feat: silent pre-indexing with configurable status bar indicator

Port PR #979's silent pre-indexing and add an Indexing Display setting
(Popup / Status Bar Text / Status Bar Icon) so users can choose how
indexing feedback is shown.

Silent pre-indexing runs on text-only penultimate pages when a status
bar option is selected, with a standard requestUpdate to clear the
indicator. Image pages skip silent indexing to avoid e-ink grayscale
pipeline conflicts; the normal popup handles those transitions. Direct
chapter jumps always show the original small popup regardless of setting.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/I18n/I18nKeys.h

@@ -390,6 +390,10 @@ enum class StrId : uint16_t {
   STR_TZ_HAWAII,
   STR_TZ_CUSTOM,
   STR_SET_UTC_OFFSET,
+  STR_INDEXING_DISPLAY,
+  STR_INDEXING_POPUP,
+  STR_INDEXING_STATUS_TEXT,
+  STR_INDEXING_STATUS_ICON,
   // Sentinel - must be last
   _COUNT
 };

lib/I18n/translations/czech.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Zobrazení indexování"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Text stavového řádku"
+STR_INDEXING_STATUS_ICON: "Ikona stavového řádku"

lib/I18n/translations/english.yaml

@@ -356,3 +356,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Indexing Display"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Status Bar Text"
+STR_INDEXING_STATUS_ICON: "Status Bar Icon"

lib/I18n/translations/french.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Affichage indexation"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Texte barre d'état"
+STR_INDEXING_STATUS_ICON: "Icône barre d'état"

lib/I18n/translations/german.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Indexierungsanzeige"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Statusleistentext"
+STR_INDEXING_STATUS_ICON: "Statusleistensymbol"

lib/I18n/translations/portuguese.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Exibição de indexação"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Texto da barra"
+STR_INDEXING_STATUS_ICON: "Ícone da barra"

lib/I18n/translations/russian.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Отображение индексации"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Текст в строке"
+STR_INDEXING_STATUS_ICON: "Иконка в строке"

lib/I18n/translations/spanish.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Mostrar indexación"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Texto barra estado"
+STR_INDEXING_STATUS_ICON: "Icono barra estado"

lib/I18n/translations/swedish.yaml

@@ -335,3 +335,7 @@ STR_TZ_ALASKA: "Alaska"
 STR_TZ_HAWAII: "Hawaii"
 STR_TZ_CUSTOM: "Custom"
 STR_SET_UTC_OFFSET: "Set UTC Offset"
+STR_INDEXING_DISPLAY: "Indexeringsvisning"
+STR_INDEXING_POPUP: "Popup"
+STR_INDEXING_STATUS_TEXT: "Statusfältstext"
+STR_INDEXING_STATUS_ICON: "Statusfältsikon"

src/CrossPointSettings.cpp

@@ -143,6 +143,7 @@ uint8_t CrossPointSettings::writeSettings(FsFile& file, bool count_only) const {
   writer.writeItem(file, clockSize);
   writer.writeItem(file, timezone);
   writer.writeItem(file, timezoneOffsetHours);
+  writer.writeItem(file, indexingDisplay);
 
   return writer.item_count;
 }
@@ -285,6 +286,8 @@ bool CrossPointSettings::loadFromFile() {
     serialization::readPod(inputFile, timezoneOffsetHours);
     if (timezoneOffsetHours < -12 || timezoneOffsetHours > 14) timezoneOffsetHours = 0;
     if (++settingsRead >= fileSettingsCount) break;
+    readAndValidate(inputFile, indexingDisplay, INDEXING_DISPLAY_COUNT);
+    if (++settingsRead >= fileSettingsCount) break;
   } while (false);
 
   if (frontButtonMappingRead) {

src/CrossPointSettings.h

@@ -52,6 +52,13 @@ class CrossPointSettings {
     STATUS_BAR_MODE_COUNT
   };
 
+  enum INDEXING_DISPLAY {
+    INDEXING_POPUP = 0,
+    INDEXING_STATUS_TEXT = 1,
+    INDEXING_STATUS_ICON = 2,
+    INDEXING_DISPLAY_COUNT
+  };
+
   enum ORIENTATION {
     PORTRAIT = 0,       // 480x800 logical coordinates (current default)
     LANDSCAPE_CW = 1,   // 800x480 logical coordinates, rotated 180° (swap top/bottom)
@@ -157,6 +164,8 @@ class CrossPointSettings {
   uint8_t sleepScreenLetterboxFill = LETTERBOX_DITHERED;
   // Status bar settings
   uint8_t statusBar = FULL;
+  // Indexing feedback display mode (popup, status bar text, status bar icon)
+  uint8_t indexingDisplay = INDEXING_POPUP;
   // Text rendering settings
   uint8_t extraParagraphSpacing = 1;
   uint8_t textAntiAliasing = 1;

