103 lines
3.4 KiB
Swift
103 lines
3.4 KiB
Swift
//
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// WaterfallFlowLayout.swift
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// wallpaper_BProject
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//
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// Created by 忆海16 on 2024/8/29.
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//
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import Foundation
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import UIKit
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// 自定义瀑布流布局
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class WaterfallFlowLayout: UICollectionViewFlowLayout {
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let heightInt = [300,320,310,280,290]
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// 瀑布流列数
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var numberOfColumns: Int = 2
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// 单元格的内边距
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var cellPadding: CGFloat = 2
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// 用于缓存所有计算过的布局属性
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private var cache: [UICollectionViewLayoutAttributes] = []
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// 用于记录内容的高度
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private var contentHeight: CGFloat = 0
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// 返回集合视图内容的总尺寸
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override var collectionViewContentSize: CGSize {
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return CGSize(width: collectionView?.bounds.width ?? 0, height: contentHeight)
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}
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// 准备布局，每次布局无效时都会调用
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override func prepare() {
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// 如果缓存为空，且有 collectionView 存在，则计算布局
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guard cache.isEmpty, let collectionView = collectionView else { return }
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// 计算每列的宽度
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let columnWidth = collectionView.bounds.width / CGFloat(numberOfColumns)
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// 初始化每列的 X 偏移量
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var xOffset: [CGFloat] = []
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for column in 0..<numberOfColumns {
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xOffset.append(CGFloat(column) * columnWidth)
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}
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// 初始化 Y 偏移量
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var column = 0
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var yOffset: [CGFloat] = .init(repeating: 0, count: numberOfColumns)
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// 遍历所有的项目（items）并计算其布局属性
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for item in 0..<collectionView.numberOfItems(inSection: 0) {
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let indexPath = IndexPath(item: item, section: 0)
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// 计算随机的单元格高度，可以替换为实际内容的高度
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// let photoHeight = CGFloat(arc4random_uniform(100) + 150)
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// let
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let height = cellPadding * 2 + CGFloat(getRandomheight() ?? 150)
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// 根据当前列的 X 偏移量和 Y 偏移量计算单元格的 frame
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let frame = CGRect(x: xOffset[column], y: yOffset[column], width: columnWidth, height: height)
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let insetFrame = frame.insetBy(dx: cellPadding, dy: cellPadding)
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// 创建布局属性并缓存
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let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
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attributes.frame = insetFrame
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cache.append(attributes)
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// 更新内容高度和当前列的 Y 偏移量
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contentHeight = max(contentHeight, frame.maxY)
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yOffset[column] = yOffset[column] + height
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// 切换到下一个列
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column = column < (numberOfColumns - 1) ? (column + 1) : 0
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}
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}
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// 返回指定矩形区域内的所有布局属性
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override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
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return cache.filter { $0.frame.intersects(rect) }
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}
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// 返回指定项目的布局属性
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override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
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return cache[indexPath.item]
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}
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func getRandomheight() -> Int? {
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return heightInt.randomElement()
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}
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}
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//let randomNumber = Int.random(in: 0...500)
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func getRandomInt() -> Int?{
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return Int.random(in: 0...500)
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}
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