add line decoration

packages/notus/lib/src/document/attributes.dart

 /// List of supported attributes:
 ///
 ///   * [NotusAttribute.bold]
+///   * [NotusAttribute.line]
 ///   * [NotusAttribute.italic]
 ///   * [NotusAttribute.link]
 ///   * [NotusAttribute.heading]
 class NotusAttribute<T> implements NotusAttributeBuilder<T> {
   static final Map<String, NotusAttributeBuilder> _registry = {
     NotusAttribute.bold.key: NotusAttribute.bold,
+    NotusAttribute.line.key: NotusAttribute.line,
     NotusAttribute.italic.key: NotusAttribute.italic,
     NotusAttribute.link.key: NotusAttribute.link,
     NotusAttribute.heading.key: NotusAttribute.heading,
   static const link = LinkAttributeBuilder._();
 
   // Line attributes
+  static const line = LineAttributeBuilder._();
+
+  /// Alias for [NotusAttribute.line.underline].
+  static NotusAttribute<String> get underline => line.underline;
+
+  /// Alias for [NotusAttribute.line.deleteline].
+  static NotusAttribute<String> get deleteline => line.deleteline;
 
   /// Heading style attribute.
   // ignore: const_eval_throws_exception
   /// Alias for [NotusAttribute.heading.level3].
   static NotusAttribute<int> get h3 => heading.level3;
 
+  /// Alias for [NotusAttribute.heading.level4].
+  static NotusAttribute<int> get h4 => heading.level4;
+
+  /// Alias for [NotusAttribute.heading.level5].
+  static NotusAttribute<int> get h5 => heading.level5;
+
+  /// Alias for [NotusAttribute.heading.level6].
+  static NotusAttribute<int> get h6 => heading.level6;
+
   /// Block attribute
   // ignore: const_eval_throws_exception
   static const block = BlockAttributeBuilder._();
   /// Returns collection of all attributes in this set.
   Iterable<NotusAttribute> get values => _data.values;
 
-  /// Puts [attribute] into this attribute set and returns result as a new set.
+  /// Puts [ 
   NotusStyle put(NotusAttribute attribute) {
     final result = Map<String, NotusAttribute>.from(_data);
     result[attribute.key] = attribute;
       NotusAttribute<String>._(key, scope, value);
 }
 
+class LineAttributeBuilder extends NotusAttributeBuilder<String> {
+  static const _kLine = 'line';
+  const LineAttributeBuilder._()
+      : super._(_kLine, NotusAttributeScope.inline);
+
+  // underline
+  NotusAttribute<String> get underline => NotusAttribute<String>._(key, scope, 'underline');
+
+  // deleteline
+  NotusAttribute<String> get deleteline => NotusAttribute<String>._(key, scope, 'deleteline');
+}
+
 /// Builder for heading attribute styles.
 ///
 /// There is no need to use this class directly, consider using
 
   /// Level 3 heading, equivalent of `H3` in HTML.
   NotusAttribute<int> get level3 => NotusAttribute<int>._(key, scope, 3);
+
+  /// Level 3 heading, equivalent of `H4` in HTML.
+  NotusAttribute<int> get level4 => NotusAttribute<int>._(key, scope, 4);
+
+  /// Level 3 heading, equivalent of `H5` in HTML.
+  NotusAttribute<int> get level5 => NotusAttribute<int>._(key, scope, 5);
+
+  /// Level 3 heading, equivalent of `H6` in HTML.
+  NotusAttribute<int> get level6 => NotusAttribute<int>._(key, scope, 6);
 }
 
 /// Builder for block attribute styles (number/bullet lists, code and quote).

