flutter-quill/lib/widgets/default_styles.dart

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:tuple/tuple.dart';

class QuillStyles extends InheritedWidget {
  final DefaultStyles data;

  QuillStyles({
    Key key,
    @required this.data,
    @required Widget child,
  })  : assert(data != null),
        assert(child != null),
        super(key: key, child: child);

  @override
  bool updateShouldNotify(QuillStyles oldWidget) {
    return data != oldWidget.data;
  }

  static DefaultStyles getStyles(BuildContext context, nullOk) {
    var widget = context.dependOnInheritedWidgetOfExactType<QuillStyles>();
    if (widget == null && nullOk) {
      return null;
    }
    assert(widget != null);
    return widget.data;
  }
}

class DefaultTextBlockStyle {
  final TextStyle style;

  final Tuple2<double, double> verticalSpacing;

  final Tuple2<double, double> lineSpacing;

  final BoxDecoration decoration;

  DefaultTextBlockStyle(
      this.style, this.verticalSpacing, this.lineSpacing, this.decoration);
}

class DefaultStyles {
  final DefaultTextBlockStyle h1;
  final DefaultTextBlockStyle h2;
  final DefaultTextBlockStyle h3;
  final DefaultTextBlockStyle paragraph;
  final TextStyle bold;
  final TextStyle italic;
  final TextStyle underline;
  final TextStyle strikeThrough;
  final TextStyle link;
  final DefaultTextBlockStyle lists;
  final DefaultTextBlockStyle quote;
  final DefaultTextBlockStyle code;
  final DefaultTextBlockStyle indent;
  final DefaultTextBlockStyle align;

  DefaultStyles(
      this.h1,
      this.h2,
      this.h3,
      this.paragraph,
      this.bold,
      this.italic,
      this.underline,
      this.strikeThrough,
      this.link,
      this.lists,
      this.quote,
      this.code,
      this.indent,
      this.align);

  static DefaultStyles getInstance(BuildContext context) {
    ThemeData themeData = Theme.of(context);
    DefaultTextStyle defaultTextStyle = DefaultTextStyle.of(context);
    TextStyle baseStyle = defaultTextStyle.style.copyWith(
      fontSize: 16.0,
      height: 1.3,
    );
    Tuple2<double, double> baseSpacing = Tuple2(6.0, 10);
    String fontFamily;
    switch (themeData.platform) {
      case TargetPlatform.iOS:
      case TargetPlatform.macOS:
        fontFamily = 'Menlo';
        break;
      case TargetPlatform.android:
      case TargetPlatform.fuchsia:
      case TargetPlatform.windows:
      case TargetPlatform.linux:
        fontFamily = 'Roboto Mono';
        break;
      default:
        throw UnimplementedError();
    }

    return DefaultStyles(
        DefaultTextBlockStyle(
            defaultTextStyle.style.copyWith(
              fontSize: 34.0,
              color: defaultTextStyle.style.color.withOpacity(0.70),
              height: 1.15,
              fontWeight: FontWeight.w300,
            ),
            Tuple2(16.0, 0.0),
            Tuple2(0.0, 0.0),
            null),
        DefaultTextBlockStyle(
            defaultTextStyle.style.copyWith(
              fontSize: 24.0,
              color: defaultTextStyle.style.color.withOpacity(0.70),
              height: 1.15,
              fontWeight: FontWeight.normal,
            ),
            Tuple2(8.0, 0.0),
            Tuple2(0.0, 0.0),
            null),
        DefaultTextBlockStyle(
            defaultTextStyle.style.copyWith(
              fontSize: 20.0,
              color: defaultTextStyle.style.color.withOpacity(0.70),
              height: 1.25,
              fontWeight: FontWeight.w500,
            ),
            Tuple2(8.0, 0.0),
            Tuple2(0.0, 0.0),
            null),
        DefaultTextBlockStyle(baseStyle, baseSpacing, Tuple2(0.0, 0.0), null),
        TextStyle(fontWeight: FontWeight.bold),
        TextStyle(fontStyle: FontStyle.italic),
        TextStyle(decoration: TextDecoration.underline),
        TextStyle(decoration: TextDecoration.lineThrough),
        TextStyle(
          color: themeData.accentColor,
          decoration: TextDecoration.underline,
        ),
        DefaultTextBlockStyle(baseStyle, baseSpacing, Tuple2(0.0, 6.0), null),
        DefaultTextBlockStyle(
            TextStyle(color: baseStyle.color.withOpacity(0.6)),
            baseSpacing,
            Tuple2(6.0, 2.0),
            BoxDecoration(
              border: Border(
                left: BorderSide(width: 4, color: Colors.grey.shade300),
              ),
            )),
        DefaultTextBlockStyle(
            TextStyle(
              color: Colors.blue.shade900.withOpacity(0.9),
              fontFamily: fontFamily,
              fontSize: 13.0,
              height: 1.15,
            ),
            baseSpacing,
            Tuple2(0.0, 0.0),
            BoxDecoration(
              color: Colors.grey.shade50,
              borderRadius: BorderRadius.circular(2),
            )),
        DefaultTextBlockStyle(baseStyle, Tuple2(0.0, 0.0), Tuple2(0.0, 0.0), null),
        DefaultTextBlockStyle(baseStyle, Tuple2(0.0, 0.0), Tuple2(0.0, 0.0), null));
  }

  DefaultStyles merge(DefaultStyles other) {
    return DefaultStyles(
        other.h1 ?? this.h1,
        other.h2 ?? this.h2,
        other.h3 ?? this.h3,
        other.paragraph ?? this.paragraph,
        other.bold ?? this.bold,
        other.italic ?? this.italic,
        other.underline ?? this.underline,
        other.strikeThrough ?? this.strikeThrough,
        other.link ?? this.link,
        other.lists ?? this.lists,
        other.quote ?? this.quote,
        other.code ?? this.code,
        other.indent ?? this.indent,
        other.align ?? this.align);
  }
}