//
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// LanternImageCell.swift
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// Lantern
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//
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// Created by 小豌先生 on 2022/6/10.
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// Copyright © 2021 Shenzhen Hive Box Technology Co.,Ltd All rights reserved.
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//
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import UIKit
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open class LanternImageCell: UIView, UIScrollViewDelegate, UIGestureRecognizerDelegate, LanternCell, LanternZoomSupportedCell {
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/// 弱引用PhotoBrowser
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open weak var lantern: Lantern?
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/// 长按删除时标记视图的坐标
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open var index: Int = 0
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/// 是否是视频
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open var isVideo: Bool = false {
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didSet {
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contentView?.isHidden = true
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if self.isVideo, let view = self.contentView {
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view.isHidden = false
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}
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}
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}
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/// 添加到imageView上的视图
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open var contentView: UIView?
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open var scrollDirection: Lantern.ScrollDirection = .horizontal {
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didSet {
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if scrollDirection == .horizontal {
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addPanGesture()
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} else if let existed = existedPan {
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scrollView.removeGestureRecognizer(existed)
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}
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}
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}
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open lazy var imageView: UIImageView = {
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let view = UIImageView()
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view.backgroundColor = .black
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view.clipsToBounds = true
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return view
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}()
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open var scrollView: UIScrollView = {
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let view = UIScrollView()
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view.maximumZoomScale = 2.0
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view.showsVerticalScrollIndicator = false
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view.showsHorizontalScrollIndicator = false
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if #available(iOS 11.0, *) {
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view.contentInsetAdjustmentBehavior = .never
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}
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return view
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}()
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deinit {
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imageView.removeObserver(self, forKeyPath: "image", context: nil)
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LanternLog.high("deinit - \(self.classForCoder)")
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}
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public required override init(frame: CGRect) {
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super.init(frame: frame)
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setup()
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}
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public required init?(coder: NSCoder) {
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super.init(coder: coder)
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setup()
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}
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/// 生成实例
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public static func generate(with lantern: Lantern) -> Self {
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let cell = Self.init(frame: .zero)
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cell.lantern = lantern
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cell.scrollDirection = lantern.scrollDirection
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return cell
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}
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/// 刷新添加视图的布局
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open func refreshContentView() {
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contentView?.frame = self.imageView.bounds
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}
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/// 子类可重写，创建子视图。完全自定义时不必调super。
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open func constructSubviews() {
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scrollView.delegate = self
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addSubview(scrollView)
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scrollView.addSubview(imageView)
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if let view = self.contentView {
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imageView.addSubview(view)
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}
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// 使用 kvo 监控 imageView 的 image 的变化
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imageView.addObserver(self,
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forKeyPath: "image",
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options: [.new],
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context: nil)
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}
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open func setup() {
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backgroundColor = .clear
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constructSubviews()
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/// 拖动手势
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addPanGesture()
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// 双击手势
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let doubleTap = UITapGestureRecognizer(target: self, action: #selector(onDoubleTap(_:)))
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doubleTap.numberOfTapsRequired = 2
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addGestureRecognizer(doubleTap)
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// 单击手势
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let singleTap = UITapGestureRecognizer(target: self, action: #selector(onSingleTap(_:)))
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singleTap.require(toFail: doubleTap)
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addGestureRecognizer(singleTap)
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}
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/// 拖拽改变视图scale
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open var panGestureChangeAction: ((LanternImageCell, CGFloat) -> Void)?
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/// 结束拖拽视图scale(true为视图消失，false为恢复)
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open var panGestureEndAction: ((LanternImageCell, Bool) -> Void)?
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/// 长按事件
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public typealias LongPressAction = (LanternImageCell, UILongPressGestureRecognizer) -> Void
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/// 长按时回调。赋值时自动添加手势，赋值为nil时移除手势
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open var longPressedAction: LongPressAction? {
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didSet {
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if oldValue != nil && longPressedAction == nil {
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removeGestureRecognizer(longPress)
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} else if oldValue == nil && longPressedAction != nil {
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addGestureRecognizer(longPress)
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}
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}
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}
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/// 已添加的长按手势
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private lazy var longPress: UILongPressGestureRecognizer = {
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UILongPressGestureRecognizer(target: self, action: #selector(onLongPress(_:)))
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}()
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private weak var existedPan: UIPanGestureRecognizer?