packages/zefyr/example/lib/src/full_page.dart

 }
 
 final doc =
-    r'[{"insert":"Zefyr"},{"insert":"\n","attributes":{"heading":1}},{"insert":"Soft and gentle rich text editing for Flutter applications.","attributes":{"i":true}},{"insert":"\n"},{"insert":"​","attributes":{"embed":{"type":"image","source":"asset://images/breeze.jpg"}}},{"insert":"\n"},{"insert":"Photo by Hiroyuki Takeda.","attributes":{"i":true}},{"insert":"\nZefyr is currently in "},{"insert":"early preview","attributes":{"b":true}},{"insert":". If you have a feature request or found a bug, please file it at the "},{"insert":"issue tracker","attributes":{"a":"https://github.com/memspace/zefyr/issues"}},{"insert":'
-    r'".\nDocumentation"},{"insert":"\n","attributes":{"heading":3}},{"insert":"Quick Start","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/quick_start.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Data Format and Document Model","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/data_and_document.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Style Attributes","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/attr'
-    r'ibutes.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Heuristic Rules","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/heuristics.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"FAQ","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/faq.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Clean and modern look"},{"insert":"\n","attributes":{"heading":2}},{"insert":"Zefyr’s rich text editor is built with simplicity and fle'
-    r'xibility in mind. It provides clean interface for distraction-free editing. Think Medium.com-like experience.\nMarkdown inspired semantics"},{"insert":"\n","attributes":{"heading":2}},{"insert":"Ever needed to have a heading line inside of a quote block, like this:\nI’m a Markdown heading"},{"insert":"\n","attributes":{"block":"quote","heading":3}},{"insert":"And I’m a regular paragraph"},{"insert":"\n","attributes":{"block":"quote"}},{"insert":"Code blocks"},{"insert":"\n","attributes":{"headin'
-    r'g":2}},{"insert":"Of course:\nimport ‘package:flutter/material.dart’;"},{"insert":"\n","attributes":{"block":"code"}},{"insert":"import ‘package:zefyr/zefyr.dart’;"},{"insert":"\n\n","attributes":{"block":"code"}},{"insert":"void main() {"},{"insert":"\n","attributes":{"block":"code"}},{"insert":" runApp(MyZefyrApp());"},{"insert":"\n","attributes":{"block":"code"}},{"insert":"}"},{"insert":"\n","attributes":{"block":"code"}},{"insert":"\n\n\n"}]';
+    r'[{"insert":"Zefyr", "attributes":{"line": "underline"}},{"insert":"\n"}]';
+    
+    
+    // ,{"insert":"\n","attributes":{"heading":1}},{"insert":"Soft and gentle rich text editing for Flutter applications.","attributes":{"i":true}},{"insert":"\n"},{"insert":"​","attributes":{"embed":{"type":"image","source":"asset://images/breeze.jpg"}}},{"insert":"\n"},{"insert":"Photo by Hiroyuki Takeda.","attributes":{"i":true}},{"insert":"\nZefyr is currently in "},{"insert":"early preview","attributes":{"b":true}},{"insert":". If you have a feature request or found a bug, please file it at the "},{"insert":"issue tracker","attributes":{"a":"https://github.com/memspace/zefyr/issues"}},{"insert":'
+    // r'".\nDocumentation"},{"insert":"\n","attributes":{"heading":3}},{"insert":"Quick Start","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/quick_start.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Data Format and Document Model","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/data_and_document.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Style Attributes","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/attr'
+    // r'ibutes.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Heuristic Rules","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/heuristics.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"FAQ","attributes":{"a":"https://github.com/memspace/zefyr/blob/master/doc/faq.md"}},{"insert":"\n","attributes":{"block":"ul"}},{"insert":"Clean and modern look"},{"insert":"\n","attributes":{"heading":2}},{"insert":"Zefyr’s rich text editor is built with simplicity and fle'
+    // r'xibility in mind. It provides clean interface for distraction-free editing. Think Medium.com-like experience.\nMarkdown inspired semantics"},{"insert":"\n","attributes":{"heading":2}},{"insert":"Ever needed to have a heading line inside of a quote block, like this:\nI’m a Markdown heading"},{"insert":"\n","attributes":{"block":"quote","heading":3}},{"insert":"And I’m a regular paragraph"},{"insert":"\n","attributes":{"block":"quote"}},{"insert":"Code blocks"},{"insert":"\n","attributes":{"headin'
+    // r'g":2}},{"insert":"Of course:\nimport ‘package:flutter/material.dart’;"},{"insert":"\n","attributes":{"block":"code"}},{"insert":"import ‘package:zefyr/zefyr.dart’;"},{"insert":"\n\n","attributes":{"block":"code"}},{"insert":"void main() {"},{"insert":"\n","attributes":{"block":"code"}},{"insert":" runApp(MyZefyrApp());"},{"insert":"\n","attributes":{"block":"code"}},{"insert":"}"},{"insert":"\n","attributes":{"block":"code"}},{"insert":"\n\n\n"}]';
 
