Formatting.

## Summary

* Add home screen
* Sits as new root screen, allows for navigation to settings or file
list

lib/Epub/Epub.cpp

@@ -73,10 +73,8 @@ bool Epub::parseContentOpf(const std::string& contentOpfFilePath) {
     coverImageItem = opfParser.items.at(opfParser.coverItemId);
   }
 
-  if (opfParser.items.count("ncx")) {
-    tocNcxItem = opfParser.items.at("ncx");
-  } else if (opfParser.items.count("ncxtoc")) {
-    tocNcxItem = opfParser.items.at("ncxtoc");
+  if (!opfParser.tocNcxPath.empty()) {
+    tocNcxItem = opfParser.tocNcxPath;
   }
 
   for (auto& spineRef : opfParser.spineRefs) {
@@ -150,6 +148,18 @@ bool Epub::load() {
     return false;
   }
 
+  // determine size of spine items
+  size_t spineItemsCount = getSpineItemsCount();
+  size_t spineItemsSize = 0;
+  for (size_t i = 0; i < spineItemsCount; i++) {
+    std::string spineItem = getSpineItem(i);
+    size_t s = 0;
+    getItemSize(spineItem, &s);
+    spineItemsSize += s;
+    cumulativeSpineItemSize.emplace_back(spineItemsSize);
+  }
+  Serial.printf("[%lu] [EBP] Book size: %u\n", millis(), spineItemsSize);
+
   Serial.printf("[%lu] [EBP] Loaded ePub: %s\n", millis(), filepath.c_str());
 
   return true;
@@ -257,6 +267,8 @@ bool Epub::getItemSize(const std::string& itemHref, size_t* size) const {
 
 int Epub::getSpineItemsCount() const { return spine.size(); }
 
+size_t Epub::getCumulativeSpineItemSize(const int spineIndex) const { return cumulativeSpineItemSize.at(spineIndex); }
+
 std::string& Epub::getSpineItem(const int spineIndex) {
   if (spineIndex < 0 || spineIndex >= spine.size()) {
     Serial.printf("[%lu] [EBP] getSpineItem index:%d is out of range\n", millis(), spineIndex);
@@ -304,3 +316,14 @@ int Epub::getTocIndexForSpineIndex(const int spineIndex) const {
   Serial.printf("[%lu] [EBP] TOC item not found\n", millis());
   return -1;
 }
+
+size_t Epub::getBookSize() const { return getCumulativeSpineItemSize(getSpineItemsCount() - 1); }
+
+// Calculate progress in book
+uint8_t Epub::calculateProgress(const int currentSpineIndex, const float currentSpineRead) {
+  size_t prevChapterSize = getCumulativeSpineItemSize(currentSpineIndex - 1);
+  size_t curChapterSize = getCumulativeSpineItemSize(currentSpineIndex) - prevChapterSize;
+  size_t bookSize = getBookSize();
+  size_t sectionProgSize = currentSpineRead * curChapterSize;
+  return round(static_cast<float>(prevChapterSize + sectionProgSize) / bookSize * 100.0);
+}

lib/Epub/Epub.h

@@ -20,6 +20,8 @@ class Epub {
   std::string filepath;
   // the spine of the EPUB file
   std::vector<std::pair<std::string, std::string>> spine;
+  // the file size of the spine items (proxy to book progress)
+  std::vector<size_t> cumulativeSpineItemSize;
   // the toc of the EPUB file
   std::vector<EpubTocEntry> toc;
   // the base path for items in the EPUB file
@@ -51,8 +53,12 @@ class Epub {
   bool getItemSize(const std::string& itemHref, size_t* size) const;
   std::string& getSpineItem(int spineIndex);
   int getSpineItemsCount() const;
-  EpubTocEntry& getTocItem(int tocTndex);
+  size_t getCumulativeSpineItemSize(const int spineIndex) const;
+  EpubTocEntry& getTocItem(int tocIndex);
   int getTocItemsCount() const;
   int getSpineIndexForTocIndex(int tocIndex) const;
   int getTocIndexForSpineIndex(int spineIndex) const;
+
+  size_t getBookSize() const;
+  uint8_t calculateProgress(const int currentSpineIndex, const float currentSpineRead);
 };

