Fixed stability issues with page thumbnail controller (#833)

zotero · Jan 19, 2024 · 8d0fda9 · 8d0fda9
1 parent ec66100
commit 8d0fda9
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Showing 3 changed files with 21 additions and 10 deletions.
diff --git a/Zotero/Scenes/Detail/PDF/Models/PDFThumbnailsState.swift b/Zotero/Scenes/Detail/PDF/Models/PDFThumbnailsState.swift
@@ -27,13 +27,23 @@ struct PDFThumbnailsState: ViewModelState {
         case fromSidebar
     }
 
+    struct Page: Hashable {
+        let id: UUID
+        let title: String
+
+        init(title: String) {
+            self.id = UUID()
+            self.title = title
+        }
+    }
+
     let thumbnailSize: CGSize
     let document: Document
     let key: String
     let libraryId: LibraryIdentifier
 
     let cache: NSCache<NSNumber, UIImage>
-    var pages: [String]
+    var pages: [Page]
     var isDark: Bool
     var loadedThumbnail: Int?
     var selectedPageIndex: Int

diff --git a/Zotero/Scenes/Detail/PDF/ViewModels/PDFThumbnailsActionHandler.swift b/Zotero/Scenes/Detail/PDF/ViewModels/PDFThumbnailsActionHandler.swift
@@ -59,7 +59,8 @@ struct PDFThumbnailsActionHandler: ViewModelActionHandler {
     }
 
     private func loadPages(viewModel: ViewModel<PDFThumbnailsActionHandler>) {
-        let labels = (0..<viewModel.state.document.pageCount).map({ viewModel.state.document.pageLabelForPage(at: $0, substituteWithPlainLabel: true) ?? "" })
+        guard viewModel.state.document.pageCount > 0 else { return }
+        let labels = (0..<viewModel.state.document.pageCount).map({ PDFThumbnailsState.Page(title: viewModel.state.document.pageLabelForPage(at: $0, substituteWithPlainLabel: true) ?? "") })
         update(viewModel: viewModel) { state in
             state.pages = labels
             state.changes = .pages

diff --git a/Zotero/Scenes/Detail/PDF/Views/PDFThumbnailsViewController.swift b/Zotero/Scenes/Detail/PDF/Views/PDFThumbnailsViewController.swift
@@ -16,15 +16,15 @@ class PDFThumbnailsViewController: UICollectionViewController {
     private let viewModel: ViewModel<PDFThumbnailsActionHandler>
     private let disposeBag: DisposeBag
 
-    private var dataSource: UICollectionViewDiffableDataSource<Int, String>!
+    private var dataSource: UICollectionViewDiffableDataSource<Int, PDFThumbnailsState.Page>!
 
-    private lazy var cellRegistration: UICollectionView.CellRegistration<PDFThumbnailsCell, String> = {
-        return UICollectionView.CellRegistration<PDFThumbnailsCell, String> { [weak self] cell, indexPath, label in
+    private lazy var cellRegistration: UICollectionView.CellRegistration<PDFThumbnailsCell, PDFThumbnailsState.Page> = {
+        return UICollectionView.CellRegistration<PDFThumbnailsCell, PDFThumbnailsState.Page> { [weak self] cell, indexPath, page in
             let image = self?.viewModel.state.cache.object(forKey: NSNumber(value: indexPath.row))
             if image == nil {
                 self?.viewModel.process(action: .load(UInt(indexPath.row)))
             }
-            cell.contentConfiguration = PDFThumbnailsCell.ContentConfiguration(label: label, image: image)
+            cell.contentConfiguration = PDFThumbnailsCell.ContentConfiguration(label: page.title, image: image)
         }
     }()
 
@@ -42,11 +42,11 @@ class PDFThumbnailsViewController: UICollectionViewController {
 
         super.init(collectionViewLayout: layout)
     }
-    
+
     required init?(coder: NSCoder) {
         fatalError("init(coder:) has not been implemented")
     }
-    
+
     override func viewDidLoad() {
         super.viewDidLoad()
 
@@ -88,8 +88,8 @@ class PDFThumbnailsViewController: UICollectionViewController {
     }
 
     private func update(state: PDFThumbnailsState) {
-        if state.changes.contains(.pages) {
-            var snapshot = NSDiffableDataSourceSnapshot<Int, String>()
+        if state.changes.contains(.pages) && !state.pages.isEmpty {
+            var snapshot = NSDiffableDataSourceSnapshot<Int, PDFThumbnailsState.Page>()
             snapshot.appendSections([0])
             snapshot.appendItems(state.pages)
             dataSource.apply(snapshot) { [weak self] in