fix epub reader playback and trial navigation

Sources/RDEpubReaderView/ReaderView/RDEpubReaderView.swift

@@ -50,6 +50,10 @@ enum RDEpubReaderTapDebug {
 
 public class RDEpubReaderView: UIView {
 
+    /// The readable-content gutter between two landscape pages. Each page
+    /// contributes half of this value from its inner content inset.
+    public static let landscapeDualPageGap: CGFloat = 10
+
     enum TapEvent {
 
         case none
@@ -93,6 +97,9 @@ public class RDEpubReaderView: UIView {
 
     public var currentPage: Int = -1 {
         didSet {
+            if currentPage != oldValue {
+                updatePageContentVisibility()
+            }
             if let delegate = delegate, currentPage != oldValue, delegate.responds(to: #selector(RDEpubReaderDelegate.pageNum(readerView:pageNum:))) {
                 delegate.pageNum(readerView: self, pageNum: currentPage)
             }
@@ -233,6 +240,13 @@ public class RDEpubReaderView: UIView {
         )
     }
 
+    /// Whether a page occupies the leading (left in LTR) side of a landscape
+    /// spread. Cover pages remain full-screen and are treated as leading.
+    public func isLeadingPage(_ pageNum: Int) -> Bool {
+        guard pagesPerScreen > 1, !isFullScreenPage(pageNum) else { return true }
+        return dualPagePair(for: pageNum).left == pageNum
+    }
+
     private func dualPagePair(for pageNum: Int) -> (left: Int, right: Int?) {
         let totalPages = numberOfPages()
         return spreadResolver.dualPagePair(
@@ -380,6 +394,13 @@ public class RDEpubReaderView: UIView {
         layout.isLandscapeDualPage = landscapeDualPageEnabled && isNowLandscape
         layout.coverPageIndex = coverPageIndex
 
+        // Cached page views are configured with orientation-dependent content
+        // insets and Web render requests. Reusing a portrait-preloaded page in
+        // the rebuilt landscape page controller leaves the portrait safe-area
+        // inset on all four edges (and keeps fixed-layout Web content under the
+        // landscape sensor area). Drop them before requesting the new spread.
+        invalidatePageCaches()
+
         switch currentDisplayType {
         case .pageCurl:
 
@@ -503,11 +524,14 @@ public class RDEpubReaderView: UIView {
     }
 
     func pageViewForDisplay(pageNum: Int) -> UIView {
-        preloadController.pageViewForDisplay(
+        let pageView = preloadController.pageViewForDisplay(
             pageNum: pageNum,
             environment: preloadEnvironment,
-            contentViewProvider: pageContentViewForPreload(pageNum:reusableView:)
+            contentViewProvider: pageContentViewForDisplay(pageNum:reusableView:)
         )
+        (pageView as? RDEpubReaderPageVisibilityHandling)?
+            .readerPageVisibilityDidChange(isVisible: isReaderPageVisible(pageNum))
+        return pageView
     }
 
     func primePageCache(around pageNum: Int, preferredForward: Bool? = nil) {
@@ -521,7 +545,50 @@ public class RDEpubReaderView: UIView {
     }
 
     private func pageContentViewForPreload(pageNum: Int, reusableView: UIView?) -> UIView? {
-        contentViewForPage(pageNum, reusableView: reusableView)
+        let allowsPreloading = resolvedPageProvider?
+            .readerView?(self, shouldPreloadPageAt: pageNum) ?? true
+        guard allowsPreloading else { return nil }
+        return contentViewForPage(pageNum, reusableView: reusableView)
+    }
+
+    private func pageContentViewForDisplay(pageNum: Int, reusableView: UIView?) -> UIView? {
+        return contentViewForPage(pageNum, reusableView: reusableView)
+    }
+
+    func isReaderPageVisible(_ pageNum: Int) -> Bool {
+        guard currentPage >= 0 else { return pageNum == 0 }
+        if landscapeDualPageEnabled && isLandscape {
+            let pair = dualPagePair(for: currentPage)
+            return pageNum == pair.left || pageNum == pair.right
+        }
+        return pageNum == currentPage
+    }
+
+    private func updatePageContentVisibility() {
+        var visiblePageNumbers = Set<Int>()
+        if currentPage >= 0 {
+            visiblePageNumbers.insert(currentPage)
+            if landscapeDualPageEnabled && isLandscape,
+               let rightPage = dualPagePair(for: currentPage).right {
+                visiblePageNumbers.insert(rightPage)
+            }
+        }
+
+        preloadController.updatePageVisibility(visiblePageNumbers: visiblePageNumbers)
+
+        for viewController in pageViewController.viewControllers ?? [] {
+            guard let pageController = viewController as? RDEpubReaderPageChildViewController,
+                  let contentView = pageController.contentView else { continue }
+            (contentView as? RDEpubReaderPageVisibilityHandling)?
+                .readerPageVisibilityDidChange(isVisible: visiblePageNumbers.contains(pageController.pageNum))
+        }
+
+        for indexPath in collectionView.indexPathsForVisibleItems {
+            guard let cell = collectionView.cellForItem(at: indexPath) as? RDEpubReaderContentCell,
+                  let contentView = cell.containerView else { continue }
+            (contentView as? RDEpubReaderPageVisibilityHandling)?
+                .readerPageVisibilityDidChange(isVisible: visiblePageNumbers.contains(indexPath.item))
+        }
     }
 
     public override func didMoveToSuperview() {