744 lines
32 KiB
Swift
744 lines
32 KiB
Swift
import UIKit
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// MARK: - 章节分页诊断数据
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/// 单个章节的分页诊断信息，用于调试和质量检测。
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/// 记录页数、分页原因、附件/块级元素统计等。
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public struct RDEPUBTextChapterPaginationDiagnostic: Equatable {
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public var href: String
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public var title: String
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public var pageCount: Int
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/// 每页的分页原因列表
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public var breakReasons: [RDEPUBTextPageBreakReason]
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/// 包含附件的页数
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public var attachmentPageCount: Int
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/// 因块级/附件边界调整而分页的页数
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public var blockAdjustedPageCount: Int
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public var blockKinds: [RDEPUBTextBlockKind]
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public var semanticHints: [RDEPUBTextSemanticHint]
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public var attachmentPlacements: [RDEPUBTextAttachmentPlacement]
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/// 采样诊断日志（最多 4 条）
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public var sampleNotes: [String]
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}
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// MARK: - 页面数据模型
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/// 分页后的单页数据，包含全书绝对页码、所属章节、内容范围等。
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///
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/// 每个 `RDEPUBTextPage` 由 `RDEPUBTextLayoutFrame` 生成，
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/// `contentRange` 标记了该页在章节富文本中的字符范围。
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public struct RDEPUBTextPage: Equatable {
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/// 全书绝对页码（从 0 开始）
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public var absolutePageIndex: Int
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public var chapterIndex: Int
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public var spineIndex: Int
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public var href: String
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public var chapterTitle: String
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/// 该页在所属章节中的相对页码（从 0 开始）
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public var pageIndexInChapter: Int
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public var totalPagesInChapter: Int
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/// 所属章节的完整富文本内容（用于跨页查询）
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public var chapterContent: NSAttributedString
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/// 该页的富文本片段
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public var content: NSAttributedString
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/// 该页在章节富文本中的范围
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public var contentRange: NSRange
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public var pageStartOffset: Int
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public var pageEndOffset: Int
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/// 页的元数据（分页原因、附件、语义标记等）
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public var metadata: RDEPUBTextPageMetadata
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}
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// MARK: - 章节数据模型
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/// 渲染并分页后的单个章节，包含完整富文本和分页结果。
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public struct RDEPUBTextChapter: Equatable {
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public var chapterIndex: Int
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public var spineIndex: Int
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public var href: String
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public var title: String
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/// 章节完整富文本内容
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public var attributedContent: NSAttributedString
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/// fragment ID → 字符偏移量映射（用于锚点定位）
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public var fragmentOffsets: [String: Int]
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public var pageBreakReasons: [RDEPUBTextPageBreakReason]
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public var pages: [RDEPUBTextPage]
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}
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// MARK: - 分页书籍模型
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/// 整本 EPUB 的分页书籍模型，包含所有章节、页面和全局索引表。
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///
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/// 这是 EPUBTextRendering 层的最终产物，由 `RDEPUBTextBookBuilder.build()` 生成。
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/// 通过 `chapterData(for:)` 或 `chapterData(atChapterIndex:)` 获取 `RDEPUBChapterData` 进行查询。
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public struct RDEPUBTextBook {
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public var chapters: [RDEPUBTextChapter]
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public var pages: [RDEPUBTextPage]
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/// 全局索引表：fileIndex/row/column → 绝对字符偏移量
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public let indexTable: RDEPUBTextIndexTable
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/// 对标 WXRead 的位置转换器（文件位置 <-> 全书字符位置 <-> 页码）
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public var positionConverter: RDEPUBTextPositionConverter {
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RDEPUBTextPositionConverter(book: self)
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}
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public init(chapters: [RDEPUBTextChapter], pages: [RDEPUBTextPage]) {
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self.chapters = chapters
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self.pages = pages
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self.indexTable = RDEPUBTextIndexTable(chapters: chapters)
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}
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public static func == (lhs: RDEPUBTextBook, rhs: RDEPUBTextBook) -> Bool {
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lhs.chapters == rhs.chapters && lhs.pages == rhs.pages
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}
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/// 按 href 获取章节的数据访问层（包含索引表）
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public func chapterData(for href: String) -> RDEPUBChapterData? {
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guard let chapter = chapters.first(where: { $0.href == href }) else { return nil }
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return RDEPUBChapterData(chapter: chapter, indexTable: indexTable)