lib/Epub/Epub/parsers/ContentOpfParser.cpp

@@ -3,6 +3,10 @@
 #include <HardwareSerial.h>
 #include <ZipFile.h>
 
+namespace {
+constexpr const char MEDIA_TYPE_NCX[] = "application/x-dtbncx+xml";
+}
+
 bool ContentOpfParser::setup() {
   parser = XML_ParserCreate(nullptr);
   if (!parser) {
@@ -111,16 +115,28 @@ void XMLCALL ContentOpfParser::startElement(void* userData, const XML_Char* name
   if (self->state == IN_MANIFEST && (strcmp(name, "item") == 0 || strcmp(name, "opf:item") == 0)) {
     std::string itemId;
     std::string href;
+    std::string mediaType;
 
     for (int i = 0; atts[i]; i += 2) {
       if (strcmp(atts[i], "id") == 0) {
         itemId = atts[i + 1];
       } else if (strcmp(atts[i], "href") == 0) {
         href = self->baseContentPath + atts[i + 1];
+      } else if (strcmp(atts[i], "media-type") == 0) {
+        mediaType = atts[i + 1];
       }
     }
 
     self->items[itemId] = href;
+
+    if (mediaType == MEDIA_TYPE_NCX) {
+      if (self->tocNcxPath.empty()) {
+        self->tocNcxPath = href;
+      } else {
+        Serial.printf("[%lu] [COF] Warning: Multiple NCX files found in manifest. Ignoring duplicate: %s\n", millis(),
+                      href.c_str());
+      }
+    }
     return;
   }
 

lib/GfxRenderer/GfxRenderer.cpp

@@ -132,13 +132,19 @@ void GfxRenderer::displayBuffer(const EInkDisplay::RefreshMode refreshMode) cons
   einkDisplay.displayBuffer(refreshMode);
 }
 
-// TODO: Support partial window update
-// void GfxRenderer::flushArea(const int x, const int y, const int width, const int height) const {
-//   const int rotatedX = y;
-//   const int rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x;
-//
-//   einkDisplay.displayBuffer(EInkDisplay::FAST_REFRESH, rotatedX, rotatedY, height, width);
-// }
+void GfxRenderer::displayWindow(const int x, const int y, const int width, const int height) const {
+  // Rotate coordinates from portrait (480x800) to landscape (800x480)
+  // Rotation: 90 degrees clockwise
+  // Portrait coordinates: (x, y) with dimensions (width, height)
+  // Landscape coordinates: (rotatedX, rotatedY) with dimensions (rotatedWidth, rotatedHeight)
+
+  const int rotatedX = y;
+  const int rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x - width + 1;
+  const int rotatedWidth = height;
+  const int rotatedHeight = width;
+
+  einkDisplay.displayWindow(rotatedX, rotatedY, rotatedWidth, rotatedHeight);
+}
 
 // Note: Internal driver treats screen in command orientation, this library treats in portrait orientation
 int GfxRenderer::getScreenWidth() { return EInkDisplay::DISPLAY_HEIGHT; }
@@ -164,7 +170,7 @@ int GfxRenderer::getLineHeight(const int fontId) const {
 
 uint8_t* GfxRenderer::getFrameBuffer() const { return einkDisplay.getFrameBuffer(); }
 
-void GfxRenderer::swapBuffers() const { einkDisplay.swapBuffers(); }
+size_t GfxRenderer::getBufferSize() { return EInkDisplay::BUFFER_SIZE; }
 
 void GfxRenderer::grayscaleRevert() const { einkDisplay.grayscaleRevert(); }
 
@@ -174,6 +180,90 @@ void GfxRenderer::copyGrayscaleMsbBuffers() const { einkDisplay.copyGrayscaleMsb
 