src/SettingsList.h

@@ -65,6 +65,10 @@ inline std::vector<SettingInfo> getSettingsList() {
           {StrId::STR_NONE_OPT, StrId::STR_NO_PROGRESS, StrId::STR_STATUS_BAR_FULL_PERCENT,
            StrId::STR_STATUS_BAR_FULL_BOOK, StrId::STR_STATUS_BAR_BOOK_ONLY, StrId::STR_STATUS_BAR_FULL_CHAPTER},
           "statusBar", StrId::STR_CAT_DISPLAY),
+      SettingInfo::Enum(
+          StrId::STR_INDEXING_DISPLAY, &CrossPointSettings::indexingDisplay,
+          {StrId::STR_INDEXING_POPUP, StrId::STR_INDEXING_STATUS_TEXT, StrId::STR_INDEXING_STATUS_ICON},
+          "indexingDisplay", StrId::STR_CAT_DISPLAY),
       SettingInfo::Enum(StrId::STR_HIDE_BATTERY, &CrossPointSettings::hideBatteryPercentage,
                         {StrId::STR_NEVER, StrId::STR_IN_READER, StrId::STR_ALWAYS}, "hideBatteryPercentage",
                         StrId::STR_CAT_DISPLAY),

src/activities/reader/EpubReaderActivity.cpp

@@ -36,6 +36,11 @@ constexpr unsigned long longPressConfirmMs = 700;
 constexpr int statusBarMargin = 19;
 constexpr int progressBarMarginTop = 1;
 
+// 8x8 1-bit hourglass icon for the indexing status bar indicator.
+// Format: MSB-first, 0 = black pixel, 1 = white pixel (e-ink convention).
+constexpr uint8_t kIndexingIcon[] = {0x00, 0x81, 0xC3, 0xE7, 0xE7, 0xC3, 0x81, 0x00};
+constexpr int kIndexingIconSize = 8;
+
 int clampPercent(int percent) {
   if (percent < 0) {
     return 0;
@@ -838,16 +843,17 @@ void EpubReaderActivity::render(Activity::RenderLock&& lock) {
                             (showProgressBar ? (metrics.bookProgressBarHeight + progressBarMarginTop) : 0);
   }
 
+  const uint16_t viewportWidth = renderer.getScreenWidth() - orientedMarginLeft - orientedMarginRight;
+  const uint16_t viewportHeight = renderer.getScreenHeight() - orientedMarginTop - orientedMarginBottom;
+
   if (!section) {
     loadingSection = true;
+    preIndexedNextSpine = -1;
 
     const auto filepath = epub->getSpineItem(currentSpineIndex).href;
     LOG_DBG("ERS", "Loading file: %s, index: %d", filepath.c_str(), currentSpineIndex);
     section = std::unique_ptr<Section>(new Section(epub, currentSpineIndex, renderer));
 
-    const uint16_t viewportWidth = renderer.getScreenWidth() - orientedMarginLeft - orientedMarginRight;
-    const uint16_t viewportHeight = renderer.getScreenHeight() - orientedMarginTop - orientedMarginBottom;
-
     if (!section->loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
                                   SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
                                   viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle)) {
@@ -921,17 +927,85 @@ void EpubReaderActivity::render(Activity::RenderLock&& lock) {
       LOG_ERR("ERS", "Failed to load page from SD - clearing section cache");
       section->clearCache();
       section.reset();
+      silentIndexingActive = false;
       requestUpdate();  // Try again after clearing cache
       // TODO: prevent infinite loop if the page keeps failing to load for some reason
       return;
     }
+
+    silentIndexingActive = false;
+    const bool textOnlyPage = !p->hasImages();
+    if (textOnlyPage &&
+        SETTINGS.indexingDisplay != CrossPointSettings::INDEXING_DISPLAY::INDEXING_POPUP &&
+        section->pageCount >= 1 &&
+        ((section->pageCount == 1 && section->currentPage == 0) ||
+         (section->pageCount >= 2 && section->currentPage == section->pageCount - 2)) &&
+        currentSpineIndex + 1 < epub->getSpineItemsCount() &&
+        preIndexedNextSpine != currentSpineIndex + 1) {
+      Section probe(epub, currentSpineIndex + 1, renderer);
+      if (probe.loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
+                                SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
+                                viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle)) {
+        preIndexedNextSpine = currentSpineIndex + 1;
+      } else {
+        silentIndexingActive = true;
+      }
+    }
+
     const auto start = millis();
     renderContents(std::move(p), orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
     LOG_DBG("ERS", "Rendered page in %dms", millis() - start);
+
+    if (silentIndexingActive) {
+      silentIndexNextChapterIfNeeded(viewportWidth, viewportHeight);
+      requestUpdate();
+    }
   }
   saveProgress(currentSpineIndex, section->currentPage, section->pageCount);
 }
 
