从WPF MVVM Caliburn绑定到用户控件的属性

Question

In MS VS2015 Professional I develop WPF application with Caliburn.Micro using MVVM pattern. I use usercontrol in my application. The usercontrol was also developed with Caliburn.Micro but not in MVVM. The usercontrol has two dependency properties:

public static DependencyProperty XmaxProperty =
                  DependencyProperty.Register("Xmax", typeof(double),
                  typeof(LineChart),
                  new FrameworkPropertyMetadata(10.0, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));

public double Xmax
{
    get { return (double)GetValue(XmaxProperty); }
    set { SetValue(XmaxProperty, value); }
}

and

public static readonly DependencyProperty DataCollectionProperty = DependencyProperty.Register("DataCollection",
          typeof(BindableCollection<LineSeriesControl>), typeof(LineChart),
          new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnDataChanged));

public BindableCollection<LineSeriesControl> DataCollection
{
    get { return (BindableCollection<LineSeriesControl>)GetValue(DataCollectionProperty); }
    set { SetValue(DataCollectionProperty, value); }
}

private static void OnDataChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    var lc = sender as LineChart;
    var dc = e.NewValue as BindableCollection<LineSeriesControl>;
    if (dc != null)
        dc.CollectionChanged += lc.dc_CollectionChanged;
}

private void dc_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
    if (DataCollection != null)
    {
        CheckCount = 0;
        if (DataCollection.Count > 0)
            CheckCount = DataCollection.Count;
    }
}

In my application I define two properties:

public BindableCollection<LineSeriesControl> DataCollection { get; set; }

and

public Double Xmax { get; set; }

In my MainWindowView.xaml file in my application I include usercontrol to my application

xmlns:local="clr-namespace:ChartControl;assembly=ChartControl"

where ChartControl is the name of the control and create binding:

<local:LineChart Grid.Row="2" Grid.Column="0" DataCollection="{Binding DataCollection}" Xmax="{Binding Xmax}"/>

Then by button click the next code executes:

public void DisplayChart()
{
    this.DataCollection.Clear();
    LineSeriesControl ds = new LineSeriesControl();
    . . . . . . . . . . . . . . . . . .
    for (int i = 0; i < 50; i++)
    {
        double x = i / 5.0;
        double y = Math.Sin(x);
        ds.LinePoints.Add(new Point(x, y));
    }
    . . . . . . . . . . . . . . . . . . . . . . .
    this.Xmax = ds.LinePoints.Count + 100;
    . . . . . . . . . . . . . . . . . . . . . . .
    this.DataCollection.Add(ds);
}

Xmax is assigned by 150 (I've checked it in debugger) and in DataCollection one instance of LineSeriesControl is added. DataCollection binds perfectly well and code in the usercontrol uses it perfectly well but the binding of Xmax is not successful . The property Xmax in usercontrol has the value of 0. Why it has place? What I've done wrongly? Please help.

Answer 1

You have to call PropertyChanged event on your property in order for the bound DP to get a new value via binding.

 private Double _xmax;
 public Double Xmax 
 { 
    get{ return _xmax;} 
    set
    {
         _xmax = value;
         NotifyOfPropertyChange(() => Xmax);
    }