WPF Customcontrol NumUpDownScroller

//D:\C\WpfApp10\Themes\Generic.xaml
 <Style TargetType="{x:Type local:NumUpDownScroller}"
        x:Key="NumUpDownScrollerStyle1">
     <Setter Property="Template">
         <Setter.Value>
             <ControlTemplate TargetType="{x:Type local:NumUpDownScroller}">
                 <Border BorderBrush="{TemplateBinding BorderBrush}"
                         BorderThickness="{TemplateBinding BorderThickness}"
                         Background="{TemplateBinding Background}"
                         Width="50"
                         Height="150">
                     <StackPanel Orientation="Vertical" Margin="5">
                         <Button x:Name="PART_UpBtn"
                                 Content="Up"/>
                         <TextBlock Text="{Binding Path=NumStr,RelativeSource={RelativeSource AncestorType={x:Type local:NumUpDownScroller}}}"
                                    HorizontalAlignment="Center"/>
                         <Button x:Name="PART_DownBtn"
                                 Content="Down"/>
                     </StackPanel>
                 </Border>
             </ControlTemplate>
         </Setter.Value>
     </Setter>
 </Style>

//D:\C\WpfApp10\NumUpDownScroller.cs

using System;
using System.Collections.Generic;
using System.Text;
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 WpfApp10
{
    /// <summary>
    /// Follow steps 1a or 1b and then 2 to use this custom control in a XAML file.
    ///
    /// Step 1a) Using this custom control in a XAML file that exists in the current project.
    /// Add this XmlNamespace attribute to the root element of the markup file where it is 
    /// to be used:
    ///
    ///     xmlns:MyNamespace="clr-namespace:WpfApp10"
    ///
    ///
    /// Step 1b) Using this custom control in a XAML file that exists in a different project.
    /// Add this XmlNamespace attribute to the root element of the markup file where it is 
    /// to be used:
    ///
    ///     xmlns:MyNamespace="clr-namespace:WpfApp10;assembly=WpfApp10"
    ///
    /// You will also need to add a project reference from the project where the XAML file lives
    /// to this project and Rebuild to avoid compilation errors:
    ///
    ///     Right click on the target project in the Solution Explorer and
    ///     "Add Reference"->"Projects"->[Browse to and select this project]
    ///
    ///
    /// Step 2)
    /// Go ahead and use your control in the XAML file.
    ///
    ///     <MyNamespace:NumUpDownScroller/>
    ///
    /// </summary>
    public class NumUpDownScroller : Control
    {
        private Button upBtn, downBtn;
        static NumUpDownScroller()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(NumUpDownScroller), new FrameworkPropertyMetadata(typeof(NumUpDownScroller)));
        }


        private int num = 0;

        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();

            var tempUpBtn = GetTemplateChild("PART_UpBtn") as Button;
            if(tempUpBtn!=null)
            {
                upBtn = tempUpBtn;
                upBtn.Click += UpBtn_Click;
            }

            var tempDownBtn = GetTemplateChild("PART_DownBtn") as Button;
            if (tempDownBtn != null)
            {
                downBtn= tempDownBtn;
                downBtn.Click += DownBtn_Click;
            }
        }

        private void DownBtn_Click(object sender, RoutedEventArgs e)
        {
            if(--num<0)
            {
                num = 60;               
            }
            NumStr = $"{num:D2}";
        }

        private void UpBtn_Click(object sender, RoutedEventArgs e)
        {
            if(++num>60)
            {
                num = 0;                
            }
            NumStr = $"{num:D2}";
        }

        public string NumStr
        {
            get { return (string)GetValue(NumStrProperty); }
            set { SetValue(NumStrProperty, value); }
        }

        // Using a DependencyProperty as the backing store for NumStr.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty NumStrProperty =
            DependencyProperty.Register(nameof(NumStr), 
                typeof(string), 
                typeof(NumUpDownScroller), 
                new PropertyMetadata("0",OnNumStrChanged));

        private static void OnNumStrChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            
        }
    }
}

 

 

//D:\C\WpfApp10\App.xaml
<Application x:Class="WpfApp10.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:WpfApp10"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/Themes/Generic.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>


//D:\C\WpfApp10\MainWindow.xaml
 <local:NumUpDownScroller Grid.Row="1"
                          Grid.Column="0"
                          Style="{StaticResource NumUpDownScrollerStyle1}"/>