Rotation Support (#77)

•  What is the goal of this PR?  
Implement a horizontal EPUB reading mode so books can be read in
landscape orientation (both 90° and 270°), while keeping the rest of the
UI in portrait.

•  What changes are included?
◦  Rendering / Display
▪ Added an orientation model to GfxRenderer (Portrait, LandscapeNormal,
LandscapeFlipped) and made:
▪ drawPixel, drawImage, displayWindow map logical coordinates
differently depending on orientation.
▪ getScreenWidth() / getScreenHeight() return orientation‑aware logical
dimensions (480×800 in portrait, 800×480 in landscape).
◦  Settings / Configuration
▪  Extended CrossPointSettings with:
▪  landscapeReading (toggle for portrait vs. landscape EPUB reading).
▪ landscapeFlipped (toggle to flip landscape 180° so both horizontal
holding directions are supported).
▪ Updated settings serialization/deserialization to persist these fields
while remaining backward‑compatible with existing settings files.
▪  Updated SettingsActivity to expose two new toggles:
▪  “Landscape Reading”
▪  “Flip Landscape (swap top/bottom)”
◦  EPUB Reader
▪  In EpubReaderActivity:
▪ On onEnter, set GfxRenderer orientation based on the new settings
(Portrait, LandscapeNormal, or LandscapeFlipped).
▪ On onExit, reset orientation back to Portrait so Home, WiFi, Settings,
etc. continue to render as before.
▪ Adjusted renderStatusBar to position the status bar and battery
indicator relative to GfxRenderer::getScreenHeight() instead of
hard‑coded Y coordinates, so it stays correctly at the bottom in both
portrait and landscape.
◦  EPUB Caching / Layout
▪ Extended Section cache metadata (section.bin) to include the logical
screenWidth and screenHeight used when pages were generated; bumped
SECTION_FILE_VERSION.
▪  Updated loadCacheMetadata to compare:
▪ font/margins/line compression/extraParagraphSpacing and screen
dimensions; mismatches now invalidate and clear the cache.
▪ Updated persistPageDataToSD and all call sites in EpubReaderActivity
to pass the current GfxRenderer::getScreenWidth() / getScreenHeight() so
portrait and landscape caches are kept separate and correctly sized.



Additional Context

•  Cache behavior / migration
◦ Existing section.bin files (old SECTION_FILE_VERSION) will be detected
as incompatible and their caches cleared and rebuilt once per chapter
when first opened after this change.
◦ Within a given orientation, caches will be reused as before. Switching
orientation (portrait ↔ landscape) will cause a one‑time re‑index of
each chapter in the new orientation.
•  Scope and risks
◦ Orientation changes are scoped to the EPUB reader; the Home screen,
Settings, WiFi selection, sleep screens, and web server UI continue to
assume portrait orientation.
◦ The renderer’s orientation is a static/global setting; if future code
uses GfxRenderer outside the reader while a reader instance is active,
it should be aware that orientation is no longer implicitly fixed.
◦ All drawing primitives now go through orientation‑aware coordinate
transforms; any code that previously relied on edge‑case behavior or
out‑of‑bounds writes might surface as logged “Outside range” warnings
instead.
•  Testing suggestions / areas to focus on
◦  Verify in hardware:
▪ Portrait mode still renders correctly (boot, home, settings, WiFi,
reader).
▪  Landscape reading in both directions:
▪  Landscape Reading = ON, Flip Landscape = OFF.
▪  Landscape Reading = ON, Flip Landscape = ON.
▪ Status bar (page X/Y, % progress, battery icon) is fully visible and
aligned at the bottom in all three combinations.
◦  Open the same book:
▪  In portrait first, then switch to landscape and reopen it.
▪  Confirm that:
▪ Old portrait caches are rebuilt once for landscape (you should see the
“Indexing…” page).
▪ Progress save/restore still works (resume opens to the correct page in
the current orientation).
◦ Ensure grayscale rendering (the secondary pass in
EpubReaderActivity::renderContents) still looks correct in both
orientations.

