home screen performance fix

src/activities/home/HomeActivity.cpp

@@ -18,6 +18,12 @@
 #include "fontIds.h"
 #include "util/StringUtils.h"
 
+// Static member definitions for persistent cover buffer
+bool HomeActivity::coverRendered = false;
+bool HomeActivity::coverBufferStored = false;
+uint8_t* HomeActivity::coverBuffer = nullptr;
+std::string HomeActivity::cachedCoverPath;
+
 void HomeActivity::taskTrampoline(void* param) {
   auto* self = static_cast<HomeActivity*>(param);
   self->displayTaskLoop();
@@ -41,50 +47,94 @@ void HomeActivity::onEnter() {
   // Check if OPDS browser URL is configured
   hasOpdsUrl = strlen(SETTINGS.opdsServerUrl) > 0;
 
-  if (hasContinueReading) {
-    // Extract filename from path for display
-    lastBookTitle = APP_STATE.openEpubPath;
-    const size_t lastSlash = lastBookTitle.find_last_of('/');
+  if (!hasContinueReading) {
+    // No book to continue reading - clear any stale cover cache
+    if (coverBufferStored) {
+      freeCoverBuffer();
+      coverRendered = false;
+      cachedCoverPath.clear();
+    }
+  } else {
+    // Extract filename from path for display (fallback if no cached title)
+    std::string filenameFromPath = APP_STATE.openEpubPath;
+    const size_t lastSlash = filenameFromPath.find_last_of('/');
     if (lastSlash != std::string::npos) {
-      lastBookTitle = lastBookTitle.substr(lastSlash + 1);
+      filenameFromPath = filenameFromPath.substr(lastSlash + 1);
     }
 
-    // If epub, try to load the metadata for title/author and cover
-    if (StringUtils::checkFileExtension(lastBookTitle, ".epub")) {
+    // Check if we have cached title/author from CrossPointState
+    const bool hasCachedMetadata = !APP_STATE.openBookTitle.empty();
+
+    if (hasCachedMetadata) {
+      // Use cached title and author - no need to load the book file
+      lastBookTitle = APP_STATE.openBookTitle;
+      lastBookAuthor = APP_STATE.openBookAuthor;
+    } else {
+      // No cached metadata - use filename as fallback
+      lastBookTitle = filenameFromPath;
+    }
+
+    // If epub, try to get cover image (and populate cache if needed)
+    if (StringUtils::checkFileExtension(filenameFromPath, ".epub")) {
       Epub epub(APP_STATE.openEpubPath, "/.crosspoint");
-      epub.load(false);
-      if (!epub.getTitle().empty()) {
-        lastBookTitle = std::string(epub.getTitle());
-      }
-      if (!epub.getAuthor().empty()) {
-        lastBookAuthor = std::string(epub.getAuthor());
+      // Only load epub metadata if we don't have cached title/author
+      if (!hasCachedMetadata) {
+        epub.load(false);
+        if (!epub.getTitle().empty()) {
+          lastBookTitle = std::string(epub.getTitle());
+          APP_STATE.openBookTitle = lastBookTitle;
+        }
+        if (!epub.getAuthor().empty()) {
+          lastBookAuthor = std::string(epub.getAuthor());
+          APP_STATE.openBookAuthor = lastBookAuthor;
+        }
+        // Save updated cache to file
+        APP_STATE.saveToFile();
       }
       // Try to generate thumbnail image for Continue Reading card
       if (epub.generateThumbBmp()) {
         coverBmpPath = epub.getThumbBmpPath();
         hasCoverImage = true;
       }
-    } else if (StringUtils::checkFileExtension(lastBookTitle, ".xtch") ||
-               StringUtils::checkFileExtension(lastBookTitle, ".xtc")) {
+    } else if (StringUtils::checkFileExtension(filenameFromPath, ".xtch") ||
+               StringUtils::checkFileExtension(filenameFromPath, ".xtc")) {
       // Handle XTC file
       Xtc xtc(APP_STATE.openEpubPath, "/.crosspoint");
-      if (xtc.load()) {
-        if (!xtc.getTitle().empty()) {
-          lastBookTitle = std::string(xtc.getTitle());
+      if (!hasCachedMetadata) {
+        if (xtc.load()) {
+          if (!xtc.getTitle().empty()) {
+            lastBookTitle = std::string(xtc.getTitle());
+            APP_STATE.openBookTitle = lastBookTitle;
+            APP_STATE.saveToFile();
+          }
         }
-        // Try to generate thumbnail image for Continue Reading card
-        if (xtc.generateThumbBmp()) {
-          coverBmpPath = xtc.getThumbBmpPath();
-          hasCoverImage = true;
+        // Remove extension from title if we don't have metadata
+        if (StringUtils::checkFileExtension(lastBookTitle, ".xtch")) {
+          lastBookTitle.resize(lastBookTitle.length() - 5);
+          APP_STATE.openBookTitle = lastBookTitle;
+          APP_STATE.saveToFile();
+        } else if (StringUtils::checkFileExtension(lastBookTitle, ".xtc")) {
+          lastBookTitle.resize(lastBookTitle.length() - 4);
+          APP_STATE.openBookTitle = lastBookTitle;
+          APP_STATE.saveToFile();
         }
       }
-      // Remove extension from title if we don't have metadata
-      if (StringUtils::checkFileExtension(lastBookTitle, ".xtch")) {
-        lastBookTitle.resize(lastBookTitle.length() - 5);
-      } else if (StringUtils::checkFileExtension(lastBookTitle, ".xtc")) {
-        lastBookTitle.resize(lastBookTitle.length() - 4);
+      // Try to generate thumbnail image for Continue Reading card
+      if (xtc.generateThumbBmp()) {
+        coverBmpPath = xtc.getThumbBmpPath();
+        hasCoverImage = true;
       }
     }
+
+    // Check if cached cover buffer is still valid (same book)
+    if (hasCoverImage && coverBufferStored && cachedCoverPath == coverBmpPath) {
+      // Cover buffer is still valid, mark as rendered to skip reload
+      coverRendered = true;
+    } else if (hasCoverImage && coverBufferStored && cachedCoverPath != coverBmpPath) {
+      // Book changed, invalidate cached buffer
+      freeCoverBuffer();
+      coverRendered = false;
+    }
   }
 
