How do I display push pins only in viewable area of map

I am trying to display pushpins on a map but as i have lots of pushpins i only want to display the ones within the viewable area of the map which should hopefully make the map more responsive.

I get my list of x y points from a query to a database. This is the code I have so far..

        List<Pushpin> ListofPoints = new List<Pushpin>();

        foreach (var element in query)
        {
            //Add a pin to the map
            Pushpin pushpin = new Pushpin();
            Location location = new Location();
            location.Latitude = Convert.ToDouble(element.X); 
            location.Longitude = Convert.ToDouble(element.Y); 
            pushpin.Location = location;            
            ListofPoints.Add(pushpin);
            map1.Children.Add(pushpin);

        }


        // Position map based on a collection of Pushpins points
        var x = from l in ListofPoints
                select l.Location;
        map1.SetView(LocationRect.CreateLocationRect(x));
        ListofPoints.Clear();

开发者_高级运维

Can anyone give my any advice/code on how to only display the points on the viewable area of map?

Thanks

---

Use the ViewChangeStart and ViewChangeEnd events to get the current view after the change and then requery your dataset and update the displayed pins as necessary.