 void GfxRenderer::displayGrayBuffer() const { einkDisplay.displayGrayBuffer(); }
 
+void GfxRenderer::freeBwBufferChunks() {
+  for (auto& bwBufferChunk : bwBufferChunks) {
+    if (bwBufferChunk) {
+      free(bwBufferChunk);
+      bwBufferChunk = nullptr;
+    }
+  }
+}
+
+/**
+ * This should be called before grayscale buffers are populated.
+ * A `restoreBwBuffer` call should always follow the grayscale render if this method was called.
+ * Uses chunked allocation to avoid needing 48KB of contiguous memory.
+ */
+void GfxRenderer::storeBwBuffer() {
+  const uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+
+  // Allocate and copy each chunk
+  for (size_t i = 0; i < BW_BUFFER_NUM_CHUNKS; i++) {
+    // Check if any chunks are already allocated
+    if (bwBufferChunks[i]) {
+      Serial.printf("[%lu] [GFX] !! BW buffer chunk %zu already stored - this is likely a bug, freeing chunk\n",
+                    millis(), i);
+      free(bwBufferChunks[i]);
+      bwBufferChunks[i] = nullptr;
+    }
+
+    const size_t offset = i * BW_BUFFER_CHUNK_SIZE;
+    bwBufferChunks[i] = static_cast<uint8_t*>(malloc(BW_BUFFER_CHUNK_SIZE));
+
+    if (!bwBufferChunks[i]) {
+      Serial.printf("[%lu] [GFX] !! Failed to allocate BW buffer chunk %zu (%zu bytes)\n", millis(), i,
+                    BW_BUFFER_CHUNK_SIZE);
+      // Free previously allocated chunks
+      freeBwBufferChunks();
+      return;
+    }
+
+    memcpy(bwBufferChunks[i], frameBuffer + offset, BW_BUFFER_CHUNK_SIZE);
+  }
+
+  Serial.printf("[%lu] [GFX] Stored BW buffer in %zu chunks (%zu bytes each)\n", millis(), BW_BUFFER_NUM_CHUNKS,
+                BW_BUFFER_CHUNK_SIZE);
+}
+
+/**
+ * This can only be called if `storeBwBuffer` was called prior to the grayscale render.
+ * It should be called to restore the BW buffer state after grayscale rendering is complete.
+ * Uses chunked restoration to match chunked storage.
+ */
+void GfxRenderer::restoreBwBuffer() {
+  // Check if any all chunks are allocated
+  bool missingChunks = false;
+  for (const auto& bwBufferChunk : bwBufferChunks) {
+    if (!bwBufferChunk) {
+      missingChunks = true;
+      break;
+    }
+  }
+
+  if (missingChunks) {
+    freeBwBufferChunks();
+    return;
+  }
+
+  uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+  for (size_t i = 0; i < BW_BUFFER_NUM_CHUNKS; i++) {
+    // Check if chunk is missing
+    if (!bwBufferChunks[i]) {
+      Serial.printf("[%lu] [GFX] !! BW buffer chunks not stored - this is likely a bug\n", millis());
+      freeBwBufferChunks();
+      return;
+    }
+
+    const size_t offset = i * BW_BUFFER_CHUNK_SIZE;
+    memcpy(frameBuffer + offset, bwBufferChunks[i], BW_BUFFER_CHUNK_SIZE);
+  }
+
+  einkDisplay.cleanupGrayscaleBuffers(frameBuffer);
+
+  freeBwBufferChunks();
+  Serial.printf("[%lu] [GFX] Restored and freed BW buffer chunks\n", millis());
+}
+
 void GfxRenderer::renderChar(const EpdFontFamily& fontFamily, const uint32_t cp, int* x, const int* y,
                              const bool pixelState, const EpdFontStyle style) const {
   const EpdGlyph* glyph = fontFamily.getGlyph(cp, style);

lib/GfxRenderer/GfxRenderer.h

@@ -10,11 +10,18 @@ class GfxRenderer {
   enum RenderMode { BW, GRAYSCALE_LSB, GRAYSCALE_MSB };
 
