protected virtual void BoundsSizeChanged()
{
//We are changing orientation and we need to tell our layout
//to update based on new size constrains
ItemsViewLayout.ConstrainTo(CollectionView.Bounds.Size);
//We call ReloadData so our VisibleCells also update their size
CollectionView.ReloadData();
}
protected virtual void UpdateDefaultCell(DefaultCell cell, NSIndexPath indexPath)
{
cell.Label.Text = ItemsSource[indexPath].ToString();
if (cell is ItemsViewCell constrainedCell)
{
ItemsViewLayout.PrepareCellForLayout(constrainedCell);
}
}
public CarouselViewController(CarouselView itemsView, ItemsViewLayout layout) : base(itemsView, layout)
{
Carousel = itemsView;
CollectionView.AllowsSelection = false;
CollectionView.AllowsMultipleSelection = false;
Carousel.PropertyChanged += CarouselViewPropertyChanged;
Carousel.Scrolled += CarouselViewScrolled;
_oldViews = new List <View>();
}
protected virtual void UpdateLayout()
{
_layout = SelectLayout();
if (Controller != null)
{
Controller.UpdateLayout(_layout);
}
}
protected virtual void UpdateTemplatedCell(TemplatedCell cell, NSIndexPath indexPath)
{
cell.ContentSizeChanged -= CellContentSizeChanged;
cell.Bind(ItemsView.ItemTemplate, ItemsSource[indexPath], ItemsView);
cell.ContentSizeChanged += CellContentSizeChanged;
ItemsViewLayout.PrepareCellForLayout(cell);
}
void CheckForEmptySource()
{
var wasEmpty = _isEmpty;
_isEmpty = ItemsSource.ItemCount == 0;
if (wasEmpty != _isEmpty)
{
UpdateEmptyViewVisibility(_isEmpty);
}
if (wasEmpty && !_isEmpty)
{
// If we're going from empty to having stuff, it's possible that we've never actually measured
// a prototype cell and our itemSize or estimatedItemSize are wrong/unset
// So trigger a constraint update; if we need a measurement, that will make it happen
ItemsViewLayout.ConstrainTo(CollectionView.Bounds.Size);
}
}
public override void ViewWillLayoutSubviews()
{
base.ViewWillLayoutSubviews();
// We can't set this constraint up on ViewDidLoad, because Forms does other stuff that resizes the view
// and we end up with massive layout errors. And View[Will/Did]Appear do not fire for this controller
// reliably. So until one of those options is cleared up, we set this flag so that the initial constraints
// are set up the first time this method is called.
if (!_initialConstraintsSet)
{
_size = CollectionView.Bounds.Size;
ItemsViewLayout.ConstrainTo(_size);
UpdateEmptyView();
_initialConstraintsSet = true;
}
else
{
LayoutEmptyView();
}
}
internal UIEdgeInsets GetInsetForSection(ItemsViewLayout itemsViewLayout,
UICollectionView collectionView, nint section)
{
var uIEdgeInsets = ItemsViewLayout.GetInsetForSection(collectionView, itemsViewLayout, section);
if (!ItemsView.IsGrouped)
{
return(uIEdgeInsets);
}
// If we're grouping, we'll need to inset the sections to maintain the item spacing between the
// groups and/or their group headers/footers
var itemsLayout = ItemsView.ItemsLayout;
var scrollDirection = itemsViewLayout.ScrollDirection;
nfloat lineSpacing = itemsViewLayout.GetMinimumLineSpacingForSection(collectionView, itemsViewLayout, section);
if (itemsLayout is GridItemsLayout)
{
nfloat itemSpacing = itemsViewLayout.GetMinimumInteritemSpacingForSection(collectionView, itemsViewLayout, section);
if (scrollDirection == UICollectionViewScrollDirection.Horizontal)
{
return(new UIEdgeInsets(itemSpacing + uIEdgeInsets.Top, lineSpacing + uIEdgeInsets.Left,
uIEdgeInsets.Bottom, uIEdgeInsets.Right));
}
return(new UIEdgeInsets(lineSpacing + uIEdgeInsets.Top, itemSpacing + uIEdgeInsets.Left,
uIEdgeInsets.Bottom, uIEdgeInsets.Right));
}
if (scrollDirection == UICollectionViewScrollDirection.Horizontal)
{
return(new UIEdgeInsets(uIEdgeInsets.Top, lineSpacing + uIEdgeInsets.Left,
uIEdgeInsets.Bottom, uIEdgeInsets.Right));
}
return(new UIEdgeInsets(lineSpacing + uIEdgeInsets.Top, uIEdgeInsets.Left,
uIEdgeInsets.Bottom, uIEdgeInsets.Right));
}
public void UpdateLayout(ItemsViewLayout newLayout)
{
// Ignore calls to this method if the new layout is the same as the old one
if (CollectionView.CollectionViewLayout == newLayout)
{
return;
}
ItemsViewLayout = newLayout;
ItemsViewLayout.GetPrototype = GetPrototype;
Delegator = CreateDelegator();
CollectionView.Delegate = Delegator;
// Make sure the new layout is sized properly
ItemsViewLayout.ConstrainTo(CollectionView.Bounds.Size);
CollectionView.SetCollectionViewLayout(ItemsViewLayout, false);
// Reload the data so the currently visible cells get laid out according to the new layout
CollectionView.ReloadData();
}
public ItemsViewDelegator(ItemsViewLayout itemsViewLayout, TViewController itemsViewController)
{
ItemsViewLayout = itemsViewLayout;
ViewController = itemsViewController;
}
public GroupableItemsViewDelegator(ItemsViewLayout itemsViewLayout, TViewController itemsViewController)
: base(itemsViewLayout, itemsViewController)
{
}
protected override TViewController CreateController(TItemsView itemsView, ItemsViewLayout layout)
{
return(new StructuredItemsViewController <TItemsView>(itemsView, layout) as TViewController);
}
protected abstract TViewController CreateController(TItemsView newElement, ItemsViewLayout layout);
public StructuredItemsViewController(TItemsView structuredItemsView, ItemsViewLayout layout)
: base(structuredItemsView, layout)
{
}
public CarouselViewDelegator(ItemsViewLayout itemsViewLayout, CarouselViewController itemsViewController)
: base(itemsViewLayout, itemsViewController)
{
}
protected ItemsViewController(TItemsView itemsView, ItemsViewLayout layout) : base(layout)
{
ItemsView = itemsView;
ItemsViewLayout = layout;
}
public GroupableItemsViewController(TItemsView groupableItemsView, ItemsViewLayout layout)
: base(groupableItemsView, layout)
{
_isGrouped = ItemsView.IsGrouped;
}
public SelectableItemsViewController(TItemsView selectableItemsView, ItemsViewLayout layout)
: base(selectableItemsView, layout)
{
}
protected override CarouselViewController CreateController(CarouselView newElement, ItemsViewLayout layout)
{
return(new CarouselViewController(newElement, layout));
}
