/// <summary>
/// The logic for use when the selected items of the <see cref="ModelSearcher" /> change.
/// </summary>
/// <param name="e">The EventArgs for the instance.</param>
protected virtual void OnModelSearcherSelectedItemsChanged(NotifyCollectionChangedEventArgs e)
{
var firstTwoCount = ModelSearcher.SelectedItems.Take(2).Count();
if (firstTwoCount == 2)
{
var currentItems = ModelSearcher.CurrentItems.ToList();
var selectedItems = ModelSearcher.SelectedItems.OrderBy(item => currentItems.IndexOf(item)).Select(item => item.Id);
_backForwardNavigator.UpdateNavigationCollection(selectedItems);
if (selectedItems.Contains(_backForwardNavigator.CurrentItem) == false)
{
_backForwardNavigator.UpdateCurrentItem(selectedItems.First());
}
}
else
{
_backForwardNavigator.UpdateNavigationCollection(ModelSearcher.CurrentItems.Select(item => item.Id));
// Small quirk where if a bunch of items are selected, and then navigated through, re-selecting
// the first item in that list does not trigger a refresh because technically, that first item
// was the old selected item, and the new selected item. Refreshes are only triggered when the item changes.
// This next piece of code remedies that.
if (e.Action == NotifyCollectionChangedAction.Remove && firstTwoCount == 1)
{
_backForwardNavigator.UpdateCurrentItem(ModelSearcher.SelectedItems[0].Id);
}
}
}
/// <summary>
/// The logic used to swap the <see cref="Navigation" />.
/// </summary>
/// <param name="newValue">The new <see cref="Navigation" />.</param>
/// <param name="oldValue">The old <see cref="Navigation" /></param>
/// <returns>Task for async use.</returns>
protected virtual async Task BackForwardNavigatorSwapped(IExtendedNavigator <int> newValue, IExtendedNavigator <int> oldValue)
{
if (oldValue != null)
{
await newValue.UpdateCurrentItem(oldValue.CurrentItem);
oldValue.CurrentItemChangedCallback = null;
}
SetUpNewNavigator();
}