  private:
+  static constexpr size_t BW_BUFFER_CHUNK_SIZE = 8000;  // 8KB chunks to allow for non-contiguous memory
+  static constexpr size_t BW_BUFFER_NUM_CHUNKS = EInkDisplay::BUFFER_SIZE / BW_BUFFER_CHUNK_SIZE;
+  static_assert(BW_BUFFER_CHUNK_SIZE * BW_BUFFER_NUM_CHUNKS == EInkDisplay::BUFFER_SIZE,
+                "BW buffer chunking does not line up with display buffer size");
+
   EInkDisplay& einkDisplay;
   RenderMode renderMode;
+  uint8_t* bwBufferChunks[BW_BUFFER_NUM_CHUNKS] = {nullptr};
   std::map<int, EpdFontFamily> fontMap;
   void renderChar(const EpdFontFamily& fontFamily, uint32_t cp, int* x, const int* y, bool pixelState,
                   EpdFontStyle style) const;
+  void freeBwBufferChunks();
 
  public:
   explicit GfxRenderer(EInkDisplay& einkDisplay) : einkDisplay(einkDisplay), renderMode(BW) {}
@@ -27,6 +34,8 @@ class GfxRenderer {
   static int getScreenWidth();
   static int getScreenHeight();
   void displayBuffer(EInkDisplay::RefreshMode refreshMode = EInkDisplay::FAST_REFRESH) const;
+  // EXPERIMENTAL: Windowed update - display only a rectangular region (portrait coordinates)
+  void displayWindow(int x, int y, int width, int height) const;
   void invertScreen() const;
   void clearScreen(uint8_t color = 0xFF) const;
 
@@ -49,9 +58,11 @@ class GfxRenderer {
   void copyGrayscaleLsbBuffers() const;
   void copyGrayscaleMsbBuffers() const;
   void displayGrayBuffer() const;
+  void storeBwBuffer();
+  void restoreBwBuffer();
 
   // Low level functions
   uint8_t* getFrameBuffer() const;
-  void swapBuffers() const;
+  static size_t getBufferSize();
   void grayscaleRevert() const;
 };

open-x4-sdk

@@ -1 +1 @@
-Subproject commit 4d0dcd5ff87fcd86eb2966a123e85b03284a03db
+Subproject commit 98a5aa1f8969ccd317c9b45bf0fa84b6c82e167f

platformio.ini

@@ -20,6 +20,7 @@ build_flags =
   -DARDUINO_USB_MODE=1
   -DARDUINO_USB_CDC_ON_BOOT=1
   -DMINIZ_NO_ZLIB_COMPATIBLE_NAMES=1
+  -DEINK_DISPLAY_SINGLE_BUFFER_MODE=1
 # https://libexpat.github.io/doc/api/latest/#XML_GE
   -DXML_GE=0
   -DXML_CONTEXT_BYTES=1024

src/main.cpp

@@ -21,6 +21,7 @@
 #include "screens/EpubReaderScreen.h"
 #include "screens/FileSelectionScreen.h"
 #include "screens/FullScreenMessageScreen.h"
+#include "screens/HomeScreen.h"
 #include "screens/SettingsScreen.h"
 #include "screens/SleepScreen.h"
 
@@ -150,6 +151,7 @@ void enterDeepSleep() {
 }
 
 void onGoHome();
+void onGoToFileSelection();
 void onSelectEpubFile(const std::string& path) {
   exitScreen();
   enterNewScreen(new FullScreenMessageScreen(renderer, inputManager, "Loading..."));
@@ -159,16 +161,21 @@ void onSelectEpubFile(const std::string& path) {
     appState.openEpubPath = path;
     appState.saveToFile();
     exitScreen();
-    enterNewScreen(new EpubReaderScreen(renderer, inputManager, std::move(epub), onGoHome));
+    enterNewScreen(new EpubReaderScreen(renderer, inputManager, std::move(epub), onGoToFileSelection));
   } else {
     exitScreen();
     enterNewScreen(
         new FullScreenMessageScreen(renderer, inputManager, "Failed to load epub", REGULAR, EInkDisplay::HALF_REFRESH));
     delay(2000);
-    onGoHome();
+    onGoToFileSelection();
   }
 }
 
