Add default styles and text line

lib/models/documents/nodes/line.dart

@@ -17,6 +17,14 @@ class Line extends Container<Leaf> {
   @override
   int get length => super.length + 1;
 
+  bool get hasEmbed {
+    if (childCount != 1) {
+      return false;
+    }
+
+    return children.single is Embed;
+  }
+
   Line get nextLine {
     if (!isLast) {
       return next is Block ? (next as Block).first : next;

lib/models/documents/nodes/node.dart

@@ -41,6 +41,30 @@ abstract class Node extends LinkedListEntry<Node> {
     return node;
   }
 
+  int getOffset() {
+    int offset = 0;
+
+    if (isFirst) {
+      return offset;
+    }
+
+    Node cur = this;
+    do {
+      cur = cur.previous;
+      offset += cur.length;
+    } while (!cur.isFirst);
+    return offset;
+  }
+
+  int getDocumentOffset() {
+    return parent is! Root ? parent.getDocumentOffset() : 0 + getOffset();
+  }
+
+  bool containsOffset(int offset) {
+    return getDocumentOffset() <= offset &&
+        offset < getDocumentOffset() + this.length;
+  }
+
   @override
   void insertBefore(Node entry) {
     assert(entry.parent == null && parent != null);

lib/models/documents/style.dart

@@ -29,6 +29,8 @@ class Style {
 
   Iterable<Attribute> get values => _attributes.values;
 
+  Map<String, Attribute> get attributes => _attributes;
+
   bool get isEmpty => _attributes.isEmpty;
 
   bool get isNotEmpty => _attributes.isNotEmpty;

lib/widgets/box.dart

@@ -0,0 +1,38 @@
+import 'package:flutter/rendering.dart';
+import 'package:flutter_quill/models/documents/nodes/container.dart';
+
+abstract class RenderContentProxyBox implements RenderBox {
+  double getPreferredLineHeight();
+
+  Offset getOffsetForCaret(TextPosition position, Rect caretPrototype);
+
+  TextPosition getPositionForOffset(Offset offset);
+
+  double getFullHeightForCaret(TextPosition position);
+
+  TextRange getWordBoundary(TextPosition position);
+
+  List<TextBox> getBoxesForSelection(TextSelection textSelection);
+}
+
+abstract class RenderEditableBox extends RenderBox {
+  Container getContainer();
+
+  double preferredLineHeight(TextPosition position);
+
+  Offset getOffsetForCaret(TextPosition position);
+
+  TextPosition getPositionForOffset(Offset offset);
+
+  TextPosition getPositionAbove(TextPosition position);
+
+  TextPosition getPositionBelow(TextPosition position);
+
+  TextRange getWordBoundary(TextPosition position);
+
+  TextRange getLineBoundary(TextPosition position);
+
+  TextSelectionPoint getBaseEndpointForSelection(TextSelection textSelection);
+
+  TextSelectionPoint getExtentEndpointForSelection(TextSelection textSelection);
+}

lib/widgets/cursor.dart

@@ -1,5 +1,8 @@
+import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
+import 'box.dart';
+
 const Duration _FADE_DURATION = Duration(milliseconds: 250);
 
 class CursorStyle {
@@ -53,10 +56,9 @@ class CursorStyle {
 }
 
 class CursorCont extends ChangeNotifier {
-
   final ValueNotifier<bool> show;
   final ValueNotifier<bool> _blink;
-  final ValueNotifier<Color> _color;
+  final ValueNotifier<Color> color;
   AnimationController _blinkOpacityCont;
   CursorStyle _style;
 
@@ -70,14 +72,89 @@ class CursorCont extends ChangeNotifier {
         show = show ?? ValueNotifier<bool>(false),
         _style = style,
         _blink = ValueNotifier(false),
-        _color = ValueNotifier(style.color) {
+        color = ValueNotifier(style.color) {
     _blinkOpacityCont =
         AnimationController(vsync: tickerProvider, duration: _FADE_DURATION);
     _blinkOpacityCont.addListener(_onColorTick);
   }
 