 Delta getDelta() {
   return Delta.fromJson(json.decode(doc) as List);
         ],
       ),
       body: ZefyrScaffold(
-        child: ZefyrEditor(
-          autofocus: false,
-          controller: _controller,
-          focusNode: _focusNode,
-          mode: ZefyrMode.edit,
-          imageDelegate: CustomImageDelegate(),
-          keyboardAppearance: _darkTheme ? Brightness.dark : Brightness.light,
+        child: ZefyrTheme(
+          data: ZefyrThemeData(
+            // attributeTheme: AttributeTheme(
+            //   link: TextStyle(
+            //     color: Colors.red,
+            //   ),
+            // ),
+          ),
+          child: ZefyrEditor(
+            autofocus: false,
+            controller: _controller,
+            focusNode: _focusNode,
+            mode: ZefyrMode.edit,
+            imageDelegate: CustomImageDelegate(),
+            linkDelegate: CustomLinkDelegate(),
+            keyboardAppearance: _darkTheme ? Brightness.dark : Brightness.light,
+          ),
         ),
       ),
     );

packages/zefyr/example/lib/src/images.dart

     // return compressFile.uri.toString();
   }
 }
+
+class CustomLinkDelegate implements ZefyrLinkDelegate {
+
+  @override
+  Future<ZefyrLinkEntity> fillLink(BuildContext context, ZefyrLinkEntity value) async {
+    TextEditingController _controller = TextEditingController();
+    return showGeneralDialog<ZefyrLinkEntity>(
+      context: context,
+      pageBuilder: (BuildContext buildContext, Animation<double> animation,
+          Animation<double> secondaryAnimation) {
+        return GestureDetector(
+          onTap: () {
+            Navigator.pop(buildContext);
+          },
+          child: Material(
+            type: MaterialType.transparency,
+            child: Center(
+              child: Container(
+                height: 200,
+                width: 200,
+                color: Colors.white,
+                child: Column(
+                  children: <Widget>[
+                    TextField(controller: _controller,),
+                    FlatButton(
+                      onPressed: () {
+                        Navigator.pop(buildContext, ZefyrLinkEntity(
+                          text: '测试用',
+                          url: _controller.text,
+                        ));
+                      },
+                      child: Text('确定'),
+                    )
+                  ],
+                ),
+              ),
+            ),
+          ),
+        );
+      },
+      barrierDismissible: true,
+      barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
+      barrierColor: Colors.black45,
+      transitionDuration: const Duration(milliseconds: 150),
+      transitionBuilder: _buildMaterialDialogTransitions,
+      useRootNavigator: true,
+    );
+  }
+  
+}
+
+Widget _buildMaterialDialogTransitions(
+    BuildContext context,
+    Animation<double> animation,
+    Animation<double> secondaryAnimation,
+    Widget child) {
+  return FadeTransition(
+    opacity: CurvedAnimation(
+      parent: animation,
+      curve: Curves.easeOut,
+    ),
+    child: child,
+  );
+}

packages/zefyr/lib/src/widgets/buttons.dart

 import 'package:photo_manager/photo_manager.dart';
 import 'package:url_launcher/url_launcher.dart';
 