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

lib/Epub/Epub/Page.cpp

@@ -7,7 +7,9 @@ namespace {
 constexpr uint8_t PAGE_FILE_VERSION = 3;
 }
 
-void PageLine::render(GfxRenderer& renderer, const int fontId) { block->render(renderer, fontId, xPos, yPos); }
+void PageLine::render(GfxRenderer& renderer, const int fontId, const int xOffset, const int yOffset) {
+  block->render(renderer, fontId, xPos + xOffset, yPos + yOffset);
+}
 
 void PageLine::serialize(File& file) {
   serialization::writePod(file, xPos);
@@ -27,9 +29,9 @@ std::unique_ptr<PageLine> PageLine::deserialize(File& file) {
   return std::unique_ptr<PageLine>(new PageLine(std::move(tb), xPos, yPos));
 }
 
-void Page::render(GfxRenderer& renderer, const int fontId) const {
+void Page::render(GfxRenderer& renderer, const int fontId, const int xOffset, const int yOffset) const {
   for (auto& element : elements) {
-    element->render(renderer, fontId);
+    element->render(renderer, fontId, xOffset, yOffset);
   }
 }
 

lib/Epub/Epub/Page.h

@@ -17,7 +17,7 @@ class PageElement {
   int16_t yPos;
   explicit PageElement(const int16_t xPos, const int16_t yPos) : xPos(xPos), yPos(yPos) {}
   virtual ~PageElement() = default;
-  virtual void render(GfxRenderer& renderer, int fontId) = 0;
+  virtual void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) = 0;
   virtual void serialize(File& file) = 0;
 };
 
@@ -28,7 +28,7 @@ class PageLine final : public PageElement {
  public:
   PageLine(std::shared_ptr<TextBlock> block, const int16_t xPos, const int16_t yPos)
       : PageElement(xPos, yPos), block(std::move(block)) {}
-  void render(GfxRenderer& renderer, int fontId) override;
+  void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) override;
   void serialize(File& file) override;
   static std::unique_ptr<PageLine> deserialize(File& file);
 };
@@ -37,7 +37,7 @@ class Page {
  public:
   // the list of block index and line numbers on this page
   std::vector<std::shared_ptr<PageElement>> elements;
-  void render(GfxRenderer& renderer, int fontId) const;
+  void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) const;
   void serialize(File& file) const;
   static std::unique_ptr<Page> deserialize(File& file);
 };

lib/Epub/Epub/ParsedText.cpp

@@ -18,14 +18,14 @@ void ParsedText::addWord(std::string word, const EpdFontStyle fontStyle) {
 }
 
 // Consumes data to minimize memory usage
-void ParsedText::layoutAndExtractLines(const GfxRenderer& renderer, const int fontId, const int horizontalMargin,
+void ParsedText::layoutAndExtractLines(const GfxRenderer& renderer, const int fontId, const int viewportWidth,
                                        const std::function<void(std::shared_ptr<TextBlock>)>& processLine,
                                        const bool includeLastLine) {
   if (words.empty()) {
     return;
   }
 
-  const int pageWidth = renderer.getScreenWidth() - horizontalMargin;
+  const int pageWidth = viewportWidth;
   const int spaceWidth = renderer.getSpaceWidth(fontId);
   const auto wordWidths = calculateWordWidths(renderer, fontId);
   const auto lineBreakIndices = computeLineBreaks(pageWidth, spaceWidth, wordWidths);

lib/Epub/Epub/ParsedText.h

@@ -34,7 +34,7 @@ class ParsedText {
   TextBlock::BLOCK_STYLE getStyle() const { return style; }
   size_t size() const { return words.size(); }
   bool isEmpty() const { return words.empty(); }
-  void layoutAndExtractLines(const GfxRenderer& renderer, int fontId, int horizontalMargin,
+  void layoutAndExtractLines(const GfxRenderer& renderer, int fontId, int viewportWidth,
                              const std::function<void(std::shared_ptr<TextBlock>)>& processLine,
                              bool includeLastLine = true);
 };

