Improve ColorChanged event implementations

src/Avalonia.Controls.ColorPicker/ColorPreviewer/ColorPreviewer.cs

@@ -81,16 +81,26 @@ namespace Avalonia.Controls.Primitives
             base.OnApplyTemplate(e);
         }
 
+        /// <inheritdoc/>
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            if (change.Property == HsvColorProperty)
+            {
+                OnColorChanged(new ColorChangedEventArgs(
+                    change.GetOldValue<HsvColor>().ToRgb(),
+                    change.GetNewValue<HsvColor>().ToRgb()));
+            }
+
+            base.OnPropertyChanged(change);
+        }
+
         /// <summary>
         /// Called before the <see cref="ColorChanged"/> event occurs.
         /// </summary>
-        /// <param name="newColor">The newly selected color.</param>
-        protected virtual void OnColorChanged(HsvColor newColor)
+        /// <param name="e">The <see cref="ColorChangedEventArgs"/> defining old/new colors.</param>
+        protected virtual void OnColorChanged(ColorChangedEventArgs e)
         {
-            var oldColor = HsvColor;
-            HsvColor = newColor;
-
-            ColorChanged?.Invoke(this, new ColorChangedEventArgs(oldColor.ToRgb(), newColor.ToRgb()));
+            ColorChanged?.Invoke(this, e);
         }
 
         /// <summary>
@@ -111,7 +121,10 @@ namespace Avalonia.Controls.Primitives
             catch { }
 
             HsvColor newHsvColor = AccentColorConverter.GetAccent(hsvColor, accentStep);
-            OnColorChanged(newHsvColor);
+            HsvColor oldHsvColor = HsvColor;
+
+            HsvColor = newHsvColor;
+            OnColorChanged(new ColorChangedEventArgs(oldHsvColor.ToRgb(), newHsvColor.ToRgb()));
         }
     }
 }

src/Avalonia.Controls.ColorPicker/ColorSlider/ColorSlider.cs

@@ -15,6 +15,11 @@ namespace Avalonia.Controls.Primitives
         protected const string pcDarkSelector = ":dark-selector";
         protected const string pcLightSelector = ":light-selector";
 
+        /// <summary>
+        /// Event for when the selected color changes within the slider.
+        /// </summary>
+        public event EventHandler<ColorChangedEventArgs>? ColorChanged;
+
         private const double MaxHue = 359.99999999999999999;
         private bool disableUpdates = false;
 
@@ -321,6 +326,10 @@ namespace Avalonia.Controls.Primitives
                 }
 
                 UpdatePseudoClasses();
+                OnColorChanged(new ColorChangedEventArgs(
+                    change.GetOldValue<Color>(),
+                    change.GetNewValue<Color>()));
+
                 disableUpdates = false;
             }
             else if (change.Property == HsvColorProperty)
@@ -336,6 +345,10 @@ namespace Avalonia.Controls.Primitives
                 }
 
                 UpdatePseudoClasses();
+                OnColorChanged(new ColorChangedEventArgs(
+                    change.GetOldValue<HsvColor>().ToRgb(),
+                    change.GetNewValue<HsvColor>().ToRgb()));
+
                 disableUpdates = false;
             }
             else if (change.Property == BoundsProperty)
@@ -351,6 +364,7 @@ namespace Avalonia.Controls.Primitives
             {
                 disableUpdates = true;
 
+                Color oldColor = Color;
                 (var color, var hsvColor) = GetColorFromSliderValues();
 
                 if (ColorModel == ColorModel.Hsva)
@@ -365,10 +379,21 @@ namespace Avalonia.Controls.Primitives
                 }
 
                 UpdatePseudoClasses();
+                OnColorChanged(new ColorChangedEventArgs(oldColor, Color));
+
                 disableUpdates = false;
             }
 
             base.OnPropertyChanged(change);
         }
+
+        /// <summary>
+        /// Called before the <see cref="ColorChanged"/> event occurs.
+        /// </summary>
+        /// <param name="e">The <see cref="ColorChangedEventArgs"/> defining old/new colors.</param>
+        protected virtual void OnColorChanged(ColorChangedEventArgs e)
+        {
+            ColorChanged?.Invoke(this, e);
+        }
     }
 }