+import 'link.dart';
 import 'scope.dart';
 import 'theme.dart';
 import 'toolbar.dart';
     return toolbar.buildButton(
       context,
       ZefyrToolbarAction.link,
-      onPressed: enabled ? showOverlay : null,
+      // onPressed: enabled ? showOverlay : null,
+      onPressed: showOverlay,
     );
   }
 
     return defaultValue;
   }
 
-  void showOverlay() {
+  OverlayEntry _overlayEntry;
+
+  Future<void> showOverlay() async {
     final toolbar = ZefyrToolbar.of(context);
-    toolbar.showOverlay(buildOverlay, ZefyrToolbarAction.link).whenComplete(cancelEdit);
+    var _selection = toolbar.editor.selection;
+    var value = ZefyrLinkEntity();
+    if (hasLink(toolbar.editor.selectionStyle)) {
+      value = value.copyWith(url: toolbar.editor.selectionStyle.value(NotusAttribute.link));
+    }
+    // 已选中
+    if(!toolbar.editor.selection.isCollapsed) {
+      var text = toolbar.editor.controller.document.toPlainText().substring(toolbar.editor.selection.start, toolbar.editor.selection.end);
+      value = value.copyWith(text: text);
+    };
+    var result = await toolbar.editor.linkDelegate.fillLink(context, value);
+    
+    if (result != null) {
+      toolbar.editor.updateSelection(_selection, source: ChangeSource.local);
+      _selection = toolbar.editor.selection;
+      toolbar.editor.controller.replaceText(_selection.start, _selection.end - _selection.start, result.text, selection: _selection.copyWith(
+        baseOffset: _selection.start,
+        extentOffset: _selection.start + result.text.length,
+      ));
+      toolbar.editor.formatSelection(NotusAttribute.link.fromString(result.url));
+    }
   }
 
   void closeOverlay() {

packages/zefyr/lib/src/widgets/common.dart

     if (style.containsSame(NotusAttribute.bold)) {
       result = result.merge(theme.attributeTheme.bold);
     }
+    if (style.contains(NotusAttribute.line)) {
+      final _style = style.get(NotusAttribute.line);
+      if (_style == NotusAttribute.line.underline) {
+        result = result.merge(theme.attributeTheme.underline);
+      } else if (_style == NotusAttribute.line.deleteline) {
+        result = result.merge(theme.attributeTheme.deleteline);
+      }
+    }
     if (style.containsSame(NotusAttribute.italic)) {
       result = result.merge(theme.attributeTheme.italic);
     }

packages/zefyr/lib/src/widgets/controller.dart

       // Add the attribute to our toggledStyle. It will be used later upon insertion.
       _toggledStyles = toggledStyles.put(attribute);
     }
+    // if (attribute.key == NotusAttribute.underline.key) {
+    //   if ((attribute.value ?? false) == true) {
+    //     toggledStyles.merge(NotusAttribute.deleteline);
+    //   }
+    // }
+    // if (attribute.key == NotusAttribute.deleteline.key) {
+    //   if ((attribute.value ?? false) == true) {
+    //     toggledStyles.merge(NotusAttribute.underline);
+    //   }
+    // }
+    // if (change.last.key == '')
 
