Create CardsCollectionViewVerticalLayout.swift

CardsCollectionViewHorizontalLayout.swift

@@ -0,0 +1,140 @@
+//
+//  CardsCollectionViewHorizontalLayout.swift
+//  CardsLayout
+//
+//  Created by Filipp Fediakov on 03.01.18.
+//  Copyright © 2018 filletofish. All rights reserved.
+//
+
+import UIKit
+
+
+protocol CardsCollectionViewLayout {
+    var itemSize: CGSize { get set }
+    var spacing: CGPoint { get set }
+    var maximumVisibleItems: Int { get set }
+}
+
+
+open class CardsCollectionViewHorizontalLayout: UICollectionViewLayout, CardsCollectionViewLayout {
+
+    // MARK: Layout configuration
+
+    public var itemSize: CGSize = CGSize(width: 200, height: 300) {
+        didSet {
+            invalidateLayout()
+        }
+    }
+
+    public var spacing: CGPoint = CGPoint(x: 10.0, y: 10.0) {
+        didSet {
+            invalidateLayout()
+        }
+    }
+
+    public var maximumVisibleItems: Int = 4 {
+        didSet {
+            invalidateLayout()
+        }
+    }
+
+    // MARK: - UICollectionViewLayout
+
+    override open var collectionView: UICollectionView {
+        return super.collectionView!
+    }
+
+    override open var collectionViewContentSize: CGSize {
+        let itemsCount = CGFloat(collectionView.numberOfItems(inSection: 0))
+        return CGSize(width: collectionView.bounds.width * itemsCount,
+                      height: collectionView.bounds.height)
+    }
+
+    override open func prepare() {
+        super.prepare()
+        assert(collectionView.numberOfSections == 1, "Multiple sections aren't supported!")
+    }
+
+    override open func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
+        let totalItemsCount = collectionView.numberOfItems(inSection: 0)
+        let minVisibleIndex = max(Int(collectionView.contentOffset.x) / Int(collectionView.bounds.width), 0)
+        let maxVisibleIndex = min(minVisibleIndex + maximumVisibleItems, totalItemsCount)
+        let visibleIndices = minVisibleIndex..<maxVisibleIndex
+        let attributes: [UICollectionViewLayoutAttributes?] = visibleIndices.map { index in
+            let indexPath = IndexPath(item: index, section: 0)
+            return self.layoutAttributesForItem(at: indexPath)
+        }
+        let filteredAttributes = attributes.flatMap { $0 }
+        return filteredAttributes
+    }
+
+    override open func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
+        let minVisibleIndex = Int(collectionView.contentOffset.x) / Int(collectionView.bounds.width)
+        let deltaOffset = CGFloat(Int(collectionView.contentOffset.x) % Int(collectionView.bounds.width))
+        let percentageDeltaOffset = CGFloat(deltaOffset) / collectionView.bounds.width
+        let visibleIndex = indexPath.row - minVisibleIndex
+
+        let attributes = UICollectionViewLayoutAttributes(forCellWith:indexPath)
+        attributes.size = itemSize
+        let midY = self.collectionView.bounds.midY
+        let midX = self.collectionView.bounds.midX
+        attributes.center = CGPoint(x: midX + spacing.x * CGFloat(visibleIndex),
+                                    y: midY + spacing.y * CGFloat(visibleIndex))
+        attributes.zIndex = maximumVisibleItems - visibleIndex
+        attributes.transform = scaleTransform(forVisibleIndex: visibleIndex,
+                                              percentageOffset: percentageDeltaOffset)
+
+
+        switch visibleIndex {
+        case 0:
+            attributes.center.x -= deltaOffset
+            attributes.isHidden = false
+            break
+        case 1..<maximumVisibleItems:
+            attributes.center.x -= spacing.x * percentageDeltaOffset
+            attributes.center.y -= spacing.y * percentageDeltaOffset
+            if visibleIndex == maximumVisibleItems - 1 {
+                attributes.alpha = percentageDeltaOffset
+            } else {
+                attributes.alpha = 1.0
+            }
+
+            attributes.isHidden = false
+            break
+        default:
+            attributes.alpha = 0
+            attributes.isHidden = true
+            break
+        }
+        return attributes
+    }
+
+    override open func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
+        return true
+    }
+}
+
+
+extension CardsCollectionViewLayout {
+    private func scale(at index: Int) -> CGFloat {
+        let translatedCoefficient = CGFloat(index) - CGFloat(self.maximumVisibleItems) / 2
+        return CGFloat(pow(0.95, translatedCoefficient))
+    }
+
+    func scaleTransform(forVisibleIndex visibleIndex: Int, percentageOffset: CGFloat) -> CGAffineTransform {
+        guard visibleIndex != 0 else {
+            let scaleAtZeroIndex = scale(at: visibleIndex)
+            return CGAffineTransform(scaleX: scaleAtZeroIndex, y: scaleAtZeroIndex)
+        }
+
+        guard visibleIndex < maximumVisibleItems else {
+            return CGAffineTransform.identity
+        }
+
+        var rawScale = scale(at: visibleIndex)
+        let previousScale = scale(at: visibleIndex - 1)
+        let delta = (previousScale - rawScale) * percentageOffset
+        rawScale += delta
+        return CGAffineTransform(scaleX: rawScale, y: rawScale)
+    }
+}