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}
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/// 按 spine 索引获取章节的数据访问层。
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public func chapterData(forSpineIndex spineIndex: Int) -> RDEPUBChapterData? {
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guard let chapter = chapters.first(where: { $0.spineIndex == spineIndex }) else { return nil }
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return RDEPUBChapterData(chapter: chapter, indexTable: indexTable)
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}
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/// 按章节序号获取章节的数据访问层
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public func chapterData(atChapterIndex index: Int) -> RDEPUBChapterData? {
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guard chapters.indices.contains(index) else { return nil }
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return RDEPUBChapterData(chapter: chapters[index], indexTable: indexTable)
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}
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/// 按绝对页码（从 1 开始）获取章节的数据访问层。
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public func chapterData(forPageNumber pageNumber: Int) -> RDEPUBChapterData? {
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guard let page = page(at: pageNumber) else { return nil }
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return chapterData(forSpineIndex: page.spineIndex)
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}
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/// 根据持久化位置解析所属章节的数据访问层。
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public func chapterData(
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for location: RDEPUBLocation,
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resolver: RDEPUBResourceResolver,
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bookIdentifier: String?
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) -> RDEPUBChapterData? {
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guard let normalizedLocation = resolver.normalizedLocation(location, bookIdentifier: bookIdentifier) else {
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return nil
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}
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return chapterData(for: normalizedLocation.href)
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}
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/// 全书章节信息快照；对标 WXRead 由章节模型直接提供章节元数据。
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public var chapterInfos: [EPUBChapterInfo] {
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chapters.map { chapter in
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EPUBChapterInfo(
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spineIndex: chapter.spineIndex,
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title: chapter.title,
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pageCount: chapter.pages.count
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)
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}
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}
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/// 按页码（从 1 开始）获取对应页面
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public func page(at pageNumber: Int) -> RDEPUBTextPage? {
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guard pageNumber > 0, pages.indices.contains(pageNumber - 1) else {
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return nil
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}
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return pages[pageNumber - 1]
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}
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/// 根据持久化位置计算对应页码（从 1 开始）。
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///
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/// 解析优先级：
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/// 1. rangeAnchor 锚点定位
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/// 2. fragment 片段 ID
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/// 3. navigationProgression 进度百分比回退
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public func pageNumber(for location: RDEPUBLocation, resolver: RDEPUBResourceResolver, bookIdentifier: String?) -> Int? {
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guard let normalizedLocation = resolver.normalizedLocation(location, bookIdentifier: bookIdentifier),
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let chapterData = chapterData(for: normalizedLocation.href) else {
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return nil
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}
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if let anchor = normalizedLocation.rangeAnchor?.start,
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let page = positionConverter.pageNumber(for: anchor) {
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return page
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}
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if let anchor = indexTable.anchor(for: normalizedLocation),
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let page = positionConverter.pageNumber(for: anchor) {
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return page
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}
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return chapterData.pageNumber(for: normalizedLocation)
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}
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/// 根据页码生成持久化位置（RDEPUBLocation），包含起止锚点
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public func location(forPageNumber pageNumber: Int, bookIdentifier: String?) -> RDEPUBLocation? {
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guard let chapterData = chapterData(forPageNumber: pageNumber),
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let page = page(at: pageNumber) else {
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return nil
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}
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return chapterData.location(forPage: page, bookIdentifier: bookIdentifier)
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}
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}
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// MARK: - 分页书籍构建器
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/// 从 EPUB publication 构建分页书籍模型的核心构建器。
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///
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/// 渲染链路：遍历 spine → 渲染每章 HTML → 分页 → 合并/规范化尾页 → 构建 RDEPUBTextBook
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///
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/// 特性：
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/// - 支持分页缓存（WXRead 模式：只缓存页范围，不缓存富文本）
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/// - 性能采样（记录每章渲染/分页耗时）
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/// - 尾页规范化（丢弃纯空白尾页、合并过短尾页）
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/// - 封面章节特殊处理
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public final class RDEPUBTextBookBuilder {
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private let renderer: RDEPUBTextRenderer
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private let cache: RDEPUBTextBookCache?