lib/Epub/Epub/Section.cpp

@@ -8,8 +8,8 @@
 #include "parsers/ChapterHtmlSlimParser.h"
 
 namespace {
-constexpr uint8_t SECTION_FILE_VERSION = 5;
+constexpr uint8_t SECTION_FILE_VERSION = 6;
-}
+}  // namespace
 
 void Section::onPageComplete(std::unique_ptr<Page> page) {
   const auto filePath = cachePath + "/page_" + std::to_string(pageCount) + ".bin";
@@ -26,9 +26,8 @@ void Section::onPageComplete(std::unique_ptr<Page> page) {
   pageCount++;
 }
 
-void Section::writeCacheMetadata(const int fontId, const float lineCompression, const int marginTop,
+void Section::writeCacheMetadata(const int fontId, const float lineCompression, const bool extraParagraphSpacing,
-                                 const int marginRight, const int marginBottom, const int marginLeft,
+                                 const int viewportWidth, const int viewportHeight) const {
-                                 const bool extraParagraphSpacing) const {
   File outputFile;
   if (!FsHelpers::openFileForWrite("SCT", cachePath + "/section.bin", outputFile)) {
     return;
@@ -36,18 +35,15 @@ void Section::writeCacheMetadata(const int fontId, const float lineCompression,
   serialization::writePod(outputFile, SECTION_FILE_VERSION);
   serialization::writePod(outputFile, fontId);
   serialization::writePod(outputFile, lineCompression);
-  serialization::writePod(outputFile, marginTop);
-  serialization::writePod(outputFile, marginRight);
-  serialization::writePod(outputFile, marginBottom);
-  serialization::writePod(outputFile, marginLeft);
   serialization::writePod(outputFile, extraParagraphSpacing);
+  serialization::writePod(outputFile, viewportWidth);
+  serialization::writePod(outputFile, viewportHeight);
   serialization::writePod(outputFile, pageCount);
   outputFile.close();
 }
 
-bool Section::loadCacheMetadata(const int fontId, const float lineCompression, const int marginTop,
+bool Section::loadCacheMetadata(const int fontId, const float lineCompression, const bool extraParagraphSpacing,
-                                const int marginRight, const int marginBottom, const int marginLeft,
+                                const int viewportWidth, const int viewportHeight) {
-                                const bool extraParagraphSpacing) {
   const auto sectionFilePath = cachePath + "/section.bin";
   File inputFile;
   if (!FsHelpers::openFileForRead("SCT", sectionFilePath, inputFile)) {
@@ -65,20 +61,18 @@ bool Section::loadCacheMetadata(const int fontId, const float lineCompression, c
       return false;
     }
 
-    int fileFontId, fileMarginTop, fileMarginRight, fileMarginBottom, fileMarginLeft;
+    int fileFontId, fileViewportWidth, fileViewportHeight;
     float fileLineCompression;
     bool fileExtraParagraphSpacing;
     serialization::readPod(inputFile, fileFontId);
     serialization::readPod(inputFile, fileLineCompression);
-    serialization::readPod(inputFile, fileMarginTop);
-    serialization::readPod(inputFile, fileMarginRight);
-    serialization::readPod(inputFile, fileMarginBottom);
-    serialization::readPod(inputFile, fileMarginLeft);
     serialization::readPod(inputFile, fileExtraParagraphSpacing);
+    serialization::readPod(inputFile, fileViewportWidth);
+    serialization::readPod(inputFile, fileViewportHeight);
 
