Extract the table of contents from an LCP-protected PDF

CHANGELOG.md

@@ -4,7 +4,18 @@ All notable changes to this project will be documented in this file. Take a look
 
 **Warning:** Features marked as *alpha* may change or be removed in a future release without notice. Use with caution.
 
-<!-- ## [Unreleased] -->
+## [Unreleased]
+
+### Added
+
+#### Shared
+
+* `TableOfContentsService` can now be used to customize the computation of `publication.tableOfContents()`.
+
+#### LCP
+
+* The table of contents of an LCP-protected PDF is now extracted directly from the PDF if the `tableOfContents` property in `manifest.json` is empty.
+
 
 ## [3.0.0-alpha.3]
 

Sources/Navigator/EPUB/EPUBNavigatorViewController.swift

@@ -449,7 +449,9 @@ open class EPUBNavigatorViewController: UIViewController,
     }
 
     /// Mapping between reading order hrefs and the table of contents title.
-    private lazy var tableOfContentsTitleByHref: [AnyURL: String] = {
+    private lazy var tableOfContentsTitleByHref = memoize(computeTableOfContentsTitleByHref)
+
+    private func computeTableOfContentsTitleByHref() async -> [AnyURL: String] {
         func fulfill(linkList: [Link]) -> [AnyURL: String] {
             var result = [AnyURL: String]()
 
@@ -465,8 +467,12 @@ open class EPUBNavigatorViewController: UIViewController,
             return result
         }
 
-        return fulfill(linkList: publication.tableOfContents)
-    }()
+        guard let toc = try? await publication.tableOfContents().get() else {
+            return [:]
+        }
+
+        return fulfill(linkList: toc)
+    }
 
     /// Goes to the next or previous page in the given scroll direction.
     private func go(to direction: EPUBSpreadView.Direction, options: NavigatorGoOptions) async -> Bool {
@@ -642,8 +648,8 @@ open class EPUBNavigatorViewController: UIViewController,
         {
             // Gets the current locator from the positionList, and fill its missing data.
             let positionIndex = Int(ceil(progression * Double(positionList.count - 1)))
-            return positionList[positionIndex].copy(
-                title: tableOfContentsTitleByHref[equivalent: href],
+            return await positionList[positionIndex].copy(
+                title: tableOfContentsTitleByHref()[equivalent: href],
                 locations: { $0.progression = progression }
             )
         } else {

Sources/Shared/Publication/Publication.swift

@@ -9,7 +9,7 @@ import Foundation
 
 /// Shared model for a Readium Publication.
 public class Publication: Closeable, Loggable {
-    private var manifest: Manifest
+    public var manifest: Manifest
     private let container: Container
     private let services: [PublicationService]
 
@@ -20,8 +20,6 @@ public class Publication: Closeable, Loggable {
     public var readingOrder: [Link] { manifest.readingOrder }
     /// Identifies resources that are necessary for rendering the publication.
     public var resources: [Link] { manifest.resources }
-    /// Identifies the collection that contains a table of contents.
-    public var tableOfContents: [Link] { manifest.tableOfContents }
     public var subcollections: [String: [PublicationCollection]] { manifest.subcollections }
 
     public init(

Sources/Shared/Publication/Services/Search/StringSearchService.swift

@@ -143,7 +143,7 @@ public class StringSearchService: SearchService {
                 return []
             }
 
-            let title = publication.tableOfContents.titleMatchingHREF(link.href)
+            let title = await publication.tableOfContents().getOrNil()?.titleMatchingHREF(link.href)
             resourceLocator = resourceLocator.copy(
                 title: Optional(title ?? link.title)
             )

Sources/Shared/Publication/Services/Table Of Contents/TableOfContentsService.swift