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private let layoutConfig: RDEPUBTextLayoutConfig
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private let sampler: RDEPUBTextPerformanceSampler
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/// 最后一次构建的资源引用诊断（样式表、图片等）
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public private(set) var lastBuildResourceDiagnostics: [RDEPUBTextResourceReferenceDiagnostic] = []
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/// 最后一次构建的分页诊断（每章一页的分页原因、附件统计等）
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public private(set) var lastBuildPaginationDiagnostics: [RDEPUBTextChapterPaginationDiagnostic] = []
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/// 最后一次构建的性能采样数据
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public private(set) var lastBuildPerformanceSamples: [RDEPUBTextPerformanceSample] = []
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/// 最后一次构建的缓存命中/未命中统计
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public private(set) var lastBuildCacheStats: (hits: Int, misses: Int) = (0, 0)
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public init(
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renderer: RDEPUBTextRenderer,
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cache: RDEPUBTextBookCache? = nil,
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layoutConfig: RDEPUBTextLayoutConfig = .default
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) {
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self.renderer = renderer
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self.cache = cache
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self.layoutConfig = layoutConfig
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self.sampler = RDEPUBTextPerformanceSampler()
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}
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/// 默认构造器，使用 DTCoreText 渲染器
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public convenience init() {
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self.init(renderer: RDEPUBDTCoreTextRenderer())
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}
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/// 生成最近一次构建的语义摘要，用于 Phase 7 质量检测日志
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public func phase7SemanticSummary(title: String? = nil) -> String? {
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guard !lastBuildPaginationDiagnostics.isEmpty else { return nil }
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let blockKinds = uniqueValues(from: lastBuildPaginationDiagnostics.flatMap(\.blockKinds))
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let semanticHints = uniqueValues(from: lastBuildPaginationDiagnostics.flatMap(\.semanticHints))
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let attachmentPlacements = uniqueValues(from: lastBuildPaginationDiagnostics.flatMap(\.attachmentPlacements))
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let note = lastBuildPaginationDiagnostics
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.flatMap(\.sampleNotes)
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.first(where: { $0.contains("semantic") || $0.contains("attachment") || $0.contains("block kinds") })
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var parts = [
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title,
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"章节 \(lastBuildPaginationDiagnostics.count)",
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blockKinds.isEmpty ? nil : "block kinds [\(blockKinds.map(\.rawValue).joined(separator: ","))]",
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semanticHints.isEmpty ? nil : "hints [\(semanticHints.map(\.rawValue).joined(separator: ","))]",
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attachmentPlacements.isEmpty ? nil : "placements [\(attachmentPlacements.map(\.rawValue).joined(separator: ","))]"
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].compactMap { $0 }
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if let note {
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parts.append(note)
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}
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return parts.joined(separator: " · ")
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}
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/// 核心构建方法：从 EPUB publication 构建分页书籍。
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///
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/// 流程：
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/// 1. 生成缓存键，尝试加载分页缓存
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/// 2. 遍历 spine 中的线性 HTML 章节
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/// 3. 渲染每章 HTML → NSAttributedString
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/// 4. 跳过空白的封面/扉页章节