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/// 添加拖动手势
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open func addPanGesture() {
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guard existedPan == nil else {
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return
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}
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let pan = UIPanGestureRecognizer(target: self, action: #selector(onPan(_:)))
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pan.delegate = self
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// 必须加在图片容器上，否则长图下拉不能触发
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scrollView.addGestureRecognizer(pan)
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existedPan = pan
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}
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open override func layoutSubviews() {
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super.layoutSubviews()
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scrollView.frame = bounds
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scrollView.setZoomScale(1.0, animated: false)
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let size = computeImageLayoutSize(for: imageView.image, in: scrollView)
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let origin = computeImageLayoutOrigin(for: size, in: scrollView)
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imageView.frame = CGRect(origin: origin, size: size)
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scrollView.setZoomScale(1.0, animated: false)
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refreshContentView()
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}
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open func viewForZooming(in scrollView: UIScrollView) -> UIView? {
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imageView
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}
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open func scrollViewDidZoom(_ scrollView: UIScrollView) {
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imageView.center = computeImageLayoutCenter(in: scrollView)
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}
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open func computeImageLayoutSize(for image: UIImage?, in scrollView: UIScrollView) -> CGSize {
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guard let imageSize = image?.size, imageSize.width > 0 && imageSize.height > 0 else {
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return bounds.size
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}
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var width: CGFloat
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var height: CGFloat
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let containerSize = scrollView.bounds.size
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if scrollDirection == .horizontal {
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// 横竖屏判断
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if containerSize.width < containerSize.height {
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width = containerSize.width
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height = imageSize.height / imageSize.width * width
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} else {
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height = containerSize.height
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width = imageSize.width / imageSize.height * height
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if width > containerSize.width {
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width = containerSize.width
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height = imageSize.height / imageSize.width * width
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}
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}
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} else {
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width = containerSize.width
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height = imageSize.height / imageSize.width * width
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if height > containerSize.height {
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height = containerSize.height
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width = imageSize.width / imageSize.height * height
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}
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}
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return CGSize(width: width, height: height)
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}
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open func computeImageLayoutOrigin(for imageSize: CGSize, in scrollView: UIScrollView) -> CGPoint {
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let containerSize = scrollView.bounds.size
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var y = (containerSize.height - imageSize.height) * 0.5
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y = max(0, y)
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var x = (containerSize.width - imageSize.width) * 0.5
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x = max(0, x)
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return CGPoint(x: x, y: y)
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}
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open func computeImageLayoutCenter(in scrollView: UIScrollView) -> CGPoint {
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var x = scrollView.contentSize.width * 0.5
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var y = scrollView.contentSize.height * 0.5
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let offsetX = (bounds.width - scrollView.contentSize.width) * 0.5
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if offsetX > 0 {
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x += offsetX
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}
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let offsetY = (bounds.height - scrollView.contentSize.height) * 0.5
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if offsetY > 0 {
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y += offsetY
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}
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return CGPoint(x: x, y: y)
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}
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/// 单击
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@objc open func onSingleTap(_ tap: UITapGestureRecognizer) {
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lantern?.dismiss()
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}
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/// 双击
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@objc open func onDoubleTap(_ tap: UITapGestureRecognizer) {
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// 如果当前没有任何缩放，则放大到目标比例，否则重置到原比例
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if scrollView.zoomScale < 1.1 {
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// 以点击的位置为中心，放大
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let pointInView = tap.location(in: imageView)
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let width = scrollView.bounds.size.width / scrollView.maximumZoomScale
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let height = scrollView.bounds.size.height / scrollView.maximumZoomScale
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let x = pointInView.x - (width / 2.0)
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let y = pointInView.y - (height / 2.0)
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scrollView.zoom(to: CGRect(x: x, y: y, width: width, height: height), animated: true)
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} else {
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scrollView.setZoomScale(1.0, animated: true)
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}
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}
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/// 长按
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@objc open func onLongPress(_ press: UILongPressGestureRecognizer) {
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if press.state == .began {
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longPressedAction?(self, press)
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}
