Added documentations to explain the three offset values.

Updated ready.

README.md

@@ -67,14 +67,8 @@ collectionView.collectionViewLayout = layout
 
 ### Customization
 
-Animators implement the protocol `LayoutAttributesAnimator`. Most of the built-in ones have additional parameters that you can tweak the transitions.
-You can also write your own animators.
-
-## TODO
-
-- [ ] Support non-paging mode.
-- [ ] Support non-full screen items.  
-- [ ] Support item selection notifications.
+Most of the built-in animators work best in **Paging** mode and they have additional parameters that you can tweak for better transitions.
+You can also write your own animators by implementing the protocol `LayoutAttributesAnimator`.
 
 ## Author
 

Source/AnimatedCollectionViewLayout.swift

@@ -77,8 +77,13 @@ public class AnimatedCollectionViewLayoutAttributes: UICollectionViewLayoutAttri
     public var contentView: UIView?
     public var scrollDirection: UICollectionViewScrollDirection = .vertical
 
+    /// The ratio of the distance between the start of the cell and the start of the collectionView and the height/width of the cell depending on the scrollDirection. It's 0 when the start of the cell aligns the start of the collectionView. It gets positive when the cell moves towards the scrolling direction (right/down) while getting negative when moves opposite.
     public var startOffset: CGFloat = 0
+
+    /// The ratio of the distance between the center of the cell and the center of the collectionView and the height/width of the cell depending on the scrollDirection. It's 0 when the center of the cell aligns the center of the collectionView. It gets positive when the cell moves towards the scrolling direction (right/down) while getting negative when moves opposite.
     public var middleOffset: CGFloat = 0
+
+    /// The ratio of the distance between the **start** of the cell and the end of the collectionView and the height/width of the cell depending on the scrollDirection. It's 0 when the **start** of the cell aligns the end of the collectionView. It gets positive when the cell moves towards the scrolling direction (right/down) while getting negative when moves opposite.
     public var endOffset: CGFloat = 0
 
     public override func copy(with zone: NSZone? = nil) -> Any {