+void onGoToFileSelection() {
+  exitScreen();
+  enterNewScreen(new FileSelectionScreen(renderer, inputManager, onSelectEpubFile, onGoHome));
+}
+
 void onGoToSettings() {
   exitScreen();
   enterNewScreen(new SettingsScreen(renderer, inputManager, onGoHome));
@@ -176,7 +183,7 @@ void onGoToSettings() {
 
 void onGoHome() {
   exitScreen();
-  enterNewScreen(new FileSelectionScreen(renderer, inputManager, onSelectEpubFile, onGoToSettings));
+  enterNewScreen(new HomeScreen(renderer, inputManager, onGoToFileSelection, onGoToSettings));
 }
 
 void setup() {
@@ -221,8 +228,7 @@ void setup() {
     }
   }
 
-  exitScreen();
-  enterNewScreen(new FileSelectionScreen(renderer, inputManager, onSelectEpubFile, onGoToSettings));
+  onGoHome();
 
   // Ensure we're not still holding the power button before leaving setup
   waitForPowerRelease();

src/screens/EpubReaderScreen.cpp

@@ -31,7 +31,6 @@ void EpubReaderScreen::onEnter() {
 
   epub->setupCacheDir();
 
-  // TODO: Move this to a state object
   if (SD.exists((epub->getCachePath() + "/progress.bin").c_str())) {
     File f = SD.open((epub->getCachePath() + "/progress.bin").c_str());
     uint8_t data[4];
@@ -99,7 +98,7 @@ void EpubReaderScreen::handleInput() {
   }
 
   if (inputManager.wasPressed(InputManager::BTN_BACK)) {
-    onGoHome();
+    onGoBack();
     return;
   }
 
@@ -210,20 +209,20 @@ void EpubReaderScreen::renderScreen() {
       Serial.printf("[%lu] [ERS] Cache not found, building...\n", millis());
 
       {
+        renderer.grayscaleRevert();
+
         const int textWidth = renderer.getTextWidth(READER_FONT_ID, "Indexing...");
         constexpr int margin = 20;
-        const int x = (GfxRenderer::getScreenWidth() - textWidth - margin * 2) / 2;
-        constexpr int y = 50;
-        const int w = textWidth + margin * 2;
-        const int h = renderer.getLineHeight(READER_FONT_ID) + margin * 2;
-        renderer.grayscaleRevert();
-        uint8_t* fb1 = renderer.getFrameBuffer();
-        renderer.swapBuffers();
-        memcpy(fb1, renderer.getFrameBuffer(), EInkDisplay::BUFFER_SIZE);
-        renderer.fillRect(x, y, w, h, 0);
+        // Round all coordinates to 8 pixel boundaries
+        const int x = ((GfxRenderer::getScreenWidth() - textWidth - margin * 2) / 2 + 7) / 8 * 8;
+        constexpr int y = 56;
+        const int w = (textWidth + margin * 2 + 7) / 8 * 8;
+        const int h = (renderer.getLineHeight(READER_FONT_ID) + margin * 2 + 7) / 8 * 8;
+        renderer.fillRect(x, y, w, h, false);
         renderer.drawText(READER_FONT_ID, x + margin, y + margin, "Indexing...");
         renderer.drawRect(x + 5, y + 5, w - 10, h - 10);
-        renderer.displayBuffer();
+        // EXPERIMENTAL: Still suffers from ghosting
+        renderer.displayWindow(x, y, w, h);
         pagesUntilFullRefresh = 0;
       }
 
@@ -297,6 +296,9 @@ void EpubReaderScreen::renderContents(std::unique_ptr<Page> page) {
     pagesUntilFullRefresh--;
   }
 
+  // Save bw buffer to reset buffer state after grayscale data sync
+  renderer.storeBwBuffer();
+
   // grayscale rendering
   // TODO: Only do this if font supports it
   {
@@ -315,12 +317,21 @@ void EpubReaderScreen::renderContents(std::unique_ptr<Page> page) {
     renderer.displayGrayBuffer();
     renderer.setRenderMode(GfxRenderer::BW);
   }
+
+  // restore the bw data
+  renderer.restoreBwBuffer();
 }
 
