realtime uppdate

Question

I have a service that start a timer

    public class TurbinesService(DeviceLanguageService deviceLanguageService) {

        private const int HoursDay = 24;
        private const int MinutesDay = 60;
        private const double IncrementValue = 0.0007;
        private readonly DeviceLanguageService _deviceLanguageService = deviceLanguageService;
        private bool isRunning;
        private ObservableCollection<TurbinePin> _turbinePins = [];

        public ObservableCollection<TurbinePin> GetTurbinePins(ICommand pinClickedCommand) {
            _turbinePins = [
                new() {
                Turbine = new Turbine(_deviceLanguageService) {
                    Id = 1,
                    Name = "Solar Generator",
                    Label = "Charge station",
                    Address = "Av. de las Américas, Guayaquil 090513, Ecuador",
                    Location = new Location(-2.151993, -79.886109),
                    InstalationDateTime = new DateTime(2024, 8, 2),
                    Images = ["charge_station.png", "wind_turbine.png"]
                },
                PinClickedCommand = pinClickedCommand
            }
            ];

            foreach (var pin in _turbinePins) {
                CalculateAndSetValues(pin.Turbine!);
            }

            return _turbinePins;
        }

        public void StartIncrementingAllTurbines() {
            if (!isRunning) {
                isRunning = true;
                foreach (var pin in _turbinePins) {
                    StartIncrementingRemovedCo2Kilograms(pin.Turbine!);
                }
            }
        }

        private void CalculateAndSetValues(Turbine turbine) {
            var energyPerDay = RoundToDecimals(turbine.TurbinePower * turbine.TurbineCapacityFactor * HoursDay);
            var energyPerHour = RoundToDecimals(energyPerDay / HoursDay, 4);
            var energyPerSecond = RoundToDecimals(energyPerHour / MinutesDay, 5);
            var removedCo2PerSecond = RoundToDecimals(energyPerSecond * turbine.TurbineEmissionOffset, 5);
            var daysPassedSinceInstallation = (DateTime.Today - turbine.InstalationDateTime).Days;
            var energyProduced = RoundToDecimals(energyPerDay * daysPassedSinceInstallation);
            var removedCo2Kilograms = RoundToDecimals(turbine.CalculatedRemovedCo2Kilograms, 3);

            turbine.RemovedCo2Kilograms = removedCo2Kilograms;
            Debug.WriteLine($"Initial RemovedCo2Kilograms: {turbine.RemovedCo2Kilograms}");
        }

        private async void StartIncrementingRemovedCo2Kilograms(Turbine turbine) {
            while (isRunning) {
                await Task.Delay(1000);  // Increment every second

                // Increment RemovedCo2Kilograms by 0.0007
                UpdateRemovedCo2Kilograms(turbine, IncrementValue);
            }
        }

        private void UpdateRemovedCo2Kilograms(Turbine turbine, double increment) {
            turbine.RemovedCo2Kilograms += increment;

            // Round to 3 decimal places
            turbine.RemovedCo2Kilograms = RoundToDecimals(turbine.RemovedCo2Kilograms, 3);
            Debug.WriteLine($"Updated RemovedCo2Kilograms: {turbine.RemovedCo2Kilograms}");
        }

        private double RoundToDecimals(double value, int decimals = 2) {
            return Math.Round(value, decimals);
        }
    }
}

And I call this OnAppStart so it will start the timer

 public App(AppShell appShell, TurbinesService _turbinesService) {
     Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense(AppConstants.SYNCFUSION_KEY);

     InitializeComponent();

     MainPage = appShell;

     turbinesService = _turbinesService;
 }

 protected override void OnStart() {
     base.OnStart();
     // Start the incrementation logic here
     turbinesService.StartIncrementingAllTurbines();
 }

I want to use this in two places

    public partial class TurbinesCollectionPageViewModel(TurbinesService turbinesService)
        : ChargingStationsMapPageViewModel(turbinesService) {

    }

  <CollectionView.ItemTemplate>
      <DataTemplate x:DataType="model:TurbinePin">
          <Grid>
              <Border Style="{StaticResource CommonBorderStyle}">
                  <Grid
                      ColumnDefinitions="Auto,*"
                      RowDefinitions="30,*,*">
                      <Label
                          Style="{StaticResource CommonLabelStyle}"
                          Text="{Binding Turbine.Name}" />
                      <Label
                          Grid.Row="1"
                          Style="{StaticResource CommonLabelStyle}"
                          Text="{Binding Turbine.Address}" />
                      <Label
                          Grid.Row="2"
                          Style="{StaticResource CommonLabelStyle}"
                          Text="{Binding Turbine.LocalizedInstalationDateTime}" />

