public static UICollectionViewLayoutAttributes FindNextItem(UICollectionViewLayoutAttributes[] items,
UICollectionViewScrollDirection direction, int step, CGPoint scrollingVelocity, int currentIndex)
{
var velocity = direction == UICollectionViewScrollDirection.Horizontal
? scrollingVelocity.X
: scrollingVelocity.Y;
if (velocity == 0)
{
// The user isn't scrolling at all, just stay where we are
return(items[currentIndex]);
}
// Move the index up or down by increment, depending on the velocity
if (velocity > 0)
{
currentIndex = currentIndex + step;
}
else if (velocity < 0)
{
currentIndex = currentIndex - step;
}
// Make sure we're not out of bounds
currentIndex = Clamp(currentIndex, 0, items.Length - 1);
return(items[currentIndex]);
}
public static UICollectionViewScrollPosition ToCollectionViewScrollPosition(this ScrollToPosition scrollToPosition,
UICollectionViewScrollDirection scrollDirection = UICollectionViewScrollDirection.Vertical, bool isLtr = false)
{
if (scrollDirection == UICollectionViewScrollDirection.Horizontal)
{
return(scrollToPosition.ToHorizontalCollectionViewScrollPosition(isLtr));
}
return(scrollToPosition.ToVerticalCollectionViewScrollPosition());
}
public LayoutConfiguration Default()
{
ShowsFirstActionItem = true;
ShowsSecondActionItem = true;
ShowsCameraItem = true;
ShowsAssetItems = true;
ScrollDirection = UICollectionViewScrollDirection.Horizontal;
NumberOfAssetItemsInRow = 2;
InterItemSpacing = 1;
ActionSectionSpacing = 1;
CameraSectionSpacing = 10;
SectionIndexForActions = 0;
SectionIndexForCamera = 1;
SectionIndexForAssets = 2;
FirstNameOfActionItem = "Camera";
SecondNameOfActionItem = "Photos";
return(this);
}
static CGPoint GetViewportOffset(CGRect itemFrame, CGRect viewport, SnapPointsAlignment snapPointsAlignment,
UICollectionViewScrollDirection scrollDirection)
{
if (scrollDirection == UICollectionViewScrollDirection.Horizontal)
{
if (snapPointsAlignment == SnapPointsAlignment.Start)
{
return(new CGPoint(viewport.Left - itemFrame.Left, 0));
}
if (snapPointsAlignment == SnapPointsAlignment.End)
{
return(new CGPoint(viewport.Right - itemFrame.Right, 0));
}
var centerViewport = Center(viewport);
var centerItem = Center(itemFrame);
return(new CGPoint(centerViewport.X - centerItem.X, 0));
}
if (snapPointsAlignment == SnapPointsAlignment.Start)
{
return(new CGPoint(0, viewport.Top - itemFrame.Top));
}
if (snapPointsAlignment == SnapPointsAlignment.End)
{
return(new CGPoint(0, viewport.Bottom - itemFrame.Bottom));
}
var centerViewport1 = Center(viewport);
var centerItem1 = Center(itemFrame);
return(new CGPoint(0, centerViewport1.Y - centerItem1.Y));
}
/// Returns size for item considering number of rows and scroll direction, if preferredWidthOrHeight is nil, square size is returned
public CGSize SizeForItem(int numberOfItemsInRow, nfloat?preferredWidthOrHeight,
UICollectionView collectionView,
UICollectionViewScrollDirection scrollDirection)
{
switch (scrollDirection)
{
case UICollectionViewScrollDirection.Horizontal:
var itemHeight = collectionView.Frame.Height;
itemHeight -= collectionView.ContentInset.Top + collectionView.ContentInset.Bottom;
itemHeight -= (numberOfItemsInRow - 1) * Configuration.InterItemSpacing;
itemHeight /= numberOfItemsInRow;
return(new CGSize(preferredWidthOrHeight ?? itemHeight, itemHeight));
case UICollectionViewScrollDirection.Vertical:
var itemWidth = collectionView.Frame.Width;
itemWidth -= collectionView.ContentInset.Left + collectionView.ContentInset.Right;
itemWidth -= (numberOfItemsInRow - 1) * Configuration.InterItemSpacing;
itemWidth /= numberOfItemsInRow;
return(new CGSize(itemWidth, preferredWidthOrHeight ?? itemWidth));
default:
throw new ArgumentException("Should be invoked only with UICollectionViewScrollDirection");
}
}
void Initialize(UICollectionViewScrollDirection scrollDirection)
{
ScrollDirection = scrollDirection;
}
void HandlePanGesture(UIPanGestureRecognizer sender)
{
if (sender.State == UIGestureRecognizerState.Changed)
{
fingerTranslation = sender.TranslationInView(this.CollectionView);
if (_hasShouldAlterTranslationDelegateMethod)
{