     // Transform selection against the composed change and give priority to
     // the change. This is needed in cases when format operation actually

packages/zefyr/lib/src/widgets/editable_text.dart

         return ZefyrHeading(node: node);
       }
       return ZefyrParagraph(node: node);
+      //  else if (node.style.contains(NotusAttribute.line)) {
+      //   return ZefyrLineDecoration(node: node);
+      // }
     }
 
     final BlockNode block = node;

packages/zefyr/lib/src/widgets/editor.dart

 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
+import 'package:zefyr/src/widgets/link.dart';
 
 import 'controller.dart';
 import 'editable_text.dart';
 import 'image.dart';
-import 'input.dart';
 import 'mode.dart';
 import 'scaffold.dart';
 import 'scope.dart';
     this.padding = const EdgeInsets.symmetric(horizontal: 16.0),
     this.toolbarDelegate,
     this.imageDelegate,
+    this.linkDelegate,
     this.selectionControls,
     this.physics,
     this.keyboardAppearance,
   /// This delegate is required if embedding images is allowed.
   final ZefyrImageDelegate imageDelegate;
 
+  final ZefyrLinkDelegate linkDelegate;
+
   /// Optional delegate for building the text selection handles and toolbar.
   ///
   /// If not provided then platform-specific implementation is used by default.
 
 class _ZefyrEditorState extends State<ZefyrEditor> {
   ZefyrImageDelegate _imageDelegate;
+  ZefyrLinkDelegate _linkDelegate;
   ZefyrScope _scope;
   ZefyrThemeData _themeData;
   GlobalKey<ZefyrToolbarState> _toolbarKey;
   void initState() {
     super.initState();
     _imageDelegate = widget.imageDelegate;
+    _linkDelegate = widget.linkDelegate;
   }
 
   @override
       _imageDelegate = widget.imageDelegate;
       _scope.imageDelegate = _imageDelegate;
     }
+    if (widget.linkDelegate != oldWidget.linkDelegate) {
+      _linkDelegate = widget.linkDelegate;
+      _scope.linkDelegate = _linkDelegate;
+    }
   }
 
   @override
       _scope = ZefyrScope.editable(
         mode: widget.mode,
         imageDelegate: _imageDelegate,
+        linkDelegate: _linkDelegate,
         controller: widget.controller,
         focusNode: widget.focusNode,
         focusScope: FocusScope.of(context),

packages/zefyr/lib/src/widgets/image.dart

 import 'package:meta/meta.dart';
 import 'package:notus/notus.dart';
 import 'package:zefyr/zefyr.dart';
-import 'package:photo_manager/photo_manager.dart';
 
 import 'editable_box.dart';
 

packages/zefyr/lib/src/widgets/link.dart

+import 'package:flutter/material.dart';
+import 'package:meta/meta.dart';
+
+class ZefyrLinkEntity {
+  const ZefyrLinkEntity({this.text = '', this.url = ''});
+  final String text;
+  final String url;
+
+  ZefyrLinkEntity copyWith({
+    String text,
+    String url,
+  }) {
+    return ZefyrLinkEntity(
+      text: text ?? this.text,
+      url: url ?? this.url,
+    );
+  }
+
+  @override
+  String toString() => 'text: $text, url: $url';
+}
+
+@experimental
+abstract class ZefyrLinkDelegate {
+
+  Future<ZefyrLinkEntity> fillLink(BuildContext context, ZefyrLinkEntity value);
+}

packages/zefyr/lib/src/widgets/list.dart

       );
       padding = blockTheme.linePadding;
     }
-
+    //  else if (node.style.contains(NotusAttribute.line)) {
+    //   textStyle = ZefyrLineDecoration.themeOf(node, context);
+    //   padding = theme.defaultLineTheme.padding;
+    //   content = ZefyrLineDecoration(node: node);
+    // }
     Widget bullet =
         SizedBox(width: 24.0, child: Text(bulletText, style: textStyle));
     if (padding != null) {

