Implement INotifyPropertyChanged for brushes.

Dashboard.Common/Collections/HashList.cs

@@ -1,7 +1,6 @@
 using System.Collections;
-using System.Collections.Generic;
 
-namespace Dashboard
+namespace Dashboard.Collections
 {
     public class HashList<T> : IReadOnlyList<T>
         where T : notnull

Dashboard.Common/Drawing/Brush.cs

@@ -1,27 +1,111 @@
+using System.Collections.Specialized;
+using System.ComponentModel;
 using System.Drawing;
-using System.Numerics;
+using System.Runtime.CompilerServices;
 
 namespace Dashboard.Drawing
 {
-    public abstract class Brush
+    public abstract class Brush : INotifyPropertyChanged, ICloneable
     {
+        public event PropertyChangedEventHandler? PropertyChanged;
+
+        public virtual object Clone()
+        {
+            return MemberwiseClone();
+        }
+
+        protected void SetField<T>(ref T field, T value, [CallerMemberName] string property = "")
+        {
+            field = value;
+            OnPropertyChanged(property);
+        }
+
+        protected virtual void OnPropertyChanged(string property)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
+        }
     }
 
-    public class SolidColorBrush(Color color) : Brush
+    public sealed class SolidColorBrush(Color color) : Brush
     {
         public Color Color { get; } = color;
     }
 
     public class ImageBrush(Image image) : Brush
     {
-        public Image Image { get; set; } = image;
+        public Image Image 
-        public Box2d TextureCoordinates { get; set; } = new Box2d(0, 0, 1, 1);
+        {
+            get;
+            set => SetField(ref field, value);
+        } = image;
+
+        public Box2d TextureCoordinates
+        {
+            get;
+            set => SetField(ref field, value);
+        } = new Box2d(0, 0, 1, 1);
     }
 
     public class NinePatchImageBrush(Image image) : Brush
     {
-        public Image Image { get; set; } = image;
+        public Image Image
-        public Box2d CenterCoordinates { get; set; } = new Box2d(0, 0, 1, 1);
+        { 
-        public Vector4 Extents { get; set; } = Vector4.Zero;
+            get;
+            set => SetField(ref field, value);
+        } = image;
+
+        public Box2d CenterCoordinates
+        {
+            get;
+            set => SetField(ref field, value);
+        } = new Box2d(0, 0, 1, 1);
+
+        public Extents Extents
+        {
+            get;
+            set => SetField(ref field, value);
+        } = Extents.None;
+    }
+
+    public class GradientBrush : Brush
+    {
+        public Gradient Gradient 
+        {
+            get;
+            set
+            {
+                Unsubscribe(field);
+                Subscribe(value);
+
+                SetField(ref field, value);
+            }
+        }
+
+        public GradientBrush(Gradient gradient)
+        {
+            Gradient = gradient;
+        }
+
+        private void Subscribe(Gradient gradient)
+        {
+            gradient.PropertyChanged   += GradientPropertyChanged;
+            gradient.CollectionChanged += GradientCollectionChanged;
+        }
+
+        private void Unsubscribe(Gradient? gradient)
+        {
+            gradient?.PropertyChanged   -= GradientPropertyChanged;
+            gradient?.CollectionChanged -= GradientCollectionChanged;
+        }
+
+        private void GradientCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+        {
+            OnPropertyChanged(nameof(Gradient));
+        }
+
+        private void GradientPropertyChanged(object? sender, PropertyChangedEventArgs e)
+        {
+            OnPropertyChanged(nameof(Gradient));
+        }
     }
 }

Dashboard.Common/Drawing/Gradient.cs

@@ -1,9 +1,11 @@
 using System.Collections;
-using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.ComponentModel;
 using System.Drawing;
 using System.Numerics;
+using System.Runtime.CompilerServices;
 
-namespace Dashboard
+namespace Dashboard.Drawing
 {
     /// <summary>
     /// Enumeration of the kinds of gradients available.
@@ -25,29 +27,41 @@ namespace Dashboard
     /// </summary>
     /// <param name="Position">The position of the gradient stop. Must be [0,1].</param>
     /// <param name="Color">The color value for the stop.</param>
-    public record struct GradientStop(float Position, Color Color);
+    public readonly record struct GradientStop(float Position, Color Color);
 
