长章节内存优化 P1：章节级共享显示内容与 layouter，高亮转 overlay

- 新增 RDEPUBChapterDisplayContentCache（LRU 2，主线程限定，控制器持有）：整章显示串构建时一次性注入全章主题色与暗黑图替换，配套共享 DTCoreTextLayouter；签名 = 章节内容对象标识 + 主题双色 + 暗黑图配置，设置/主题变化自动失效重建 - RDEPUBTextContentView.configure 改为引用共享 entry，删除每次翻页的整章可变拷贝与按页属性写入 - 高亮/下划线改走 overlay decoration（高亮背景层、下划线前景层），移除 applyHighlightsToContent 与 render view 的属性绘制路径，高亮增删不再触发整章重建 - 内存警告时清空 display cache；shouldAvoidReaderPageCaching 保持保守（P1-4 待真机数据）验证：编译通过；高亮/批注/选区/翻页/设置 13 项 UI 回归全过。 SearchTests 10 项失败经二分确认为先存回归（5a41066 与 e4e629a 均复现，最后已知通过为 2026-06-08），与本次改动无关，待单独排查。 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-08 16:09:40 +09:00
parent e4e629a06c
commit c4be426299
7 changed files with 1369 additions and 1343 deletions
@@ -0,0 +1,114 @@
+import UIKit
+
+#if canImport(DTCoreText)
+import DTCoreText
+#endif
+
+/// Chapter-level shared display content and layouter
+/// (LONG_CHAPTER_MEMORY_OPTIMIZATION_PLAN.md P1-1 / P1-3).
+///
+/// One entry holds the chapter-length display string (theme text color and
+/// dark-image adjustment injected once over the full chapter at build time)
+/// plus the DTCoreTextLayouter wrapping its framesetter. Page views reference
+/// the shared string and request per-page layout frames; they must never
+/// mutate the shared string — the framesetter and any live layout frame hold
+/// it. Page-level decoration (highlights, search, selection) is drawn by the
+/// overlay views instead.
+///
+/// Main-thread only.
+final class RDEPUBChapterDisplayContentCache {
+
+#if canImport(DTCoreText)
+
+    struct Entry {
+        let content: NSAttributedString
+        let layouter: DTCoreTextLayouter?
+        fileprivate let signature: Signature
+    }
+
+    fileprivate struct Signature: Equatable {
+        let chapterContentID: ObjectIdentifier
+        let contentLength: Int
+        let textColor: UIColor
+        let backgroundColor: UIColor
+        let darkImageAdjustmentEnabled: Bool
+        let darkImageBlendRatio: CGFloat
+
+        init(page: RDEPUBTextPage, configuration: RDEPUBReaderConfiguration) {
+            chapterContentID = ObjectIdentifier(page.chapterContent)
+            contentLength = page.chapterContent.length
+            textColor = configuration.theme.contentTextColor
+            backgroundColor = configuration.theme.contentBackgroundColor
+            darkImageAdjustmentEnabled = configuration.darkImageAdjustmentEnabled
+            darkImageBlendRatio = configuration.darkImageBlendRatio
+        }
+    }
+
+    /// Current chapter plus one adjacent chapter during page-curl/scroll
+    /// transitions across a chapter boundary.
+    private static let capacity = 2
+
+    private var entries: [String: Entry] = [:]
+
+    private var accessOrder: [String] = []
+
+    func entry(for page: RDEPUBTextPage, configuration: RDEPUBReaderConfiguration) -> Entry {
+        dispatchPrecondition(condition: .onQueue(.main))
+        let signature = Signature(page: page, configuration: configuration)
+        if let cached = entries[page.href], cached.signature == signature {
+            touch(page.href)
+            return cached
+        }
+        let entry = Self.buildEntry(page: page, configuration: configuration, signature: signature)
+        entries[page.href] = entry
+        touch(page.href)
+        evictIfNeeded()
+        RDEPUBMemoryProbe.log("displayContentBuilt href=\(page.href) length=\(entry.content.length)")
+        return entry
+    }
+
+    func removeAll() {
+        entries.removeAll()
+        accessOrder.removeAll()
+    }
+
+    private func touch(_ href: String) {
+        accessOrder.removeAll { $0 == href }
+        accessOrder.append(href)
+    }
+
+    private func evictIfNeeded() {
+        while accessOrder.count > Self.capacity {
+            let evicted = accessOrder.removeFirst()
+            entries.removeValue(forKey: evicted)
+        }
+    }
+
+    private static func buildEntry(
+        page: RDEPUBTextPage,
+        configuration: RDEPUBReaderConfiguration,
+        signature: Signature
+    ) -> Entry {
+        let content = NSMutableAttributedString(attributedString: page.chapterContent)
+        let fullRange = NSRange(location: 0, length: content.length)
+        _ = RDEPUBDarkImageAdjuster.adjustIfNeeded(
+            content,
+            in: fullRange,
+            configuration: configuration
+        )
+        content.addAttribute(
+            .foregroundColor,
+            value: configuration.theme.contentTextColor,
+            range: fullRange
+        )
+        let layouter = DTCoreTextLayouter(attributedString: content)
+        layouter?.shouldCacheLayoutFrames = false
+        return Entry(content: content, layouter: layouter, signature: signature)
+    }
+
+#else
+
+    func removeAll() {}
+
+#endif
+}
@@ -87,12 +87,16 @@ final class RDEPUBTextContentView: UIView, UIGestureRecognizerDelegate, RDReader
        return view
    }()

+    /// Chapter-level shared display string owned by the display cache.
+    /// Read-only from the page's perspective: theme color and dark-image
+    /// adjustment are baked in at build time; page decoration goes through
+    /// the overlay views.
    private var coreTextDisplayContent: NSAttributedString?

    private var coreTextDisplayRange: NSRange?

