Question

I am using C# to create a WPF interface. The display shows current coordinates of a moving object. What I am doing is trigger a thread on an interval which calls a function that checks the current position of the moving object.

Note: The function which checks the current position is called from other class(in a different .cs file) and my interface is in a another window, which is the main window.

How can I show the coordinates in the window interface? Is there a way to assign a variable which is initialized in one class(.cs) to another label toolbar in the interface(.xaml)?

Answer 1

The simplest way to do this is to add a couple of TextBlocks (or TextBox if you prefer) and bind them to a property on a view model:

<TextBlock Text="{Binding Path=XCord}" />

The trick is that since you’re using a timer or a background thread, you have to synchronize the property change notifications so that they happen on your UI thread. So you could implement the XCord property like:

    public string XCoord
    {
        get { return _xcoord; }
        set
        {
            if(!Application.Current.Dispatcher.CheckAccess())
            {
                Application.Current.Dispatcher
                    .BeginInvoke(new Action(() =>
                                            {
                                                _xcoord = value;
                                                NotifyPropertyChanged("XCoord");
                                            }));
            }
            else
            {
                _xcoord = value;
                NotifyPropertyChanged("XCoord");
            }
        }
    }

This check’s with the Dispatcher to make sure you’re not trying to set the property from the wrong thread, and if you are, it uses BeginInvoke to do the work on the UI thread. That way, when the PropertyChanged event fires, and the binding attempts to read the value and change the UI it does so from the UI thread rather than the background thread.