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/// 5. 分页：缓存命中则使用缓存的页范围，否则调用 CoreText 分页引擎
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/// 6. 尾页规范化：丢弃纯空白尾页、合并过短尾页
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/// 7. 构建 RDEPUBTextBook 并保存分页缓存
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public func build(
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parser: RDEPUBParser,
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publication: RDEPUBPublication,
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pageSize: CGSize,
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style: RDEPUBTextRenderStyle
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) throws -> RDEPUBTextBook {
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var chapters: [RDEPUBTextChapter] = []
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var flatPages: [RDEPUBTextPage] = []
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lastBuildResourceDiagnostics = []
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lastBuildPaginationDiagnostics = []
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lastBuildPerformanceSamples = []
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lastBuildCacheStats = (0, 0)
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sampler.reset()
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let buildStart = CFAbsoluteTimeGetCurrent()
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// 缓存查询 — WXRead 模式：只加载每章的页范围，不缓存富文本
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let bookID = publication.metadata.identifier ?? publication.metadata.title
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let cacheKey = makeCacheKey(bookID: bookID, pageSize: pageSize, style: style)
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let cachedPagination = cacheKey.flatMap { cache?.load(key: $0) }
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for (spineIndex, item) in publication.spine.enumerated() where item.linear {
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guard item.mediaType.contains("html") || item.mediaType.contains("xhtml"),
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let rawHTML = parser.htmlString(forRelativePath: item.href) else {
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continue
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}
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// 从目录表中解析章节标题
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let chapterTitle = resolvedChapterTitle(for: item, toc: publication.tableOfContents)
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let request = RDEPUBTextRendererSupport.makeChapterRenderRequest(
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href: item.href,
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title: chapterTitle,
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rawHTML: rawHTML,
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baseURL: parser.fileURL(forRelativePath: item.href)?.deletingLastPathComponent(),
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style: style,
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resourceResolver: publication.resourceResolver,
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contentLanguageCode: publication.metadata.language
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)
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// 渲染 HTML → NSAttributedString
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let renderStart = CFAbsoluteTimeGetCurrent()
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let rendered = try renderer.renderChapter(request: request)
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let renderDuration = CFAbsoluteTimeGetCurrent() - renderStart
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lastBuildResourceDiagnostics.append(contentsOf: rendered.resourceDiagnostics)
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let plainText = rendered.attributedString.string.trimmingCharacters(in: .whitespacesAndNewlines)
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if item.href.lowercased().contains("cover") {
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print("[EPUB][Cover] rendered href=\(item.href) textLength=\(plainText.count) attrLength=\(rendered.attributedString.length) attachments=\(attachmentCount(in: rendered.attributedString))")
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}
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// 跳过空白的封面/扉页章节
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if shouldSkipChapter(item: item, content: rendered.attributedString, text: plainText) {
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if item.href.lowercased().contains("cover") {
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print("[EPUB][Cover] skipped href=\(item.href)")
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}