   void _onColorTick() {
-    _color.value = _style.color.withOpacity(_blinkOpacityCont.value);
+    color.value = _style.color.withOpacity(_blinkOpacityCont.value);
     _blink.value = show.value && _blinkOpacityCont.value > 0;
   }
 }
+
+class CursorPainter {
+  final RenderContentProxyBox editable;
+  final CursorStyle style;
+  final Rect prototype;
+  final Color color;
+  final double devicePixelRatio;
+
+  CursorPainter(this.editable, this.style, this.prototype, this.color,
+      this.devicePixelRatio);
+
+  paint(Canvas canvas, Offset offset, TextPosition position) {
+    assert(prototype != null);
+
+    Offset caretOffset =
+        editable.getOffsetForCaret(position, prototype) + offset;
+    Rect caretRect = prototype.shift(caretOffset);
+    if (style.offset != null) {
+      caretRect = caretRect.shift(style.offset);
+    }
+
+    if (caretRect.left < 0.0) {
+      caretRect = caretRect.shift(Offset(-caretRect.left, 0.0));
+    }
+
+    double caretHeight = editable.getFullHeightForCaret(position);
+    if (caretHeight != null) {
+      switch (defaultTargetPlatform) {
+        case TargetPlatform.android:
+        case TargetPlatform.fuchsia:
+        case TargetPlatform.linux:
+        case TargetPlatform.windows:
+          caretRect = Rect.fromLTWH(
+            caretRect.left,
+            caretRect.top - 2.0,
+            caretRect.width,
+            caretHeight,
+          );
+          break;
+        case TargetPlatform.iOS:
+        case TargetPlatform.macOS:
+          caretRect = Rect.fromLTWH(
+            caretRect.left,
+            caretRect.top + (caretHeight - caretRect.height) / 2,
+            caretRect.width,
+            caretRect.height,
+          );
+          break;
+        default:
+          throw UnimplementedError();
+      }
+    }
+
+    Offset caretPosition = editable.localToGlobal(caretRect.topLeft);
+    double pixelMultiple = 1.0 / devicePixelRatio;
+    caretRect = caretRect.shift(Offset(
+        caretPosition.dx.isFinite
+            ? (caretPosition.dx / pixelMultiple).round() * pixelMultiple -
+                caretPosition.dx
+            : caretPosition.dx,
+        caretPosition.dy.isFinite
+            ? (caretPosition.dy / pixelMultiple).round() * pixelMultiple -
+                caretPosition.dy
+            : caretPosition.dy));
+
+    Paint paint = Paint()..color = color;
+    if (style.radius == null) {
+      canvas.drawRect(caretRect, paint);
+      return;
+    }
+
+    RRect caretRRect = RRect.fromRectAndRadius(caretRect, style.radius);
+    canvas.drawRRect(caretRRect, paint);
+  }
+}

lib/widgets/default_styles.dart

@@ -0,0 +1,134 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/widgets.dart';
+import 'package:tuple/tuple.dart';
+
+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;
+
+  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);
+
+  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 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),
+            )));
+  }
+}

