[ADD] Full-screen app screenshot preview

AltStore/Views/App Detail/AppScreenshotsPreview.swift

@@ -0,0 +1,69 @@
+//
+//  AppScreenshotsPreview.swift
+//  SideStore
+//
+//  Created by Fabian Thies on 23.12.22.
+//  Copyright © 2022 SideStore. All rights reserved.
+//
+
+import SwiftUI
+import AsyncImage
+import AltStoreCore
+
+struct AppScreenshotsPreview: View {
+    
+    @Environment(\.dismiss)
+    private var dismiss
+    
+    let urls: [URL]
+    let aspectRatio: CGFloat
+    @State var index: Int
+    
+    init(urls: [URL], aspectRatio: CGFloat = 9/16, initialIndex: Int = 0) {
+        self.urls = urls
+        self.aspectRatio = aspectRatio
+        self._index = State(initialValue: initialIndex)
+    }
+    
+    var body: some View {
+        TabView(selection: $index) {
+            ForEach(Array(urls.enumerated()), id: \.offset) { (i, url) in
+                AsyncImage(url: url) { image in
+                    image
+                        .resizable()
+                } placeholder: {
+                    Rectangle()
+                        .foregroundColor(Color(.secondarySystemBackground))
+                        .aspectRatio(aspectRatio, contentMode: .fill)
+                }
+                .aspectRatio(aspectRatio, contentMode: .fit)
+                .cornerRadius(8)
+                .padding()
+                .tag(i)
+            }
+        }
+        .tabViewStyle(PageTabViewStyle(indexDisplayMode: .never))
+        .toolbar {
+            ToolbarItem(placement: .navigationBarTrailing) {
+                SwiftUI.Button {
+                    self.dismiss()
+                } label: {
+                    Text("Close")
+                }
+            }
+        }
+    }
+}
+
+extension AppScreenshotsPreview: Equatable {
+    /// Prevent re-rendering of the view if the parameters didn't change
+    static func == (lhs: AppScreenshotsPreview, rhs: AppScreenshotsPreview) -> Bool {
+        lhs.urls == rhs.urls
+    }
+}
+
+//struct AppScreenshotsPreview_Previews: PreviewProvider {
+//    static var previews: some View {
+//        AppScreenshotsPreview()
+//    }
+//}

AltStore/Views/App Detail/AppScreenshotsScrollView.swift

@@ -19,25 +19,36 @@ struct AppScreenshotsScrollView: View {
     var aspectRatio: CGFloat = 9/16
     var height: CGFloat = 400
     
+    @State var selectedScreenshotIndex: Int?
+    
     var body: some View {
         ScrollView(.horizontal, showsIndicators: false) {
             HStack {
-                ForEach(urls) { url in
-                    AsyncImage(url: url) { image in
-                        image
-                            .resizable()
-                    } placeholder: {
-                        Rectangle()
-                            .foregroundColor(.secondary)
+                ForEach(Array(urls.enumerated()), id: \.offset) { i, url in
+                    SwiftUI.Button {
+                        self.selectedScreenshotIndex = i
+                    } label: {
+                        AsyncImage(url: url) { image in
+                            image
+                                .resizable()
+                        } placeholder: {
+                            Rectangle()
+                                .foregroundColor(.secondary)
+                        }
+                        .aspectRatio(aspectRatio, contentMode: .fit)
+                        .cornerRadius(8)
                     }
-                    .aspectRatio(aspectRatio, contentMode: .fit)
-                    .cornerRadius(8)
                 }
             }
             .padding(.horizontal)
         }
         .frame(height: height)
         .shadow(radius: 12)
+        .sheet(item: self.$selectedScreenshotIndex) { index in
+            NavigationView {
+                AppScreenshotsPreview(urls: urls, aspectRatio: aspectRatio, initialIndex: index)
+            }
+        }
     }
 }
 
@@ -47,3 +58,9 @@ extension AppScreenshotsScrollView: Equatable {
         lhs.urls == rhs.urls && lhs.aspectRatio == rhs.aspectRatio && lhs.height == rhs.height
     }
 }
+
+extension Int: Identifiable {
+    public var id: Int {
+        self
+    }
+}