                      <Label
                          Grid.RowSpan="3"
                          Grid.Column="1"
                          Grid.ColumnSpan="2"
                          Text="{Binding Turbine.RemovedCo2Kilograms}"
                          VerticalOptions="Center"
                          VerticalTextAlignment="Center" />

and here

 [QueryProperty(nameof(SelectedTurbine), "SelectedTurbine")]
 public partial class TurbineDetailPageViewModel : ObservableObject {
     [ObservableProperty]
     Turbine? selectedTurbine;
     [RelayCommand]
     void Appear() {
         if (SelectedTurbine == null) {
             return;
         }
     }

<Border
    Grid.Row="4"
    Grid.Column="1"
    Padding="5">
    <Label
        BackgroundColor="Yellow"
        FontAttributes="Bold"
        HorizontalTextAlignment="Center"
        Text="{Binding SelectedTurbine.RemovedCo2Kilograms, StringFormat='{0} kg Co2'}" />
</Border>

but it doesn't update in real time, is not incrementing (I just see a static number)

Net 8

Maui 8.0.9

Answer 1

Hello,

As you said, you have resolved the problem.

I was using this

private async void StartIncrementingRemovedCo2Kilograms(Turbine turbine) {
            while (isRunning) {
                await Task.Delay(1000);  // Increment every second

                // Increment RemovedCo2Kilograms by 0.0007
                UpdateRemovedCo2Kilograms(turbine, IncrementValue);
            }
        }

        private void UpdateRemovedCo2Kilograms(Turbine turbine, double increment) {
            turbine.RemovedCo2Kilograms += increment;

            // Round to 3 decimal places
            turbine.RemovedCo2Kilograms = RoundToDecimals(turbine.RemovedCo2Kilograms, 3);
            Debug.WriteLine($"Updated RemovedCo2Kilograms: {turbine.RemovedCo2Kilograms}");
        }

        private double RoundToDecimals(double value, int decimals = 2) {
            return Math.Round(value, decimals);
        }
    }

What I should have done is

       public TurbinesService(DeviceLanguageService deviceLanguageService, IDispatcher application) {
           _deviceLanguageService = deviceLanguageService;
           _dispatcher = application;
           InitializeTimer(); // Just initialize the timer, do not start it here

       }

       // Initialize the timer
       private void InitializeTimer() {
           _timer = _dispatcher.CreateTimer(); // Use the injected dispatcher
           _timer.Interval = TimeSpan.FromSeconds(1);
           _timer.Tick += (s, e) => UpdateTurbinesCo2();
       }

       public ObservableCollection<TurbinePin> GetTurbinePins(ICommand pinClickedCommand) {
           _turbinePins = [
               new() {
                   Turbine = new Turbine(_deviceLanguageService) {
                       Id = 1,
                       Name = "Estación Ciudadela Simón Bolívar",
                       Label = "Charge station",
                       Address = "Av. de las Américas, Guayaquil 090513, Ecuador",
                       Location = new Location(-2.151993, -79.886109),
                       InstalationDateTime = new DateTime(2024, 8, 2),
                       Images = ["charge_station.png", "wind_turbine.png"]
                   },
                   PinClickedCommand = pinClickedCommand
               }
           ];

           foreach (var pin in _turbinePins) {
               CalculateAndSetValues(pin.Turbine!);
           }

           // Do not start the timer here
           return _turbinePins;
       }

       // Start the timer explicitly
       public void StartTimer() {
           if (!isTimerRunning) {
               _timer!.Start();
               isTimerRunning = true;
           }
       }

       // Method to handle updating CO2 every second
       private void UpdateTurbinesCo2() {
           foreach (var pin in _turbinePins) {
               var turbine = pin.Turbine;
               if (turbine != null) {
                   turbine.RemovedCo2Kilograms += turbine.RemovedCo2PerSecond;  // Update CO2 every second
                   turbine.RemovedCo2Kilograms = RoundToDecimals(turbine.RemovedCo2Kilograms, 3);
               }
           }
       }

and register a dispatcher as a dependency

Thanks for your sharing.

Best Regards,

Wenyan Zhang

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