chore: add avalonia Slider demo.

src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SliderDemo.axaml

@@ -0,0 +1,90 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="HandyControlDemo.UserControl.SliderDemo"
+             xmlns:hc="https://handyorg.github.io/handycontrol"
+             Background="{DynamicResource RegionBrush}">
+    <ScrollViewer>
+        <hc:UniformSpacingPanel Margin="32"
+                                Orientation="Horizontal"
+                                Spacing="32"
+                                ClipToBounds="False"
+                                ChildWrapping="Wrap">
+            <hc:UniformSpacingPanel Orientation="Vertical"
+                                    Spacing="32">
+                <Slider Width="400"
+                        IsSnapToTickEnabled="True"
+                        TickFrequency="1"
+                        Maximum="10"
+                        Value="8" />
+                <Slider Width="400"
+                        IsSnapToTickEnabled="True"
+                        TickFrequency="1"
+                        Maximum="10"
+                        Value="3"
+                        IsEnabled="False" />
+                <Slider Width="400"
+                        IsSnapToTickEnabled="True"
+                        TickFrequency="5"
+                        Maximum="100"
+                        TickPlacement="TopLeft"
+                        Value="10" />
+                <Slider Width="400"
+                        hc:TipElement.IsVisible="True"
+                        hc:TipElement.Placement="Top"
+                        IsSnapToTickEnabled="True"
+                        Maximum="100"
+                        Value="60"
+                        TickFrequency="10"
+                        TickPlacement="BottomRight" />
+                <Slider Width="400"
+                        hc:TipElement.IsVisible="True"
+                        hc:TipElement.Placement="Bottom"
+                        hc:TipElement.StringFormat="N2"
+                        TickFrequency="1"
+                        Maximum="10"
+                        Value="5"
+                        TickPlacement="Outside" />
+            </hc:UniformSpacingPanel>
+            <hc:UniformSpacingPanel Spacing="32">
+                <Slider Height="400"
+                        IsSnapToTickEnabled="True"
+                        TickFrequency="1"
+                        Maximum="10"
+                        Value="8"
+                        Orientation="Vertical" />
+                <Slider Height="400"
+                        IsSnapToTickEnabled="True"
+                        TickFrequency="1"
+                        Maximum="10"
+                        Value="3"
+                        IsEnabled="False"
+                        Orientation="Vertical" />
+                <Slider Height="400"
+                        IsSnapToTickEnabled="True"
+                        TickFrequency="5"
+                        Maximum="100"
+                        TickPlacement="TopLeft"
+                        Value="10"
+                        Orientation="Vertical" />
+                <Slider Height="400"
+                        hc:TipElement.IsVisible="True"
+                        hc:TipElement.Placement="Right"
+                        IsSnapToTickEnabled="True"
+                        Maximum="100"
+                        Value="60"
+                        TickFrequency="10"
+                        TickPlacement="BottomRight"
+                        Orientation="Vertical" />
+                <Slider Height="400"
+                        hc:TipElement.IsVisible="True"
+                        hc:TipElement.Placement="Left"
+                        hc:TipElement.StringFormat="N2"
+                        TickFrequency="1"
+                        Maximum="10"
+                        Value="5"
+                        TickPlacement="Outside"
+                        Orientation="Vertical" />
+            </hc:UniformSpacingPanel>
+        </hc:UniformSpacingPanel>
+    </ScrollViewer>
+</UserControl>

src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/SliderDemo.axaml.cs

@@ -0,0 +1,9 @@
+namespace HandyControlDemo.UserControl;
+
+public partial class SliderDemo : Avalonia.Controls.UserControl
+{
+    public SliderDemo()
+    {
+        InitializeComponent();
+    }
+}

src/Avalonia/HandyControl_Avalonia/Controls/Attach/ContentControlAttach.cs

@@ -0,0 +1,49 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Data;
+
+namespace HandyControl.Controls;
+
+public class ContentControlAttach
+{
+    public static readonly AttachedProperty<string> ContentStringFormatProperty =
+        AvaloniaProperty.RegisterAttached<ContentControlAttach, AvaloniaObject, string>("ContentStringFormat");
+
+    public static void SetContentStringFormat(AvaloniaObject element, string value) =>
+        element.SetValue(ContentStringFormatProperty, value);
+
+    public static string GetContentStringFormat(AvaloniaObject element) =>
+        element.GetValue(ContentStringFormatProperty);
+
+    public static readonly AttachedProperty<object?> ContentProperty =
+        AvaloniaProperty.RegisterAttached<ContentControlAttach, AvaloniaObject, object?>("Content");
+
+    public static void SetContent(AvaloniaObject element, object? value) => element.SetValue(ContentProperty, value);
+
+    public static object? GetContent(AvaloniaObject element) => element.GetValue(ContentProperty);
+
+    static ContentControlAttach()
+    {
+        ContentStringFormatProperty.Changed.AddClassHandler<AvaloniaObject>(OnContentChanged);
+        ContentProperty.Changed.AddClassHandler<AvaloniaObject>(OnContentChanged);
+    }
+
+    private static void OnContentChanged(AvaloniaObject element, AvaloniaPropertyChangedEventArgs e)
+    {
+        if (element is not ContentControl contentControl)
+        {
+            return;
+        }
+
+        contentControl.ClearValue(ContentControl.ContentProperty);
+
+        var binding = new Binding("(ContentControlAttach.Content)")
+        {
+            Source = contentControl,
+            StringFormat = contentControl.GetValue(ContentStringFormatProperty),
+            TypeResolver = (_, _) => typeof(ContentControlAttach)
+        };
+
+        contentControl.Bind(ContentControl.ContentProperty, binding);
+    }
+}

