194 lines
8.5 KiB
Swift
194 lines
8.5 KiB
Swift
//
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// WaterfallMutiSectionFlowLayout.swift
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// gymbo
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//
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// Created by drogan Zheng on 2020/5/7.
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// Copyright © 2020 Gymbo.co. All rights reserved.
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// https://github.com/RoganZheng/WaterfallMultiSectionFlowLayout
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//
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import UIKit
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@objc protocol WaterfallMutiSectionDelegate: NSObjectProtocol {
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// 必选delegate实现
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/// collectionItem高度
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func heightForRowAtIndexPath(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, indexPath: IndexPath, itemWidth: CGFloat) -> CGFloat
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// 可选delegate实现
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/// 每个section 列数（默认2列）
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@objc optional func columnNumber(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> Int
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/// header高度（默认为0）
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@objc optional func referenceSizeForHeader(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> CGSize
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/// footer高度（默认为0）
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@objc optional func referenceSizeForFooter(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> CGSize
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/// 每个section 边距（默认为0）
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@objc optional func insetForSection(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> UIEdgeInsets
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/// 每个section item上下间距（默认为0）
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@objc optional func lineSpacing(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> CGFloat
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/// 每个section item左右间距（默认为0）
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@objc optional func interitemSpacing(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> CGFloat
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/// section头部header与上个section尾部footer间距（默认为0）
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@objc optional func spacingWithLastSection(collectionView collection: UICollectionView, layout: WaterfallMutiSectionFlowLayout, section: Int) -> CGFloat
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}
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class WaterfallMutiSectionFlowLayout: UICollectionViewFlowLayout {
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weak var delegate: WaterfallMutiSectionDelegate?
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private var sectionInsets: UIEdgeInsets = .zero
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private var columnCount: Int = 2
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private var lineSpacing: CGFloat = 0
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private var interitemSpacing: CGFloat = 0
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private var headerSize: CGSize = .zero
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private var footerSize: CGSize = .zero
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//存放attribute的数组
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private var attrsArray: [UICollectionViewLayoutAttributes] = []
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//存放每个section中各个列的最后一个高度
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private var columnHeights: [CGFloat] = []
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//collectionView的Content的高度
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private var contentHeight: CGFloat = 0
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//记录上个section高度最高一列的高度
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private var lastContentHeight: CGFloat = 0
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//每个section的header与上个section的footer距离
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private var spacingWithLastSection: CGFloat = 0
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override func prepare() {
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super.prepare()
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self.contentHeight = 0
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self.lastContentHeight = 0
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self.spacingWithLastSection = 0
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self.lineSpacing = 0
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self.sectionInsets = .zero
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self.headerSize = .zero
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self.footerSize = .zero
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self.columnHeights.removeAll()
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self.attrsArray.removeAll()
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let sectionCount = self.collectionView!.numberOfSections
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// 遍历section
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for idx in 0..<sectionCount {
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let indexPath = IndexPath(item: 0, section: idx)
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if let columnCount = self.delegate?.columnNumber?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.columnCount = columnCount
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}
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if let inset = self.delegate?.insetForSection?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.sectionInsets = inset
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}
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if let spacingLastSection = self.delegate?.spacingWithLastSection?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.spacingWithLastSection = spacingLastSection
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}
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// 生成header
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let itemCount = self.collectionView!.numberOfItems(inSection: idx)
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let headerAttri = self.layoutAttributesForSupplementaryView(ofKind: UICollectionView.elementKindSectionHeader, at: indexPath)
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if let header = headerAttri {
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self.attrsArray.append(header)
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self.columnHeights.removeAll()
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}
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self.lastContentHeight = self.contentHeight
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// 初始化区 y值
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for _ in 0..<self.columnCount {
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self.columnHeights.append(self.contentHeight)
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}
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// 多少个item
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for item in 0..<itemCount {
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let indexPat = IndexPath(item: item, section: idx)
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let attri = self.layoutAttributesForItem(at: indexPat)
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if let attri = attri {
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self.attrsArray.append(attri)
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}
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}
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// 初始化footer
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let footerAttri = self.layoutAttributesForSupplementaryView(ofKind: UICollectionView.elementKindSectionFooter, at: indexPath)
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if let footer = footerAttri {
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self.attrsArray.append(footer)
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}
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}
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}
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override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
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return self.attrsArray
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}
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override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
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if let column = self.delegate?.columnNumber?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.columnCount = column
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}
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if let lineSpacing = self.delegate?.lineSpacing?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.lineSpacing = lineSpacing
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}
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if let interitem = self.delegate?.interitemSpacing?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.interitemSpacing = interitem
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}
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let attri = UICollectionViewLayoutAttributes(forCellWith: indexPath)
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let weight = self.collectionView!.frame.size.width
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let itemSpacing = CGFloat(self.columnCount - 1) * self.interitemSpacing
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let allWeight = weight - self.sectionInsets.left - self.sectionInsets.right - itemSpacing
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let cellWeight = allWeight / CGFloat(self.columnCount)
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let cellHeight: CGFloat = (self.delegate?.heightForRowAtIndexPath(collectionView: self.collectionView!, layout: self, indexPath: indexPath, itemWidth: cellWeight))!
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var tmpMinColumn = 0
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var minColumnHeight = self.columnHeights[0]
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for i in 0..<self.columnCount {
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let columnH = self.columnHeights[i]
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if minColumnHeight > columnH {
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minColumnHeight = columnH
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tmpMinColumn = i
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}
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}
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let cellX = self.sectionInsets.left + CGFloat(tmpMinColumn) * (cellWeight + self.interitemSpacing)
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var cellY: CGFloat = 0
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cellY = minColumnHeight
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if cellY != self.lastContentHeight {
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cellY += self.lineSpacing
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}
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if self.contentHeight < minColumnHeight {
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self.contentHeight = minColumnHeight
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}
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attri.frame = CGRect(x: cellX, y: cellY, width: cellWeight, height: cellHeight)
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self.columnHeights[tmpMinColumn] = attri.frame.maxY
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//取最大的
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for i in 0..<self.columnHeights.count {
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if self.contentHeight < self.columnHeights[i] {
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self.contentHeight = self.columnHeights[i]
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}
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}
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return attri
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}
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override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
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let attri = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: elementKind, with: indexPath)
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if elementKind == UICollectionView.elementKindSectionHeader {
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if let headerSize = self.delegate?.referenceSizeForHeader?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.headerSize = headerSize
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}
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self.contentHeight += self.spacingWithLastSection
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attri.frame = CGRect(x: 0, y: self.contentHeight, width: self.headerSize.width, height: self.headerSize.height)
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self.contentHeight += self.headerSize.height
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self.contentHeight += self.sectionInsets.top
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} else if elementKind == UICollectionView.elementKindSectionFooter {
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if let footerSize = self.delegate?.referenceSizeForFooter?(collectionView: self.collectionView!, layout: self, section: indexPath.section) {
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self.footerSize = footerSize
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}
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self.contentHeight += self.sectionInsets.bottom
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attri.frame = CGRect(x: 0, y: self.contentHeight, width: self.footerSize.width, height: self.footerSize.height)
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self.contentHeight += self.footerSize.height
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}
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return attri
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}
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override var collectionViewContentSize: CGSize {
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return CGSize(width: self.collectionView!.frame.size.width, height: self.contentHeight)
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}
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}
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