Using GridView/ListView’s Built-in Animations

The GridView and ListView controls in Windows 8 both come with built-in animation for various operations. When the controls are bound to an ObservableCollection the will do a fancy animation whenever an item is

  • Added to the collection (even if it’s added in the middle of the collection, in which case the other elements will slide away to give room for the new element)
  • Removed from the collection

I mention the two animations/operations above specifically because I rarely see developers taking advantage of this built-in functionality. Most of the time, when applications fetch new data, they simply clear the previous data, and insert the new data, even though there might be elements that were both present in the new and the old data set. This is commonly seen in news/feed application that retrieve new posts — an obvious use for the built animations.

To see an example of these animations in action see my Open Nearby app (You might have to add a location in Denmark, if you are not from here). There is an option to filter the shops in the app bar. When this filter is applied the add/remove operations are used to filter away shops that no longer fit in the result set, and likewise it is filled up with new shops that does.

It can be a hassle to synchronize the old dataset for the GridView/ListView with freshly fetched data. Below is a few extension methods that will make it easier to get going:

public static void SyncCollection<T>(this ObservableCollection<T> observableCollection, IEnumerable<T> dataToSync, Func<T, T, bool> insertBefore, Func<T, T, bool> equality)
    var recentlyToRemove = observableCollection.Where(s => dataToSync.All(ss => !equality(ss,s))).ToList();
    var recentlyToAdd = dataToSync.Where(s => observableCollection.All(ss => !equality(ss, s)));
    foreach (var item in recentlyToRemove)
    foreach (var item in recentlyToAdd)
        InsertInOrder(item, observableCollection, insertBefore);
private static void InsertInOrder<T>(T item, ObservableCollection<T> observableCollection, Func<T, T, bool> insertBefore)
    for (int i = 0; i < observableCollection.Count; i++)
        if (insertBefore(item, observableCollection[i]))
            observableCollection.Insert(i, item);
    // if empty or last


Here’s an example of usage from Open Nearby:

var newShops = ...// newly fetched shops from data service;

ObservableCollection<Shop> previousShops = ..// the old data current being shown in the view;

Qua.WS.ObservableCollectionExtensions.SyncCollection(previousShops, newShops,
(newShop, oldShop) => newShop.Distance.DistanceInKilometers < oldShop.Distance.DistanceInKilometers,
(shop1, shop2) => shop1.Id == shop2.Id);

The Importance of Localizing Your Apps

Besides making your application more comfortable to the user by servicing the text and images in their native language there is an extra benefit of localizing your Windows 8 applications.

The Store application has an option to ‘Make it easier to find apps in my preferred languages’ under Settings -> Preferences. This option hides all application that are not localized to the language that the user selected when installing Windows 8. For a Danish user whom selected Danish as the primary language this means that the Store only display apps that are localized into Danish. This is crucial to note, since your app might not even show up in the Store depending on the user’s preference.

Checking for Connectivity the Bulletproof Way

A huge amount of the currently released apps in the Store does a check upon app start up to see if connectivity is available. If this is not the case, then the user is redirected to an offline page, and there is no way to continue use of the app.

This is a major concern, when several of the apps does not correctly check for connectivity. One such case, is when the user connects to a VPN. In that case the main connection will be changed to ‘Limited’ even though the user still has an active connection to the internet.

The below snippet will check all the connection profiles for internet access:

public static bool IsConnected
var profiles = NetworkInformation.GetConnectionProfiles();
var internetProfile = NetworkInformation.GetInternetConnectionProfile();
return profiles.Any(s => s.GetNetworkConnectivityLevel() == NetworkConnectivityLevel.InternetAccess)
|| (internetProfile != null
&& internetProfile.GetNetworkConnectivityLevel() == NetworkConnectivityLevel.InternetAccess);

The naive way to check for internet access would be: NetworkInformation.GetInternetConnectionProfile().GetNetworkConnectivityLevel()== NetworkConnectivityLevel.InternetAccess , but this approach fails in the scenario described above.

Remember ScrollViewer Position

Often in Windows 8 apps the user will be presented with long horizontal groups of content. After having navigated to these items, and then returning to the original page there is no built in functionality to remember where in the list that the user scrolled to.

Creating this feature is relatively quick:

  1. Whenever the user leaves the page, remember the current scroll position.
  2. Whenever the user navigates back to the page, retrieve the previous scroll position
  3. When all your content is loaded, scroll to the previous position
// Step 1
private double? horizontalOffsetState;

protected override void SaveState(Dictionary<string, object> pageState)

var myScrollViewer = … // your scroll viewer
var offset = myScrollViewer.HorizontalOffset;

pageState["horizontalOffset"] = offset;

// Step 2
protected override void LoadState(object navigationParameter,Dictionary<string, object> pageState)
base.LoadState(navigationParameter, pageState);

if (pageState != null)
horizontalOffsetState = (double) pageState["horizontalOffset"];

// step 3 - put in constructor or loadstate/navigatedTo
this.Loaded += (sender, args) =>
var myScrollViewer = … // your scroll viewer
if (horizontalOffsetState.HasValue)