     /// <summary>
     /// Represents a linear gradient.
     /// </summary>
-    public struct Gradient : ICollection<GradientStop>, ICloneable, IEquatable<Gradient>
+    public class Gradient : ICollection<GradientStop>, ICloneable, IEquatable<Gradient>, INotifyPropertyChanged, INotifyCollectionChanged
     {
         private readonly List<GradientStop> _stops = new List<GradientStop>();
 
         /// <summary>
         /// Gradient type.
         /// </summary>
-        public GradientType Type { get; set; } = GradientType.Axial;
+        public GradientType Type
+        {
+            get;
+            set => SetField(ref field, value);
+        } = GradientType.Axial;
 
         /// <summary>
         /// First gradient control point.
         /// </summary>
-        public Vector2 C0 { get; set; } = Vector2.Zero;
+        public Vector2 C0
+        { 
+            get;
+            set => SetField(ref field, value);
+        } = Vector2.Zero;
 
         /// <summary>
         /// Second gradient control point.
         /// </summary>
-        public Vector2 C1 { get; set; } = Vector2.One;
+        public Vector2 C1
+        { 
+            get;
+            set => SetField(ref field, value);
+        } = Vector2.One;
 
         /// <summary>
         /// Number of stops in a gradient.
@@ -69,6 +83,10 @@ namespace Dashboard
             }
         }
 
+        public event PropertyChangedEventHandler? PropertyChanged;
+        public event NotifyCollectionChangedEventHandler? CollectionChanged;
+
+
         public Gradient()
         {
         }
@@ -164,11 +182,13 @@ namespace Dashboard
                 index = _stops.Count;
 
             _stops.Insert(index, item);
+            OnCollectionChanged(NotifyCollectionChangedAction.Add);
         }
 
         public void Clear()
         {
             _stops.Clear();
+            OnCollectionChanged(NotifyCollectionChangedAction.Reset);
         }
 
         public bool Contains(GradientStop item)
@@ -183,30 +203,51 @@ namespace Dashboard
 
         public bool Remove(GradientStop item)
         {
-            return _stops.Remove(item);
+            if (!_stops.Remove(item))
+                return false;
+
+            OnCollectionChanged(NotifyCollectionChangedAction.Remove);
+            return true;
         }
 
         public void RemoveAt(int index)
         {
             _stops.RemoveAt(index);
+            OnCollectionChanged(NotifyCollectionChangedAction.Remove);
         }
 
         public override int GetHashCode()
         {
             HashCode code = new HashCode();
+
             code.Add(Count);
+            code.Add(Type);
+            code.Add(C0);
+            code.Add(C1);
+
             foreach (GradientStop item in this)
                 code.Add(item.GetHashCode());
             return code.ToHashCode();
         }
 
-        public bool Equals(Gradient other)
+        public bool Equals(Gradient? other)
         {
             return
+                other != null &&
                 Type == other.Type &&
                 C0 == other.C0 &&
                 C1 == other.C1 &&
-                _stops.Equals(other._stops);
+                _stops.SequenceEqual(other._stops);
+        }
+
+        private bool NotEquals(Gradient? other)
+        {
+            return
+                other == null ||
+                Type != other.Type ||
+                C0 != other.C0 ||
+                C1 != other.C1 ||
+                !_stops.SequenceEqual(other._stops);
         }
 
         public override bool Equals(object? obj)
@@ -214,14 +255,30 @@ namespace Dashboard
             return obj is Gradient other && Equals(other);
         }
 
-        public static bool operator ==(Gradient left, Gradient right)
+        public static bool operator ==(Gradient? left, Gradient? right)
         {
-            return left.Equals(right);
+            return left?.Equals(right) ?? right == null;
         }
 
-        public static bool operator !=(Gradient left, Gradient right)
+        public static bool operator !=(Gradient? left, Gradient? right)
         {
-            return !left.Equals(right);
+            return left?.NotEquals(right) ?? right != null;
+        }
+
+        protected void SetField<T>(ref T field, T value, [CallerMemberName] string name = "")
+        {
+            field = value;
+            OnPropertyChanged(name);
+        }
+
+        protected virtual void OnPropertyChanged(string property)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
+        }
+
+        protected virtual void OnCollectionChanged(NotifyCollectionChangedAction action)
+        {
+            CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(action));
         }
     }
 }

Dashboard.Common/Extents.cs

@@ -25,5 +25,7 @@ namespace Dashboard
         public Extents(float value) : this(new Vector4(value))
         {
         }
+
+        public static readonly Extents None = new Extents(0);
     }
 }