Keyboard navigation improvements for macOS

Views/SearchResults.swift

@@ -24,6 +24,7 @@ struct SearchResults: View {
     @Environment(\.managedObjectContext) private var managedObjectContext
     @EnvironmentObject private var viewModel: SearchViewModel
     @EnvironmentObject private var navigation: NavigationViewModel
+    @FocusState private var focusedSearchItem: URL? // macOS only
     @FetchRequest(
         sortDescriptors: [NSSortDescriptor(keyPath: \ZimFile.size, ascending: false)],
         predicate: ZimFile.Predicate.isDownloaded,
@@ -75,22 +76,55 @@ struct SearchResults: View {
         } else if viewModel.results.isEmpty {
             Message(text: "search_result.zimfile.no_result.message".localized)
         } else {
-            ScrollView {
-                LazyVGrid(columns: [GridItem(.flexible(minimum: 300, maximum: 700), alignment: .center)]) {
-                    ForEach(viewModel.results) { result in
-                        Button {
-                            recentSearchTexts = {
-                                var searchTexts = Defaults[.recentSearchTexts]
-                                searchTexts.removeAll(where: { $0 == viewModel.searchText })
-                                searchTexts.insert(viewModel.searchText, at: 0)
-                                return searchTexts
-                            }()
-                            NotificationCenter.openURL(result.url)
-                        } label: {
-                            ArticleCell(result: result, zimFile: viewModel.zimFiles[result.zimFileID])
-                        }.buttonStyle(.plain)
+            ScrollViewReader { scrollReader in
+                ScrollView {
+                    LazyVGrid(columns: [GridItem(.flexible(minimum: 300, maximum: 700), alignment: .center)]) {
+                        ForEach(viewModel.results) { result in
+                            Button {
+                                recentSearchTexts = {
+                                    var searchTexts = Defaults[.recentSearchTexts]
+                                    searchTexts.removeAll(where: { $0 == viewModel.searchText })
+                                    searchTexts.insert(viewModel.searchText, at: 0)
+                                    return searchTexts
+                                }()
+                                NotificationCenter.openURL(result.url)
+                            } label: {
+                                ArticleCell(result: result, zimFile: viewModel.zimFiles[result.zimFileID])
+                            }
+                            .buttonStyle(.plain)
+                            .modifier(
+                                Focusable( // macOS only
+                                    $focusedSearchItem,
+                                    equals: result.url,
+                                    onReturn: {
+                                        NotificationCenter.openURL(result.url)
+                                    },
+                                    onDismiss: {
+                                        $focusedSearchItem.wrappedValue = nil
+                                        dismissSearch()
+                                    })
+                            )
+                        }
+                    }.padding()
+                }
+                .onReceive(self.focusedSearchItem.publisher) { focusedURL in
+                    scrollReader.scrollTo(focusedURL, anchor: .center)
+                }
+                .modifier(MoveCommand(perform: { direction in
+                    // macOS only
+                    if let focusedSearchItem,
+                       let index = viewModel.results.firstIndex(where: { $0.url == focusedSearchItem }) {
+                        let nextIndex: Int
+                        switch direction {
+                        case .up: nextIndex = viewModel.results.index(before: index)
+                        case .down: nextIndex = viewModel.results.index(after: index)
+                        default: nextIndex = viewModel.results.startIndex
+                        }
+                        if (viewModel.results.startIndex..<viewModel.results.endIndex).contains(nextIndex) {
+                            $focusedSearchItem.wrappedValue = viewModel.results[nextIndex].url
+                        }
                     }
-                }.padding()
+                }))
             }
         }
     }
@@ -129,6 +163,7 @@ struct SearchResults: View {
                 } header: { searchFilterHeader }
             }
         }
+        .modifier(NotFocusable()) // macOS only
     }
 
     private var recentSearchHeader: some View {

Views/ViewModifiers/Focusable.swift

@@ -0,0 +1,65 @@
+// This file is part of Kiwix for iOS & macOS.
+//
+// Kiwix is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// any later version.
+//
+// Kiwix is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Kiwix; If not, see https://www.gnu.org/licenses/.
+
+import SwiftUI
+
+struct NotFocusable: ViewModifier {
+
+    func body(content: Content) -> some View {
+        #if os(macOS)
+        content.focusable(false)
+        #else
+        content
+        #endif
+    }
+}
+
+struct Focusable<Value: Hashable>: ViewModifier {
+
+    private let value: Value
+    private let focusState: FocusState<Value>.Binding
+    private let onReturn: () -> Void
+    private let onDissmiss: () -> Void
+
+    init(
+        _ binding: FocusState<Value>.Binding,
+        equals value: Value,
+        onReturn: @escaping () -> Void,
+        onDismiss: @escaping () -> Void
+    ) {
+        self.focusState = binding
+        self.value = value
+        self.onReturn = onReturn
+        self.onDissmiss = onDismiss
+    }
+
+    func body(content: Content) -> some View {
+        #if os(macOS)
+        content
+            .id(value)
+            .focusable()
+            .focused(focusState, equals: value)
+            .modifier(KeyPressHandler(key: .return, action: {
+                onReturn()
+            }))
+            .modifier(KeyPressHandler(key: .escape, action: {
+                onDissmiss()
+            }))
+        #else
+        content
+        #endif
+
+    }
+}

Views/ViewModifiers/KeyPressHandler.swift

@@ -0,0 +1,44 @@
+// This file is part of Kiwix for iOS & macOS.
+//
+// Kiwix is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// any later version.
+//
+// Kiwix is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Kiwix; If not, see https://www.gnu.org/licenses/.
+
+import SwiftUI
+
+struct KeyPressHandler: ViewModifier {
+
+    let key: KeyEquivalent
+    let action: () -> Void
+
+    func body(content: Content) -> some View {
+        #if os(macOS)
+        if #available(macOS 14.0, *) {
+            newApi(content: content)
+        } else {
+            content
+        }
+        #else
+        content
+        #endif
+    }
+
+    @available(macOS 14.0, iOS 17.0, *)
+    private func newApi(content: Content) -> some View {
+        content.onKeyPress(key, action: {
+            Task { await MainActor.run {
+                action()
+            }}
+            return .handled
+        })
+    }
+}

Views/ViewModifiers/MoveCommand.swift

@@ -0,0 +1,58 @@
+// This file is part of Kiwix for iOS & macOS.
+//
+// Kiwix is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// any later version.
+//
+// Kiwix is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Kiwix; If not, see https://www.gnu.org/licenses/.
+
+import SwiftUI
+
+enum MoveDirection: Sendable {
+
+    // swiftlint:disable:next identifier_name
+    case up
+    case down
+    case left
+    case right
+
+    #if os(macOS)
+    init?(from direction: MoveCommandDirection) {
+        switch direction {
+        case .up: self = .up
+        case .down: self = .down
+        case .left: self = .left
+        case .right: self = .right
+        @unknown default: return nil
+        }
+    }
+    #endif
+}
+
+struct MoveCommand: ViewModifier {
+
+    private let action: ((MoveDirection) -> Void)?
+
+    init(perform action: ((MoveDirection) -> Void)?) {
+        self.action = action
+    }
+
+    func body(content: Content) -> some View {
+        #if os(macOS)
+        content.onMoveCommand { (direction: MoveCommandDirection) in
+            if let mappedDirection = MoveDirection(from: direction) {
+                action?(mappedDirection)
+            }
+        }
+        #else
+        content
+        #endif
+    }
+}