@@ -0,0 +1,39 @@
+//
+//  Copyright 2024 Readium Foundation. All rights reserved.
+//  Use of this source code is governed by the BSD-style license
+//  available in the top-level LICENSE file of the project.
+//
+
+import Foundation
+
+public typealias TableOfContentsServiceFactory = (PublicationServiceContext) -> TableOfContentsService?
+
+/// Returns or computes a table of contents for the publication.
+public protocol TableOfContentsService: PublicationService {
+    func tableOfContents() async -> ReadResult<[Link]>
+}
+
+// MARK: Publication Helpers
+
+public extension Publication {
+    /// Returns the table of contents for this publication.
+    func tableOfContents() async -> ReadResult<[Link]> {
+        if let service = findService(TableOfContentsService.self) {
+            return await service.tableOfContents()
+        } else {
+            return .success(manifest.tableOfContents)
+        }
+    }
+}
+
+// MARK: PublicationServicesBuilder Helpers
+
+public extension PublicationServicesBuilder {
+    mutating func setTableOfContentsServiceFactory(_ factory: TableOfContentsServiceFactory?) {
+        if let factory = factory {
+            set(TableOfContentsService.self, factory)
+        } else {
+            remove(TableOfContentsService.self)
+        }
+    }
+}

Sources/Streamer/Parser/PDF/Services/LCPDFTableOfContentsService.swift

@@ -0,0 +1,62 @@
+//
+//  Copyright 2024 Readium Foundation. All rights reserved.
+//  Use of this source code is governed by the BSD-style license
+//  available in the top-level LICENSE file of the project.
+//
+
+import Foundation
+import ReadiumInternal
+import ReadiumShared
+
+/// This ``TableOfContentsService`` will load the table of contents of the
+/// single PDF resource in an LCPDF package, if the table of contents is missing
+/// from the `manifest.json` file.
+final class LCPDFTableOfContentsService: TableOfContentsService, PDFPublicationService, Loggable {
+    private let manifest: Manifest
+    private let container: Container
+    var pdfFactory: PDFDocumentFactory
+
+    init(
+        manifest: Manifest,
+        container: Container,
+        pdfFactory: PDFDocumentFactory
+    ) {
+        self.manifest = manifest
+        self.container = container
+        self.pdfFactory = pdfFactory
+    }
+
+    func tableOfContents() async -> ReadResult<[Link]> {
+        await _tableOfContents()
+    }
+
+    private lazy var _tableOfContents = memoize(makeTableOfContents)
+
+    private func makeTableOfContents() async -> ReadResult<[Link]> {
+        guard
+            manifest.tableOfContents.isEmpty,
+            manifest.readingOrder.count == 1,
+            let url = manifest.readingOrder.first?.url(),
+            let resource = container[url]
+        else {
+            return .success(manifest.tableOfContents)
+        }
+
+        do {
+            let toc = try await pdfFactory.open(resource: resource, at: url, password: nil).tableOfContents()
+            return .success(toc.linksWithDocumentHREF(url))
+        } catch {
+            return .failure(.decoding(error))
+        }
+    }
+
+    static func makeFactory(pdfFactory: PDFDocumentFactory) -> (PublicationServiceContext) -> LCPDFTableOfContentsService? {
+        { context in
+            LCPDFTableOfContentsService(
+                manifest: context.manifest,
+                container: context.container,
+                pdfFactory: pdfFactory
+            )
+        }
+    }
+}

Sources/Streamer/Parser/Readium/ReadiumWebPubParser.swift

@@ -114,6 +114,7 @@ public class ReadiumWebPubParser: PublicationParser, Loggable {
                             $0.setLocatorServiceFactory(AudioLocatorService.makeFactory())
 
                         } else if manifest.conforms(to: .pdf), format.conformsTo(.lcp), let pdfFactory = pdfFactory {
+                            $0.setTableOfContentsServiceFactory(LCPDFTableOfContentsService.makeFactory(pdfFactory: pdfFactory))
                             $0.setPositionsServiceFactory(LCPDFPositionsService.makeFactory(pdfFactory: pdfFactory))
                         }
 

