Fix issue #249

src/activities/reader/EpubReaderActivity.cpp

@@ -334,6 +334,11 @@ void EpubReaderActivity::onExit() {
   Activity::onExit();
   logReaderMemSnapshot("onExit_before_release");
 
+  // If a pre-render left the next page in the frame buffer, redraw the current page so the
+  // next activity (notably SleepActivity's OVERLAY mode) sees what the user was looking at.
+  // Must run before section.reset() and the orientation reset below.
+  restoreCurrentPageToBufferIfPreRendered();
+
   // Save bookmarks before exit
   bookmarkStore.save();
   if (epub) {
@@ -2231,6 +2236,31 @@ void EpubReaderActivity::displayPreRenderedPage(const Page& page, const int orie
   }
 }
 
+void EpubReaderActivity::restoreCurrentPageToBufferIfPreRendered() {
+  if (!preRenderedPage.ready || !section || !epub) {
+    return;
+  }
+
+  int orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft;
+  renderer.getOrientedViewableTRBL(&orientedMarginTop, &orientedMarginRight, &orientedMarginBottom,
+                                   &orientedMarginLeft);
+  const int statusBarTopHeight = UITheme::getStatusBarTopHeight(automaticPageTurnActive);
+  const int statusBarBottomHeight = UITheme::getStatusBarBottomHeight(automaticPageTurnActive);
+  orientedMarginTop += std::max(static_cast<int>(SETTINGS.screenMargin), statusBarTopHeight);
+  orientedMarginLeft += SETTINGS.screenMargin;
+  orientedMarginRight += SETTINGS.screenMargin;
+  orientedMarginBottom += std::max(static_cast<int>(SETTINGS.screenMargin), statusBarBottomHeight);
+
+  auto p = section->loadPageFromSectionFile();
+  if (!p) {
+    return;
+  }
+  renderPageContentOnly(*p, orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
+  preRenderedPage.ready = false;
+  pendingPreRender = false;
+  usePreRenderedBuffer = false;
+}
+
 void EpubReaderActivity::renderStatusBar() const {
   // Calculate progress in book
   const int currentPage = section->currentPage + 1;

src/activities/reader/EpubReaderActivity.h

@@ -261,6 +261,10 @@ class EpubReaderActivity final : public Activity {
   // that was last rendered into the buffer (needed for image AA re-render).
   void displayPreRenderedPage(const Page& page, int orientedMarginTop, int orientedMarginRight,
                               int orientedMarginBottom, int orientedMarginLeft);
+  // If the frame buffer currently holds a pre-rendered next page, redraw the current page
+  // into it (no status bar, no flush). Restores the invariant other activities — notably
+  // SleepActivity's OVERLAY mode — rely on when transitioning out of the reader.
+  void restoreCurrentPageToBufferIfPreRendered();
   void renderStatusBar() const;
   // Snapshot of the three status-bar signals that can change while a page is otherwise idle.
   // Compared in shouldSkipPeriodicUpdate() to suppress no-op minute-tick re-renders that on