Accurately displays dynamically-sized screenshots in AppViewController

AltStore/App Detail/Screenshots/AppScreenshotCollectionViewCell.swift

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+//
+//  AppScreenshotCollectionViewCell.swift
+//  AltStore
+//
+//  Created by Riley Testut on 10/11/23.
+//  Copyright © 2023 Riley Testut. All rights reserved.
+//
+
+import UIKit
+
+import AltStoreCore
+
+class AppScreenshotCollectionViewCell: UICollectionViewCell
+{
+    let imageView: UIImageView
+    
+    var aspectRatio: CGSize = AppScreenshot.defaultAspectRatio {
+        didSet {
+            self.updateAspectRatio()
+        }
+    }
+    
+    private var isRounded: Bool = false {
+        didSet {
+            self.setNeedsLayout()
+            self.layoutIfNeeded()
+        }
+    }
+    
+    private var aspectRatioConstraint: NSLayoutConstraint?
+    
+    override init(frame: CGRect)
+    {
+        self.imageView = UIImageView(frame: .zero)
+        self.imageView.clipsToBounds = true
+        self.imageView.layer.cornerCurve = .continuous
+        self.imageView.layer.borderColor = UIColor.tertiaryLabel.cgColor
+                
+        super.init(frame: frame)
+        
+        self.imageView.translatesAutoresizingMaskIntoConstraints = false
+        self.contentView.addSubview(self.imageView)
+        
+        let widthConstraint = self.imageView.widthAnchor.constraint(equalTo: self.contentView.widthAnchor)
+        widthConstraint.priority = UILayoutPriority(999)
+        
+        let heightConstraint = self.imageView.heightAnchor.constraint(equalTo: self.contentView.heightAnchor)
+        heightConstraint.priority = UILayoutPriority(999)
+        
+        NSLayoutConstraint.activate([
+            widthConstraint,
+            heightConstraint,
+            self.imageView.widthAnchor.constraint(lessThanOrEqualTo: self.contentView.widthAnchor),
+            self.imageView.heightAnchor.constraint(lessThanOrEqualTo: self.contentView.heightAnchor),
+            self.imageView.centerXAnchor.constraint(equalTo: self.contentView.centerXAnchor),
+            self.imageView.centerYAnchor.constraint(equalTo: self.contentView.centerYAnchor)
+        ])
+        
+        self.updateAspectRatio()
+        self.updateTraits()
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) 
+    {
+        super.traitCollectionDidChange(previousTraitCollection)
+        
+        self.updateTraits()
+    }
+    
+    override func layoutSubviews()
+    {
+        super.layoutSubviews()
+        
+        guard self.imageView.bounds.width != 0 else {
+            self.setNeedsLayout()
+            return
+        }
+        
+        if self.isRounded
+        {
+            let cornerRadius = self.imageView.bounds.width / 9.0 // Based on iPhone 15
+            self.imageView.layer.cornerRadius = cornerRadius
+        }
+        else
+        {
+            let cornerRadius = self.imageView.bounds.width / 25.0 // Based on iPhone 8
+            self.imageView.layer.cornerRadius = cornerRadius
+        }
+    }
+}
+
+private extension AppScreenshotCollectionViewCell
+{
+    func updateAspectRatio()
+    {
+        self.aspectRatioConstraint?.isActive = false
+        
+        self.aspectRatioConstraint = self.imageView.widthAnchor.constraint(equalTo: self.imageView.heightAnchor, multiplier: self.aspectRatio.width / self.aspectRatio.height)
+        self.aspectRatioConstraint?.isActive = true
+        
+        let aspectRatio: Double
+        if self.aspectRatio.width > self.aspectRatio.height
+        {
+            aspectRatio = self.aspectRatio.height / self.aspectRatio.width
+        }
+        else
+        {
+            aspectRatio = self.aspectRatio.width / self.aspectRatio.height
+        }
+        
+        let tolerance = 0.001 as Double
+        let modernAspectRatio = AppScreenshot.defaultAspectRatio.width / AppScreenshot.defaultAspectRatio.height
+        
+        let isRounded = (aspectRatio >= modernAspectRatio - tolerance) && (aspectRatio <= modernAspectRatio + tolerance)
+        self.isRounded = isRounded
+    }
+    
+    func updateTraits()
+    {
+        let displayScale = (self.traitCollection.displayScale == 0.0) ? 1.0 : self.traitCollection.displayScale
+        self.imageView.layer.borderWidth = 1.0 / displayScale
+    }
+}