-    if (fontId != fileFontId || lineCompression != fileLineCompression || marginTop != fileMarginTop ||
+    if (fontId != fileFontId || lineCompression != fileLineCompression ||
-        marginRight != fileMarginRight || marginBottom != fileMarginBottom || marginLeft != fileMarginLeft ||
+        extraParagraphSpacing != fileExtraParagraphSpacing || viewportWidth != fileViewportWidth ||
-        extraParagraphSpacing != fileExtraParagraphSpacing) {
+        viewportHeight != fileViewportHeight) {
       inputFile.close();
       Serial.printf("[%lu] [SCT] Deserialization failed: Parameters do not match\n", millis());
       clearCache();
@@ -113,9 +107,9 @@ bool Section::clearCache() const {
   return true;
 }
 
-bool Section::persistPageDataToSD(const int fontId, const float lineCompression, const int marginTop,
+bool Section::persistPageDataToSD(const int fontId, const float lineCompression, const bool extraParagraphSpacing,
-                                  const int marginRight, const int marginBottom, const int marginLeft,
+                                  const int viewportWidth, const int viewportHeight,
-                                  const bool extraParagraphSpacing, const std::function<void()>& progressSetupFn,
+                                  const std::function<void()>& progressSetupFn,
                                   const std::function<void(int)>& progressFn) {
   constexpr size_t MIN_SIZE_FOR_PROGRESS = 50 * 1024;  // 50KB
   const auto localPath = epub->getSpineItem(spineIndex).href;
@@ -163,8 +157,8 @@ bool Section::persistPageDataToSD(const int fontId, const float lineCompression,
   }
 
   ChapterHtmlSlimParser visitor(
-      tmpHtmlPath, renderer, fontId, lineCompression, marginTop, marginRight, marginBottom, marginLeft,
+      tmpHtmlPath, renderer, fontId, lineCompression, extraParagraphSpacing, viewportWidth, viewportHeight,
-      extraParagraphSpacing, [this](std::unique_ptr<Page> page) { this->onPageComplete(std::move(page)); }, progressFn);
+      [this](std::unique_ptr<Page> page) { this->onPageComplete(std::move(page)); }, progressFn);
   success = visitor.parseAndBuildPages();
 
   SD.remove(tmpHtmlPath.c_str());
@@ -173,7 +167,7 @@ bool Section::persistPageDataToSD(const int fontId, const float lineCompression,
     return false;
   }
 
-  writeCacheMetadata(fontId, lineCompression, marginTop, marginRight, marginBottom, marginLeft, extraParagraphSpacing);
+  writeCacheMetadata(fontId, lineCompression, extraParagraphSpacing, viewportWidth, viewportHeight);
 
   return true;
 }

lib/Epub/Epub/Section.h

@@ -13,8 +13,8 @@ class Section {
   GfxRenderer& renderer;
   std::string cachePath;
 
-  void writeCacheMetadata(int fontId, float lineCompression, int marginTop, int marginRight, int marginBottom,
+  void writeCacheMetadata(int fontId, float lineCompression, bool extraParagraphSpacing, int viewportWidth,
-                          int marginLeft, bool extraParagraphSpacing) const;
+                          int viewportHeight) const;
   void onPageComplete(std::unique_ptr<Page> page);
 
  public:
@@ -27,13 +27,12 @@ class Section {
         renderer(renderer),
         cachePath(epub->getCachePath() + "/" + std::to_string(spineIndex)) {}
   ~Section() = default;
-  bool loadCacheMetadata(int fontId, float lineCompression, int marginTop, int marginRight, int marginBottom,
+  bool loadCacheMetadata(int fontId, float lineCompression, bool extraParagraphSpacing, int viewportWidth,
-                         int marginLeft, bool extraParagraphSpacing);
+                         int viewportHeight);
   void setupCacheDir() const;
   bool clearCache() const;
-  bool persistPageDataToSD(int fontId, float lineCompression, int marginTop, int marginRight, int marginBottom,
+  bool persistPageDataToSD(int fontId, float lineCompression, bool extraParagraphSpacing, int viewportWidth,
-                           int marginLeft, bool extraParagraphSpacing,
+                           int viewportHeight, const std::function<void()>& progressSetupFn = nullptr,
-                           const std::function<void()>& progressSetupFn = nullptr,
                            const std::function<void(int)>& progressFn = nullptr);
   std::unique_ptr<Page> loadPageFromSD() const;
 };

