Add cursor

lib/models/documents/attribute.dart

@@ -1,5 +1,3 @@
-import 'package:quiver_hashcode/hashcode.dart';
-
 enum AttributeScope {
   INLINE, // refer to https://quilljs.com/docs/formats/#inline
   BLOCK, // refer to https://quilljs.com/docs/formats/#block
@@ -71,21 +69,23 @@ class Attribute<T> {
     return attribute;
   }
 
+
   @override
-  bool operator ==(Object other) {
-    if (identical(this, other)) return true;
-    if (other is! Attribute<T>) return false;
-    Attribute<T> typedOther = other;
-    return key == typedOther.key &&
-        scope == typedOther.scope &&
-        value == typedOther.value;
-  }
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Attribute &&
+          runtimeType == other.runtimeType &&
+          key == other.key &&
+          scope == other.scope &&
+          value == other.value;
 
   @override
-  int get hashCode => hash3(key, scope, value);
+  int get hashCode => key.hashCode ^ scope.hashCode ^ value.hashCode;
 
   @override
-  String toString() => '$key: $value';
+  String toString() {
+    return 'Attribute{key: $key, scope: $scope, value: $value}';
+  }
 }
 
 class BoldAttribute extends Attribute<bool> {

lib/widgets/cursor.dart

@@ -0,0 +1,83 @@
+import 'package:flutter/widgets.dart';
+
+const Duration _FADE_DURATION = Duration(milliseconds: 250);
+
+class CursorStyle {
+  final Color color;
+  final Color backgroundColor;
+  final double width;
+  final double height;
+  final Radius radius;
+  final Offset offset;
+  final bool opacityAnimates;
+  final bool paintAboveText;
+
+  const CursorStyle({
+    @required this.color,
+    @required this.backgroundColor,
+    this.width = 1.0,
+    this.height,
+    this.radius,
+    this.offset,
+    this.opacityAnimates = false,
+    this.paintAboveText = false,
+  })  : assert(color != null),
+        assert(backgroundColor != null),
+        assert(opacityAnimates != null),
+        assert(paintAboveText != null);
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is CursorStyle &&
+          runtimeType == other.runtimeType &&
+          color == other.color &&
+          backgroundColor == other.backgroundColor &&
+          width == other.width &&
+          height == other.height &&
+          radius == other.radius &&
+          offset == other.offset &&
+          opacityAnimates == other.opacityAnimates &&
+          paintAboveText == other.paintAboveText;
+
+  @override
+  int get hashCode =>
+      color.hashCode ^
+      backgroundColor.hashCode ^
+      width.hashCode ^
+      height.hashCode ^
+      radius.hashCode ^
+      offset.hashCode ^
+      opacityAnimates.hashCode ^
+      paintAboveText.hashCode;
+}
+
+class CursorCont extends ChangeNotifier {
+
+  final ValueNotifier<bool> show;
+  final ValueNotifier<bool> _blink;
+  final ValueNotifier<Color> _color;
+  AnimationController _blinkOpacityCont;
+  CursorStyle _style;
+
+  CursorCont({
+    @required ValueNotifier<bool> show,
+    @required CursorStyle style,
+    @required TickerProvider tickerProvider,
+  })  : assert(show != null),
+        assert(style != null),
+        assert(tickerProvider != null),
+        show = show ?? ValueNotifier<bool>(false),
+        _style = style,
+        _blink = ValueNotifier(false),
+        _color = ValueNotifier(style.color) {
+    _blinkOpacityCont =
+        AnimationController(vsync: tickerProvider, duration: _FADE_DURATION);
+    _blinkOpacityCont.addListener(_onColorTick);
+  }
+
+  void _onColorTick() {
+    _color.value = _style.color.withOpacity(_blinkOpacityCont.value);
+    _blink.value = show.value && _blinkOpacityCont.value > 0;
+  }
+}