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continue
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}
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let chapterIndex = chapters.count
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let content = NSMutableAttributedString(attributedString: rendered.attributedString)
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// 分页：封面图片章节走特殊路径，缓存命中则跳过分页引擎
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let paginateStart = CFAbsoluteTimeGetCurrent()
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let layoutFrames: [RDEPUBTextLayoutFrame]
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let isCacheHit: Bool
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if isAttachmentOnlyCoverChapter(item: item, content: content, plainText: plainText) {
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// 纯图片封面：整个内容作为一页
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layoutFrames = [
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RDEPUBTextLayoutFrame(
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contentRange: NSRange(location: 0, length: content.length),
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breakReason: .chapterEnd,
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blockRange: nil,
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attachmentRanges: attachmentRanges(in: content),
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attachmentKinds: [],
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blockKinds: [],
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semanticHints: [],
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attachmentPlacements: [],
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trailingFragmentID: nil,
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diagnostics: [
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"page break: chapterEnd",
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"cover fallback: single attachment page",
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"page range: \(NSStringFromRange(NSRange(location: 0, length: content.length)))"
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]
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)
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]
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isCacheHit = false
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} else if let cached = cachedPagination?[item.href] {
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// 缓存命中：直接使用缓存的页范围，跳过 CoreText 分页
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layoutFrames = cached.pageRanges.enumerated().map { idx, range in
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let breakReason = idx < cached.breakReasons.count ? cached.breakReasons[idx] : .frameLimit
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return RDEPUBTextLayoutFrame(
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contentRange: range,
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breakReason: breakReason,
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blockRange: nil,
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attachmentRanges: [],
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attachmentKinds: [],
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blockKinds: [],
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semanticHints: cached.semanticHints,
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attachmentPlacements: [],
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trailingFragmentID: nil,
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diagnostics: ["page break: \(breakReason.rawValue)", "page range: \(NSStringFromRange(range))", "source: cache hit"]
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)
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}
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isCacheHit = true
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} else {
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// 缓存未命中：调用 CoreText 分页引擎
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layoutFrames = content.length > 0
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? content.rd_paginatedFrames(size: pageSize, fragmentOffsets: rendered.fragmentOffsets, config: layoutConfig)
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: []
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isCacheHit = false
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}
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let paginateDuration = CFAbsoluteTimeGetCurrent() - paginateStart
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// 尾页规范化：丢弃纯空白尾页、合并过短尾页
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let normalizedFrames = normalizeTrailingFrames(
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layoutFrames,
