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Pods/ZLPhotoBrowser/Sources/Animation/ZLPhotoPreviewPopInteractiveTransition.swift

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+//
+//  ZLPhotoPreviewPopInteractiveTransition.swift
+//  ZLPhotoBrowser
+//
+//  Created by long on 2020/9/3.
+//
+//  Copyright (c) 2020 Long Zhang <495181165@qq.com>
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+
+import UIKit
+
+class ZLPhotoPreviewPopInteractiveTransition: UIPercentDrivenInteractiveTransition {
+    weak var transitionContext: UIViewControllerContextTransitioning?
+    
+    weak var viewController: ZLPhotoPreviewController?
+    
+    var shadowView: UIView?
+    
+    var imageView: UIImageView?
+    
+    var imageViewOriginalFrame: CGRect = .zero
+    
+    var startPanPoint: CGPoint = .zero
+    
+    var interactive: Bool = false
+    
+    var shouldStartTransition: ((CGPoint) -> Bool)?
+    
+    var startTransition: (() -> Void)?
+    
+    var cancelTransition: (() -> Void)?
+    
+    var finishTransition: (() -> Void)?
+    
+    init(viewController: ZLPhotoPreviewController) {
+        super.init()
+        self.viewController = viewController
+        let dismissPan = UIPanGestureRecognizer(target: self, action: #selector(dismissPanAction(_:)))
+        viewController.view.addGestureRecognizer(dismissPan)
+    }
+    
+    @objc func dismissPanAction(_ pan: UIPanGestureRecognizer) {
+        let point = pan.location(in: viewController?.view)
+        
+        if pan.state == .began {
+            guard shouldStartTransition?(point) == true else {
+                interactive = false
+                return
+            }
+            startPanPoint = point
+            interactive = true
+            startTransition?()
+            viewController?.navigationController?.popViewController(animated: true)
+        } else if pan.state == .changed {
+            guard interactive else {
+                return
+            }
+            let result = panResult(pan)
+            imageView?.frame = result.frame
+            shadowView?.alpha = pow(result.scale, 2)
+            
+            update(result.scale)
+        } else if pan.state == .cancelled || pan.state == .ended {
+            guard interactive else {
+                return
+            }
+            
+            let vel = pan.velocity(in: viewController?.view)
+            let p = pan.translation(in: viewController?.view)
+            let percent: CGFloat = max(0.0, p.y / (viewController?.view.bounds.height ?? UIScreen.main.bounds.height))
+            
+            let dismiss = vel.y > 300 || (percent > 0.1 && vel.y > -300)
+            
+            if dismiss {
+                finish()
+            } else {
+                cancel()
+            }
+            imageViewOriginalFrame = .zero
+            startPanPoint = .zero
+            interactive = false
+        }
+    }
+    
+    func panResult(_ pan: UIPanGestureRecognizer) -> (frame: CGRect, scale: CGFloat) {
+        // 拖动偏移量
+        let translation = pan.translation(in: viewController?.view)
+        let currentTouch = pan.location(in: viewController?.view)
+        
+        // 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]
+        let scale = min(1.0, max(0.3, 1 - translation.y / UIScreen.main.bounds.height))
+        
+        let width = imageViewOriginalFrame.size.width * scale
+        let height = imageViewOriginalFrame.size.height * scale
+        
+        // 计算x和y。保持手指在图片上的相对位置不变。
+        let xRate = (startPanPoint.x - imageViewOriginalFrame.origin.x) / imageViewOriginalFrame.size.width
+        let currentTouchDeltaX = xRate * width
+        let x = currentTouch.x - currentTouchDeltaX
+        
+        let yRate = (startPanPoint.y - imageViewOriginalFrame.origin.y) / imageViewOriginalFrame.size.height
+        let currentTouchDeltaY = yRate * height
+        let y = currentTouch.y - currentTouchDeltaY
+        
+        return (CGRect(x: x.isNaN ? 0 : x, y: y.isNaN ? 0 : y, width: width, height: height), scale)
+    }
+    
+    override func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning) {
+        self.transitionContext = transitionContext
+        startAnimate()
+    }
+    
+    func startAnimate() {
+        guard let transitionContext = transitionContext else {
+            return
+        }
+        
+        guard let fromVC = transitionContext.viewController(forKey: .from) as? ZLPhotoPreviewController,
+              let toVC = transitionContext.viewController(forKey: .to) as? ZLThumbnailViewController else {
+            return
+        }
+        
+        let containerView = transitionContext.containerView
+        containerView.addSubview(toVC.view)
+        
+        guard let cell = fromVC.collectionView.cellForItem(at: IndexPath(row: fromVC.currentIndex, section: 0)) as? ZLPreviewBaseCell else {
+            return
+        }
+        
+        shadowView = UIView(frame: containerView.bounds)
+        shadowView?.backgroundColor = ZLPhotoUIConfiguration.default().previewVCBgColor
+        containerView.addSubview(shadowView!)