packages/zefyr/lib/src/widgets/paragraph.dart

   }
 }
 
+class ZefyrLineDecoration extends StatelessWidget {
+  ZefyrLineDecoration({Key key, @required this.node, this.blockStyle})
+      : super(key: key);
+
+  final LineNode node;
+  final TextStyle blockStyle;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = ZefyrTheme.of(context);
+    TextStyle style = themeOf(node, context);
+    if (blockStyle != null) {
+      style = style.merge(blockStyle);
+    }
+    return ZefyrLine(
+      node: node,
+      style: style,
+      padding: theme.defaultLineTheme.padding,
+    );
+  }
+
+  static TextStyle themeOf(LineNode node, BuildContext context) {
+    final theme = ZefyrTheme.of(context);
+    final style = node.style.get(NotusAttribute.line);
+    if (style == NotusAttribute.line.underline) {
+      return theme.attributeTheme.underline;
+    } else if (style == NotusAttribute.line.deleteline) {
+      return theme.attributeTheme.deleteline;
+    }
+    throw UnimplementedError('Unsupported heading style $style');
+  }
+}
+
 /// Represents heading-styled line in [ZefyrEditor].
 class ZefyrHeading extends StatelessWidget {
   ZefyrHeading({Key key, @required this.node, this.blockStyle})
       return theme.attributeTheme.heading2;
     } else if (style == NotusAttribute.heading.level3) {
       return theme.attributeTheme.heading3;
+    } else if (style == NotusAttribute.heading.level4) {
+      return theme.attributeTheme.heading4;
+    } else if (style == NotusAttribute.heading.level5) {
+      return theme.attributeTheme.heading5;
+    } else if (style == NotusAttribute.heading.level6) {
+      return theme.attributeTheme.heading6;
     }
     throw UnimplementedError('Unsupported heading style $style');
   }

packages/zefyr/lib/src/widgets/scope.dart

 import 'editor.dart';
 import 'image.dart';
 import 'input.dart';
+import 'link.dart';
 import 'mode.dart';
 import 'render_context.dart';
 import 'toolbar.dart';
     @required FocusNode focusNode,
     @required FocusScopeNode focusScope,
     ZefyrImageDelegate imageDelegate,
+    ZefyrLinkDelegate linkDelegate,
   })  : assert(mode != null),
         assert(controller != null),
         assert(focusNode != null),
         _mode = mode,
         _controller = controller,
         _imageDelegate = imageDelegate,
+        _linkDelegate = linkDelegate,
         _focusNode = focusNode,
         _focusScope = focusScope,
         _cursorTimer = CursorTimer(),
     }
   }
 
+  ZefyrLinkDelegate _linkDelegate;
+  ZefyrLinkDelegate get linkDelegate => _linkDelegate;
+  set linkDelegate(ZefyrLinkDelegate value) {
+    if (_linkDelegate != value) {
+      _linkDelegate = value;
+      notifyListeners();
+    }
+  }
+
   ZefyrMode _mode;
   ZefyrMode get mode => _mode;
   set mode(ZefyrMode value) {

packages/zefyr/lib/src/widgets/theme.dart

   /// Style used to render "bold" text.
   final TextStyle bold;
 
+  /// Style used to render "underline" text.
+  final TextStyle underline;
+
+  /// Style used to render "deleteline" text.
+  final TextStyle deleteline;
+
   /// Style used to render "italic" text.
   final TextStyle italic;
 
   /// Style theme used to render smaller headings.
   final LineTheme heading3;
 
+  /// Style theme used to render largest headings.
+  final LineTheme heading4;
+
+  /// Style theme used to render medium headings.
+  final LineTheme heading5;
+
+  /// Style theme used to render smaller headings.
+  final LineTheme heading6;
+
   /// Style theme used to render bullet lists.
   final BlockTheme bulletList;
 