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp

@@ -155,7 +155,7 @@ void XMLCALL ChapterHtmlSlimParser::characterData(void* userData, const XML_Char
   if (self->currentTextBlock->size() > 750) {
     Serial.printf("[%lu] [EHP] Text block too long, splitting into multiple pages\n", millis());
     self->currentTextBlock->layoutAndExtractLines(
-        self->renderer, self->fontId, self->marginLeft + self->marginRight,
+        self->renderer, self->fontId, self->viewportWidth,
         [self](const std::shared_ptr<TextBlock>& textBlock) { self->addLineToPage(textBlock); }, false);
   }
 }
@@ -301,15 +301,14 @@ bool ChapterHtmlSlimParser::parseAndBuildPages() {
 
 void ChapterHtmlSlimParser::addLineToPage(std::shared_ptr<TextBlock> line) {
   const int lineHeight = renderer.getLineHeight(fontId) * lineCompression;
-  const int pageHeight = GfxRenderer::getScreenHeight() - marginTop - marginBottom;
 
-  if (currentPageNextY + lineHeight > pageHeight) {
+  if (currentPageNextY + lineHeight > viewportHeight) {
     completePageFn(std::move(currentPage));
     currentPage.reset(new Page());
-    currentPageNextY = marginTop;
+    currentPageNextY = 0;
   }
 
-  currentPage->elements.push_back(std::make_shared<PageLine>(line, marginLeft, currentPageNextY));
+  currentPage->elements.push_back(std::make_shared<PageLine>(line, 0, currentPageNextY));
   currentPageNextY += lineHeight;
 }
 
@@ -321,12 +320,12 @@ void ChapterHtmlSlimParser::makePages() {
 
   if (!currentPage) {
     currentPage.reset(new Page());
-    currentPageNextY = marginTop;
+    currentPageNextY = 0;
   }
 
   const int lineHeight = renderer.getLineHeight(fontId) * lineCompression;
   currentTextBlock->layoutAndExtractLines(
-      renderer, fontId, marginLeft + marginRight,
+      renderer, fontId, viewportWidth,
       [this](const std::shared_ptr<TextBlock>& textBlock) { addLineToPage(textBlock); });
   // Extra paragraph spacing if enabled
   if (extraParagraphSpacing) {

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h

@@ -32,11 +32,9 @@ class ChapterHtmlSlimParser {
   int16_t currentPageNextY = 0;
   int fontId;
   float lineCompression;
-  int marginTop;
-  int marginRight;
-  int marginBottom;
-  int marginLeft;
   bool extraParagraphSpacing;
+  int viewportWidth;
+  int viewportHeight;
 
   void startNewTextBlock(TextBlock::BLOCK_STYLE style);
   void makePages();
@@ -47,19 +45,17 @@ class ChapterHtmlSlimParser {
 
  public:
   explicit ChapterHtmlSlimParser(const std::string& filepath, GfxRenderer& renderer, const int fontId,
-                                 const float lineCompression, const int marginTop, const int marginRight,
+                                 const float lineCompression, const bool extraParagraphSpacing, const int viewportWidth,
-                                 const int marginBottom, const int marginLeft, const bool extraParagraphSpacing,
+                                 const int viewportHeight,
                                  const std::function<void(std::unique_ptr<Page>)>& completePageFn,
                                  const std::function<void(int)>& progressFn = nullptr)
       : filepath(filepath),
         renderer(renderer),
         fontId(fontId),
         lineCompression(lineCompression),
-        marginTop(marginTop),
-        marginRight(marginRight),
-        marginBottom(marginBottom),
-        marginLeft(marginLeft),
         extraParagraphSpacing(extraParagraphSpacing),
+        viewportWidth(viewportWidth),
+        viewportHeight(viewportHeight),
         completePageFn(completePageFn),
         progressFn(progressFn) {}
   ~ChapterHtmlSlimParser() = default;

lib/GfxRenderer/GfxRenderer.cpp

@@ -4,6 +4,37 @@
 
 void GfxRenderer::insertFont(const int fontId, EpdFontFamily font) { fontMap.insert({fontId, font}); }
 