lib/widgets/proxy.dart

@@ -0,0 +1,292 @@
+import 'package:flutter/rendering.dart';
+import 'package:flutter/widgets.dart';
+
+import 'box.dart';
+
+class BaselineProxy extends SingleChildRenderObjectWidget {
+  final TextStyle textStyle;
+  final EdgeInsets padding;
+
+  BaselineProxy({Key key, Widget child, this.textStyle, this.padding})
+      : super(key: key, child: child);
+
+  @override
+  RenderBaselineProxy createRenderObject(BuildContext context) {
+    return RenderBaselineProxy(
+      null,
+      textStyle,
+      padding,
+    );
+  }
+
+  @override
+  void updateRenderObject(
+      BuildContext context, covariant RenderBaselineProxy renderObject) {
+    renderObject
+      ..textStyle = textStyle
+      ..padding = padding;
+  }
+}
+
+class RenderBaselineProxy extends RenderProxyBox {
+  RenderBaselineProxy(
+    RenderParagraph child,
+    TextStyle textStyle,
+    EdgeInsets padding,
+  )   : _prototypePainter = TextPainter(
+            text: TextSpan(text: ' ', style: textStyle),
+            textDirection: TextDirection.ltr,
+            strutStyle:
+                StrutStyle.fromTextStyle(textStyle, forceStrutHeight: true)),
+        super(child);
+
+  final TextPainter _prototypePainter;
+
+  set textStyle(TextStyle value) {
+    assert(value != null);
+    if (_prototypePainter.text.style == value) {
+      return;
+    }
+    _prototypePainter.text = TextSpan(text: ' ', style: value);
+    markNeedsLayout();
+  }
+
+  EdgeInsets _padding;
+
+  set padding(EdgeInsets value) {
+    assert(value != null);
+    if (_padding == value) {
+      return;
+    }
+    _padding = value;
+    markNeedsLayout();
+  }
+
+  @override
+  double computeDistanceToActualBaseline(TextBaseline baseline) =>
+      _prototypePainter.computeDistanceToActualBaseline(baseline) +
+          _padding?.top ??
+      0.0;
+
+  @override
+  void performLayout() {
+    super.performLayout();
+    _prototypePainter.layout();
+  }
+}
+
+class EmbedProxy extends SingleChildRenderObjectWidget {
+  EmbedProxy(Widget child) : super(child: child);
+
+  @override
+  RenderEmbedProxy createRenderObject(BuildContext context) =>
+      RenderEmbedProxy(null);
+}
+
+class RenderEmbedProxy extends RenderProxyBox implements RenderContentProxyBox {
+  RenderEmbedProxy(RenderBox child) : super(child);
+
+  @override
+  List<TextBox> getBoxesForSelection(TextSelection selection) {
+    if (!selection.isCollapsed) {
+      return <TextBox>[
+        TextBox.fromLTRBD(0.0, 0.0, size.width, size.height, TextDirection.ltr)
+      ];
+    }
+
+    double left = selection.extentOffset == 0 ? 0.0 : size.width;
+    double right = selection.extentOffset == 0 ? 0.0 : size.width;
+    return <TextBox>[
+      TextBox.fromLTRBD(left, 0.0, right, size.height, TextDirection.ltr)
+    ];
+  }
+
+  @override
+  double getFullHeightForCaret(TextPosition position) => size.height;
+
+  @override
+  Offset getOffsetForCaret(TextPosition position, Rect caretPrototype) {
+    assert(position.offset != null &&
+        position.offset <= 1 &&
+        position.offset >= 0);
+    return position.offset == 0 ? Offset.zero : Offset(size.width, 0.0);
+  }
+
+  @override
+  TextPosition getPositionForOffset(Offset offset) =>
+      TextPosition(offset: offset.dx > size.width / 2 ? 1 : 0);
+
+  @override
+  TextRange getWordBoundary(TextPosition position) =>
+      TextRange(start: 0, end: 1);
+
+  @override
+  double getPreferredLineHeight() {
+    return size.height;
+  }
+}
+
+class RichTextProxy extends SingleChildRenderObjectWidget {
+  final TextStyle textStyle;
+  final TextDirection textDirection;
+  final double textScaleFactor;
+  final Locale locale;
+  final StrutStyle strutStyle;
+  final TextWidthBasis textWidthBasis;
+  final TextHeightBehavior textHeightBehavior;
+
+  @override
+  RenderParagraphProxy createRenderObject(BuildContext context) {
+    return RenderParagraphProxy(null, textStyle, textDirection, textScaleFactor,
+        strutStyle, locale, textWidthBasis, textHeightBehavior);
+  }
+
+  RichTextProxy(
+      RichText child,
+      this.textStyle,