CardsCollectionViewVerticalLayout.swift

@@ -0,0 +1,108 @@
+//
+//  CardsCollectionViewVerticalLayout.swift
+//  CardsLayout
+//
+//  Created by Filipp Fediakov on 18.08.17.
+//  Copyright © 2017 filletofish. All rights reserved.
+//
+
+import UIKit
+
+open class CardsCollectionViewVerticalLayout: UICollectionViewLayout, CardsCollectionViewLayout {
+
+    // MARK: Layout configuration
+
+    public var itemSize: CGSize = CGSize(width: 200, height: 300) {
+      didSet{
+        invalidateLayout()
+      }
+    }
+
+    public var spacing: CGPoint = CGPoint(x: 10.0, y: 20.0) {
+        didSet{
+            invalidateLayout()
+        }
+    }
+
+    public var maximumVisibleItems: Int = 4 {
+        didSet{
+            invalidateLayout()
+        }
+    }
+
+    // MARK: - UICollectionViewLayout
+
+    override open var collectionView: UICollectionView {
+        return super.collectionView!
+    }
+
+    override open var collectionViewContentSize: CGSize {
+        let itemsCount = CGFloat(collectionView.numberOfItems(inSection: 0))
+        return CGSize(width: collectionView.bounds.width,
+                      height: collectionView.bounds.height * itemsCount)
+    }
+
+    override open func prepare() {
+        super.prepare()
+        assert(collectionView.numberOfSections == 1, "Multiple sections aren't supported!")
+    }
+
+    override open func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
+        let totalItemsCount = collectionView.numberOfItems(inSection: 0)
+        let minVisibleIndex = max(Int(collectionView.contentOffset.y) / Int(collectionView.bounds.height), 0)
+        let maxVisibleIndex = min(minVisibleIndex + maximumVisibleItems, totalItemsCount)
+        let visibleIndices = minVisibleIndex..<maxVisibleIndex
+        let attributes: [UICollectionViewLayoutAttributes?] = visibleIndices.map { index in
+            let indexPath = IndexPath(item: index, section: 0)
+            return self.layoutAttributesForItem(at: indexPath)
+        }
+        let filteredAttributes = attributes.flatMap { $0 }
+        return filteredAttributes
+    }
+
+    override open func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
+        let minVisibleIndex = Int(collectionView.contentOffset.y) / Int(collectionView.bounds.height)
+        let deltaOffset = CGFloat(Int(collectionView.contentOffset.y) % Int(collectionView.bounds.height))
+        let percentageDeltaOffset = CGFloat(deltaOffset) / collectionView.bounds.height
+        let visibleIndex = indexPath.row - minVisibleIndex
+
+        let attributes = UICollectionViewLayoutAttributes(forCellWith:indexPath)
+        attributes.size = itemSize
+        let midY = self.collectionView.bounds.midY
+        let midX = self.collectionView.bounds.midX
+        attributes.center = CGPoint(x: midX + spacing.x * CGFloat(visibleIndex),
+                                    y: midY + spacing.y * CGFloat(visibleIndex))
+        attributes.zIndex = maximumVisibleItems - visibleIndex
+        attributes.transform = scaleTransform(forVisibleIndex: visibleIndex,
+                                              percentageOffset: percentageDeltaOffset)
+
+
+        switch visibleIndex {
+        case 0:
+            attributes.center.y -= deltaOffset
+            attributes.isHidden = false
+            break
+        case 1..<maximumVisibleItems:
+            attributes.center.x -= spacing.x * percentageDeltaOffset
+            attributes.center.y -= spacing.y * percentageDeltaOffset
+            if visibleIndex == maximumVisibleItems - 1 {
+                attributes.alpha = percentageDeltaOffset
+            } else {
+                attributes.alpha = 1.0
+            }
+
+            attributes.isHidden = false
+            break
+        default:
+            attributes.alpha = 0
+            attributes.isHidden = true
+            break
+        }
+        return attributes
+    }
+
+
+    override open func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
+        return true
+    }
+}