I've just published a couple of blog posts (Part 1, Part 2) that give my solution to this problem. I have also posted a sample to GitHub that implements my own take on the VirtualCollection concept (I don't know how this compares with Infragistics's control, because I haven't used that).
To show how easy it is to use, here are a few snippets from the sample. First, here's how you use VirtualCollection, the class that coordinates fetching the data:
public class MainViewModel : ViewModel
{
private NetflixTitlesSource _source;
public VirtualCollection<Title> Items { get; private set; }
public MainViewModel()
{
_source = new NetflixTitlesSource();
Items = new VirtualCollection<Title>(_source, pageSize: 20, cachedPages: 5);
}
protected override void OnViewLoaded()
{
Items.Refresh();
}
}
In XAML you simply bind the Items property to the ItemsSource property of a ListBox or DataGrid
For each data source you must implement a VirtualCollectionSource. Here's what the two key methods of NetflixTitlesSource look like:
public class NetflixTitlesSource : VirtualCollectionSource<Title>
{
protected override Task<int> GetCount()
{
return GetQueryResults(0, 1, null)
.ContinueWith(t => (int)t.Result.TotalCount, TaskContinuationOptions.ExecuteSynchronously);
}
protected override Task<IList<Title>> GetPageAsyncOverride(int start, int pageSize, IList<SortDescription> sortDescriptions)
{
return GetQueryResults(start, pageSize, sortDescriptions)
.ContinueWith(t => (IList<Title>)((IEnumerable<Title>)t.Result).ToList(), TaskContinuationOptions.ExecuteSynchronously);
}
private Task<QueryOperationResponse<Title>> GetQueryResults(int start, int pageSize, IList<SortDescription> sortDescriptions)
{
// code to query the Netflix OData API
}
}