+void GfxRenderer::rotateCoordinates(const int x, const int y, int* rotatedX, int* rotatedY) const {
+  switch (orientation) {
+    case Portrait: {
+      // Logical portrait (480x800) → panel (800x480)
+      // Rotation: 90 degrees clockwise
+      *rotatedX = y;
+      *rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x;
+      break;
+    }
+    case LandscapeClockwise: {
+      // Logical landscape (800x480) rotated 180 degrees (swap top/bottom and left/right)
+      *rotatedX = EInkDisplay::DISPLAY_WIDTH - 1 - x;
+      *rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - y;
+      break;
+    }
+    case PortraitInverted: {
+      // Logical portrait (480x800) → panel (800x480)
+      // Rotation: 90 degrees counter-clockwise
+      *rotatedX = EInkDisplay::DISPLAY_WIDTH - 1 - y;
+      *rotatedY = x;
+      break;
+    }
+    case LandscapeCounterClockwise: {
+      // Logical landscape (800x480) aligned with panel orientation
+      *rotatedX = x;
+      *rotatedY = y;
+      break;
+    }
+  }
+}
+
 void GfxRenderer::drawPixel(const int x, const int y, const bool state) const {
   uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
 
@@ -13,15 +44,14 @@ void GfxRenderer::drawPixel(const int x, const int y, const bool state) const {
     return;
   }
 
-  // Rotate coordinates: portrait (480x800) -> landscape (800x480)
+  int rotatedX = 0;
-  // Rotation: 90 degrees clockwise
+  int rotatedY = 0;
-  const int rotatedX = y;
+  rotateCoordinates(x, y, &rotatedX, &rotatedY);
-  const int rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x;
 
-  // Bounds checking (portrait: 480x800)
+  // Bounds checking against physical panel dimensions
   if (rotatedX < 0 || rotatedX >= EInkDisplay::DISPLAY_WIDTH || rotatedY < 0 ||
       rotatedY >= EInkDisplay::DISPLAY_HEIGHT) {
-    Serial.printf("[%lu] [GFX] !! Outside range (%d, %d)\n", millis(), x, y);
+    Serial.printf("[%lu] [GFX] !! Outside range (%d, %d) -> (%d, %d)\n", millis(), x, y, rotatedX, rotatedY);
     return;
   }
 
@@ -115,8 +145,11 @@ void GfxRenderer::fillRect(const int x, const int y, const int width, const int
 }
 
 void GfxRenderer::drawImage(const uint8_t bitmap[], const int x, const int y, const int width, const int height) const {
-  // Flip X and Y for portrait mode
+  // TODO: Rotate bits
-  einkDisplay.drawImage(bitmap, y, x, height, width);
+  int rotatedX = 0;
+  int rotatedY = 0;
+  rotateCoordinates(x, y, &rotatedX, &rotatedY);
+  einkDisplay.drawImage(bitmap, rotatedX, rotatedY, width, height);
 }
 
 void GfxRenderer::drawBitmap(const Bitmap& bitmap, const int x, const int y, const int maxWidth,
@@ -205,23 +238,34 @@ void GfxRenderer::displayBuffer(const EInkDisplay::RefreshMode refreshMode) cons
   einkDisplay.displayBuffer(refreshMode);
 }
 
