protected override void OnPropertyChanging([CallerMemberName] string propertyName = null)
{
base.OnPropertyChanging(propertyName);
if (propertyName == ItemsSourceProperty.PropertyName)
{
if (ItemsSource != null)
{
if (ItemsSource is INotifyCollectionChanged itemsSource)
{
itemsSource.CollectionChanged -= ItemsSource_CollectionChanged;
}
_useItemsSource = false;
Tabs.Clear();
}
}
else if (propertyName == SelectedTabIndexProperty.PropertyName)
{
if (SelectedTabIndex == -1)
{
_prevSelectedTabItem = null;
}
else
{
_prevSelectedTabItem = Tabs.ElementAtOrDefault(SelectedTabIndex);
}
}
}
private void InitContentTemplate(object item, TabViewItem tabItem)
{
if (ContentTemplate != null)
{
var template = ContentTemplate;
if (ContentTemplate is DataTemplateSelector selector)
{
template = selector.SelectTemplate(item, this);
}
var tabContent = template.CreateContent() as View;
if (tabContent.BindingContext == null)
{
tabContent.BindingContext = item;
}
tabItem.Content = tabContent;
}
else
{
var tabContent = new Label();
tabContent.Text = item.ToString();
tabItem.Content = tabContent;
}
}
private void InitItems(IEnumerable source, bool useIndex = false, int index = 0)
{
if (source == null)
{
return;
}
foreach (var item in source)
{
var tabItem = new TabViewItem();
InitContentTemplate(item, tabItem);
tabItem.BindingContext = item;
tabItem.Header = item;
if (useIndex)
{
Tabs.Insert(index, tabItem);
}
else
{
Tabs.Add(tabItem);
}
}
}
private void SelectClosestTab(TabViewItem tab, List <TabViewItem> tabs)
{
if (tabs.Count == 1)
{
SelectedTabIndex = -1;
}
else
{
var index = tabs.IndexOf(tab);
if (index == tabs.Count - 1)
{
var tabToSelect = tabs.ElementAtOrDefault(index - 1);
SelectedTabIndex = Tabs.IndexOf(tabToSelect);
}
else if (index >= 0)
{
var tabToSelect = tabs.ElementAtOrDefault(index + 1);
SelectedTabIndex = Tabs.IndexOf(tabToSelect);
}
}
}