+      this.textDirection,
+      this.textScaleFactor,
+      this.locale,
+      this.strutStyle,
+      this.textWidthBasis,
+      this.textHeightBehavior)
+      : assert(child != null),
+        assert(textStyle != null),
+        assert(textDirection != null),
+        assert(locale != null),
+        assert(strutStyle != null),
+        super(child: child);
+
+  @override
+  void updateRenderObject(
+      BuildContext context, covariant RenderParagraphProxy renderObject) {
+    renderObject.textStyle = textStyle;
+    renderObject.textDirection = textDirection;
+    renderObject.textScaleFactor = textScaleFactor;
+    renderObject.locale = locale;
+    renderObject.strutStyle = strutStyle;
+    renderObject.textWidthBasis = textWidthBasis;
+    renderObject.textHeightBehavior = textHeightBehavior;
+  }
+}
+
+class RenderParagraphProxy extends RenderProxyBox
+    implements RenderContentProxyBox {
+  RenderParagraphProxy(
+    RenderParagraph child,
+    TextStyle textStyle,
+    TextDirection textDirection,
+    double textScaleFactor,
+    StrutStyle strutStyle,
+    Locale locale,
+    TextWidthBasis textWidthBasis,
+    TextHeightBehavior textHeightBehavior,
+  )   : _prototypePainter = TextPainter(
+            text: TextSpan(text: ' ', style: textStyle),
+            textAlign: TextAlign.left,
+            textDirection: textDirection,
+            textScaleFactor: textScaleFactor,
+            strutStyle: strutStyle,
+            locale: locale,
+            textWidthBasis: textWidthBasis,
+            textHeightBehavior: textHeightBehavior),
+        super(child);
+
+  final TextPainter _prototypePainter;
+
+  set textStyle(TextStyle value) {
+    assert(value != null);
+    if (_prototypePainter.text.style == value) {
+      return;
+    }
+    _prototypePainter.text = TextSpan(text: ' ', style: value);
+    markNeedsLayout();
+  }
+
+  set textDirection(TextDirection value) {
+    assert(value != null);
+    if (_prototypePainter.textDirection == value) {
+      return;
+    }
+    _prototypePainter.textDirection = value;
+    markNeedsLayout();
+  }
+
+  set textScaleFactor(double value) {
+    assert(value != null);
+    if (_prototypePainter.textScaleFactor == value) {
+      return;
+    }
+    _prototypePainter.textScaleFactor = value;
+    markNeedsLayout();
+  }
+
+  set strutStyle(StrutStyle value) {
+    assert(value != null);
+    if (_prototypePainter.strutStyle == value) {
+      return;
+    }
+    _prototypePainter.strutStyle = value;
+    markNeedsLayout();
+  }
+
+  set locale(Locale value) {
+    if (_prototypePainter.locale == value) {
+      return;
+    }
+    _prototypePainter.locale = value;
+    markNeedsLayout();
+  }
+
+  set textWidthBasis(TextWidthBasis value) {
+    assert(value != null);
+    if (_prototypePainter.textWidthBasis == value) {
+      return;
+    }
+    _prototypePainter.textWidthBasis = value;
+    markNeedsLayout();
+  }
+
+  set textHeightBehavior(TextHeightBehavior value) {
+    if (_prototypePainter.textHeightBehavior == value) {
+      return;
+    }
+    _prototypePainter.textHeightBehavior = value;
+    markNeedsLayout();
+  }
+
+  @override
+  RenderParagraph get child => super.child;
+
+  @override
+  double getPreferredLineHeight() {
+    return _prototypePainter.preferredLineHeight;
+  }
+
+  @override
+  Offset getOffsetForCaret(TextPosition position, Rect caretPrototype) =>
+      child.getOffsetForCaret(position, caretPrototype);
+
+  @override
+  TextPosition getPositionForOffset(Offset offset) =>
+      child.getPositionForOffset(offset);
+
+  @override
+  double getFullHeightForCaret(TextPosition position) =>
+      child.getFullHeightForCaret(position);
+
+  @override
+  TextRange getWordBoundary(TextPosition position) =>
+      child.getWordBoundary(position);
+
+  @override
+  List<TextBox> getBoxesForSelection(TextSelection selection) =>
+      child.getBoxesForSelection(selection);
+
+  @override
+  performLayout() {
+    super.performLayout();
+    _prototypePainter.layout(
+        minWidth: constraints.minWidth, maxWidth: constraints.maxWidth);
+  }
+}

