Brtdku

I have a array property, in which I want to notify whenever any elements of that array gets changed.

private double _OffsetAngles = new double[3];

public double OffsetAngles

    {

        get { return _OffsetAngles; }

        set

        {

            _OffsetAngles = value;

            NotifyPropertyChanged();

        }

    }

if any of the elements of OffsetAngles gets changed, I want to get the notification.
i.e. if I set OffsetAngles[1] = 20; //Trigger should happen.
if I set OffsetAngles[0] = 40; //Trigger should happen again.

Imagine that you are not using double but some class. And then that the filed of that class has changed. Should the array raise property changed? Surely not. So there are multiple solutions that you may consider:

• use ObservableCollection and its SetItem method


• use ObservableCollection and instead of assigning value remove and insert the value


• instead of double use some class that implements INotifyPropertyChanged and when the dobule changes raise this event, it should be right approach if the purpose is data binding


• recreate the Array each time (cumbersome and inefficient but still works)

So as others have mentioned, in your case you fire the NotifyPropertyChanged() when the array itself is changed, not any element of the array.

If you want the elements to be able to fire the event you would have to implement a class like:

public class NotifyingData<T> : INotifyPropertyChanged 

{

    public event PropertyChangedEventHandler PropertyChanged;



    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")

    {

        if (PropertyChanged != null)

        {

            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

        }

    }



    private T _Data;

    public T Data

    {

        get { return _Data; }

        set { _Data = value; NotifyPropertyChanged(); }

    }

}

and then populate your array with that class:

_OffsetAngles[0] = new NotifyingData<double> { Data = 10 };

I don't have access to VS right now, so there might be some errors, but this should be the right concept for you.

This example shows how to create and bind to a collection that derives from the ObservableCollection class, which is a collection class that provides notifications when items get added or removed.

public class NameList : ObservableCollection<PersonName>  

{  

    public NameList() : base()  

    {  

        Add(new PersonName("Willa", "Cather"));  

        Add(new PersonName("Isak", "Dinesen"));  

        Add(new PersonName("Victor", "Hugo"));  

        Add(new PersonName("Jules", "Verne"));  

    }  

  }  



  public class PersonName  

  {  

      private string firstName;  

      private string lastName;  



      public PersonName(string first, string last)  

      {  

          this.firstName = first;  

          this.lastName = last;  

      }  



      public string FirstName  

      {  

          get { return firstName; }  

          set { firstName = value; }  

      }  



      public string LastName  

      {  

          get { return lastName; }  

          set { lastName = value; }  

      }  

  } 

The objects in your collection must satisfy the requirements described in the Binding Sources Overview. In particular, if you are using OneWay or TwoWay (for example, you want your UI to update when the source properties change dynamically), you must implement a suitable property changed notification mechanism such as the INotifyPropertyChanged interface.

Ref: https://docs.microsoft.com/en-us/dotnet/framework/wpf/data/how-to-create-and-bind-to-an-observablecollection

I had the same issue a while ago. I had to update a DataTable whenever the data changed and that's how I solved it on my program :

public ObservableCollection<KeyStroke> keyList = new ObservableCollection<KeyStroke>();

public class KeyStroke : INotifyPropertyChanged

{

    // KeyStroke class storing data about each key and how many types it received

    private int id;

    private int numPress;

    public KeyStroke(int id, int numPress)

    {

        Id = id;

        NumPress = numPress;

    }

    public int Id

    {

        get => id;

        set

        {

            id = value;

            NotifyPropertyChanged("Id");

        }

    }

    public int NumPress

    {

        get { return this.numPress; }

        set

        {

            this.numPress = value;

            NotifyPropertyChanged("NumPress");

        }

    }



    public event PropertyChangedEventHandler PropertyChanged; //This handle the propertyChanged

    private void NotifyPropertyChanged(String propertyName)

    {

        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName)); //This is the WPF code for the DataGrid but you can replace it by whatever you need

    }

}

This should help you. You can also put conditions inside the getter/setters of the properties but I think it's not really pretty