public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new ViewModel(this);
        }
    }
    public class TimeModel : INotifyPropertyChanged
    {
        private DateTime time1;
        public DateTime Time1
        {
            get { return time1; }
            set
            {
                time1 = value;
                OnPropertyChanged("Time1");
                OnPropertyChanged("Time3");
            }
        }
        private DateTime time2;
        public DateTime Time2
        {
            get { return time2; }
            set
            {
                time2 = value;
                OnPropertyChanged("Time2");
                OnPropertyChanged("Time3");
            }
        }
        public DateTime Time3
        {
            get
            {

                var date = new DateTime(Time1.Year, Time1.Month, Time1.Day, Time1.Hour + Time2.Hour, Time1.Minute + Time2.Minute, Time1.Second + Time2.Second);
                return date;
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(String propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
    public class ViewModel : INotifyPropertyChanged
    {
        private MainWindow _window;
        private ReportViewer _reportviewer;
        private ObservableCollection<TimeModel> _testData;
        public ObservableCollection<TimeModel> TestData
        {
            get { return _testData; }
            set
            {
                _testData = value;
                OnPropertyChanged("TestData");
            }
        }
        public ViewModel(MainWindow win)
        {
            _window = win;
            this._reportviewer = _window._reportviewer;
            Initialize();
            TestData = (ObservableCollection<TimeModel>)TestData1;
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(String propertyName)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        private IEnumerable<TimeModel> TestData1 = new ObservableCollection<TimeModel>() 
        {new TimeModel() { Time1 = new DateTime(2022, 10, 31, 1, 0, 0), Time2 = new DateTime(2022, 10, 31, 1, 0, 0) },
         new TimeModel() { Time1 = new DateTime(2022, 10, 31, 2, 0, 0), Time2 = new DateTime(2022, 10, 31, 2, 0, 0) }
        };
        public static string ContentStart = @"Report1.rdlc";
        private void Initialize()
        {
            _reportviewer.LocalReport.DataSources.Clear();
            var rpds_model = new ReportDataSource() { Name = "DataSet1", Value = TestData1 };
            _reportviewer.LocalReport.DataSources.Add(rpds_model);
            _reportviewer.LocalReport.EnableExternalImages = true;
            _reportviewer.LocalReport.ReportPath = ContentStart;  
            _reportviewer.SetDisplayMode(DisplayMode.PrintLayout);  
            _reportviewer.Refresh();  
            _reportviewer.RefreshReport();  
        }
    }