Windows Store App: How to make ListView with expandable/enlargeable ListItems?

Question

I have a Listview with items, in a C# Windows Store App (is that what you call these? I heard they\'re not called Metro Apps anymore).

Similar to the ExpandableListView

Answer 1

I ended up with a solution that works but doesn't look too fancy. It switches DataTemplate when you click items but there's no animation: it switches instantly.

Here's the important code parts:

XAML

XAML.CS

public sealed partial class MainPage : Page
{
    private DataTemplate dtSmall;
    private DataTemplate dtEnlarged;

    public MainPage()
    {
        this.InitializeComponent();
        dtSmall = (DataTemplate)Resources["dtSmall"];
        dtEnlarged = (DataTemplate)Resources["dtEnlarged"];
    }

    // A selected item is treated as an expanded/enlarged item
    private void LVEnlargeable_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        /* First we set all the items that has been deselected
        to be collapsed, aka. using the dtSmall DataTemplate.
        We expect 0 or 1 item to have been deselected
        but handle all cases easily with a foreach loop.
        */
        foreach (var item in e.RemovedItems)
        {
            // Set the DataTemplate of the deselected ListViewItems
            ((ListViewItem)(sender as ListView).ContainerFromItem(item)).ContentTemplate = dtSmall;
        }

        /* Then we set all the items that has been selected
        to be expanded.
        We should probably throw an Exception if more than 1 was found,
        because it's unwanted behavior, but we'll ignore that for now.
        */
        foreach (var item in e.AddedItems)
        {
            ((ListViewItem)(sender as ListView).ContainerFromItem(e.AddedItems[0])).ContentTemplate = dtEnlarged;
        }
    }

    /* We need click events because SelectionChanged-events
    cannot detect clicks on an already selected item */
    private void LVEnlargeable_ItemClick(object sender, ItemClickEventArgs e)
    {
        ListView lv = (sender as ListView);

        /* Having set the IsItemClickEnabled property on the ListView to True
        we have to handle selection events manually.
        If nothing is selected when this click occurs, then select this item*/
        if (lv.SelectedItem == null)
        {
            lv.SelectedItem = e.ClickedItem;
        }
        else
        {
            // Clicking on an expanded/selected/enlarged item will deselect it
            if (lv.SelectedItem.Equals(e.ClickedItem))
            {
                lv.SelectedItem = null;
            }
            else
            {   /* If it's not a selected item, then select it
                    (and let SelectionChanged unselect the already selected item) */
                lv.SelectedItem = e.ClickedItem;
            }
        }
    }
}

I haven't tested if this isolated code is enough, on its own, for this solution, but I hope it is, and this code at least contain the key points. It's late and I just wanted to post something for the curious-minded people. If this shows not to work for you, then please leave a comment about the issue and I'll make sure to add the missing parts.

I also messed with the ListViewItemStyleContainer's ListViewItemPresenter to have better selection effects etc. but I figure it's best to keep it short. If you find this interesting as well, then feel free to leave a comment for that too, and I'll try include it.