((UICollectionViewDataSourceDraggable)this.CollectionView.DataSource).CollectionViewAlterTranslation(this.CollectionView, fingerTranslation);
}
IUICollectionViewLayoutWarpable /*UICollectionViewLayout*/ /*<UICollectionViewLayout_Warpable>*/ layout = (IUICollectionViewLayoutWarpable /*UICollectionViewLayout*/ /*<UICollectionViewLayout_Warpable>*/)this.CollectionView.CollectionViewLayout;
// if (layout.RespondsToSelector(new Selector ("dragDirection")))
{
UICollectionViewScrollDirection direction = (UICollectionViewScrollDirection)layout.DragDirection();
if (direction == UICollectionViewScrollDirection.Horizontal)
{
fingerTranslation.Y = 0;
}
else if (direction == UICollectionViewScrollDirection.Vertical)
{
fingerTranslation.X = 0;
}
}
mockCell.Center = mockCenter.Add(fingerTranslation);
if (canScroll)
{
IUICollectionViewLayoutWarpable /*UICollectionViewLayout*/ /*<UICollectionViewLayout_Warpable>*/ scrollLayout = (IUICollectionViewLayoutWarpable /*UICollectionViewLayout*/ /*<UICollectionViewLayout_Warpable>*/)this.CollectionView.CollectionViewLayout;
if (scrollLayout.ScrollDirection() == UICollectionViewScrollDirection.Vertical)
{
if (mockCell.Center.Y < (this.CollectionView.Bounds.GetMinY() + this.ScrollingEdgeInsets.Top))
{
this.SetupScrollTimerInDirection(ScrollingDirection.Up);
}
else
{
if (mockCell.Center.Y > (this.CollectionView.Bounds.GetMaxY() - this.ScrollingEdgeInsets.Bottom))
{
this.SetupScrollTimerInDirection(ScrollingDirection.Down);
}
else
{
this.InvalidatesScrollTimer();
}
}
}
else
{
if (mockCell.Center.X < (this.CollectionView.Bounds.GetMinX() + this.ScrollingEdgeInsets.Left))
{
this.SetupScrollTimerInDirection(ScrollingDirection.Left);
}
else
{
if (mockCell.Center.X > (this.CollectionView.Bounds.GetMaxX() - this.ScrollingEdgeInsets.Right))
{
this.SetupScrollTimerInDirection(ScrollingDirection.Right);
}
else
{
this.InvalidatesScrollTimer();
}
}
}
}
if (scrollingDirection > ScrollingDirection.Unknown)
{
return;
}
PointF point = sender.LocationInView(this.CollectionView);
NSIndexPath indexPath = this.IndexPathForItemClosestToPoint(point);
this.WarpToIndexPath(indexPath);
if (this.DropOnToDeleteView != null && this.DropOnToDeleteView.Superview != null)
{
bool highlighted = this.DropOnToDeleteView.Frame.Contains(point);
this.DropOnToDeleteView.Highlighted = highlighted;
if (!highlighted)
{
PointF center = this.DropOnToDeleteView.Center;
float distance = (center.X - point.X) * (center.X - point.X) + (center.Y - point.Y) * (center.Y - point.Y);
this.DropOnToDeleteView.Alpha = (float)(2f - Math.Atan(distance / 10000.0f)) / 2f;
}
else
{
this.DropOnToDeleteView.Alpha = 1.0f;
}
}
}
}
public static CGPoint AdjustContentOffset(CGPoint proposedContentOffset, CGRect itemFrame,
CGRect viewport, SnapPointsAlignment alignment, UICollectionViewScrollDirection scrollDirection)
{
var offset = GetViewportOffset(itemFrame, viewport, alignment, scrollDirection);
return(new CGPoint(proposedContentOffset.X - offset.X, proposedContentOffset.Y - offset.Y));
}
public static CGPoint FindAlignmentTarget(SnapPointsAlignment snapPointsAlignment,
CGPoint contentOffset, UICollectionView collectionView, UICollectionViewScrollDirection scrollDirection)
{
var inset = collectionView.ContentInset;
var bounds = collectionView.Bounds;
switch (scrollDirection)
{
case UICollectionViewScrollDirection.Vertical:
var y = FindAlignmentTarget(snapPointsAlignment, contentOffset.Y, inset.Top,
contentOffset.Y + bounds.Height, inset.Bottom);
return(new CGPoint(contentOffset.X, y));
case UICollectionViewScrollDirection.Horizontal:
var x = FindAlignmentTarget(snapPointsAlignment, contentOffset.X, inset.Left,
contentOffset.X + bounds.Width, inset.Right);
return(new CGPoint(x, contentOffset.Y));
default:
throw new ArgumentOutOfRangeException();
}
}
public Layout(UICollectionViewScrollDirection scrollDirection)
{
ScrollDirection = scrollDirection;
MinimumInteritemSpacing = ZeroMinimumInteritemSpacing;
MinimumLineSpacing = ZeroMinimumLineSpacing;
}
public LayoutState(CGSize size, UICollectionViewScrollDirection direction)
{
Direction = direction;
Size = size;
}
