Use of ItemsRequestEventArgs

[Manfred]

Hi,

I am just new to this kind of coding and I have one question:
the example for adding dynamic layer is just the old version, so it doesn't show the use of ItemsRequestEventArgs.

Can you guys give me a hint how to use that in my code?
I added the class MapDynamicSource and modified ItemsRequest to
public void ItemsRequest(object sender, ItemsRequestEventArgs e)

But I have no idea how to call that.

Best regards
Manfred

[Andrey]

Hi Manfred,

The dynamic layer was redesigned in 2010.Q3 version. You can look at our online example which uses the new ItemsRequest functionality.
http://demos.telerik.com/silverlight/#Map/DynamicLayer

The ItemsRequestEventArgs contains all parameters which are required for requesting items. For example you have the following ItemsRequest which was designed for Q2 and new one:

public class DynamicSource : IMapDynamicSource
{
    public void ItemsRequest(double minZoom, double maxZoom, Telerik.Windows.Controls.Map.Location upperLeft, Telerik.Windows.Controls.Map.Location lowerRight, Action<System.Collections.ICollection> callback)
    {
        // ...
    }

    public void ItemsRequest(object sender, ItemsRequestEventArgs e)
    {
        //
    }
}

The parameters of the old ItemsRequest method could be obtained from the ItemsRequestEventArgs instance in the new request as the following way:
    minZoom = e.MinZoom
    maxZoom = e.MaxZoom
    upperLeft = e.UpperLeft
    lowerRight = e.LowerRight
Also the ItemsRequestEventArgs contains the CompleteItemsRequest method which you should use instead of the callback.

As a simple migration way you can change the code of dynamic source class to use a code which was designed for Q2 just using new delegate type instead of Action<System.Collections.ICollection> for callback. The sample code is below.

public class DynamicSource : IMapDynamicSource
{
    // …
    public delegate void CallbackDelegate(IEnumerable<object> items);

    public void ItemsRequest(object sender, ItemsRequestEventArgs e)
    {
        this.ItemsRequest(e.MinZoom, e.MaxZoom, e.UpperLeft, e.LowerRight, e.CompleteItemsRequest);
    }

    // Q2 style items request
    public void ItemsRequest(double minZoom, double maxZoom, Location upperLeft, Location lowerRight, CallbackDelegate callback)
    {
        List<object> objects = new List<object>();
        // …
        callback(objects);
    }

Greetings,
Andrey Murzov
the Telerik team