   /// Creates a [AttributeTheme] given a set of exact values.
   AttributeTheme({
     this.bold,
+    this.underline,
+    this.deleteline,
     this.italic,
     this.link,
     this.heading1,
     this.heading2,
     this.heading3,
+    this.heading4,
+    this.heading5,
+    this.heading6,
     this.bulletList,
     this.numberList,
     this.quote,
 
     return AttributeTheme(
       bold: TextStyle(fontWeight: FontWeight.bold),
+      underline: defaultLineTheme.textStyle.copyWith(decoration: TextDecoration.underline),
+      deleteline: defaultLineTheme.textStyle.copyWith(decoration: TextDecoration.lineThrough),
       italic: TextStyle(fontStyle: FontStyle.italic),
       link: TextStyle(
         decoration: TextDecoration.underline,
       ),
       heading1: LineTheme(
         textStyle: defaultLineTheme.textStyle.copyWith(
-          fontSize: 34.0,
+          fontSize: 38.0,
           color: defaultLineTheme.textStyle.color.withOpacity(0.7),
           height: 1.15,
           fontWeight: FontWeight.w300,
       ),
       heading2: LineTheme(
         textStyle: defaultLineTheme.textStyle.copyWith(
-          fontSize: 24.0,
+          fontSize: 34.0,
           color: defaultLineTheme.textStyle.color.withOpacity(0.7),
           height: 1.15,
           fontWeight: FontWeight.normal,
         ),
-        padding: EdgeInsets.only(top: 8.0),
+        padding: EdgeInsets.only(top: 16.0),
       ),
       heading3: LineTheme(
         textStyle: defaultLineTheme.textStyle.copyWith(
-          fontSize: 20.0,
+          fontSize: 30.0,
+          color: defaultLineTheme.textStyle.color.withOpacity(0.7),
+          height: 1.15,
+          fontWeight: FontWeight.w500,
+        ),
+        padding: EdgeInsets.only(top: 16.0),
+      ),
+      heading4: LineTheme(
+        textStyle: defaultLineTheme.textStyle.copyWith(
+          fontSize: 26.0,
+          color: defaultLineTheme.textStyle.color.withOpacity(0.7),
+          height: 1.15,
+          fontWeight: FontWeight.w500,
+        ),
+        padding: EdgeInsets.only(top: 12.0),
+      ),
+      heading5: LineTheme(
+        textStyle: defaultLineTheme.textStyle.copyWith(
+          fontSize: 22.0,
           color: defaultLineTheme.textStyle.color.withOpacity(0.7),
           height: 1.15,
           fontWeight: FontWeight.w500,
         ),
         padding: EdgeInsets.only(top: 8.0),
       ),
+      heading6: LineTheme(
+        textStyle: defaultLineTheme.textStyle.copyWith(
+          fontSize: 18.0,
+          color: defaultLineTheme.textStyle.color.withOpacity(0.7),
+          height: 1.15,
+          fontWeight: FontWeight.w500,
+        ),
+        padding: EdgeInsets.only(top: 4.0),
+      ),
       bulletList: BlockTheme(
         padding: EdgeInsets.symmetric(vertical: 8.0),
         linePadding: EdgeInsets.symmetric(vertical: 2.0),
   /// been merged with the matching property from the `other` object.
   AttributeTheme copyWith({
     TextStyle bold,
+    TextStyle underline,
     TextStyle italic,
     TextStyle link,
     LineTheme heading1,
     LineTheme heading2,
     LineTheme heading3,
+    LineTheme heading4,
+    LineTheme heading5,
+    LineTheme heading6,
     BlockTheme bulletList,
     BlockTheme numberList,
     BlockTheme quote,
   }) {
     return AttributeTheme(
       bold: bold ?? this.bold,
+      underline: underline ?? this.underline,
       italic: italic ?? this.italic,
       link: link ?? this.link,
       heading1: heading1 ?? this.heading1,
       heading2: heading2 ?? this.heading2,
       heading3: heading3 ?? this.heading3,
+      heading4: heading4 ?? this.heading4,
+      heading5: heading5 ?? this.heading5,
+      heading6: heading6 ?? this.heading6,
       bulletList: bulletList ?? this.bulletList,
       numberList: numberList ?? this.numberList,
       quote: quote ?? this.quote,
     if (other == null) return this;
     return copyWith(
       bold: bold?.merge(other.bold) ?? other.bold,
+      underline: underline?.merge(other.underline) ?? other.underline,
       italic: italic?.merge(other.italic) ?? other.italic,
       link: link?.merge(other.link) ?? other.link,
       heading1: heading1?.merge(other.heading1) ?? other.heading1,
       heading2: heading2?.merge(other.heading2) ?? other.heading2,
       heading3: heading3?.merge(other.heading3) ?? other.heading3,
+      heading4: heading4?.merge(other.heading4) ?? other.heading4,
+      heading5: heading5?.merge(other.heading5) ?? other.heading5,
+      heading6: heading6?.merge(other.heading6) ?? other.heading6,
       bulletList: bulletList?.merge(other.bulletList) ?? other.bulletList,
       numberList: numberList?.merge(other.numberList) ?? other.numberList,
       quote: quote?.merge(other.quote) ?? other.quote,
     if (other.runtimeType != runtimeType) return false;
     final AttributeTheme otherTheme = other;
     return (otherTheme.bold == bold) &&
+        (otherTheme.underline == underline) &&
         (otherTheme.italic == italic) &&
         (otherTheme.link == link) &&
         (otherTheme.heading1 == heading1) &&
         (otherTheme.heading2 == heading2) &&
         (otherTheme.heading3 == heading3) &&
+        (otherTheme.heading4 == heading4) &&
+        (otherTheme.heading5 == heading5) &&
+        (otherTheme.heading6 == heading6) &&
         (otherTheme.bulletList == bulletList) &&
         (otherTheme.numberList == numberList) &&
         (otherTheme.quote == quote) &&
   int get hashCode {
     return hashList([
       bold,
+      underline,
       italic,
       link,
       heading1,
       heading2,
       heading3,
+      heading4,
+      heading5,
+      heading6,
       bulletList,
       numberList,
       quote,