-void GfxRenderer::displayWindow(const int x, const int y, const int width, const int height) const {
+// Note: Internal driver treats screen in command orientation; this library exposes a logical orientation
-  // Rotate coordinates from portrait (480x800) to landscape (800x480)
+int GfxRenderer::getScreenWidth() const {
-  // Rotation: 90 degrees clockwise
+  switch (orientation) {
-  // Portrait coordinates: (x, y) with dimensions (width, height)
+    case Portrait:
-  // Landscape coordinates: (rotatedX, rotatedY) with dimensions (rotatedWidth, rotatedHeight)
+    case PortraitInverted:
-
+      // 480px wide in portrait logical coordinates
-  const int rotatedX = y;
+      return EInkDisplay::DISPLAY_HEIGHT;
-  const int rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x - width + 1;
+    case LandscapeClockwise:
-  const int rotatedWidth = height;
+    case LandscapeCounterClockwise:
-  const int rotatedHeight = width;
+      // 800px wide in landscape logical coordinates
-
+      return EInkDisplay::DISPLAY_WIDTH;
-  einkDisplay.displayWindow(rotatedX, rotatedY, rotatedWidth, rotatedHeight);
+  }
+  return EInkDisplay::DISPLAY_HEIGHT;
 }
 
-// Note: Internal driver treats screen in command orientation, this library treats in portrait orientation
+int GfxRenderer::getScreenHeight() const {
-int GfxRenderer::getScreenWidth() { return EInkDisplay::DISPLAY_HEIGHT; }
+  switch (orientation) {
-int GfxRenderer::getScreenHeight() { return EInkDisplay::DISPLAY_WIDTH; }
+    case Portrait:
+    case PortraitInverted:
+      // 800px tall in portrait logical coordinates
+      return EInkDisplay::DISPLAY_WIDTH;
+    case LandscapeClockwise:
+    case LandscapeCounterClockwise:
+      // 480px tall in landscape logical coordinates
+      return EInkDisplay::DISPLAY_HEIGHT;
+  }
+  return EInkDisplay::DISPLAY_WIDTH;
+}
 
 int GfxRenderer::getSpaceWidth(const int fontId) const {
   if (fontMap.count(fontId) == 0) {
@@ -432,3 +476,32 @@ void GfxRenderer::renderChar(const EpdFontFamily& fontFamily, const uint32_t cp,
 
   *x += glyph->advanceX;
 }
+
+void GfxRenderer::getOrientedViewableTRBL(int* outTop, int* outRight, int* outBottom, int* outLeft) const {
+  switch (orientation) {
+    case Portrait:
+      *outTop = VIEWABLE_MARGIN_TOP;
+      *outRight = VIEWABLE_MARGIN_RIGHT;
+      *outBottom = VIEWABLE_MARGIN_BOTTOM;
+      *outLeft = VIEWABLE_MARGIN_LEFT;
+      break;
+    case LandscapeClockwise:
+      *outTop = VIEWABLE_MARGIN_LEFT;
+      *outRight = VIEWABLE_MARGIN_TOP;
+      *outBottom = VIEWABLE_MARGIN_RIGHT;
+      *outLeft = VIEWABLE_MARGIN_BOTTOM;
+      break;
+    case PortraitInverted:
+      *outTop = VIEWABLE_MARGIN_BOTTOM;
+      *outRight = VIEWABLE_MARGIN_LEFT;
+      *outBottom = VIEWABLE_MARGIN_TOP;
+      *outLeft = VIEWABLE_MARGIN_RIGHT;
+      break;
+    case LandscapeCounterClockwise:
+      *outTop = VIEWABLE_MARGIN_RIGHT;
+      *outRight = VIEWABLE_MARGIN_BOTTOM;
+      *outBottom = VIEWABLE_MARGIN_LEFT;
+      *outLeft = VIEWABLE_MARGIN_TOP;
+      break;
+  }
+}

lib/GfxRenderer/GfxRenderer.h

@@ -12,6 +12,14 @@ class GfxRenderer {
  public:
   enum RenderMode { BW, GRAYSCALE_LSB, GRAYSCALE_MSB };
 
