Question

I got some issues while trying to bind an ObservableCollection made from 2 others.
First I need to bind ActiveSketchs, Second i have to bind Sketchs (Which is ActivesSketchs.Union(InactiveSketchs) separately.

I thought the code below would work but it doesn’t. The ActiveSketch binding works correctly, but not the Sketchs one :

    private ObservableCollection<Sketch> _sketchs;
    public ObservableCollection<Sketch> Sketchs
    {
        get { return _sketchs = new ObservableCollection<Sketch>(ActiveSketchs.Union(InactiveSketchs)); }
        set { _sketchs = value; }
    }

    private ObservableCollection<Sketch> _activeSketchs;
    public ObservableCollection<Sketch> ActiveSketchs
    {
        get { return _activeSketchs; }
        set { _activeSketchs = value; }
    }

    private ObservableCollection<Sketch> _inactiveSketchs;
    public ObservableCollection<Sketch> InactiveSketchs
    {
        get { return _inactiveSketchs; }
        set { _inactiveSketchs = value; }
    }

And here’s how i set the source item :

    HeadbandRight.ItemsSource = Sketchs;
    HeadbandLeft.ItemsSource = Sketchs;
    MainScatterViewer.ItemsSource = ActiveSketchs;

Answer 1

You should use a CollectionViewSource to get filtered items from your list :

public InitFunction()
{
    this.Sketchs = new ObservableCollection<Sketch>();

    this.ActiveSketchs = new CollectionViewSource();
    this.ActiveSketchs.Source = this.Sketches ;
    this.ActiveSketchs.Filter += (s, e) =>
    {
        var sketch = e.Item as Sketch;

        e.Accepted = sketch.IsActive; // or whatever test you need
    };

    HeadbandRight.ItemsSource = Sketchs;
    HeadbandLeft.ItemsSource = Sketchs;
    MainScatterViewer.ItemsSource = ActiveSketchs.View;
}

public ObservableCollection<Sketch> Sketchs { get; set; }

public CollectionViewSource ActiveSketchs { get; set; }

Full example here : http://uicraftsman.com/blog/2010/10/27/filtering-data-using-collectionviewsource/