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}
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/// 记录pan手势开始时imageView的位置
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private var beganFrame = CGRect.zero
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/// 记录pan手势开始时，手势位置
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private var beganTouch = CGPoint.zero
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/// 响应拖动
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@objc open func onPan(_ pan: UIPanGestureRecognizer) {
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guard imageView.image != nil else {
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return
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}
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switch pan.state {
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case .began:
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beganFrame = imageView.frame
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beganTouch = pan.location(in: scrollView)
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case .changed:
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let result = panResult(pan)
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imageView.frame = result.frame
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refreshContentView()
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lantern?.maskView.alpha = result.scale * result.scale
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lantern?.setStatusBar(hidden: result.scale > 0.99)
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lantern?.pageIndicator?.isHidden = result.scale < 0.99
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self.panGestureChangeAction?(self, result.scale)
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case .ended, .cancelled:
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imageView.frame = panResult(pan).frame
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refreshContentView()
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let isDown = pan.velocity(in: self).y > 0
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self.panGestureEndAction?(self, isDown)
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if isDown {
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lantern?.dismiss()
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} else {
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lantern?.maskView.alpha = 1.0
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lantern?.setStatusBar(hidden: true)
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lantern?.pageIndicator?.isHidden = false
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resetImageViewPosition()
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}
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default:
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resetImageViewPosition()
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}
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}
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/// 计算拖动时图片应调整的frame和scale值
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private func panResult(_ pan: UIPanGestureRecognizer) -> (frame: CGRect, scale: CGFloat) {
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// 拖动偏移量
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let translation = pan.translation(in: scrollView)
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let currentTouch = pan.location(in: scrollView)
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// 由下拉的偏移值决定缩放比例，越往下偏移，缩得越小。scale值区间[0.3, 1.0]
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let scale = min(1.0, max(0.3, 1 - translation.y / bounds.height))
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let width = beganFrame.size.width * scale
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let height = beganFrame.size.height * scale
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// 计算x和y。保持手指在图片上的相对位置不变。
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// 即如果手势开始时，手指在图片X轴三分之一处，那么在移动图片时，保持手指始终位于图片X轴的三分之一处
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let xRate = (beganTouch.x - beganFrame.origin.x) / beganFrame.size.width
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let currentTouchDeltaX = xRate * width
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let x = currentTouch.x - currentTouchDeltaX
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let yRate = (beganTouch.y - beganFrame.origin.y) / beganFrame.size.height
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let currentTouchDeltaY = yRate * height
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let y = currentTouch.y - currentTouchDeltaY
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return (CGRect(x: x.isNaN ? 0 : x, y: y.isNaN ? 0 : y, width: width, height: height), scale)
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}
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/// 复位ImageView
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private func resetImageViewPosition() {
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// 如果图片当前显示的size小于原size，则重置为原size
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let size = computeImageLayoutSize(for: imageView.image, in: scrollView)
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let needResetSize = imageView.bounds.size.width < size.width || imageView.bounds.size.height < size.height
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UIView.animate(withDuration: 0.25) {
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self.imageView.center = self.computeImageLayoutCenter(in: self.scrollView)
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if needResetSize {
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self.imageView.bounds.size = size
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}
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self.refreshContentView()
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}
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}
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open override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
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// 只处理pan手势
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guard let pan = gestureRecognizer as? UIPanGestureRecognizer else {
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return true
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}
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let velocity = pan.velocity(in: self)
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// 向上滑动时，不响应手势
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if velocity.y < 0 {
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return false
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}
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// 横向滑动时，不响应pan手势
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if abs(Int(velocity.x)) > Int(velocity.y) {
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return false
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}
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// 向下滑动，如果图片顶部超出可视区域，不响应手势
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if scrollView.contentOffset.y > 0 {
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return false
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}
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// 响应允许范围内的下滑手势
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return true
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}
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open var showContentView: UIView {
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return imageView
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}
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open override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
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guard let imgView = object as? UIImageView, imgView == imageView, keyPath == "image" else {
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super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
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return
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}
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// 重新布局
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setNeedsLayout()
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}
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}
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