AltStore/App Detail/Screenshots/AppScreenshotsViewController.swift

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+//
+//  AppScreenshotsViewController.swift
+//  AltStore
+//
+//  Created by Riley Testut on 9/18/23.
+//  Copyright © 2023 Riley Testut. All rights reserved.
+//
+
+import UIKit
+
+import AltStoreCore
+import Roxas
+
+import Nuke
+
+class AppScreenshotsViewController: UICollectionViewController
+{
+    let app: StoreApp
+    
+    private lazy var dataSource = self.makeDataSource()
+    
+    init?(app: StoreApp, coder: NSCoder)
+    {
+        self.app = app
+        
+        super.init(coder: coder)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad()
+    {
+        super.viewDidLoad()
+        
+        self.collectionView.showsHorizontalScrollIndicator = false
+        
+        // Allow parent background color to show through.
+        self.collectionView.backgroundColor = nil
+        
+        // Match the parent table view margins.
+        self.collectionView.directionalLayoutMargins.top = 0
+        self.collectionView.directionalLayoutMargins.bottom = 0
+        self.collectionView.directionalLayoutMargins.leading = 20
+        self.collectionView.directionalLayoutMargins.trailing = 20
+        
+        let collectionViewLayout = self.makeLayout()
+        self.collectionView.collectionViewLayout = collectionViewLayout
+        
+        self.collectionView.register(AppScreenshotCollectionViewCell.self, forCellWithReuseIdentifier: RSTCellContentGenericCellIdentifier)
+        
+        self.collectionView.dataSource = self.dataSource
+        self.collectionView.prefetchDataSource = self.dataSource
+    }
+}
+
+private extension AppScreenshotsViewController
+{
+    func makeLayout() -> UICollectionViewCompositionalLayout
+    {
+        let layoutConfig = UICollectionViewCompositionalLayoutConfiguration()
+        layoutConfig.contentInsetsReference = .layoutMargins
+        
+        let preferredHeight = 400.0
+        let estimatedWidth = preferredHeight * (AppScreenshot.defaultAspectRatio.width / AppScreenshot.defaultAspectRatio.height)
+        
+        let layout = UICollectionViewCompositionalLayout(sectionProvider: { (sectionIndex, layoutEnvironment) -> NSCollectionLayoutSection? in
+            
+            let itemSize = NSCollectionLayoutSize(widthDimension: .estimated(estimatedWidth), heightDimension: .fractionalHeight(1.0))
+            let item = NSCollectionLayoutItem(layoutSize: itemSize)
+            
+            let groupSize = NSCollectionLayoutSize(widthDimension: .estimated(estimatedWidth), heightDimension: .absolute(preferredHeight))
+            let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize, subitems: [item])
+            
+            let layoutSection = NSCollectionLayoutSection(group: group)
+            layoutSection.interGroupSpacing = 10
+            layoutSection.orthogonalScrollingBehavior = .groupPaging
+            
+            return layoutSection
+        }, configuration: layoutConfig)
+        
+        return layout
+    }
+    
+    func makeDataSource() -> RSTArrayCollectionViewPrefetchingDataSource<AppScreenshot, UIImage>
+    {
+        let dataSource = RSTArrayCollectionViewPrefetchingDataSource<AppScreenshot, UIImage>(items: self.app.screenshots)
+        dataSource.cellConfigurationHandler = { (cell, screenshot, indexPath) in
+            let cell = cell as! AppScreenshotCollectionViewCell
+            cell.imageView.image = nil
+            cell.imageView.isIndicatingActivity = true
+            
+            var aspectRatio = screenshot.size ?? AppScreenshot.defaultAspectRatio
+            if aspectRatio.width > aspectRatio.height
+            {
+                aspectRatio = CGSize(width: aspectRatio.height, height: aspectRatio.width)
+            }
+            
+            cell.aspectRatio = aspectRatio
+        }
+        dataSource.prefetchHandler = { (screenshot, indexPath, completionHandler) in
+            let imageURL = screenshot.imageURL
+            return RSTAsyncBlockOperation() { (operation) in
+                let request = ImageRequest(url: imageURL, processors: [.screenshot])
+                ImagePipeline.shared.loadImage(with: request, progress: nil) { result in
+                    guard !operation.isCancelled else { return operation.finish() }
+                    
+                    switch result
+                    {
+                    case .success(let response): completionHandler(response.image, nil)
+                    case .failure(let error): completionHandler(nil, error)
+                    }
+                }
+            }
+        }
+        dataSource.prefetchCompletionHandler = { (cell, image, indexPath, error) in
+            let cell = cell as! AppScreenshotCollectionViewCell
+            cell.imageView.isIndicatingActivity = false
+            cell.imageView.image = image
+            
+            if let error = error
+            {
+                print("Error loading image:", error)
+            }
+        }
+        
+        return dataSource
+    }
+}
+
+@available(iOS 17, *)
+#Preview(traits: .portrait) {
+    DatabaseManager.shared.startForPreview()
+    
+    let fetchRequest = StoreApp.fetchRequest()
+    let storeApp = try! DatabaseManager.shared.viewContext.fetch(fetchRequest).first!
+    
+    let storyboard = UIStoryboard(name: "Main", bundle: .main)
+    let appViewConttroller = storyboard.instantiateViewController(withIdentifier: "appViewController") as! AppViewController
+    appViewConttroller.app = storeApp
+    
+    let navigationController = UINavigationController(rootViewController: appViewConttroller)
+    return navigationController
+}