948004eed1
源码注释： - 为 ~60 个 Swift 文件补充缺失的 doc comment（file header、类型、属性、方法） - 修正 4 处错误注释：翻页模式数量、搜索行为描述、手势识别器描述、悬空文档块 文档维护： - 删除重复文档：WXRead/读书EPUB阅读器实现架构.md（与微信读书版完全一致） - 合并重叠文档：阅读器规划.md → 阅读器功能开发计划.md（单一真值） - 修正过时内容：所有文档中"四种翻页模式"→"三种"，移除 horizontalCoverScroll - 更新架构图：补齐 EPUBUI/ReaderController、Paging/、Typesetter/ 等子目录 - 更新 index.md 索引：新增开发计划和架构对比文档引用
88 lines
3.0 KiB
Swift
88 lines
3.0 KiB
Swift
//
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// RDReaderSpreadResolver.swift
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// ReadViewSDK
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//
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// 文件职责：页面展开（spread）解析器，负责计算双页模式下的页面配对和翻页目标。
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//
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import Foundation
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/// 页面展开解析器
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/// 处理横屏双页模式下的页码配对逻辑，包括封面页独占、双页对齐、
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/// 以及相邻页面跳转等计算。
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struct RDReaderSpreadResolver {
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/// 判断指定页码是否为全屏独占页面（如封面页在双页模式下独占一屏）
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func isFullScreenPage(
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_ pageNum: Int,
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landscapeDualPageEnabled: Bool,
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isLandscape: Bool,
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coverPageIndex: Int?
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) -> Bool {
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guard landscapeDualPageEnabled, isLandscape, let coverIndex = coverPageIndex else { return false }
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return pageNum == coverIndex
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}
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/// 计算指定页码在双页模式下的左右页配对，返回 (左页, 右页?)。
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/// 封面页独占时单独处理，后续页面按两页一组配对。
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func dualPagePair(
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for pageNum: Int,
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totalPages: Int,
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coverPageIndex: Int?
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) -> (left: Int, right: Int?) {
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if let coverIndex = coverPageIndex {
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if pageNum == coverIndex {
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return (coverIndex, nil)
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}
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let adjustedIndex = pageNum - (coverIndex + 1)
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let pairStart = coverIndex + 1 + (adjustedIndex / 2) * 2
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let left = pairStart
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let right = pairStart + 1 < totalPages ? pairStart + 1 : nil
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return (left, right)
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}
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let left = (pageNum / 2) * 2
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let right = left + 1 < totalPages ? left + 1 : nil
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return (left, right)
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}
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/// 计算从指定页码出发的下一个（或上一个）双页展开的起始页码
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func adjacentDualPage(
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from pageNum: Int,
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totalPages: Int,
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coverPageIndex: Int?,
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forward: Bool
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) -> Int? {
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let pair = dualPagePair(for: pageNum, totalPages: totalPages, coverPageIndex: coverPageIndex)
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if forward {
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let nextStart = (pair.right ?? pair.left) + 1
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return nextStart < totalPages ? nextStart : nil
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}
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let prevEnd = pair.left - 1
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guard prevEnd >= 0 else { return nil }
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return dualPagePair(for: prevEnd, totalPages: totalPages, coverPageIndex: coverPageIndex).left
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}
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/// 计算下一页（或上一页）的页码，自动根据单页/双页模式选择合适的算法
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func nextPage(
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from currentPage: Int,
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totalPages: Int,
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pagesPerScreen: Int,
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coverPageIndex: Int?,
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forward: Bool
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) -> Int? {
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if pagesPerScreen > 1 {
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return adjacentDualPage(
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from: currentPage,
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totalPages: totalPages,
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coverPageIndex: coverPageIndex,
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forward: forward
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)
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}
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let target = currentPage + (forward ? 1 : -1)
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guard target >= 0, target < totalPages else { return nil }
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return target
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}
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}
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