Color picker - Avoid overlapping colors

src/Artemis.Core/Models/Profile/Colors/ColorGradient.cs

@@ -51,6 +51,7 @@ public class ColorGradient : IList<ColorGradientStop>, IList, INotifyCollectionC
         {
             ColorGradientStop stop = new(colorGradientStop.Color, colorGradientStop.Position);
             stop.PropertyChanged += ItemOnPropertyChanged;
+            stop.ColorGradient = this;
             _stops.Add(stop);
         }
     }
@@ -66,6 +67,7 @@ public class ColorGradient : IList<ColorGradientStop>, IList, INotifyCollectionC
         {
             ColorGradientStop stop = new(colorGradientStop.Color, colorGradientStop.Position);
             stop.PropertyChanged += ItemOnPropertyChanged;
+            stop.ColorGradient = this;
             _stops.Add(stop);
         }
     }
@@ -465,6 +467,7 @@ public class ColorGradient : IList<ColorGradientStop>, IList, INotifyCollectionC
     public void Add(ColorGradientStop item)
     {
         _stops.Add(item);
+        item.ColorGradient = this;
         item.PropertyChanged += ItemOnPropertyChanged;
 
         OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, item, _stops.IndexOf(item)));

src/Artemis.Core/Models/Profile/Colors/ColorGradientStop.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using SkiaSharp;
 
 namespace Artemis.Core;
@@ -35,9 +36,11 @@ public class ColorGradientStop : CorePropertyChanged
     public float Position
     {
         get => _position;
-        set => SetAndNotify(ref _position, value);
+        set => SetAndNotify(ref _position, GetUpdatedPosition(value));
     }
 
+    internal ColorGradient? ColorGradient { get; set; }
+
     #region Equality members
 
     /// <inheritdoc cref="object.Equals(object)" />
@@ -64,5 +67,32 @@ public class ColorGradientStop : CorePropertyChanged
         return HashCode.Combine(_color, _position);
     }
 
+    /// <summary>
+    ///     Gets the position of the given color stop in a safe manner that avoids overlap with other stops.
+    /// </summary>
+    /// <param name="stopPosition">The new position.</param>
+    private float GetUpdatedPosition(float stopPosition)
+    {
+        if (ColorGradient == null)
+            return stopPosition;
+        // Find the first available spot going down
+        while (ColorGradient.Any(s => !ReferenceEquals(s, this) && Math.Abs(s.Position - stopPosition) < 0.001f))
+            stopPosition -= 0.001f;
+
+        // If we ran out of space, try going up
+        if (stopPosition < 0)
+        {
+            stopPosition = 0;
+            while (ColorGradient.Any(s => !ReferenceEquals(s, this) && Math.Abs(s.Position - stopPosition) < 0.001f))
+                stopPosition += 0.001f;
+        }
+
+        // If we ran out of space there too, movement isn't possible
+        if (stopPosition > 1)
+            stopPosition = Position;
+
+        return stopPosition;
+    }
+
     #endregion
 }

src/Artemis.UI.Shared/Behaviors/LostFocusNumericUpDownBindingBehavior.cs

@@ -0,0 +1,63 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Data;
+using Avalonia.Interactivity;
+using Avalonia.Xaml.Interactivity;
+using FluentAvalonia.UI.Controls;
+
+namespace Artemis.UI.Shared.Behaviors;
+
+/// <summary>
+///     Represents a behavior that can be used to make a numeric up down only update it's binding on focus loss.
+/// </summary>
+public class LostFocusNumericUpDownBindingBehavior : Behavior<NumericUpDown>
+{
+    /// <summary>
+    ///     Gets or sets the value of the binding.
+    /// </summary>
+    public static readonly StyledProperty<double> ValueProperty = AvaloniaProperty.Register<LostFocusNumericUpDownBindingBehavior, double>(
+        nameof(Value), defaultBindingMode: BindingMode.TwoWay);
+
+    static LostFocusNumericUpDownBindingBehavior()
+    {
+        ValueProperty.Changed.Subscribe(e => ((LostFocusNumericUpDownBindingBehavior) e.Sender).OnBindingValueChanged());
+    }
+
+    /// <summary>
+    ///     Gets or sets the value of the binding.
+    /// </summary>
+    public double Value
+    {
+        get => GetValue(ValueProperty);
+        set => SetValue(ValueProperty, value);
+    }
+
+    /// <inheritdoc />
+    protected override void OnAttached()
+    {
+        if (AssociatedObject != null)
+            AssociatedObject.LostFocus += OnLostFocus;
+        base.OnAttached();
+    }
+
+    /// <inheritdoc />
+    protected override void OnDetaching()
+    {
+        if (AssociatedObject != null)
+            AssociatedObject.LostFocus -= OnLostFocus;
+        base.OnDetaching();
+    }
+
+    private void OnLostFocus(object? sender, RoutedEventArgs e)
+    {
+        if (AssociatedObject != null)
+            Value = AssociatedObject.Value;
+    }
+
+    private void OnBindingValueChanged()
+    {
+        if (AssociatedObject != null)
+            AssociatedObject.Value = Value;
+    }
+}

src/Artemis.UI.Shared/Styles/Controls/GradientPicker.axaml

@@ -4,7 +4,8 @@
         xmlns:core="clr-namespace:Artemis.Core;assembly=Artemis.Core"
         xmlns:fluent="clr-namespace:FluentAvalonia.UI.Controls;assembly=FluentAvalonia"
         xmlns:converters="clr-namespace:Artemis.UI.Shared.Converters"
-        xmlns:gradientPicker="clr-namespace:Artemis.UI.Shared.Controls.GradientPicker">
+        xmlns:gradientPicker="clr-namespace:Artemis.UI.Shared.Controls.GradientPicker"
+        xmlns:behaviors="clr-namespace:Artemis.UI.Shared.Behaviors">
     <Styles.Resources>
         <VisualBrush x:Key="LightCheckerboardBrush" TileMode="Tile" Stretch="Uniform" DestinationRect="3,0,10,10">
             <VisualBrush.Visual>
@@ -198,7 +199,11 @@
                                             <Border CornerRadius="4" Margin="-2" Background="{Binding Color, Converter={StaticResource SKColorToBrushConverter}}" />
                                         </Border>
                                         <TextBox Grid.Column="1" Text="{Binding Color, Converter={StaticResource SKColorToStringConverter}}" />
-                                        <NumericUpDown Grid.Column="2" Value="{Binding Position}" FormatString="F3" ShowButtonSpinner="False" Margin="5 0" />
+                                        <NumericUpDown Grid.Column="2" FormatString="F3" ShowButtonSpinner="False" Margin="5 0" Minimum="0" Maximum="1" Increment="0.01">
+                                            <Interaction.Behaviors>
+                                                <behaviors:LostFocusNumericUpDownBindingBehavior Value="{Binding Position}"/>
+                                            </Interaction.Behaviors>
+                                        </NumericUpDown>
                                         <Button Name="DeleteButton"
                                                 Grid.Column="3"
                                                 Classes="icon-button"