+bool EpubReaderActivity::silentIndexNextChapterIfNeeded(const uint16_t viewportWidth, const uint16_t viewportHeight) {
+  if (preIndexedNextSpine == currentSpineIndex + 1) {
+    silentIndexingActive = false;
+    return false;
+  }
+
+  const bool shouldPreIndex =
+      (section->pageCount == 1 && section->currentPage == 0) ||
+      (section->pageCount >= 2 && section->currentPage == section->pageCount - 2);
+  if (!epub || !section || !shouldPreIndex) {
+    silentIndexingActive = false;
+    return false;
+  }
+
+  const int nextSpineIndex = currentSpineIndex + 1;
+  if (nextSpineIndex < 0 || nextSpineIndex >= epub->getSpineItemsCount()) {
+    silentIndexingActive = false;
+    return false;
+  }
+
+  Section nextSection(epub, nextSpineIndex, renderer);
+  if (nextSection.loadSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
+                                  SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
+                                  viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle)) {
+    preIndexedNextSpine = nextSpineIndex;
+    silentIndexingActive = false;
+    return false;
+  }
+
+  LOG_DBG("ERS", "Silently indexing next chapter: %d", nextSpineIndex);
+  if (!nextSection.createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
+                                     SETTINGS.extraParagraphSpacing, SETTINGS.paragraphAlignment, viewportWidth,
+                                     viewportHeight, SETTINGS.hyphenationEnabled, SETTINGS.embeddedStyle)) {
+    LOG_ERR("ERS", "Failed silent indexing for chapter: %d", nextSpineIndex);
+    silentIndexingActive = false;
+    return false;
+  }
+  preIndexedNextSpine = nextSpineIndex;
+  silentIndexingActive = false;
+  return true;
+}
+
 void EpubReaderActivity::saveProgress(int spineIndex, int currentPage, int pageCount) {
   FsFile f;
   if (Storage.openFileForWrite("ERS", epub->getCachePath() + "/progress.bin", f)) {
@@ -1151,4 +1225,15 @@ void EpubReaderActivity::renderStatusBar(const int orientedMarginRight, const in
                       titleMarginLeftAdjusted + orientedMarginLeft + (availableTitleSpace - titleWidth) / 2, textY,
                       title.c_str());
   }
+
+  if (silentIndexingActive && SETTINGS.statusBar != CrossPointSettings::STATUS_BAR_MODE::NONE) {
+    const int batteryWidth = showBattery ? (showBatteryPercentage ? 50 : 20) : 0;
+    const int indicatorX = orientedMarginLeft + batteryWidth + 8;
+    if (SETTINGS.indexingDisplay == CrossPointSettings::INDEXING_DISPLAY::INDEXING_STATUS_TEXT) {
+      renderer.drawText(SMALL_FONT_ID, indicatorX, textY, tr(STR_INDEXING));
+    } else if (SETTINGS.indexingDisplay == CrossPointSettings::INDEXING_DISPLAY::INDEXING_STATUS_ICON) {
+      renderer.drawIcon(kIndexingIcon, indicatorX, textY - kIndexingIconSize + 2, kIndexingIconSize,
+                        kIndexingIconSize);
+    }
+  }
 }

src/activities/reader/EpubReaderActivity.h

@@ -25,12 +25,15 @@ class EpubReaderActivity final : public ActivityWithSubactivity {
   bool skipNextButtonCheck = false;        // Skip button processing for one frame after subactivity exit
   bool ignoreNextConfirmRelease = false;   // Suppress short-press after long-press Confirm
   volatile bool loadingSection = false;    // True during the entire !section block (read from main loop)
+  bool silentIndexingActive = false;       // True while silently pre-indexing the next chapter
+  int preIndexedNextSpine = -1;            // Spine index already pre-indexed (prevents re-render loop)
   const std::function<void()> onGoBack;
   const std::function<void()> onGoHome;
 
   void renderContents(std::unique_ptr<Page> page, int orientedMarginTop, int orientedMarginRight,
                       int orientedMarginBottom, int orientedMarginLeft);
   void renderStatusBar(int orientedMarginRight, int orientedMarginBottom, int orientedMarginLeft) const;
+  bool silentIndexNextChapterIfNeeded(uint16_t viewportWidth, uint16_t viewportHeight);
   void saveProgress(int spineIndex, int currentPage, int pageCount);
   // Jump to a percentage of the book (0-100), mapping it to spine and page.
   void jumpToPercent(int percent);