-    /// Framesetter over the full chapter copy, rebuilt when the display
-    /// content changes; layout frames are recomputed per bounds change.
+    /// Shared chapter-level layouter (owned by the display cache); layout
+    /// frames are recomputed per page range and bounds change.
    private var coreTextLayouter: DTCoreTextLayouter?
 #endif

@@ -397,7 +401,8 @@ final class RDEPUBTextContentView: UIView, UIGestureRecognizerDelegate, RDReader
        chapterCFIMap: RDEPUBCFIMap? = nil,
        chapterFragmentOffsets: [String: Int] = [:],
        highlights: [RDEPUBHighlight] = [],
-        searchState: RDEPUBSearchState? = nil
+        searchState: RDEPUBSearchState? = nil,
+        displayCache: RDEPUBChapterDisplayContentCache? = nil
    ) {
        loadingSpinner.stopAnimating()
        currentPage = page
@@ -437,37 +442,26 @@ final class RDEPUBTextContentView: UIView, UIGestureRecognizerDelegate, RDReader
        coverImageView.image = nil

 #if canImport(DTCoreText)
-        // In-context display: keep the full chapter string and lay out only the
-        // page's range. CTTypesetter line breaks are context-sensitive, so
+        // In-context display: lay out the full chapter string and render only
+        // the page's range. CTTypesetter line breaks are context-sensitive, so
        // re-wrapping a page substring can break ±1 character away from the
        // paginator's line ends (lone characters spilling onto the last line);
        // laying out the same chapter string the paginator used cannot.
        // String indices in the layout frame are therefore chapter-absolute.
-        let displayContent = NSMutableAttributedString(attributedString: page.chapterContent)
+        // The chapter string and layouter are shared per chapter via the
+        // display cache; this view must not mutate the shared string.
+        let display = (displayCache ?? RDEPUBChapterDisplayContentCache())
+            .entry(for: page, configuration: configuration)
        let pageRange = NSIntersectionRange(
            page.contentRange,
-            NSRange(location: 0, length: displayContent.length)
+            NSRange(location: 0, length: display.content.length)
        )
-        _ = RDEPUBDarkImageAdjuster.adjustIfNeeded(
-            displayContent,
-            in: pageRange,
-            configuration: configuration
-        )
-        displayContent.addAttribute(
-            .foregroundColor,
-            value: configuration.theme.contentTextColor,
-            range: pageRange
-        )
-
-        applyHighlightsToContent(displayContent, highlights: highlights, page: page)
        coreTextContentView.isHidden = false
        coreTextContentView.backgroundColor = .clear
        coreTextContentView.accessibilityIdentifier = "epub.reader.selection.text"
-        coreTextDisplayContent = displayContent
+        coreTextDisplayContent = display.content
        coreTextDisplayRange = pageRange
-        coreTextLayouter = DTCoreTextLayouter(attributedString: displayContent)
-        coreTextLayouter?.shouldCacheLayoutFrames = false
-        coreTextContentView.attributedDisplayContent = displayContent
+        coreTextLayouter = display.layouter
        updateCoreTextLayoutFrameIfNeeded()
 #else
        let selectionContent = normalizedPageContent(from: page)
@@ -521,7 +515,6 @@ final class RDEPUBTextContentView: UIView, UIGestureRecognizerDelegate, RDReader
 #if canImport(DTCoreText)
        coreTextContentView.isHidden = false
        coreTextContentView.backgroundColor = .clear
-        coreTextContentView.attributedDisplayContent = nil
        coreTextContentView.layoutFrame = nil
        coreTextDisplayContent = nil
        coreTextDisplayRange = nil
@@ -615,31 +608,6 @@ final class RDEPUBTextContentView: UIView, UIGestureRecognizerDelegate, RDReader
        return image(from: attachmentValue)
    }

