sharee.bike-App/ShareeSharedGuiLib/ViewModel/BarLevelInputViewModel.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Windows.Input;
using Xamarin.Forms;

namespace ShareeSharedGuiLib.ViewModel
{
    /// <summary>
    /// Bar based filling level view which shows filling level and allows to edit this level.
    /// </summary>
    public class BarLevelInputViewModel : INotifyPropertyChanged
    {
        public new event PropertyChangedEventHandler PropertyChanged;

        public int? _Maximum = null;

        public int? Maximum
        {
            get => _Maximum;
            set
            {
                if (_Maximum == value)
                {
                    // Nothing to do because nothing changed.
                    return;
                }

                _Maximum = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(MaximumText)));
            }
        }

        public string MaximumText => Maximum != null
            ? Maximum.Value.ToString()
            : string.Empty;

        public int? _Current = null;

        public int? Current
        {
            get => _Current;
            set
            {
                if (_Current == value)
                {
                    // Nothing to do because nothing changed.
                    return;
                }

                _Current = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Current)));
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(CurrentText)));
            }
        }

        public string CurrentText
        {
            get => Current != null
            ? Current.Value.ToString()
            : string.Empty;

            set => Current = int.TryParse(value, out int newCurrent) ? (int?)newCurrent : null;
        }
    }
}