fix regression where images were only scaled for portrait mode

ImageViewer/ViewController.swift

@@ -912,24 +912,19 @@ class ViewController: UIViewController, UIGestureRecognizerDelegate {
         var text = "\(metadata.title)\n"
 
         if let chapterTitle = metadata.chapters[currentChapter - 1].title {
-            text =
-                text + "\(chapterTitle)\n"
+            text +=
+                "\(chapterTitle)\n"
         }
-        text =
-            text + """
+        text +=
+            """
             Volume \(Int(metadata.chapters[currentChapter - 1].volume)) of \(Int(metadata.last_volume))
             Chapter \(currentChapter!) of \(Int(metadata.last_chapter))
             Page \(currentPage!) of \(metadata.chapters[currentChapter - 1].pages)
             """
-        if let size = imageLoader.size[
-            getImagePath(
-                chapter: currentChapter, volume: Int(metadata.chapters[currentChapter - 1].volume),
-                page: currentPage!, path: currentPath
-            ).path]
-        {
-            text =
-                text + "\nImage size: \(Int(size.width))x\(Int(size.height))"
-        }
+        // if let size = imageLoader.originalImage.cgImage {
+        //     text +=
+        //         "\nImage size: \(Int(size.width))x\(Int(size.height))"
+        // }
         info.text = text
     }
 
@@ -1060,6 +1055,23 @@ class ViewController: UIViewController, UIGestureRecognizerDelegate {
         }
         return nil
     }
+
+    override func viewWillTransition(
+        to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator
+    ) {
+        super.viewWillTransition(to: size, with: coordinator)
+
+        self.imageLoader.loadImage(
+            at: self.getImagePath(
+                chapter: self.currentChapter,
+                volume: Int(self.metadata.chapters[self.currentChapter - 1].volume),
+                page: self.currentPage,
+                path: self.currentPath),
+            scaling: .scaleAspectFit
+        ) { image in
+            self.imageView.image = image
+        }
+    }
 }
 
 func getGlobalState() -> GlobalState {
@@ -1259,10 +1271,15 @@ class ComicImageCell: UICollectionViewCell {
     }
 }
 
+enum Rotation {
+    case vertical
+    case horizontal
+}
+
 class ImageLoader {
-    private let cache = NSCache<NSString, UIImage>()
+    let cache = NSCache<NSString, UIImage>()
+    let horCache = NSCache<NSString, UIImage>()
     private var loadingTasks: [String: [((UIImage?) -> Void)]] = [:]
-    var size: [String: CGSize] = [:]
 
     init() {
         // 128 MiB
@@ -1273,11 +1290,27 @@ class ImageLoader {
         loadImage(at: path, scaling: scaling, completion: nil)
     }
 
-    func loadImage(at path: URL, scaling: UIView.ContentMode, completion: ((UIImage?) -> Void)?) {
+    func loadImage(
+        at path: URL, scaling: UIView.ContentMode,
+        completion: ((UIImage?) -> Void)?
+    ) {
+        let screenSize = UIScreen.main.bounds.size
+        let rotation: Rotation =
+            if screenSize.width > screenSize.height {
+                .horizontal
+            } else { .vertical }
+
+        if rotation == .vertical {
             if let cached = cache.object(forKey: path.path as NSString) {
                 completion?(cached)
                 return
             }
+        } else {
+            if let cached = horCache.object(forKey: path.path as NSString) {
+                completion?(cached)
+                return
+            }
+        }
 
         if loadingTasks[path.path] != nil {
             if let completion = completion {
@@ -1291,15 +1324,34 @@ class ImageLoader {
         queue.async { [weak self] in
             guard let self = self else { return }
             guard var image = UIImage(contentsOfFile: path.path) else { return }
-            self.size[path.path] = image.size
-            let scaledSize = aspectSize(
-                for: image.size, in: UIScreen.main.bounds.size, scaling: scaling)
-            image = resizeImage(image, to: scaledSize)
-            guard let cost = imageByteSize(image) else { return }
-            self.cache.setObject(image, forKey: path.path as NSString, cost: cost)
+
+            // If you turn pages fast, completion will not be nil and as such only the needed scaled image should be prepared
+            if completion == nil || rotation == .vertical {
+                let vertical = CGSize(
+                    width: min(screenSize.width, screenSize.height),
+                    height: max(screenSize.height, screenSize.width))
+                let vScaledSize = aspectSize(
+                    for: image.size, in: vertical, scaling: scaling)
+                let vScaleImage = resizeImage(image, to: vScaledSize)
+                guard let cost = imageByteSize(vScaleImage) else { return }
+                self.cache.setObject(vScaleImage, forKey: path.path as NSString, cost: cost)
+                image = vScaleImage
+            }
+
+            if completion == nil || rotation == .horizontal {
+                let horizontal = CGSize(
+                    width: max(screenSize.width, screenSize.height),
+                    height: min(screenSize.height, screenSize.width))
+                let hScaledSize = aspectSize(
+                    for: image.size, in: horizontal, scaling: scaling)
+                let hScaleImage = resizeImage(image, to: hScaledSize)
+                guard let cost = imageByteSize(hScaleImage) else { return }
+                self.horCache.setObject(hScaleImage, forKey: path.path as NSString, cost: cost)
+                image = hScaleImage
+            }
 
             DispatchQueue.main.async {
-                self.loadingTasks[path.path]?.forEach { $0(image) }
+                self.loadingTasks[path.path]?.forEach { $0((image)) }
                 self.loadingTasks.removeValue(forKey: path.path)
             }
         }