-    /// Marks highlight ranges on the chapter-length display copy. Ranges stay
-    /// chapter-absolute — the in-context layout frame uses the same indices.
-    private func applyHighlightsToContent(
-        _ content: NSMutableAttributedString,
-        highlights: [RDEPUBHighlight],
-        page: RDEPUBTextPage
-    ) {
-        for highlight in highlights {
-            guard highlight.location.href == page.href else { continue }
-            guard let rangeInfo = highlight.rangeInfo,
-                  let info = RDEPUBTextOffsetRangeInfo.decode(from: rangeInfo),
-                  let absoluteRange = info.nsRange else { continue }
-            let overlap = NSIntersectionRange(absoluteRange, page.contentRange)
-            guard overlap.length > 0,
-                  overlap.location + overlap.length <= content.length else { continue }
-
-            switch highlight.style {
-            case .highlight:
-                content.addAttribute(kRDEPUBHighlightAttributeName, value: highlight.uiColor, range: overlap)
-            case .underline:
-                content.addAttribute(kRDEPUBUnderlineAttributeName, value: highlight.uiColor, range: overlap)
-            }
-        }
-    }
-
    private func normalizedPageContent(from page: RDEPUBTextPage) -> NSMutableAttributedString {
        let content = NSMutableAttributedString(attributedString: page.content)
        guard content.length > 0 else { return content }
@@ -759,12 +727,12 @@ final class RDEPUBTextContentView: UIView, UIGestureRecognizerDelegate, RDReader
        backgroundOverlayView.updateSnapshot(interactionController.snapshot)

        if let page = currentPage {
+            // Highlights/underlines and search are all drawn as overlay
+            // decorations; the shared chapter display string carries no
+            // page-level annotation attributes.
            let (bgDecorations, fgDecorations) = overlayView.buildDecorations(
                page: page,
-                // Text-page highlights/underlines are already painted by the
-                // CoreText render view via display-content attributes. Keep
-                // overlay decorations for search only to avoid double drawing.
-                highlights: [],
+                highlights: currentHighlights,
                searchState: currentSearchState,
                interactionController: interactionController
            )
@@ -22,12 +22,6 @@ final class RDEPUBTextPageRenderView: UIView {
        }
    }

-    var attributedDisplayContent: NSAttributedString? {
-        didSet {
-            invalidateStaticContent()
-        }
-    }
-
    var selectionRects: [CGRect] = [] {
        didSet {
            setNeedsDisplay()
@@ -78,9 +72,6 @@ final class RDEPUBTextPageRenderView: UIView {
        if let cachedStaticImage {
            cachedStaticImage.draw(in: bounds)
        } else {
-            if let attributedDisplayContent {
-                drawHighlights(in: context, attributedString: attributedDisplayContent, layoutFrame: layoutFrame)
-            }
            layoutFrame.draw(in: context, options: drawOptions)
        }

@@ -96,59 +87,6 @@ final class RDEPUBTextPageRenderView: UIView {
        }
    }

-    private func drawHighlights(
-        in context: CGContext,
-        attributedString: NSAttributedString,
-        layoutFrame: DTCoreTextLayoutFrame
-    ) {
-        let fullRange = NSRange(location: 0, length: attributedString.length)
-
-        attributedString.enumerateAttribute(kRDEPUBHighlightAttributeName, in: fullRange) { value, range, _ in
-            guard let color = value as? UIColor else { return }
-            let rects = computeHighlightRects(for: range, layoutFrame: layoutFrame)
-            color.setFill()
-            for rect in rects {
-                context.fill(rect)
-            }
-        }
-
-        attributedString.enumerateAttribute(kRDEPUBUnderlineAttributeName, in: fullRange) { value, range, _ in
-            guard let color = value as? UIColor else { return }
-            let rects = computeHighlightRects(for: range, layoutFrame: layoutFrame)
-            color.setStroke()
-            context.setLineWidth(2)
-            for rect in rects {
-                let y = rect.maxY - 1
-                context.move(to: CGPoint(x: rect.minX, y: y))
-                context.addLine(to: CGPoint(x: rect.maxX, y: y))
-                context.strokePath()
-            }
-        }
-    }
-
-    private func computeHighlightRects(for range: NSRange, layoutFrame: DTCoreTextLayoutFrame) -> [CGRect] {
-        var rects: [CGRect] = []
-        guard let lines = layoutFrame.lines as? [DTCoreTextLayoutLine] else { return rects }
-
-        for line in lines {
-            let lineRange = line.stringRange()
-            let overlap = NSIntersectionRange(range, lineRange)
-            guard overlap.length > 0 else { continue }
-
-            let startX = line.offset(forStringIndex: overlap.location)
-            let endX = line.offset(forStringIndex: overlap.location + overlap.length)
-            let rect = CGRect(
-                x: line.baselineOrigin.x + startX,
-                y: line.baselineOrigin.y - line.ascent,
-                width: endX - startX,
-                height: line.ascent + line.descent
-            )
-            rects.append(rect)
-        }
-
-        return rects
-    }
-
    private func drawSelection(in context: CGContext) {
        guard !selectionRects.isEmpty else { return }
        selectionColor.setFill()
@@ -261,9 +199,6 @@ final class RDEPUBTextPageRenderView: UIView {
        let renderer = UIGraphicsImageRenderer(size: bounds.size, format: format)
        return renderer.image { _ in
            guard let staticContext = UIGraphicsGetCurrentContext() else { return }
-            if let attributedDisplayContent {
-                drawHighlights(in: staticContext, attributedString: attributedDisplayContent, layoutFrame: layoutFrame)
-            }
            layoutFrame.draw(in: staticContext, options: drawOptions)
        }
    }