Flutter 文本解读 6 | RichText 富文本的使用 (中)

abstract class SpanBean {
  SpanBean(this.start, this.end,{this.recognizer});

  final int start;
  final int end;

  String text(String src);

  TextStyle get style;
  
  final GestureRecognizer recognizer;
}
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//包裹规则: `data` 
class WrapSpanBean extends SpanBean {
  WrapSpanBean(int start, int end) : super(start, end);

  @override
  String text(String src) {
    return src.substring(start + 1, end - 1);
  }

  @override
  TextStyle get style => TextStyleSupport.dotWrapStyle;
}
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List _spans = []; // 使用抽象

void parseContent() {
  while (!_scanner.isDone) {
    if (_scanner.scan(RegExp('`.*?`'))) {
      int startIndex = _scanner.lastMatch.start;
      int endIndex = _scanner.lastMatch.end;
      _spans.add(WrapSpanBean(startIndex, endIndex)); // 添加实现
    }
    if (!_scanner.isDone) {
      _scanner.position++;
    }
  }
}

//链接规则: [data](link)
class LinkSpanBean extends SpanBean {
  LinkSpanBean(int start, int end, {GestureRecognizer recognizer})
      : super(start, end, recognizer: recognizer);

  @override
  TextStyle get style => TextStyleSupport.linkStyle;

  @override
  String text(String src) {
    final String target = src.substring(start, end);
    return target.split(']')[0].replaceFirst("[", '');
  }
}
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void parseContent() {
  while (!_scanner.isDone) {
    if (_scanner.scan(RegExp('`.*?`'))) {
      int startIndex = _scanner.lastMatch.start;
      int endIndex = _scanner.lastMatch.end;
      _spans.add(WrapSpanBean(startIndex, endIndex));
    }
    
    if (_scanner.scan(RegExp(r'\[.*?\)'))) {
      int startIndex = _scanner.lastMatch.start;
      int endIndex = _scanner.lastMatch.end;
      final String target = content.substring(startIndex, endIndex);
      String link = target.split('(')[1].replaceFirst(')', '');
      GestureRecognizer recognizer = TapGestureRecognizer()
        ..onTap = () {
          launch(link);
        };
      _spans.add(LinkSpanBean(startIndex, endIndex, recognizer: recognizer));
    }
    
    if (!_scanner.isDone) {
      _scanner.position++;
    }
  }
}

void dispose() {
  _spans.forEach((element) {
    element.recognizer?.dispose();
  });
}

InlineSpan parser() {
  _scanner = StringScanner(content);
  parseContent();
  final List spans = [];
  int currentPosition = 0;
  for (SpanBean span in _spans) {
    if (currentPosition != span.start) {
      spans.add(
          TextSpan(text: content.substring(currentPosition, span.start)));
    }
    
    spans.add(TextSpan(
        style: span.style,
        text: span.text(content),
        recognizer: span.recognizer));
    currentPosition = span.end;
  }
  
  if (currentPosition != content.length)
    spans.add(
        TextSpan(text: content.substring(currentPosition, content.length)));
  return TextSpan(style: TextStyleSupport.defaultStyle, children: spans);
}

RegExp(r'^#+ .*',multiLine: true)

//标题规则: #+ data
class HeadSpanBean extends SpanBean{

  HeadSpanBean(int start, int end,this.lever) : super(start, end);

  final int lever;

  @override
  TextStyle get style => TextStyleSupport.headStyleMap[lever];

  @override
  String text(String src) {
    final String target = src.substring(start, end);
    return target.replaceRange(0, lever + 1, '');
  }
}
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class TextStyleSupport {
  static const TextStyle defaultStyle =
      TextStyle(color: Colors.black, fontSize: 14);

  static const TextStyle dotWrapStyle =
      TextStyle(color: Colors.purple, fontSize: 14);

  static const TextStyle linkStyle = TextStyle(
      color: Colors.blue,
      decoration: TextDecoration.underline,
      decorationColor: Colors.blue);

  static const Map<int,TextStyle>  headStyleMap = {
    1:h1,
    2:h2,
    3:h3,
    4:h4,
    5:h5,
    6:h6,
  };

  static const TextStyle h1 =
      TextStyle(color: Colors.black, fontSize: 24, fontWeight: FontWeight.bold);
  static const TextStyle h2 =
      TextStyle(color: Colors.black, fontSize: 22, fontWeight: FontWeight.bold);
  static const TextStyle h3 =
      TextStyle(color: Colors.black, fontSize: 20, fontWeight: FontWeight.bold);
  static const TextStyle h4 =
      TextStyle(color: Colors.black, fontSize: 18, fontWeight: FontWeight.bold);
  static const TextStyle h5 =
      TextStyle(color: Colors.black, fontSize: 16, fontWeight: FontWeight.bold);
  static const TextStyle h6 =
      TextStyle(color: Colors.black, fontSize: 14, fontWeight: FontWeight.bold);
}
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if (_scanner.scan(RegExp(r'^#+ .*',multiLine: true))) {
  int startIndex = _scanner.lastMatch.start;
  int endIndex = _scanner.lastMatch.end;
  int lever = content.substring(startIndex, endIndex).split(' ')[0].length;
  _spans.add(HeadSpanBean(startIndex, endIndex,lever));
}

//加粗规则: **data**
class BoldSpanBean extends SpanBean{
  BoldSpanBean(int start, int end) : super(start, end);
  @override
  TextStyle get style => TextStyleSupport.bold;
  @override
  String text(String src) {
    return src.substring(start+2, end-2);
  }
}
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if (_scanner.scan(RegExp(r'\*\*.*?\*\*'))) {
  int startIndex = _scanner.lastMatch.start;
  int endIndex = _scanner.lastMatch.end;
  _spans.add(BoldSpanBean(startIndex, endIndex));
}

// 加粗匹配
if (_scanner.scan(RegExp(r'\*\*.*?\*\*'))) {
  int startIndex = _scanner.lastMatch.start;
  int endIndex = _scanner.lastMatch.end;
  _spans.add(BoldSpanBean(startIndex, endIndex));
}

// 倾斜匹配
if (_scanner.scan(RegExp(r'\*.*?\*'))) {
  int startIndex = _scanner.lastMatch.start;
  int endIndex = _scanner.lastMatch.end;
  _spans.add(LeanSpanBean(startIndex, endIndex));
}

//加粗规则: *data*
class LeanSpanBean extends SpanBean{

  LeanSpanBean(int start, int end) : super(start, end);

  @override
  TextStyle get style => TextStyleSupport.lean;

  @override
  String text(String src) {
    return src.substring(start+1, end-1);
  }
}
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