src/Avalonia/HandyControl_Avalonia/Controls/Attach/TipElement.cs

@@ -0,0 +1,30 @@
+using Avalonia;
+using HandyControl.Data;
+
+namespace HandyControl.Controls;
+
+public class TipElement
+{
+    public static readonly AttachedProperty<bool> IsVisibleProperty =
+        AvaloniaProperty.RegisterAttached<TipElement, AvaloniaObject, bool>("IsVisible");
+
+    public static void SetIsVisible(AvaloniaObject element, bool value) => element.SetValue(IsVisibleProperty, value);
+
+    public static bool GetIsVisible(AvaloniaObject element) => element.GetValue(IsVisibleProperty);
+
+    public static readonly AttachedProperty<PlacementType> PlacementProperty =
+        AvaloniaProperty.RegisterAttached<TipElement, AvaloniaObject, PlacementType>("Placement");
+
+    public static void SetPlacement(AvaloniaObject element, PlacementType value) =>
+        element.SetValue(PlacementProperty, value);
+
+    public static PlacementType GetPlacement(AvaloniaObject element) => element.GetValue(PlacementProperty);
+
+    public static readonly AttachedProperty<string> StringFormatProperty =
+        AvaloniaProperty.RegisterAttached<TipElement, AvaloniaObject, string>("StringFormat", defaultValue: "N1");
+
+    public static void SetStringFormat(AvaloniaObject element, string value) =>
+        element.SetValue(StringFormatProperty, value);
+
+    public static string GetStringFormat(AvaloniaObject element) => element.GetValue(StringFormatProperty);
+}

src/Avalonia/HandyControl_Avalonia/Controls/Panel/AxleCanvas.cs

@@ -0,0 +1,73 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Layout;
+
+namespace HandyControl.Controls;
+
+public class AxleCanvas : Canvas
+{
+    public static readonly StyledProperty<Orientation> OrientationProperty =
+        StackPanel.OrientationProperty.AddOwner<AxleCanvas>(new StyledPropertyMetadata<Orientation>(
+            defaultValue: Orientation.Horizontal));
+
+    public Orientation Orientation
+    {
+        get => GetValue(OrientationProperty);
+        set => SetValue(OrientationProperty, value);
+    }
+
+    protected override Size ArrangeOverride(Size finalSize)
+    {
+        foreach (Control? internalChild in Children)
+        {
+            if (internalChild == null)
+            {
+                continue;
+            }
+
+            double x = 0.0;
+            double y = 0.0;
+
+            if (Orientation == Orientation.Horizontal)
+            {
+                x = (finalSize.Width - internalChild.DesiredSize.Width) / 2;
+
+                double top = GetTop(internalChild);
+                if (!double.IsNaN(top))
+                {
+                    y = top;
+                }
+                else
+                {
+                    double bottom = GetBottom(internalChild);
+                    if (!double.IsNaN(bottom))
+                    {
+                        y = finalSize.Height - internalChild.DesiredSize.Height - bottom;
+                    }
+                }
+            }
+            else
+            {
+                y = (finalSize.Height - internalChild.DesiredSize.Height) / 2;
+
+                double left = GetLeft(internalChild);
+                if (!double.IsNaN(left))
+                {
+                    x = left;
+                }
+                else
+                {
+                    double right = GetRight(internalChild);
+                    if (!double.IsNaN(right))
+                    {
+                        x = finalSize.Width - internalChild.DesiredSize.Width - right;
+                    }
+                }
+            }
+
+            internalChild.Arrange(new Rect(new Point(x, y), internalChild.DesiredSize));
+        }
+
+        return finalSize;
+    }
+}

src/Avalonia/HandyControl_Avalonia/Data/Enum/PlacementType.cs

@@ -0,0 +1,17 @@
+namespace HandyControl.Data;
+
+public enum PlacementType
+{
+    LeftTop,
+    Left,
+    LeftBottom,
+    TopLeft,
+    Top,
+    TopRight,
+    RightTop,
+    Right,
+    RightBottom,
+    BottomLeft,
+    Bottom,
+    BottomRight,
+}

src/Avalonia/HandyControl_Avalonia/Themes/Basic/Effects.axaml

@@ -1,7 +1,7 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
 
-    <Color x:Key="EffectShadowColor">#88000000</Color>
+    <Color x:Key="EffectShadowColor">Black</Color>
 
     <DropShadowEffect x:Key="EffectShadow1"
                       BlurRadius="5"