Support/Carthage/.xcodegen

@@ -13841,6 +13841,8 @@
 ../../Sources/Shared/Publication/Services/Search
 ../../Sources/Shared/Publication/Services/Search/SearchService.swift
 ../../Sources/Shared/Publication/Services/Search/StringSearchService.swift
+../../Sources/Shared/Publication/Services/Table Of Contents
+../../Sources/Shared/Publication/Services/Table Of Contents/TableOfContentsService.swift
 ../../Sources/Shared/Publication/Subject.swift
 ../../Sources/Shared/Publication/User Settings
 ../../Sources/Shared/Publication/User Settings/UserProperties.swift
@@ -14011,6 +14013,7 @@
 ../../Sources/Streamer/Parser/PDF/PDFParser.swift
 ../../Sources/Streamer/Parser/PDF/Services
 ../../Sources/Streamer/Parser/PDF/Services/LCPDFPositionsService.swift
+../../Sources/Streamer/Parser/PDF/Services/LCPDFTableOfContentsService.swift
 ../../Sources/Streamer/Parser/PDF/Services/PDFPositionsService.swift
 ../../Sources/Streamer/Parser/PublicationParser.swift
 ../../Sources/Streamer/Parser/Readium

Support/Carthage/Readium.xcodeproj/project.pbxproj

@@ -24,6 +24,7 @@
 		0A6BF62D6FE0C04DA8B8D3CA /* AnyURL.swift in Sources */ = {isa = PBXBuildFile; fileRef = AE350D88BC82408491D8B516 /* AnyURL.swift */; };
 		0AF2BBF12939AFBF6173E333 /* Observable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5BC6AE42A31D77B548CB0BB4 /* Observable.swift */; };
 		0B9AC6EF44DA518E9F37FB49 /* ContentService.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18E809378D79D09192A0AAE1 /* ContentService.swift */; };
+		0BFCDAEC82CFF09AFC53A5D0 /* LCPDFTableOfContentsService.swift in Sources */ = {isa = PBXBuildFile; fileRef = 94414130EC3731CD9920F27D /* LCPDFTableOfContentsService.swift */; };
 		0ECE94F27E005FC454EA9D12 /* DecorableNavigator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 626CFFF131E0E840B76428F1 /* DecorableNavigator.swift */; };
 		0F1AAB56A6ADEDDE2AD7E41E /* Content.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1039900AC78465AD989D7464 /* Content.swift */; };
 		1004CE1C72C85CC3702C09C0 /* Asset.swift in Sources */ = {isa = PBXBuildFile; fileRef = AC811653B33761089E270C4A /* Asset.swift */; };
@@ -314,6 +315,7 @@
 		C9DAA3C193FA36B843113EC6 /* HTTPContainer.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4BFD453E8BF6FA24F340EE0 /* HTTPContainer.swift */; };
 		C9FBD23E459FB395377E149E /* ReadiumWebPubParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = E6E97CCA91F910315C260373 /* ReadiumWebPubParser.swift */; };
 		CAEBD6BA3F2F88E8752CB987 /* KeyEvent.swift in Sources */ = {isa = PBXBuildFile; fileRef = 422C1DA91ED351C9ABA139DF /* KeyEvent.swift */; };
+		CB95F5EAA4D0DB5177FED4F7 /* TableOfContentsService.swift in Sources */ = {isa = PBXBuildFile; fileRef = C5BCDE636CED5B883CC5F2B4 /* TableOfContentsService.swift */; };
 		CC85122A71D3145940827338 /* Comparable.swift in Sources */ = {isa = PBXBuildFile; fileRef = F90C4D94134D9F741D38D8AA /* Comparable.swift */; };
 		CCAF8FB4DBD81448C99D589A /* Language.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7BB152578CBA091A41A51B25 /* Language.swift */; };
 		CD0243B5EB8B408E34786214 /* ReadiumInternal.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 42FD63C2720614E558522675 /* ReadiumInternal.framework */; };
@@ -688,6 +690,7 @@
 		925CDE3176715EBEBF40B21F /* GeneratedCoverService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GeneratedCoverService.swift; sourceTree = "<group>"; };
 		93BF3947EBA8736BF20F36FB /* WebView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WebView.swift; sourceTree = "<group>"; };
 		9407E818636BEA4550E57F57 /* ReadiumNavigator.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = ReadiumNavigator.framework; sourceTree = BUILT_PRODUCTS_DIR; };