 void EpubReaderScreen::renderStatusBar() const {
   constexpr auto textY = 776;
+
+  // Calculate progress in book
+  float sectionChapterProg = static_cast<float>(section->currentPage) / section->pageCount;
+  uint8_t bookProgress = epub->calculateProgress(currentSpineIndex, sectionChapterProg);
+
   // Right aligned text for progress counter
-  const std::string progress = std::to_string(section->currentPage + 1) + " / " + std::to_string(section->pageCount);
+  const std::string progress = std::to_string(section->currentPage + 1) + "/" + std::to_string(section->pageCount) +
+                               "  " + std::to_string(bookProgress) + "%";
   const auto progressTextWidth = renderer.getTextWidth(SMALL_FONT_ID, progress.c_str());
   renderer.drawText(SMALL_FONT_ID, GfxRenderer::getScreenWidth() - marginRight - progressTextWidth, textY,
                     progress.c_str());

src/screens/EpubReaderScreen.h

@@ -17,7 +17,7 @@ class EpubReaderScreen final : public Screen {
   int nextPageNumber = 0;
   int pagesUntilFullRefresh = 0;
   bool updateRequired = false;
-  const std::function<void()> onGoHome;
+  const std::function<void()> onGoBack;
 
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
@@ -27,8 +27,8 @@ class EpubReaderScreen final : public Screen {
 
  public:
   explicit EpubReaderScreen(GfxRenderer& renderer, InputManager& inputManager, std::unique_ptr<Epub> epub,
-                            const std::function<void()>& onGoHome)
-      : Screen(renderer, inputManager), epub(std::move(epub)), onGoHome(onGoHome) {}
+                            const std::function<void()>& onGoBack)
+      : Screen(renderer, inputManager), epub(std::move(epub)), onGoBack(onGoBack) {}
   void onEnter() override;
   void onExit() override;
   void handleInput() override;

src/screens/FileSelectionScreen.cpp

@@ -98,8 +98,8 @@ void FileSelectionScreen::handleInput() {
       loadFiles();
       updateRequired = true;
     } else {
-      // At root level, go to settings
-      onSettingsOpen();
+      // At root level, go back home
+      onGoHome();
     }
   } else if (prevPressed) {
     selectorIndex = (selectorIndex + files.size() - 1) % files.size();
@@ -129,7 +129,7 @@ void FileSelectionScreen::render() const {
   renderer.drawCenteredText(READER_FONT_ID, 10, "CrossPoint Reader", true, BOLD);
 
   // Help text
-  renderer.drawText(SMALL_FONT_ID, 20, GfxRenderer::getScreenHeight() - 30, "Press BACK for Settings");
+  renderer.drawText(SMALL_FONT_ID, 20, GfxRenderer::getScreenHeight() - 30, "Press BACK for Home");
 
   if (files.empty()) {
     renderer.drawText(UI_FONT_ID, 20, 60, "No EPUBs found");

src/screens/FileSelectionScreen.h

@@ -17,7 +17,7 @@ class FileSelectionScreen final : public Screen {
   int selectorIndex = 0;
   bool updateRequired = false;
   const std::function<void(const std::string&)> onSelect;
-  const std::function<void()> onSettingsOpen;
+  const std::function<void()> onGoHome;
 
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
@@ -27,8 +27,8 @@ class FileSelectionScreen final : public Screen {
  public:
   explicit FileSelectionScreen(GfxRenderer& renderer, InputManager& inputManager,
                                const std::function<void(const std::string&)>& onSelect,
-                               const std::function<void()>& onSettingsOpen)
-      : Screen(renderer, inputManager), onSelect(onSelect), onSettingsOpen(onSettingsOpen) {}
+                               const std::function<void()>& onGoHome)
+      : Screen(renderer, inputManager), onSelect(onSelect), onGoHome(onGoHome) {}
   void onEnter() override;
   void onExit() override;
   void handleInput() override;