lib/widgets/text_block.dart

@@ -0,0 +1,37 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_quill/models/documents/nodes/block.dart';
+import 'package:tuple/tuple.dart';
+
+import 'box.dart';
+
+class EditableTextBlock extends StatelessWidget {
+  final Block block;
+  final TextDirection textDirection;
+  final Tuple2 verticalSpacing;
+  final TextSelection textSelection;
+  final Color color;
+  final bool enableInteractiveSelection;
+  final bool hasFocus;
+  final EdgeInsets contentPadding;
+
+  EditableTextBlock(
+      this.block,
+      this.textDirection,
+      this.verticalSpacing,
+      this.textSelection,
+      this.color,
+      this.enableInteractiveSelection,
+      this.hasFocus,
+      this.contentPadding);
+
+  @override
+  Widget build(BuildContext context) {
+    // TODO: implement build
+    throw UnimplementedError();
+  }
+}
+
+//class RenderEditableTextBlock extends RenderEditableContainerBox
+//    implements RenderEditableBox {
+//
+//    }

lib/widgets/text_line.dart

@@ -0,0 +1,552 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_quill/models/documents/attribute.dart';
+import 'package:flutter_quill/models/documents/nodes/container.dart'
+    as container;
+import 'package:flutter_quill/models/documents/nodes/leaf.dart' as leaf;
+import 'package:flutter_quill/models/documents/nodes/line.dart';
+import 'package:flutter_quill/models/documents/nodes/node.dart';
+import 'package:flutter_quill/models/documents/style.dart';
+import 'package:flutter_quill/widgets/cursor.dart';
+import 'package:flutter_quill/widgets/proxy.dart';
+import 'package:tuple/tuple.dart';
+
+import 'box.dart';
+import 'default_styles.dart';
+
+class TextLine extends StatelessWidget {
+  final Line line;
+  final TextDirection textDirection;
+
+  const TextLine({Key key, this.line, this.textDirection})
+      : assert(line != null),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    assert(debugCheckHasMediaQuery(context));
+
+    // TODO: line.hasEmbed
+
+    TextSpan textSpan = _buildTextSpan(context);
+    StrutStyle strutStyle =
+        StrutStyle.fromTextStyle(textSpan.style, forceStrutHeight: true);
+    return RichTextProxy(
+        RichText(
+          text: _buildTextSpan(context),
+          textDirection: textDirection,
+          strutStyle: strutStyle,
+          textScaleFactor: MediaQuery.textScaleFactorOf(context),
+        ),
+        textSpan.style,
+        textDirection,
+        1.0,
+        Localizations.localeOf(context, nullOk: true),
+        strutStyle,
+        TextWidthBasis.parent,
+        null);
+  }
+
+  TextSpan _buildTextSpan(BuildContext context) {
+    DefaultStyles defaultStyles = DefaultStyles.getInstance(context);
+    List<TextSpan> children =
+        line.children.map((node) => _getTextSpanFromNode(defaultStyles, node));
+
+    TextStyle textStyle = TextStyle();
+
+    Attribute header = line.style.attributes[Attribute.header.key];
+    Map<Attribute, TextStyle> m = {
+      Attribute.h1: defaultStyles.h1.style,
+      Attribute.h2: defaultStyles.h2.style,
+      Attribute.h3: defaultStyles.h3.style,
+    };
+
+    textStyle = textStyle.merge(m[header] ?? defaultStyles.paragraph.style);
+
+    Attribute block = line.style.getBlockExceptHeader();
+    TextStyle toMerge;
+    if (block == Attribute.blockQuote) {
+      toMerge = defaultStyles.quote.style;
+    } else if (block == Attribute.codeBlock) {
+      toMerge = defaultStyles.code.style;
+    } else if (block != null) {
+      toMerge = defaultStyles.lists.style;
+    }
+
+    textStyle = textStyle.merge(toMerge);
+
+    return TextSpan(children: children, style: textStyle);
+  }
+
+  TextSpan _getTextSpanFromNode(DefaultStyles defaultStyles, Node node) {
+    leaf.Text textNode = node as leaf.Text;
+    Style style = textNode.style;
+    TextStyle res = TextStyle();
+
+    Map<Attribute, TextStyle> m = {
+      Attribute.bold: defaultStyles.bold,
+      Attribute.italic: defaultStyles.italic,
+      Attribute.link: defaultStyles.link,
+      Attribute.underline: defaultStyles.underline,
+      Attribute.strikeThrough: defaultStyles.strikeThrough,
+    };
+    m.forEach((k, s) {
+      if (style.values.any((v) => v == k)) {