+		94414130EC3731CD9920F27D /* LCPDFTableOfContentsService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LCPDFTableOfContentsService.swift; sourceTree = "<group>"; };
 		9627A9AFF7C08010248E1700 /* Publication+Deprecated.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Publication+Deprecated.swift"; sourceTree = "<group>"; };
 		968B4EB4AD29DFA430C8A563 /* LicenseDocument.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LicenseDocument.swift; sourceTree = "<group>"; };
 		97BC822B36D72EF548162129 /* ReadiumShared.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = ReadiumShared.framework; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -764,6 +767,7 @@
 		C51C74A5990A3BA93B3DC587 /* ZIPArchiveOpener.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ZIPArchiveOpener.swift; sourceTree = "<group>"; };
 		C57EC6B0ADED2B0D395F2AEA /* ContentProtection.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ContentProtection.swift; sourceTree = "<group>"; };
 		C59803AADFCF32C93C9D9D29 /* ExplodedArchive.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ExplodedArchive.swift; sourceTree = "<group>"; };
+		C5BCDE636CED5B883CC5F2B4 /* TableOfContentsService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TableOfContentsService.swift; sourceTree = "<group>"; };
 		C5E7CEDF6EA681FE8119791B /* Feed.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Feed.swift; sourceTree = "<group>"; };
 		C96FD34093B3C3E83827B70C /* FileSystemError.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FileSystemError.swift; sourceTree = "<group>"; };
 		CAD79372361D085CA0500CF4 /* Properties+OPDS.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Properties+OPDS.swift"; sourceTree = "<group>"; };
@@ -1085,6 +1089,7 @@
 			isa = PBXGroup;
 			children = (
 				47B9196192A22B8AB80E6B2F /* LCPDFPositionsService.swift */,
+				94414130EC3731CD9920F27D /* LCPDFTableOfContentsService.swift */,
 				D0C2A38D366CE8560BCBAC8B /* PDFPositionsService.swift */,
 			);
 			path = Services;
@@ -1247,6 +1252,14 @@
 			path = Toolkit;
 			sourceTree = "<group>";
 		};
+		402E67E11F98508D372AC2BA /* Table Of Contents */ = {
+			isa = PBXGroup;
+			children = (
+				C5BCDE636CED5B883CC5F2B4 /* TableOfContentsService.swift */,
+			);
+			path = "Table Of Contents";
+			sourceTree = "<group>";
+		};
 		40D18A37080F5B1D114CE2E1 /* Extensions */ = {
 			isa = PBXGroup;
 			children = (
@@ -1288,6 +1301,7 @@
 				3118D7E15D685347720A0651 /* Locator */,
 				5BC52D8F4F854FDA56D10A8E /* Positions */,
 				F818D082B369A3D4BE617D46 /* Search */,
+				402E67E11F98508D372AC2BA /* Table Of Contents */,
 			);
 			path = Services;
 			sourceTree = "<group>";
@@ -2391,6 +2405,7 @@
 				914DEDFE5594761D3F180491 /* EPUBPositionsService.swift in Sources */,
 				EF15E9163EBC82672B22F6E0 /* ImageParser.swift in Sources */,
 				FCFFE5305127D9FC72549EAA /* LCPDFPositionsService.swift in Sources */,
+				0BFCDAEC82CFF09AFC53A5D0 /* LCPDFTableOfContentsService.swift in Sources */,
 				C1A94B2A9C446CB03650DC47 /* NCXParser.swift in Sources */,
 				01AD628D6DE82E1C1C4C281D /* NavigationDocumentParser.swift in Sources */,
 				2B8BC06B6B366E67C716DDA1 /* OPFMeta.swift in Sources */,
@@ -2667,6 +2682,7 @@
 				4DB4C10CB9AB5D38C56C1609 /* StringEncoding.swift in Sources */,
 				E6AC10CCF9711168BE2BE85C /* StringSearchService.swift in Sources */,
 				3E9F244ACDA938D330B9EAEA /* Subject.swift in Sources */,
+				CB95F5EAA4D0DB5177FED4F7 /* TableOfContentsService.swift in Sources */,
 				96048047B4205636ABB66DC9 /* TextTokenizer.swift in Sources */,
 				40A44414CC911BF49BB5EE60 /* Tokenizer.swift in Sources */,
 				035807359AFA2EE23E00F8AB /* TransformingContainer.swift in Sources */,