src/screens/HomeScreen.cpp

@@ -0,0 +1,99 @@
+#include "HomeScreen.h"
+
+#include <GfxRenderer.h>
+#include <SD.h>
+
+#include "config.h"
+
+void HomeScreen::taskTrampoline(void* param) {
+  auto* self = static_cast<HomeScreen*>(param);
+  self->displayTaskLoop();
+}
+
+void HomeScreen::onEnter() {
+  renderingMutex = xSemaphoreCreateMutex();
+
+  selectorIndex = 0;
+
+  // Trigger first update
+  updateRequired = true;
+
+  xTaskCreate(&HomeScreen::taskTrampoline, "HomeScreenTask",
+              2048,               // Stack size
+              this,               // Parameters
+              1,                  // Priority
+              &displayTaskHandle  // Task handle
+  );
+}
+
+void HomeScreen::onExit() {
+  // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+void HomeScreen::handleInput() {
+  const bool prevPressed =
+      inputManager.wasPressed(InputManager::BTN_UP) || inputManager.wasPressed(InputManager::BTN_LEFT);
+  const bool nextPressed =
+      inputManager.wasPressed(InputManager::BTN_DOWN) || inputManager.wasPressed(InputManager::BTN_RIGHT);
+
+  if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
+    if (selectorIndex == 0) {
+      onFileSelectionOpen();
+    } else if (selectorIndex == 1) {
+      onSettingsOpen();
+    }
+  } else if (prevPressed) {
+    selectorIndex = (selectorIndex + menuItemCount - 1) % menuItemCount;
+    updateRequired = true;
+  } else if (nextPressed) {
+    selectorIndex = (selectorIndex + 1) % menuItemCount;
+    updateRequired = true;
+  }
+}
+
+void HomeScreen::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      render();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void HomeScreen::render() const {
+  renderer.clearScreen();
+
+  const auto pageWidth = GfxRenderer::getScreenWidth();
+  const auto pageHeight = GfxRenderer::getScreenHeight();
+  renderer.drawCenteredText(READER_FONT_ID, 10, "CrossPoint Reader", true, BOLD);
+
+  // Draw selection
+  renderer.fillRect(0, 60 + selectorIndex * 30 + 2, pageWidth - 1, 30);
+  renderer.drawText(UI_FONT_ID, 20, 60, "Read", selectorIndex != 0);
+  renderer.drawText(UI_FONT_ID, 20, 90, "Settings", selectorIndex != 1);
+
+  renderer.drawRect(25, pageHeight - 40, 106, 40);
+  renderer.drawText(UI_FONT_ID, 25 + (105 - renderer.getTextWidth(UI_FONT_ID, "Back")) / 2, pageHeight - 35, "Back");
+
+  renderer.drawRect(130, pageHeight - 40, 106, 40);
+  renderer.drawText(UI_FONT_ID, 130 + (105 - renderer.getTextWidth(UI_FONT_ID, "Confirm")) / 2, pageHeight - 35,
+                    "Confirm");
+
+  renderer.drawRect(245, pageHeight - 40, 106, 40);
+  renderer.drawText(UI_FONT_ID, 245 + (105 - renderer.getTextWidth(UI_FONT_ID, "Left")) / 2, pageHeight - 35, "Left");
+
+  renderer.drawRect(350, pageHeight - 40, 106, 40);
+  renderer.drawText(UI_FONT_ID, 350 + (105 - renderer.getTextWidth(UI_FONT_ID, "Right")) / 2, pageHeight - 35, "Right");
+
+  renderer.displayBuffer();
+}

src/screens/HomeScreen.h

@@ -0,0 +1,31 @@
+#pragma once
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+
+#include "Screen.h"
+
+class HomeScreen final : public Screen {
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+  int selectorIndex = 0;
+  bool updateRequired = false;
+  const std::function<void()> onFileSelectionOpen;
+  const std::function<void()> onSettingsOpen;
+
+  static constexpr int menuItemCount = 2;
+
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  void render() const;
+
+ public:
+  explicit HomeScreen(GfxRenderer& renderer, InputManager& inputManager,
+                      const std::function<void()>& onFileSelectionOpen, const std::function<void()>& onSettingsOpen)
+      : Screen(renderer, inputManager), onFileSelectionOpen(onFileSelectionOpen), onSettingsOpen(onSettingsOpen) {}
+  void onEnter() override;
+  void onExit() override;
+  void handleInput() override;
+};