packages/zefyr/lib/src/widgets/toolbar.dart

 
 final kZefyrToolbarAttributeActions = <ZefyrToolbarAction, NotusAttributeKey>{
   ZefyrToolbarAction.bold: NotusAttribute.bold,
+  ZefyrToolbarAction.underline: NotusAttribute.underline,
+  ZefyrToolbarAction.deleteline: NotusAttribute.deleteline,
   ZefyrToolbarAction.italic: NotusAttribute.italic,
   ZefyrToolbarAction.link: NotusAttribute.link,
   // ZefyrToolbarAction.text: NotusAttribute.heading,
   ZefyrToolbarAction.headingLevel1: NotusAttribute.heading.level1,
   ZefyrToolbarAction.headingLevel2: NotusAttribute.heading.level2,
   ZefyrToolbarAction.headingLevel3: NotusAttribute.heading.level3,
+  ZefyrToolbarAction.headingLevel4: NotusAttribute.heading.level4,
+  ZefyrToolbarAction.headingLevel5: NotusAttribute.heading.level5,
+  ZefyrToolbarAction.headingLevel6: NotusAttribute.heading.level6,
   ZefyrToolbarAction.bulletList: NotusAttribute.block.bulletList,
   ZefyrToolbarAction.numberList: NotusAttribute.block.numberList,
   ZefyrToolbarAction.code: NotusAttribute.block.code,

packages/zefyr/lib/src/widgets/view.dart

         return ZefyrHeading(node: node);
       }
       return ZefyrParagraph(node: node);
+      //  else if (node.style.contains(NotusAttribute.line)) {
+      //   return ZefyrLineDecoration(node: node);
+      // }
     }
 
     final BlockNode block = node;

packages/zefyr/lib/zefyr.dart

 export 'src/widgets/field.dart';
 export 'src/widgets/horizontal_rule.dart';
 export 'src/widgets/image.dart';
+export 'src/widgets/link.dart';
 export 'src/widgets/list.dart';
 export 'src/widgets/mode.dart';
 export 'src/widgets/paragraph.dart';