TestApp/Sources/Reader/Common/Outline/OutlineTableView.swift

@@ -25,28 +25,28 @@ struct OutlineTableView: View {
     @State private var selectedSection: OutlineSection = .tableOfContents
 
     // Outlines (list of links) to display for each section.
-    private var outlines: [OutlineSection: [(level: Int, link: ReadiumShared.Link)]] = [:]
+    @State private var outlines: [OutlineSection: [(level: Int, link: ReadiumShared.Link)]] = [:]
 
     init(publication: Publication, bookId: Book.Id, bookmarkRepository: BookmarkRepository, highlightRepository: HighlightRepository) {
         self.publication = publication
         bookmarksModel = BookmarksViewModel(bookId: bookId, repository: bookmarkRepository)
         highlightsModel = HighlightsViewModel(bookId: bookId, repository: highlightRepository)
 
-        func flatten(_ links: [ReadiumShared.Link], level: Int = 0) -> [(level: Int, link: ReadiumShared.Link)] {
-            links.flatMap { [(level, $0)] + flatten($0.children, level: level + 1) }
-        }
-
         outlines = [
-            .tableOfContents: flatten(
-                !publication.tableOfContents.isEmpty
-                    ? publication.tableOfContents
-                    : publication.readingOrder
-            ),
+            .tableOfContents: [],
             .landmarks: flatten(publication.landmarks),
             .pageList: flatten(publication.pageList),
         ]
     }
 
+    private func loadTableOfContents() async {
+        guard let toc = try? await publication.tableOfContents().get() else {
+            return
+        }
+
+        outlines[.tableOfContents] = flatten(!toc.isEmpty ? toc : publication.readingOrder)
+    }
+
     var body: some View {
         VStack {
             OutlineTablePicker(selectedSection: $selectedSection)
@@ -67,8 +67,6 @@ struct OutlineTableView: View {
                                 }
                             }
                     }
-                } else {
-                    preconditionFailure("Outline \(selectedSection) can't be nil!")
                 }
 
             case .bookmarks:
@@ -93,6 +91,11 @@ struct OutlineTableView: View {
             }
         }
         .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .top)
+        .onAppear {
+            Task {
+                await loadTableOfContents()
+            }
+        }
     }
 
     private let locatorSubject = PassthroughSubject<Locator, Never>()
@@ -123,3 +126,7 @@ enum OutlineTableViewConstants {
     static let tabLandmarks = NSLocalizedString("reader_outline_tab_landmarks", comment: "Outline landmarks tab name")
     static let tabHighlights = NSLocalizedString("reader_outline_tab_highlights", comment: "Outline highlights tab name")
 }
+
+private func flatten(_ links: [ReadiumShared.Link], level: Int = 0) -> [(level: Int, link: ReadiumShared.Link)] {
+    links.flatMap { [(level, $0)] + flatten($0.children, level: level + 1) }
+}