Support text color

app/assets/sample_data.json

@@ -50,7 +50,8 @@
    {
       "attributes":{
          "underline":true,
-         "bold":true
+         "bold":true,
+         "color":"#e60000"
       },
       "insert":"only"
    },

lib/models/documents/attribute.dart

@@ -19,6 +19,8 @@ class Attribute<T> {
     Attribute.underline.key: Attribute.underline,
     Attribute.strikeThrough.key: Attribute.strikeThrough,
     Attribute.link.key: Attribute.link,
+    Attribute.color.key: Attribute.color,
+    Attribute.background.key: Attribute.background,
     Attribute.header.key: Attribute.header,
     Attribute.list.key: Attribute.list,
     Attribute.codeBlock.key: Attribute.codeBlock,
@@ -35,6 +37,10 @@ class Attribute<T> {
 
   static final LinkAttribute link = LinkAttribute(null);
 
+  static final ColorAttribute color = ColorAttribute(null);
+
+  static final BackgroundAttribute background = BackgroundAttribute(null);
+
   static final HeaderAttribute header = HeaderAttribute();
 
   static final ListAttribute list = ListAttribute(null);
@@ -91,7 +97,7 @@ class Attribute<T> {
     Attribute attribute = clone(origin, value);
     return attribute;
   }
-  
+
   static Attribute clone(Attribute origin, dynamic value) {
     return Attribute(origin.key, origin.scope, value);
   }
@@ -135,6 +141,15 @@ class LinkAttribute extends Attribute<String> {
   LinkAttribute(String val) : super('link', AttributeScope.INLINE, val);
 }
 
+class ColorAttribute extends Attribute<String> {
+  ColorAttribute(String val) : super('color', AttributeScope.INLINE, val);
+}
+
+class BackgroundAttribute extends Attribute<String> {
+  BackgroundAttribute(String val)
+      : super('background', AttributeScope.INLINE, val);
+}
+
 class HeaderAttribute extends Attribute<int> {
   HeaderAttribute({int level}) : super('header', AttributeScope.BLOCK, level);
 }

lib/widgets/text_line.dart

@@ -91,6 +91,13 @@ class TextLine extends StatelessWidget {
     return TextSpan(children: children, style: textStyle);
   }
 
+  Color _hexStringToColor(String hex) {
+    hex = hex.replaceFirst('#', '');
+    hex = hex.length == 6 ? 'ff' + hex : hex;
+    int val = int.parse(hex, radix: 16);
+    return Color(val);
+  }
+
   TextSpan _getTextSpanFromNode(DefaultStyles defaultStyles, Node node) {
     leaf.Text textNode = node as leaf.Text;
     Style style = textNode.style;
@@ -109,6 +116,12 @@ class TextLine extends StatelessWidget {
       }
     });
 
+    Attribute color = textNode.style.attributes[Attribute.color.key];
+    if (color != null && color.value != null) {
+      final textColor = _hexStringToColor(color.value);
+      res = res.merge(new TextStyle(color: textColor));
+    }
+
     return TextSpan(text: textNode.value, style: res);
   }