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using System;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;
using WFlipView = Windows.UI.Xaml.Controls.FlipView;
using WBinding = Windows.UI.Xaml.Data.Binding;
using WApp = Windows.UI.Xaml.Application;
using WSize = Windows.Foundation.Size;
using WDataTemplate = Windows.UI.Xaml.DataTemplate;
#if WINDOWS_UWP
namespace Xamarin.Forms.Platform.UWP
#else
namespace Xamarin.Forms.Platform.WinRT
#endif
{
public class CarouselViewRenderer : ViewRenderer<CarouselView, FrameworkElement>
{
WFlipView _flipView;
bool _leftAdd;
ICarouselViewController Controller
{
get { return Element; }
}
protected override void OnElementChanged(ElementChangedEventArgs<CarouselView> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
_flipView.SelectionChanged -= SelectionChanged;
_flipView.ItemsSource = null;
Element.CollectionChanged -= CollectionChanged;
}
if (e.NewElement != null)
{
if (_flipView == null)
{
_flipView = new FlipView { IsSynchronizedWithCurrentItem = false, ItemTemplate = (WDataTemplate)WApp.Current.Resources["ItemTemplate"] };
}
_flipView.ItemsSource = Element.ItemsSource;
_flipView.SelectedIndex = Element.Position;
_flipView.SelectionChanged += SelectionChanged;
Element.CollectionChanged += CollectionChanged;
}
if (_flipView != Control)
SetNativeControl(_flipView);
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "Position" && _flipView.SelectedIndex != Element.Position)
{
if (!_leftAdd)
_flipView.SelectedIndex = Element.Position;
_leftAdd = false;
}
base.OnElementPropertyChanged(sender, e);
}
void CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
Controller.SendSelectedPositionChanged(_flipView.SelectedIndex);
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
if (e.NewStartingIndex <= Element.Position)
{
_leftAdd = true;
int position = Element.Position + e.NewItems.Count;
PositionChanged(position);
}
break;
case NotifyCollectionChangedAction.Move:
break;
case NotifyCollectionChangedAction.Remove:
if (Element.Count == 0)
throw new InvalidOperationException("CarouselView must retain a least one item.");
if (e.OldStartingIndex < Element.Position)
PositionChanged(Element.Position - e.OldItems.Count);
break;
case NotifyCollectionChangedAction.Replace:
break;
case NotifyCollectionChangedAction.Reset:
break;
default:
throw new Exception($"Enum value '{(int)e.Action}' is not a member of NotifyCollectionChangedAction enumeration.");
}
}
void PositionChanged(int position)
{
if (!_leftAdd)
_flipView.SelectedIndex = position;
Element.Position = position;
Controller.SendSelectedPositionChanged(position);
}
void SelectionChanged(object sender, SelectionChangedEventArgs e)
{
object[] addedItems = e.AddedItems.ToArray();
object[] removedItems = e.RemovedItems.ToArray();
object addedItem = addedItems.SingleOrDefault();
if (addedItem != null)
{
PositionChanged(_flipView.SelectedIndex);
Controller.SendSelectedItemChanged(addedItems.Single());
}
}
}
public class ItemControl : ContentControl
{
CarouselView _carouselView;
object _item;
View _view;
public ItemControl()
{
DataContextChanged += OnDataContextChanged;
}
CarouselView CarouselView => LoadCarouselView();
IItemViewController Controller => CarouselView;
protected override WSize ArrangeOverride(WSize finalSize)
{
_view.Layout(new Rectangle(0, 0, CarouselView.Width, CarouselView.Height));
return base.ArrangeOverride(finalSize);
}
protected override WSize MeasureOverride(WSize availableSize)
{
LoadCarouselView();
if (_item != null)
{
SetDataContext(_item);
_item = null;
}
return base.MeasureOverride(availableSize);
}
CarouselView LoadCarouselView()
{
if (_carouselView != null)
return _carouselView;
DependencyObject parent = VisualTreeHelper.GetParent(this);
CarouselViewRenderer renderer = default(CarouselViewRenderer);
do
{
if (parent == null)
return null;
renderer = parent as CarouselViewRenderer;
if (renderer != null)
break;
parent = VisualTreeHelper.GetParent(parent);
} while (true);
_carouselView = renderer.Element;
return _carouselView;
}
void OnDataContextChanged(FrameworkElement sender, DataContextChangedEventArgs args)
{
object item = args.NewValue;
if (_carouselView != null)
SetDataContext(item);
else if (item != null)
_item = item;
}
void SetDataContext(object item)
{
// type item
object type = Controller.GetItemType(item);
// activate item
_view = Controller.CreateView(type);
_view.Parent = CarouselView;
_view.Layout(new Rectangle(0, 0, CarouselView.Width, CarouselView.Height));
// render item
IVisualElementRenderer renderer = Platform.CreateRenderer(_view);
Platform.SetRenderer(_view, renderer);
Content = renderer;
// bind item
Controller.BindView(_view, item);
}
}
}
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