   selectorIndex = 0;
@@ -112,8 +162,8 @@ void HomeActivity::onExit() {
   vSemaphoreDelete(renderingMutex);
   renderingMutex = nullptr;
 
-  // Free the stored cover buffer if any
-  freeCoverBuffer();
+  // NOTE: Do NOT free cover buffer here - keep it cached for fast re-entry
+  // The buffer will be freed/replaced when the book changes
 }
 
 bool HomeActivity::storeCoverBuffer() {
@@ -291,6 +341,9 @@ void HomeActivity::render() {
 
           // Store the buffer with cover image for fast navigation
           coverBufferStored = storeCoverBuffer();
+          if (coverBufferStored) {
+            cachedCoverPath = coverBmpPath;  // Remember which cover is cached
+          }
           coverRendered = true;
 
           // First render: if selected, draw selection indicators now
@@ -552,13 +605,12 @@ void HomeActivity::render() {
   const auto labels = mappedInput.mapLabels("", "Select", "Up", "Down");
   renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
 
+  // Draw battery in bottom-left where the back button hint would normally be
   const bool showBatteryPercentage =
       SETTINGS.hideBatteryPercentage != CrossPointSettings::HIDE_BATTERY_PERCENTAGE::HIDE_ALWAYS;
-  // get percentage so we can align text properly
-  const uint16_t percentage = battery.readPercentage();
-  const auto percentageText = showBatteryPercentage ? std::to_string(percentage) + "%" : "";
-  const auto batteryX = pageWidth - 25 - renderer.getTextWidth(SMALL_FONT_ID, percentageText.c_str());
-  ScreenComponents::drawBattery(renderer, batteryX, 10, showBatteryPercentage);
+  constexpr int batteryX = 25;  // Align with first button hint position
+  const int batteryY = pageHeight - 34;  // Vertically centered in button hint area
+  ScreenComponents::drawBatteryLarge(renderer, batteryX, batteryY, showBatteryPercentage);
 
   renderer.displayBuffer();
 }

src/activities/home/HomeActivity.h

@@ -15,9 +15,13 @@ class HomeActivity final : public Activity {
   bool hasContinueReading = false;
   bool hasOpdsUrl = false;
   bool hasCoverImage = false;
-  bool coverRendered = false;      // Track if cover has been rendered once
-  bool coverBufferStored = false;  // Track if cover buffer is stored
-  uint8_t* coverBuffer = nullptr;  // HomeActivity's own buffer for cover image
+
+  // Static cover buffer - persists across activity changes to avoid reloading from SD
+  static bool coverRendered;       // Track if cover has been rendered once
+  static bool coverBufferStored;   // Track if cover buffer is stored
+  static uint8_t* coverBuffer;     // HomeActivity's own buffer for cover image
+  static std::string cachedCoverPath;  // Path of the cached cover (to detect book changes)
+
   std::string lastBookTitle;
   std::string lastBookAuthor;
   std::string coverBmpPath;

src/activities/reader/EpubReaderActivity.cpp

@@ -120,8 +120,10 @@ void EpubReaderActivity::onEnter() {
     }
   }
 
-  // Save current epub as last opened epub and add to recent books
+  // Save current epub as last opened epub and cache title/author for home screen
   APP_STATE.openEpubPath = epub->getPath();
+  APP_STATE.openBookTitle = epub->getTitle();
+  APP_STATE.openBookAuthor = epub->getAuthor();
   APP_STATE.saveToFile();
   RECENT_BOOKS.addBook(epub->getPath(), epub->getTitle(), epub->getAuthor());
 

src/activities/reader/TxtReaderActivity.cpp

@@ -97,8 +97,10 @@ void TxtReaderActivity::onEnter() {
     });
   }
 
-  // Save current txt as last opened file
+  // Save current txt as last opened file and cache title for home screen
   APP_STATE.openEpubPath = txt->getPath();
+  APP_STATE.openBookTitle = txt->getTitle();
+  APP_STATE.openBookAuthor.clear();  // TXT files don't have author metadata
   APP_STATE.saveToFile();
 
   // Trigger first update

src/activities/reader/XtcReaderActivity.cpp

@@ -83,8 +83,10 @@ void XtcReaderActivity::onEnter() {
   // Load saved progress
   loadProgress();
 
-  // Save current XTC as last opened book and add to recent books
+  // Save current XTC as last opened book and cache title for home screen
   APP_STATE.openEpubPath = xtc->getPath();
+  APP_STATE.openBookTitle = xtc->getTitle();
+  APP_STATE.openBookAuthor.clear();  // XTC files don't have author metadata
   APP_STATE.saveToFile();
   RECENT_BOOKS.addBook(xtc->getPath(), xtc->getTitle(), "");