WPF RotateCircle defines in usercontrol and reuse

//usercontrol
//xaml
<UserControl x:Class="WpfApp159.UCRotateCircle"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfApp159"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <UserControl.Resources>
        <local:SizeConverter x:Key="sizeConverter"/>
    </UserControl.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition Height="10*"/>
        </Grid.RowDefinitions>
        <TextBlock Grid.Row="0"
                   FontSize="15"
                   Foreground="Red"
                   FontWeight="Bold"
                   HorizontalAlignment="Center"
                   Text="{Binding UCRotatedAngleStr,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>
        <Ellipse x:Name="elp"
                 Grid.Row="1"
                 Width="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type UserControl}},
                 Converter={StaticResource sizeConverter},
                 ConverterParameter=2}"
                 Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type UserControl}},
                 Converter={StaticResource sizeConverter},
                 ConverterParameter=2}"
                 MouseDown="elp_MouseDown"
                 MouseMove="elp_MouseMove"
                 MouseUp="elp_MouseUp"
                 RenderTransformOrigin="0.5,0.5">
            <Ellipse.RenderTransform>
                <RotateTransform x:Name="rotateTransform"/>
            </Ellipse.RenderTransform>
            <Ellipse.Fill>
                <LinearGradientBrush StartPoint="0,0"
                             EndPoint="0,1">
                    <GradientStop Color="Orange" Offset="0.0"/>
                    <GradientStop Color="Orange" Offset="0.2"/>
                    <GradientStop Color="Yellow" Offset="0.2"/>
                    <GradientStop Color="Yellow" Offset="0.4"/>
                    <GradientStop Color="Green" Offset="0.4"/>
                    <GradientStop Color="Green" Offset="0.499"/>
                    <GradientStop Color="Red" Offset="0.499"/>
                    <GradientStop Color="Red" Offset="0.501"/>
                    <GradientStop Color="Green" Offset="0.501"/>
                    <GradientStop Color="Green" Offset="0.6"/>
                    <GradientStop Color="Cyan" Offset="0.6"/>
                    <GradientStop Color="Cyan" Offset="0.8"/>
                    <GradientStop Color="Blue" Offset="0.8"/>
                    <GradientStop Color="Blue" Offset="1.0"/>
                </LinearGradientBrush>
            </Ellipse.Fill>
        </Ellipse>
    </Grid>
</UserControl>

//cs
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp159
{
    /// <summary>
    /// Interaction logic for UCRotateCircle.xaml
    /// </summary>
    public partial class UCRotateCircle : UserControl
    {
        public UCRotateCircle()
        {
            InitializeComponent();
            this.DataContext = this;
        }

        Point originPt { get; set; }
        Point currentPt { get; set; }

        protected override void OnRenderSizeChanged(SizeChangedInfo sizeInfo)
        {
            base.OnRenderSizeChanged(sizeInfo);
            Point tempPt=new Point(elp.ActualWidth/2, elp.ActualHeight/2);
            originPt = elp.TranslatePoint(tempPt, this);
        }


        public double UCConverterParameter
        {
            get { return (double)GetValue(UCConverterParameterProperty); }
            set { SetValue(UCConverterParameterProperty, value); }
        }

        // Using a DependencyProperty as the backing store for UCConverterParameter.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty UCConverterParameterProperty =
            DependencyProperty.Register("UCConverterParameter", typeof(double),
                typeof(UCRotateCircle), new PropertyMetadata(2.0d));




        public string UCRotatedAngleStr
        {
            get { return (string)GetValue(UCRotatedAngleStrProperty); }
            set { SetValue(UCRotatedAngleStrProperty, value); }
        }

        // Using a DependencyProperty as the backing store for UCRotatedAngleStr.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty UCRotatedAngleStrProperty =
            DependencyProperty.Register("UCRotatedAngleStr", typeof(string),
                typeof(UCRotateCircle), new PropertyMetadata("0"));


        private void elp_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if(e.LeftButton == MouseButtonState.Pressed)
            {
                currentPt=e.GetPosition(this);
                elp.CaptureMouse();
            }
        }

        private void elp_MouseMove(object sender, MouseEventArgs e)
        {
            if(e.LeftButton== MouseButtonState.Pressed)
            {
                Vector prevVec=Point.Subtract(currentPt,originPt);
                Point newPt = e.GetPosition(this);
                Vector newVec=Point.Subtract(newPt,originPt);
                double deltaAngle=Vector.AngleBetween(prevVec, newVec);
                rotateTransform.Angle += deltaAngle;
                currentPt = newPt;
                UCRotatedAngleStr = Math.Round(rotateTransform.Angle, 2).ToString();
                System.Diagnostics.Debug.WriteLine($"{deltaAngle},{rotateTransform.Angle}");
            }
        }

        private void elp_MouseUp(object sender, MouseButtonEventArgs e)
        {
            if(e.LeftButton==MouseButtonState.Released)
            {
                elp.ReleaseMouseCapture();
            }
        }
    }
    public class SizeConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            double dValue = 0.0, dPara = 0.0;
            if (double.TryParse(value?.ToString(), out dValue)
                && double.TryParse(parameter?.ToString(), out dPara)
                && dPara > 0)
            {
                return dValue / dPara;
            }
            return dValue;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}

 

 

 

 

<Window x:Class="WpfApp159.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp159"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <local:UCRotateCircle Grid.Row="0"
                              Grid.Column="0"/>
        <local:UCRotateCircle Grid.Row="0"
                      Grid.Column="1"/>
        <local:UCRotateCircle Grid.Row="1"
                      Grid.Column="0"/>
        <local:UCRotateCircle Grid.Row="1"
                      Grid.Column="1"/>
    </Grid>
</Window>