+        res = _merge(res, s);
+      }
+    });
+
+    return TextSpan(text: textNode.value, style: res);
+  }
+
+  TextStyle _merge(TextStyle a, TextStyle b) {
+    final decorations = <TextDecoration>[];
+    if (a.decoration != null) {
+      decorations.add(a.decoration);
+    }
+    if (b.decoration != null) {
+      decorations.add(b.decoration);
+    }
+    return a.merge(b).apply(decoration: TextDecoration.combine(decorations));
+  }
+}
+
+class EditableTextLine extends RenderObjectWidget {
+  final Line line;
+  final Widget leading;
+  final Widget body;
+  final double indentWidth;
+  final Tuple2 verticalSpacing;
+  final TextDirection textDirection;
+  final TextSelection textSelection;
+  final Color color;
+  final bool enableInteractiveSelection;
+  final bool hasFocus;
+  final double devicePixelRatio;
+  final CursorCont cursorCont;
+
+  EditableTextLine(
+      this.line,
+      this.leading,
+      this.body,
+      this.indentWidth,
+      this.verticalSpacing,
+      this.textDirection,
+      this.textSelection,
+      this.color,
+      this.enableInteractiveSelection,
+      this.hasFocus,
+      this.devicePixelRatio,
+      this.cursorCont)
+      : assert(line != null),
+        assert(indentWidth != null),
+        assert(textSelection != null),
+        assert(color != null),
+        assert(enableInteractiveSelection != null),
+        assert(hasFocus != null),
+        assert(cursorCont != null);
+
+  @override
+  RenderObjectElement createElement() {
+    return _TextLineElement(this);
+  }
+
+  @override
+  RenderObject createRenderObject(BuildContext context) {
+    return RenderEditableTextLine(
+        line,
+        textDirection,
+        textSelection,
+        enableInteractiveSelection,
+        hasFocus,
+        devicePixelRatio,
+        _getPadding(),
+        cursorCont);
+  }
+
+  @override
+  updateRenderObject(
+      BuildContext context, covariant RenderEditableTextLine renderObject) {
+    renderObject.setLine(line);
+    renderObject.setPadding(_getPadding());
+    renderObject.setTextDirection(textDirection);
+    renderObject.setTextSelection(textSelection);
+    renderObject.setColor(color);
+    renderObject.setEnableInteractiveSelection(enableInteractiveSelection);
+    renderObject.hasFocus = hasFocus;
+    renderObject.setDevicePixelRatio(devicePixelRatio);
+    renderObject.setCursorCont(cursorCont);
+  }
+
+  EdgeInsetsGeometry _getPadding() {
+    return EdgeInsetsDirectional.only(
+        start: indentWidth,
+        top: verticalSpacing.item1,
+        bottom: verticalSpacing.item2);
+  }
+}
+
+enum TextLineSlot { LEADING, BODY }
+
+class RenderEditableTextLine extends RenderEditableBox {
+  RenderBox leading;
+  RenderContentProxyBox body;
+  Line line;
+  TextDirection textDirection;
+  TextSelection textSelection;
+  Color color;
+  bool enableInteractiveSelection;
+  bool hasFocus = false;
+  double devicePixelRatio;
+  EdgeInsetsGeometry padding;
+  CursorCont cursorCont;
+  EdgeInsets _resolvedPadding;
+  bool _containsCursor;
+  List<TextBox> _selectedRects;
+  Rect _caretPrototype;
+  final Map<TextLineSlot, RenderBox> children = <TextLineSlot, RenderBox>{};
+
+  RenderEditableTextLine(
+      this.line,
+      this.textDirection,
+      this.textSelection,
+      this.enableInteractiveSelection,
+      this.hasFocus,
+      this.devicePixelRatio,
+      this.padding,
+      this.cursorCont)
+      : assert(line != null),
+        assert(padding != null),
+        assert(padding.isNonNegative),
+        assert(devicePixelRatio != null),
+        assert(hasFocus != null),
+        assert(cursorCont != null);
+
+  setCursorCont(CursorCont c) {
+    assert(c != null);
+    if (cursorCont == c) {
+      return;
+    }
+    cursorCont = c;
+    markNeedsLayout();
+  }
+
+  setDevicePixelRatio(double d) {
+    if (devicePixelRatio == d) {
+      return;
+    }
+    devicePixelRatio = d;
+    markNeedsLayout();
+  }
+
+  setEnableInteractiveSelection(bool val) {
+    if (enableInteractiveSelection == val) {
+      return;
+    }
+
+    markNeedsLayout();
+    markNeedsSemanticsUpdate();
+  }
+
+  setColor(Color c) {
+    if (color == c) {
+      return;
+    }
+
+    color = c;
