Question

I’ve implemented a class that takes care of loading objects asynchronously and takes care of changing the cursor accordingly, namely in the UpdateCursor method:

    static Cursor cursor;

    public AsyncLoader(Func<CbT> request, Callback callback, Cursor cursor)
    {
        this.request = request;
        this.callback = callback;
        AsyncLoader<CbT>.cursor = cursor;

        LatestRequestId = Guid.NewGuid();
        UpdateCursor();
        ...
    }

    void UpdateCursor()
    {
        if (LatestRequestId == Guid.Empty)
        {
            cursor = Cursors.Arrow;
        }
        else
        {
            cursor = Cursors.AppStarting;
        }
    }

In the class where I’m going to use this class I have the Cursor property which implements INotifyProperty and it’s bound to the window’s cursor:

    private Cursor _CurrentCursor;
    public Cursor CurrentCursor
    {
        get { return _CurrentCursor; }
        set
        {
            if (value != _CurrentCursor)
            {
                _CurrentCursor = value;
                OnPropertyChanged("CurrentCursor");
            }
        }
    }

In the View:

    Cursor="{Binding CurrentCursor}"

The question is, how can I pass the CurrentCursor to the AsyncLoader, so that when the UpdateCursor runs, the changes will be reflected back to the CurrentCursor and fire the PopertyChange event?

Answer 1

One of the solution would be to create an interface

interface ICursorHolder{
    Cursor CurrentCursor{get;set;}
}

Pass instance of type ICursorHolder to the AsyncLoader and to implement this interface in your class with Cursor property

public AsyncLoader(Func<CbT> request, Callback callback, ICursorHolder cursorHolder)
{
    this.request = request;
    this.callback = callback;
    AsyncLoader<CbT>.cursorHolder = cursorHolder;//change according to your logic

    LatestRequestId = Guid.NewGuid();
    UpdateCursor();
    ...
}

void UpdateCursor()
{
    if (LatestRequestId == Guid.Empty)
    {
        cursorHolder.Cursor = Cursors.Arrow;
    }
    else
    {
        cursorHolder.Cursor = Cursors.AppStarting;
    }
}

and your class

public class ShellPresenter: PresenterBase, ICursorHolder{   
    private Cursor _CurrentCursor;
    public Cursor CurrentCursor
    {
        get { return _CurrentCursor; }
        set {
            if (value != _CurrentCursor){
                _CurrentCursor = value;
                OnPropertyChanged("CurrentCursor");
            }
        }
    }    
}

Upd1

Updated sample code

Upd2

private void CallAsync(){
   ShellPresenter shell=GetInstance();
   Loader.AsyncLoader(request,callback, shell);

}