//
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// EqualCellSpaceFlowLayout.swift
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// XQMuse
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//
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// Created by 无故事王国 on 2024/8/27.
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//
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import UIKit
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enum AlignType : NSInteger {
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case left = 0
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case center = 1
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case right = 2
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}
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class EqualCellSpaceFlowLayout: UICollectionViewFlowLayout {
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//两个Cell之间的距离
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private var horizontalSpace : CGFloat{
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didSet{
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self.minimumInteritemSpacing = horizontalSpace
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}
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}
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//cell对齐方式
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private var alignType : AlignType = AlignType.center
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//在居中对齐的时候需要知道这行所有cell的宽度总和
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var cellWidthInLine : CGFloat = 0.0
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override init() {
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horizontalSpace = 5.0
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super.init()
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scrollDirection = UICollectionView.ScrollDirection.vertical
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minimumLineSpacing = 5
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sectionInset = UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
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}
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convenience init(_ cellType:AlignType){
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self.init()
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self.alignType = cellType
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}
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convenience init(_ cellType: AlignType, _ horizontalSpace: CGFloat){
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self.init()
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self.alignType = cellType
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self.horizontalSpace = horizontalSpace
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}
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required init?(coder aDecoder: NSCoder) {
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horizontalSpace = 5.0
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super.init(coder: aDecoder)
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scrollDirection = UICollectionView.ScrollDirection.vertical
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minimumLineSpacing = 5
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sectionInset = UIEdgeInsets(top: 5, left: 5, bottom: 5, right: 5)
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}
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override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
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let layoutAttributes_super : [UICollectionViewLayoutAttributes] = super.layoutAttributesForElements(in: rect) ?? [UICollectionViewLayoutAttributes]()
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let layoutAttributes:[UICollectionViewLayoutAttributes] = NSArray(array: layoutAttributes_super, copyItems:true)as! [UICollectionViewLayoutAttributes]
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var layoutAttributes_t : [UICollectionViewLayoutAttributes] = [UICollectionViewLayoutAttributes]()
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for index in 0..<layoutAttributes.count{
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print("index in 0..<layoutAttributes.count ==============")
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let currentAttr = layoutAttributes[index]
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let previousAttr = index == 0 ? nil : layoutAttributes[index-1]
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let nextAttr = index + 1 == layoutAttributes.count ?
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nil : layoutAttributes[index+1]
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layoutAttributes_t.append(currentAttr)
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cellWidthInLine += currentAttr.frame.size.width
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let previousY :CGFloat = previousAttr == nil ? 0 : previousAttr!.frame.maxY
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let currentY :CGFloat = currentAttr.frame.maxY
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let nextY:CGFloat = nextAttr == nil ? 0 : nextAttr!.frame.maxY
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if currentY != previousY && currentY != nextY{
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if currentAttr.representedElementKind == UICollectionView.elementKindSectionHeader{
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layoutAttributes_t.removeAll()
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cellWidthInLine = 0.0
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print("currentAttr.representedElementKind == UICollectionView.elementKindSectionHeader =========== Header")
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}else if currentAttr.representedElementKind == UICollectionView.elementKindSectionFooter{
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layoutAttributes_t.removeAll()
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cellWidthInLine = 0.0
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print("currentAttr.representedElementKind == UICollectionView.elementKindSectionFooter ============ Footer")
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}else{
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self.setCellFrame(with: layoutAttributes_t)
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layoutAttributes_t.removeAll()
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cellWidthInLine = 0.0
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print("currentY != previousY && currentY != nextY ============== Item")
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}
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} else if currentY != nextY { //这里currentY == previousY 说明和上一个项目在同一行，currentY != nextY说明下一个项目要换行了，这种情况直接计算本行的对齐方式
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self.setCellFrame(with: layoutAttributes_t)
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layoutAttributes_t.removeAll()
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cellWidthInLine = 0.0
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print("currentY != nextY ======== Else")
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}
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}
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return layoutAttributes
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}
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/// 调整Cell的Frame
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///
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/// - Parameter layoutAttributes: layoutAttribute 数组
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func setCellFrame(with layoutAttributes : [UICollectionViewLayoutAttributes]){
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var nowWidth : CGFloat = 0.0
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switch alignType {
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case AlignType.left:
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nowWidth = self.sectionInset.left
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for attributes in layoutAttributes {
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var nowFrame = attributes.frame
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nowFrame.origin.x = nowWidth
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attributes.frame = nowFrame
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nowWidth += nowFrame.size.width + self.horizontalSpace
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}
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break;
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case AlignType.center:
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nowWidth = (self.collectionView!.frame.size.width - cellWidthInLine - (CGFloat(layoutAttributes.count - 1) * horizontalSpace)) / 2
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for attributes in layoutAttributes{
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var nowFrame = attributes.frame
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nowFrame.origin.x = nowWidth
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attributes.frame = nowFrame
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nowWidth += nowFrame.size.width + self.horizontalSpace
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}
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break;
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case AlignType.right:
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nowWidth = self.collectionView!.frame.size.width - self.sectionInset.right
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for var index in 0 ..< layoutAttributes.count{
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index = layoutAttributes.count - 1 - index
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let attributes = layoutAttributes[index]
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var nowFrame = attributes.frame
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nowFrame.origin.x = nowWidth - nowFrame.size.width
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attributes.frame = nowFrame
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nowWidth = nowWidth - nowFrame.size.width - horizontalSpace
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}
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break;
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}
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}
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}
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