+    if (containsTextSelection()) {
+      markNeedsPaint();
+    }
+  }
+
+  setTextSelection(TextSelection t) {
+    if (textSelection == t) {
+      return;
+    }
+
+    bool containsSelection = containsTextSelection();
+    if (attached && containsCursor()) {
+      cursorCont.removeListener(markNeedsLayout);
+      cursorCont.color.removeListener(markNeedsPaint);
+    }
+
+    textSelection = t;
+    _selectedRects = null;
+    _containsCursor = null;
+    if (attached && containsCursor()) {
+      cursorCont.addListener(markNeedsLayout);
+      cursorCont.color.addListener(markNeedsPaint);
+    }
+
+    if (containsSelection || containsTextSelection()) {
+      markNeedsPaint();
+    }
+  }
+
+  setTextDirection(TextDirection t) {
+    if (textDirection == t) {
+      return;
+    }
+    textDirection = t;
+    _resolvedPadding = null;
+    markNeedsLayout();
+  }
+
+  setLine(Line l) {
+    assert(l != null);
+    if (line == l) {
+      return;
+    }
+    line = l;
+    _containsCursor = null;
+    markNeedsLayout();
+  }
+
+  setPadding(EdgeInsetsGeometry p) {
+    assert(p != null);
+    assert(p.isNonNegative);
+    if (padding == p) {
+      return;
+    }
+    padding = p;
+    _resolvedPadding = null;
+    markNeedsLayout();
+  }
+
+  setLeading(RenderBox l) {
+    leading = _updateChild(leading, l, TextLineSlot.LEADING);
+  }
+
+  setBody(RenderContentProxyBox b) {
+    body = _updateChild(body, b, TextLineSlot.BODY);
+  }
+
+  bool containsTextSelection() {
+    return line.getDocumentOffset() <= textSelection.end &&
+        textSelection.start <= line.getDocumentOffset() + line.length - 1;
+  }
+
+  bool containsCursor() {
+    return _containsCursor ??= textSelection.isCollapsed &&
+        line.containsOffset(textSelection.baseOffset);
+  }
+
+  RenderBox _updateChild(RenderBox old, RenderBox newChild, TextLineSlot slot) {
+    if (old != null) {
+      dropChild(old);
+      children.remove(slot);
+    }
+    if (newChild != null) {
+      children[slot] = newChild;
+      adoptChild(newChild);
+    }
+    return newChild;
+  }
+
+  List<TextBox> _getBoxes(TextSelection textSelection) {
+    BoxParentData parentData = body.parentData as BoxParentData;
+    return body.getBoxesForSelection(textSelection).map((box) {
+      return TextBox.fromLTRBD(
+        box.left + parentData.offset.dx,
+        box.top + parentData.offset.dy,
+        box.right + parentData.offset.dx,
+        box.bottom + parentData.offset.dy,
+        box.direction,
+      );
+    }).toList(growable: false);
+  }
+
+  _resolvePadding() {
+    if (_resolvedPadding != null) {
+      return;
+    }
+    _resolvedPadding = padding.resolve(textDirection);
+    assert(_resolvedPadding.isNonNegative);
+  }
+
+  @override
+  TextSelectionPoint getBaseEndpointForSelection(TextSelection textSelection) {
+    return _getEndpointForSelection(textSelection, true);
+  }
+
+  @override
+  TextSelectionPoint getExtentEndpointForSelection(
+      TextSelection textSelection) {
+    return _getEndpointForSelection(textSelection, false);
+  }
+
+  TextSelectionPoint _getEndpointForSelection(
+      TextSelection textSelection, bool first) {
+    if (textSelection.isCollapsed) {
+      return TextSelectionPoint(
+          Offset(0.0, preferredLineHeight(textSelection.extent)) +
+              getOffsetForCaret(textSelection.extent),
+          null);
+    }
+    List<TextBox> boxes = _getBoxes(textSelection);
+    assert(boxes.isNotEmpty);
+    TextBox targetBox = first ? boxes.first : boxes.last;
+    return TextSelectionPoint(
+        Offset(targetBox.start, targetBox.bottom), targetBox.direction);
+  }
+
+  @override
+  TextRange getLineBoundary(TextPosition position) {
+    double lineDy = getOffsetForCaret(position)
+        .translate(0.0, 0.5 * preferredLineHeight(position))
+        .dy;
+    List<TextBox> lineBoxes =
+        _getBoxes(TextSelection(baseOffset: 0, extentOffset: line.length - 1))
+            .where((element) => element.top < lineDy && element.bottom > lineDy)
+            .toList(growable: false);
+    return TextRange(
+        start:
+            getPositionForOffset(Offset(lineBoxes.first.left, lineDy)).offset,