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content: content,
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href: item.href
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)
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let effectiveFrames = normalizedFrames.isEmpty && content.length > 0
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? [
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RDEPUBTextLayoutFrame(
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contentRange: NSRange(location: 0, length: content.length),
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breakReason: .chapterEnd,
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blockRange: nil,
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attachmentRanges: [],
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attachmentKinds: [],
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blockKinds: [],
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semanticHints: [],
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attachmentPlacements: [],
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trailingFragmentID: nil,
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diagnostics: [
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"page break: chapterEnd",
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"page range: \(NSStringFromRange(NSRange(location: 0, length: content.length)))"
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]
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)
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]
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: normalizedFrames
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if item.href.lowercased().contains("cover") {
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print("[EPUB][Cover] paginated href=\(item.href) pages=\(effectiveFrames.count) firstRange=\(effectiveFrames.first.map { NSStringFromRange($0.contentRange) } ?? "none")")
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}
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// 记录性能采样
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sampler.record(RDEPUBTextPerformanceSample(
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chapterHref: item.href,
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renderDuration: renderDuration,
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paginateDuration: paginateDuration,
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pageCount: effectiveFrames.count,
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attributedStringLength: content.length,
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cacheHit: isCacheHit
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))
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if isCacheHit {
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lastBuildCacheStats.hits += 1
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} else {
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lastBuildCacheStats.misses += 1
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}
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|
||
// 构建页面和章节模型
|
||
let chapterAttributedContent = content.copy() as! NSAttributedString
|
||
let pages = effectiveFrames.enumerated().map { localPageIndex, frame in
|
||
let range = frame.contentRange
|
||
return RDEPUBTextPage(
|
||
absolutePageIndex: flatPages.count + localPageIndex,
|
||
chapterIndex: chapterIndex,
|
||
spineIndex: spineIndex,
|
||
href: item.href,
|
||
chapterTitle: chapterTitle,
|
||
pageIndexInChapter: localPageIndex,
|
||
totalPagesInChapter: effectiveFrames.count,
|
||
chapterContent: chapterAttributedContent,
|
||
content: content.attributedSubstring(from: range),
|
||
contentRange: range,
|
||
pageStartOffset: range.location,
|
||
pageEndOffset: range.location + max(range.length - 1, 0),
|
||
metadata: frame.metadata
|
||
)
|
||
}
|
||
|
||
chapters.append(
|
||
RDEPUBTextChapter(
|
||
chapterIndex: chapterIndex,
|
||
spineIndex: spineIndex,
|
||
href: item.href,
|
||
title: chapterTitle,
|
||
attributedContent: chapterAttributedContent,
|
||
fragmentOffsets: rendered.fragmentOffsets,
|
||
pageBreakReasons: pages.map(\.metadata.breakReason),
|
||
pages: pages
|
||
)
|
||
)
|
||
lastBuildPaginationDiagnostics.append(
|
||
RDEPUBTextChapterPaginationDiagnostic(
|
||
href: item.href,
|
||
title: chapterTitle,
|
||
pageCount: pages.count,
|
||
breakReasons: pages.map(\.metadata.breakReason),
|
||
attachmentPageCount: pages.filter { !$0.metadata.attachmentKinds.isEmpty }.count,
|
||
blockAdjustedPageCount: pages.filter { $0.metadata.breakReason == .blockBoundary || $0.metadata.breakReason == .attachmentBoundary }.count,
|
||
blockKinds: uniqueValues(from: pages.flatMap(\.metadata.blockKinds)),
|
||
semanticHints: uniqueValues(from: pages.flatMap(\.metadata.semanticHints)),
|
||
