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using System;
using System.Collections.Specialized;
using System.Linq;
using Android.Content;
using Android.Support.V4.View;
using Android.Views;
using Object = Java.Lang.Object;
namespace Xamarin.Forms.Platform.Android
{
internal class CarouselPageAdapter : PagerAdapter, ViewPager.IOnPageChangeListener
{
readonly Context _context;
readonly ViewPager _pager;
bool _ignoreAndroidSelection;
CarouselPage _page;
IElementController ElementController => _page as IElementController;
public CarouselPageAdapter(ViewPager pager, CarouselPage page, Context context)
{
_pager = pager;
_page = page;
_context = context;
page.PagesChanged += OnPagesChanged;
}
public override int Count
{
get { return _page.Children.Count(); }
}
public void OnPageScrolled(int position, float positionOffset, int positionOffsetPixels)
{
}
public void OnPageScrollStateChanged(int state)
{
}
public void OnPageSelected(int position)
{
if (_ignoreAndroidSelection)
return;
int currentItem = _pager.CurrentItem;
_page.CurrentPage = currentItem >= 0 && currentItem < ElementController.LogicalChildren.Count ? ElementController.LogicalChildren[currentItem] as ContentPage : null;
}
public override void DestroyItem(ViewGroup p0, int p1, Object p2)
{
var holder = (ObjectJavaBox<Tuple<ViewGroup, Page, int>>)p2;
Page destroyedPage = holder.Instance.Item2;
IVisualElementRenderer renderer = Platform.GetRenderer(destroyedPage);
renderer.ViewGroup.RemoveFromParent();
holder.Instance.Item1.RemoveFromParent();
}
public override int GetItemPosition(Object item)
{
// The int is the current index.
var holder = (ObjectJavaBox<Tuple<ViewGroup, Page, int>>)item;
Element parent = holder.Instance.Item2.RealParent;
if (parent == null)
return PositionNone;
// Unfortunately we can't just call CarouselPage.GetIndex, because we need to know
// if the item has been removed. We could update MultiPage<T> to set removed items' index
// to -1 to support this if it ever becomes an issue.
int index = ((CarouselPage)parent).Children.IndexOf(holder.Instance.Item2);
if (index == -1)
return PositionNone;
if (index != holder.Instance.Item3)
{
holder.Instance = new Tuple<ViewGroup, Page, int>(holder.Instance.Item1, holder.Instance.Item2, index);
return index;
}
return PositionUnchanged;
}
public override Object InstantiateItem(ViewGroup container, int position)
{
ContentPage child = _page.Children.ElementAt(position);
if (Platform.GetRenderer(child) == null)
Platform.SetRenderer(child, Platform.CreateRenderer(child));
IVisualElementRenderer renderer = Platform.GetRenderer(child);
renderer.ViewGroup.RemoveFromParent();
ViewGroup frame = new PageContainer(_context, renderer);
container.AddView(frame);
return new ObjectJavaBox<Tuple<ViewGroup, Page, int>>(new Tuple<ViewGroup, Page, int>(frame, child, position));
}
public override bool IsViewFromObject(global::Android.Views.View p0, Object p1)
{
var holder = (ObjectJavaBox<Tuple<ViewGroup, Page, int>>)p1;
ViewGroup frame = holder.Instance.Item1;
return p0 == frame;
}
public void UpdateCurrentItem()
{
if (_page.CurrentPage == null)
throw new InvalidOperationException("CarouselPage has no children.");
int index = CarouselPage.GetIndex(_page.CurrentPage);
if (index >= 0 && index < _page.Children.Count)
_pager.CurrentItem = index;
}
protected override void Dispose(bool disposing)
{
if (disposing && _page != null)
{
foreach (Element element in ElementController.LogicalChildren)
{
var childPage = element as VisualElement;
if (childPage == null)
continue;
IVisualElementRenderer childPageRenderer = Platform.GetRenderer(childPage);
if (childPageRenderer != null)
{
childPageRenderer.ViewGroup.RemoveFromParent();
childPageRenderer.Dispose();
Platform.SetRenderer(childPage, null);
}
}
_page.PagesChanged -= OnPagesChanged;
_page = null;
}
base.Dispose(disposing);
}
void OnPagesChanged(object sender, NotifyCollectionChangedEventArgs e)
{
_ignoreAndroidSelection = true;
NotifyDataSetChanged();
_ignoreAndroidSelection = false;
if (_page.CurrentPage == null)
return;
UpdateCurrentItem();
}
}
}
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