+        end: getPositionForOffset(Offset(lineBoxes.last.right, lineDy)).offset);
+  }
+
+  @override
+  Offset getOffsetForCaret(TextPosition position) {
+    return body.getOffsetForCaret(position, _caretPrototype) +
+        (body.parentData as BoxParentData).offset;
+  }
+
+  @override
+  TextPosition getPositionAbove(TextPosition position) {
+    return _getPosition(position, -0.5);
+  }
+
+  @override
+  TextPosition getPositionBelow(TextPosition position) {
+    return _getPosition(position, 1.5);
+  }
+
+  TextPosition _getPosition(TextPosition textPosition, double dyScale) {
+    assert(textPosition.offset < line.length);
+    Offset offset = getOffsetForCaret(textPosition)
+        .translate(0, dyScale * preferredLineHeight(textPosition));
+    if (body.size
+        .contains(offset - (body.parentData as BoxParentData).offset)) {
+      return getPositionForOffset(offset);
+    }
+    return null;
+  }
+
+  @override
+  TextPosition getPositionForOffset(Offset offset) {
+    return body.getPositionForOffset(
+        offset - (body.parentData as BoxParentData).offset);
+  }
+
+  @override
+  TextRange getWordBoundary(TextPosition position) {
+    return body.getWordBoundary(position);
+  }
+
+  @override
+  double preferredLineHeight(TextPosition position) {
+    return body.getPreferredLineHeight();
+  }
+
+  @override
+  container.Container getContainer() {
+    return line;
+  }
+}
+
+class _TextLineElement extends RenderObjectElement {
+  _TextLineElement(EditableTextLine line) : super(line);
+
+  final Map<TextLineSlot, Element> _slotToChildren = <TextLineSlot, Element>{};
+
+  @override
+  EditableTextLine get widget => super.widget as EditableTextLine;
+
+  @override
+  RenderEditableTextLine get renderObject =>
+      super.renderObject as RenderEditableTextLine;
+
+  @override
+  visitChildren(ElementVisitor visitor) {
+    _slotToChildren.values.forEach(visitor);
+  }
+
+  @override
+  forgetChild(Element child) {
+    assert(_slotToChildren.containsValue(child));
+    assert(child.slot is TextLineSlot);
+    assert(_slotToChildren.containsKey(child.slot));
+    _slotToChildren.remove(child.slot);
+    super.forgetChild(child);
+  }
+
+  @override
+  mount(Element parent, dynamic newSlot) {
+    super.mount(parent, newSlot);
+    _mountChild(widget.leading, TextLineSlot.LEADING);
+    _mountChild(widget.body, TextLineSlot.BODY);
+  }
+
+  @override
+  update(EditableTextLine newWidget) {
+    super.update(newWidget);
+    assert(widget == newWidget);
+    _updateChild(widget.leading, TextLineSlot.LEADING);
+    _updateChild(widget.body, TextLineSlot.BODY);
+  }
+
+  @override
+  insertRenderObjectChild(RenderObject child, TextLineSlot slot) {
+    assert(child is RenderBox);
+    _updateRenderObject(child, slot);
+    assert(renderObject.children.keys.contains(slot));
+  }
+
+  @override
+  removeRenderObjectChild(RenderObject child, TextLineSlot slot) {
+    assert(child is RenderBox);
+    assert(renderObject.children[slot] == child);
+    _updateRenderObject(null, slot);
+    assert(!renderObject.children.keys.contains(slot));
+  }
+
+  @override
+  moveRenderObjectChild(RenderObject child, dynamic oldSlot, dynamic newSlot) {
+    throw UnimplementedError();
+  }
+
+  _mountChild(Widget widget, TextLineSlot slot) {
+    Element oldChild = _slotToChildren[slot];
+    Element newChild = updateChild(oldChild, widget, slot);
+    if (oldChild != null) {
+      _slotToChildren.remove(slot);
+    }
+    if (newChild != null) {
+      _slotToChildren[slot] = newChild;
+    }
+  }
+
+  _updateRenderObject(RenderObject child, TextLineSlot slot) {
+    switch (slot) {
+      case TextLineSlot.LEADING:
+        renderObject.leading = child as RenderBox;
+        break;
+      case TextLineSlot.BODY:
+        renderObject.body = child as RenderBox;
+        break;
+      default:
+        throw UnimplementedError();
+    }
+  }
+
+  _updateChild(Widget widget, TextLineSlot slot) {
+    Element oldChild = _slotToChildren[slot];
+    Element newChild = updateChild(oldChild, widget, slot);
+    if (oldChild != null) {
+      _slotToChildren.remove(slot);
+    }
+    if (newChild != null) {
+      _slotToChildren[slot] = newChild;
+    }
+  }
+}