+        
+        let fromImageViewFrame = cell.animateImageFrame(convertTo: containerView)
+        
+        imageView = UIImageView(frame: fromImageViewFrame)
+        imageView?.contentMode = .scaleAspectFill
+        imageView?.clipsToBounds = true
+        imageView?.image = cell.currentImage
+        containerView.addSubview(imageView!)
+        
+        imageViewOriginalFrame = imageView!.frame
+    }
+    
+    override func finish() {
+        super.finish()
+        finishAnimate()
+    }
+    
+    func finishAnimate() {
+        guard let transitionContext = transitionContext else {
+            return
+        }
+        guard let fromVC = transitionContext.viewController(forKey: .from) as? ZLPhotoPreviewController,
+              let toVC = transitionContext.viewController(forKey: .to) as? ZLThumbnailViewController else {
+            return
+        }
+        
+        let fromVCModel = fromVC.arrDataSources[fromVC.currentIndex]
+        let toVCVisiableIndexPaths = toVC.collectionView.indexPathsForVisibleItems
+        
+        var diff = 0
+        if !ZLPhotoConfiguration.default().sortAscending {
+            if toVC.showCameraCell {
+                diff = -1
+            }
+            if #available(iOS 14.0, *), toVC.showAddPhotoCell {
+                diff -= 1
+            }
+        }
+        var toIndex: Int?
+        for indexPath in toVCVisiableIndexPaths {
+            let idx = indexPath.row + diff
+            if idx >= toVC.arrDataSources.count || idx < 0 {
+                continue
+            }
+            let m = toVC.arrDataSources[idx]
+            if m == fromVCModel {
+                toIndex = indexPath.row
+                break
+            }
+        }
+        
+        var toFrame: CGRect?
+        
+        if let toIndex = toIndex, let toCell = toVC.collectionView.cellForItem(at: IndexPath(row: toIndex, section: 0)) {
+            toFrame = toVC.collectionView.convert(toCell.frame, to: transitionContext.containerView)
+        }
+        
+        UIView.animate(withDuration: 0.25, animations: {
+            if let toFrame = toFrame {
+                self.imageView?.frame = toFrame
+            } else {
+                self.imageView?.alpha = 0
+            }
+            self.shadowView?.alpha = 0
+        }) { _ in
+            self.imageView?.removeFromSuperview()
+            self.shadowView?.removeFromSuperview()
+            self.imageView = nil
+            self.shadowView = nil
+            self.finishTransition?()
+            transitionContext.finishInteractiveTransition()
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+        }
+    }
+    
+    override func cancel() {
+        super.cancel()
+        cancelAnimate()
+    }
+    
+    func cancelAnimate() {
+        guard let transitionContext = transitionContext else {
+            return
+        }
+        
+        UIView.animate(withDuration: 0.25, animations: {
+            self.imageView?.frame = self.imageViewOriginalFrame
+            self.shadowView?.alpha = 1
+        }) { _ in
+            self.imageView?.removeFromSuperview()
+            self.shadowView?.removeFromSuperview()
+            self.cancelTransition?()
+            transitionContext.cancelInteractiveTransition()
+            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
+        }
+    }
+}