attachmentPlacements: uniqueValues(from: pages.flatMap(\.metadata.attachmentPlacements)),
|
||
sampleNotes: Array(
|
||
pages
|
||
.flatMap(\.metadata.diagnostics)
|
||
.prefix(4)
|
||
)
|
||
)
|
||
)
|
||
flatPages.append(contentsOf: pages)
|
||
}
|
||
|
||
let book = RDEPUBTextBook(chapters: chapters, pages: flatPages)
|
||
|
||
sampler.totalBuildDuration = CFAbsoluteTimeGetCurrent() - buildStart
|
||
|
||
// 保存分页缓存（只缓存页范围和分页原因，不缓存富文本）
|
||
if let cacheKey {
|
||
let paginationCache = chapters.map { chapter in
|
||
let pageRanges = chapter.pages.map(\.contentRange)
|
||
let breakReasons = chapter.pages.map(\.metadata.breakReason)
|
||
let semanticHints = Array(Set(chapter.pages.flatMap(\.metadata.semanticHints)))
|
||
return RDEPUBTextChapterPaginationCache(
|
||
href: chapter.href,
|
||
pageRanges: pageRanges,
|
||
breakReasons: breakReasons,
|
||
semanticHints: semanticHints
|
||
)
|
||
}
|
||
cache?.save(paginationCache, key: cacheKey)
|
||
}
|
||
|
||
print(sampler.summary())
|
||
lastBuildPerformanceSamples = sampler.samples
|
||
|
||
return book
|
||
}
|
||
|
||
// MARK: - 章节标题解析
|
||
|
||
/// 从目录表中查找章节标题，找不到则回退到 spine item 的 title 或 href
|
||
private func resolvedChapterTitle(for item: RDEPUBSpineItem, toc: [EPUBTableOfContentsItem]) -> String {
|
||
if let title = flattenedTOCItems(from: toc).first(where: { tocItem in
|
||
tocItem.href.components(separatedBy: "#").first == item.href
|
||
})?.title.trimmingCharacters(in: .whitespacesAndNewlines), !title.isEmpty {
|
||
return title
|
||
}
|
||
let trimmedTitle = item.title.trimmingCharacters(in: .whitespacesAndNewlines)
|
||
return trimmedTitle.isEmpty ? item.href : trimmedTitle
|
||
}
|
||
|
||
/// 递归展开嵌套目录为扁平列表
|
||
private func flattenedTOCItems(from items: [EPUBTableOfContentsItem]) -> [EPUBTableOfContentsItem] {
|
||
items.flatMap { item in
|
||
[item] + flattenedTOCItems(from: item.children)
|
||
}
|
||
}
|
||
|
||
// MARK: - 章节过滤
|
||
|
||
/// 判断是否应跳过该章节（空白的封面/扉页，无文本且无附件）
|
||
private func shouldSkipChapter(item: RDEPUBSpineItem, content: NSAttributedString, text: String) -> Bool {
|
||
let lowercasedHref = item.href.lowercased()
|
||
var hasAttachment = false
|
||
if content.length > 0 {
|
||
content.enumerateAttribute(.attachment, in: NSRange(location: 0, length: content.length)) { value, _, stop in
|
||
guard value != nil else { return }
|
||
hasAttachment = true
|
||
stop.pointee = true
|
||
}
|
||
}
|
||
if text.isEmpty && !hasAttachment && (lowercasedHref.contains("cover") || lowercasedHref.contains("title")) {
|
||
return true
|
||
}
|
||
return false
|
||
}
|
||
|
||
// MARK: - 附件统计
|
||
|
||
/// 统计富文本中的附件数量
|
||
private func attachmentCount(in content: NSAttributedString) -> Int {
|
||
guard content.length > 0 else { return 0 }
|
||
var count = 0
|
||
content.enumerateAttribute(.attachment, in: NSRange(location: 0, length: content.length)) { value, _, _ in
|
||
if value != nil {
|
||
count += 1
|
||
}
|
||
}
|
||
return count
|
||
}
|
||
|
||
/// 获取富文本中所有附件的 NSRange 列表
|
||
private func attachmentRanges(in content: NSAttributedString) -> [NSRange] {
|
||
guard content.length > 0 else { return [] }
|
||
var ranges: [NSRange] = []
|
||
content.enumerateAttribute(.attachment, in: NSRange(location: 0, length: content.length)) { value, range, _ in
|
||
if value != nil {
|
||
ranges.append(range)
|
||
}
|
||
}
|
||
return ranges
|
||
}
|
||
|
||
// MARK: - 封面章节检测
|
||
|
||
/// 判断是否为纯图片封面章节（href 包含 cover 且有附件但几乎无文本）
|
||
private func isAttachmentOnlyCoverChapter(
|
||
item: RDEPUBSpineItem,
|
||
content: NSAttributedString,
|
||
plainText: String
|
||
) -> Bool {
|
||
let lowercasedHref = item.href.lowercased()
|
||
guard lowercasedHref.contains("cover") else { return false }
|
||
let trimmed = plainText.trimmingCharacters(in: .whitespacesAndNewlines)
|
||
return attachmentCount(in: content) > 0 && trimmed.count <= 1
|
||
}
|
||
|
||
// MARK: - 尾页规范化
|
||
|
||
/// 规范化分页结果的尾部页面：
|
||
/// 1. 丢弃纯空白的尾页
|
||
/// 2. 将过短的尾页（≤2 字符）合并到前一页
|
||
private func normalizeTrailingFrames(
|
||
_ frames: [RDEPUBTextLayoutFrame],
|
||
content: NSAttributedString,
|
||
href: String
|
||
) -> [RDEPUBTextLayoutFrame] {
|
||
guard frames.count > 1 else { return frames }
|
||
|
||
var normalized = frames
|
||
|
||
// 丢弃纯空白的尾页
|
||
while let lastFrame = normalized.last,
|
||
shouldDropWhitespaceOnlyTrailingFrame(lastFrame, in: content) {
|
||
normalized.removeLast()
|
||
let note = "normalized: dropped whitespace-only trailing page \(NSStringFromRange(lastFrame.contentRange))"
|
||
if var previousFrame = normalized.popLast() {
|
||
previousFrame.diagnostics.append(note)
|
||
normalized.append(previousFrame)
|
||
} else {
|
||
print("[EPUB][Pagination] href=\(href) dropped trailing frame \(NSStringFromRange(lastFrame.contentRange))")
|
||
}
|
||
}
|
||
|
||
// 将过短的尾页合并到前一页
|
||
guard normalized.count > 1,
|
||
let lastFrame = normalized.last,
|
||
let previousFrame = normalized.dropLast().last,
|
||
