
  @override
  void initState() {
    super.initState();
    _paginateText();
  }
  
  void _paginateText() {
    final textStyle = TextStyle(
      fontSize: 18,
      height: 1.6,
      color: Colors.black87,
    );
    
    pages = TextPagination.paginateText(
      widget.novelText,
      pageWidth,
      pageHeight,
      textStyle,
    );
  }
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.grey[100],
      body: SafeArea(
        child: LayoutBuilder(
          builder: (context, constraints) {
            pageWidth = constraints.maxWidth - 40;
            pageHeight = constraints.maxHeight - 40;
            
            if (pages.isEmpty) _paginateText();
            
            return GestureDetector(
              onTapDown: (details) {
                double screenWidth = MediaQuery.of(context).size.width;
                if (details.localPosition.dx < screenWidth / 2) {
                  _previousPage();
                } else {
                  _nextPage();
                }
              },
              child: Container(
                margin: EdgeInsets.all(20),
                padding: EdgeInsets.all(16),
                decoration: BoxDecoration(
                  color: Colors.white,
                  borderRadius: BorderRadius.circular(8),
                  boxShadow: [
                    BoxShadow(
                      color: Colors.black12,
                      blurRadius: 10,
                    ),
                  ],
                ),
                child: pages.isNotEmpty && currentPage < pages.length
                    ? Text(
                        pages[currentPage],
                        style: TextStyle(
                          fontSize: 18,
                          height: 1.6,
                          color: Colors.black87,
                        ),
                      )
                    : Center(child: CircularProgressIndicator()),
              ),
            );
          },
        ),
      ),
    );
  }
  
  void _nextPage() {
    if (currentPage < pages.length - 1) {
      setState(() {
        currentPage++;
      });
    }
  }
  
  void _previousPage() {
    if (currentPage > 0) {
      setState(() {
        currentPage--;
      });
    }
  }
}

3. 关键要点

• 文本分页：基于TextPainter计算文本占用的空间
• 智能断行：优先在标点符号后换行，保持阅读连贯性
• 手势交互：点击屏幕左右区域翻页
• 样式优化：合适的字体大小、行高和边距

4. 使用方式

// 在需要的地方使用
NovelReader(novelText: yourNovelTextString)

这种方法可以处理大多数小说文本，对于更复杂的需求（如章节识别、书签功能等），可以在基础上继续扩展。