Dynamic Horizontal Annotation using MVVM

Hi,

Was hoping you could point me in the right direction. I’m trying to create horizontal line annotations on demand using MVVM but have become stuck. I’ve have them working in MVVM when the chart loads but not when a button is clicked although I have achieved this using code behind.

I’ve tried using an observable collection of AnnotationCollection type but am struggling to add the horizontal lines annotations to it as they are of a different type.

Any pointers in the right direction would be much appreciated!

Thanks,
Tim

Example of MVVM

TradeAnnotations = CreateHorizontalAnnotations();

private AnnotationCollection _annotations;

    public AnnotationCollection TradeAnnotations
    {
        get { return _annotations; }
        set
        {
            _annotations = value;
            OnPropertyChanged("TradeAnnotations");
        }
    }

    private static AnnotationCollection CreateHorizontalAnnotations()
    {
        //var annotations = new AnnotationCollection();

        var annotations = new AnnotationCollection();

        Color strokeColor = (Color)ColorConverter.ConvertFromString("#008B45");
        Brush strokeBrush = new SolidColorBrush(strokeColor);

        HorizontalLineAnnotation annotation = new HorizontalLineAnnotation();

        annotation.ShowLabel = true;
        annotation.LabelPlacement = LabelPlacement.Axis;
        annotation.HorizontalAlignment = HorizontalAlignment.Stretch;
        annotation.IsEditable = true;
        annotation.SnapsToDevicePixels = true;
        annotation.Stroke = strokeBrush;

        annotation.X1 = DateTime.Now;
        annotation.Y1 = 129;

        annotations.Add(annotation);

        return annotations;          
    }

Example of code behind

        private void CreateHorizontalAnnotations(object sender, System.Windows.RoutedEventArgs e)
    {
        //var annotations = new AnnotationCollection();

        var annotationCollection = new AnnotationCollection();

        Color strokeColor = (Color)ColorConverter.ConvertFromString("#008B45");
        Brush strokeBrush = new SolidColorBrush(strokeColor);

        HorizontalLineAnnotation annotation = new HorizontalLineAnnotation();

        annotation.ShowLabel = true;
        annotation.LabelPlacement = LabelPlacement.Axis;
        annotation.HorizontalAlignment = HorizontalAlignment.Stretch;
        annotation.IsEditable = true;
        annotation.SnapsToDevicePixels = true;
        annotation.Stroke = strokeBrush;

        annotation.X1 = DateTime.Now;
        annotation.Y1 = 129;

        this.priceChart.Annotations.Add(annotation);
    }