shouldMergeShortTrailingFrame(lastFrame, previousFrame: previousFrame, in: content) else {
|
||
return normalized
|
||
}
|
||
|
||
let mergedFrame = mergeTrailingFrame(previousFrame, with: lastFrame)
|
||
normalized.removeLast(2)
|
||
normalized.append(mergedFrame)
|
||
return normalized
|
||
}
|
||
|
||
/// 判断尾页是否为纯空白（无可显示字符且无附件）
|
||
private func shouldDropWhitespaceOnlyTrailingFrame(
|
||
_ frame: RDEPUBTextLayoutFrame,
|
||
in content: NSAttributedString
|
||
) -> Bool {
|
||
guard frame.contentRange.length > 0,
|
||
attachmentCount(in: content, range: frame.contentRange) == 0 else {
|
||
return false
|
||
}
|
||
return visibleCharacterCount(in: content, range: frame.contentRange) == 0
|
||
}
|
||
|
||
/// 判断尾页是否过短需要合并到前一页。
|
||
/// 条件：尾页 ≤ 2 个可见字符，且前一页的字符数是尾页的 8 倍以上（至少 12 个字符）
|
||
private func shouldMergeShortTrailingFrame(
|
||
_ trailingFrame: RDEPUBTextLayoutFrame,
|
||
previousFrame: RDEPUBTextLayoutFrame,
|
||
in content: NSAttributedString
|
||
) -> Bool {
|
||
guard trailingFrame.contentRange.length > 0,
|
||
NSMaxRange(previousFrame.contentRange) == trailingFrame.contentRange.location else {
|
||
return false
|
||
}
|
||
|
||
let visibleCount = visibleCharacterCount(in: content, range: trailingFrame.contentRange)
|
||
let trailingAttachmentCount = attachmentCount(in: content, range: trailingFrame.contentRange)
|
||
guard visibleCount <= 2,
|
||
trailingFrame.contentRange.length <= 2,
|
||
visibleCount > 0 || trailingAttachmentCount > 0 else {
|
||
return false
|
||
}
|
||
|
||
let previousVisibleCount = visibleCharacterCount(in: content, range: previousFrame.contentRange)
|
||
return previousVisibleCount >= max(visibleCount * 8, 12)
|
||
}
|
||
|
||
/// 将尾页合并到前一页，保留尾页的分页原因
|
||
private func mergeTrailingFrame(
|
||
_ previousFrame: RDEPUBTextLayoutFrame,
|
||
with trailingFrame: RDEPUBTextLayoutFrame
|
||
) -> RDEPUBTextLayoutFrame {
|
||
let mergedRange = NSRange(
|
||
location: previousFrame.contentRange.location,
|
||
length: NSMaxRange(trailingFrame.contentRange) - previousFrame.contentRange.location
|
||
)
|
||
|
||
return RDEPUBTextLayoutFrame(
|
||
contentRange: mergedRange,
|
||
breakReason: trailingFrame.breakReason,
|
||
blockRange: trailingFrame.blockRange ?? previousFrame.blockRange,
|
||
attachmentRanges: uniqueRanges(from: previousFrame.attachmentRanges + trailingFrame.attachmentRanges),
|
||
attachmentKinds: uniqueValues(from: previousFrame.attachmentKinds + trailingFrame.attachmentKinds),
|
||
blockKinds: uniqueValues(from: previousFrame.blockKinds + trailingFrame.blockKinds),
|
||
semanticHints: uniqueValues(from: previousFrame.semanticHints + trailingFrame.semanticHints),
|
||
attachmentPlacements: uniqueValues(from: previousFrame.attachmentPlacements + trailingFrame.attachmentPlacements),
|
||
trailingFragmentID: trailingFrame.trailingFragmentID ?? previousFrame.trailingFragmentID,
|
||
diagnostics: previousFrame.diagnostics
|
||
+ trailingFrame.diagnostics
|
||
+ ["normalized: merged short trailing page \(NSStringFromRange(trailingFrame.contentRange)) into previous page"]
|
||
)
|
||
}
|
||
|
||
/// 统计指定范围内可见字符数（排除空白和控制字符）
|
||
private func visibleCharacterCount(
|
||
in content: NSAttributedString,
|
||
range: NSRange
|
||
) -> Int {
|
||
guard range.length > 0 else { return 0 }
|
||
let string = content.attributedSubstring(from: range).string
|
||
let filteredScalars = string.unicodeScalars.filter { scalar in
|
||
!CharacterSet.whitespacesAndNewlines.contains(scalar)
|
||
&& !CharacterSet.controlCharacters.contains(scalar)
|
||
}
|
||
return filteredScalars.count
|
||
}
|
||
|
||
// MARK: - 集合工具方法
|
||
|
||
/// 数组去重（保持顺序）
|
||
private func uniqueValues<T: Equatable>(from values: [T]) -> [T] {
|
||
values.reduce(into: [T]()) { result, value in
|
||
if !result.contains(value) {
|
||
result.append(value)
|
||
}
|
||
}
|
||
}
|
||
|
||
/// NSRange 数组去重（保持顺序）
|
||
private func uniqueRanges(from ranges: [NSRange]) -> [NSRange] {
|
||
ranges.reduce(into: [NSRange]()) { result, value in
|
||
if !result.contains(value) {
|
||
result.append(value)
|
||
}
|
||
}
|
||
}
|
||
|
||
/// 统计指定范围内附件数量
|
||
private func attachmentCount(in content: NSAttributedString, range: NSRange) -> Int {
|
||
guard content.length > 0, range.length > 0 else { return 0 }
|
||
var count = 0
|
||
content.enumerateAttribute(.attachment, in: range) { value, _, _ in
|
||
if value != nil {
|
||
count += 1
|
||
}
|
||
}
|
||
return count
|
||
}
|
||
|
||
// MARK: - 缓存键生成
|
||
|
||
/// 生成缓存键：基于书籍 ID、字号、行距、页面尺寸等参数的 SHA256 哈希
|
||
private func makeCacheKey(
|
||
bookID: String,
|
||
pageSize: CGSize,
|
||
style: RDEPUBTextRenderStyle
|
||
) -> String? {
|
||
guard let cache else { return nil }
|
||
return cache.cacheKey(
|
||
bookID: bookID,
|
||
fontSize: style.font.pointSize,
|
||
lineHeightMultiple: style.lineSpacing,
|
||
contentInsets: .zero,
|
||
pageSize: pageSize,
|
||
layoutConfigSignature: layoutConfig.cacheSignature
|
||
)
|
||
}
|
||
}
|