+  // Logical screen orientation from the perspective of callers
+  enum Orientation {
+    Portrait,                  // 480x800 logical coordinates (current default)
+    LandscapeClockwise,        // 800x480 logical coordinates, rotated 180° (swap top/bottom)
+    PortraitInverted,          // 480x800 logical coordinates, inverted
+    LandscapeCounterClockwise  // 800x480 logical coordinates, native panel orientation
+  };
+
  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;
@@ -20,24 +28,35 @@ class GfxRenderer {
 
   EInkDisplay& einkDisplay;
   RenderMode renderMode;
+  Orientation orientation;
   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();
+  void rotateCoordinates(int x, int y, int* rotatedX, int* rotatedY) const;
 
  public:
-  explicit GfxRenderer(EInkDisplay& einkDisplay) : einkDisplay(einkDisplay), renderMode(BW) {}
+  explicit GfxRenderer(EInkDisplay& einkDisplay) : einkDisplay(einkDisplay), renderMode(BW), orientation(Portrait) {}
   ~GfxRenderer() = default;
 
+  static constexpr int VIEWABLE_MARGIN_TOP = 9;
+  static constexpr int VIEWABLE_MARGIN_RIGHT = 3;
+  static constexpr int VIEWABLE_MARGIN_BOTTOM = 3;
+  static constexpr int VIEWABLE_MARGIN_LEFT = 3;
+
   // Setup
   void insertFont(int fontId, EpdFontFamily font);
 
+  // Orientation control (affects logical width/height and coordinate transforms)
+  void setOrientation(const Orientation o) { orientation = o; }
+  Orientation getOrientation() const { return orientation; }
+
   // Screen ops
-  static int getScreenWidth();
+  int getScreenWidth() const;
-  static int getScreenHeight();
+  int getScreenHeight() const;
   void displayBuffer(EInkDisplay::RefreshMode refreshMode = EInkDisplay::FAST_REFRESH) const;
-  // EXPERIMENTAL: Windowed update - display only a rectangular region (portrait coordinates)
+  // EXPERIMENTAL: Windowed update - display only a rectangular region
   void displayWindow(int x, int y, int width, int height) const;
   void invertScreen() const;
   void clearScreen(uint8_t color = 0xFF) const;
@@ -72,4 +91,5 @@ class GfxRenderer {
   uint8_t* getFrameBuffer() const;
   static size_t getBufferSize();
   void grayscaleRevert() const;
+  void getOrientedViewableTRBL(int* outTop, int* outRight, int* outBottom, int* outLeft) const;
 };

src/CrossPointSettings.cpp

@@ -10,7 +10,8 @@ CrossPointSettings CrossPointSettings::instance;
 
 namespace {
 constexpr uint8_t SETTINGS_FILE_VERSION = 1;
-constexpr uint8_t SETTINGS_COUNT = 4;
+// Increment this when adding new persisted settings fields
+constexpr uint8_t SETTINGS_COUNT = 5;
 constexpr char SETTINGS_FILE[] = "/.crosspoint/settings.bin";
 }  // namespace
 
@@ -29,6 +30,7 @@ bool CrossPointSettings::saveToFile() const {
   serialization::writePod(outputFile, extraParagraphSpacing);
   serialization::writePod(outputFile, shortPwrBtn);
   serialization::writePod(outputFile, statusBar);
+  serialization::writePod(outputFile, orientation);
   outputFile.close();
 
   Serial.printf("[%lu] [CPS] Settings saved to file\n", millis());
@@ -52,7 +54,7 @@ bool CrossPointSettings::loadFromFile() {
   uint8_t fileSettingsCount = 0;
   serialization::readPod(inputFile, fileSettingsCount);
 
-  // load settings that exist
+  // load settings that exist (support older files with fewer fields)
   uint8_t settingsRead = 0;
   do {
     serialization::readPod(inputFile, sleepScreen);
@@ -63,6 +65,8 @@ bool CrossPointSettings::loadFromFile() {
     if (++settingsRead >= fileSettingsCount) break;
     serialization::readPod(inputFile, statusBar);
     if (++settingsRead >= fileSettingsCount) break;
+    serialization::readPod(inputFile, orientation);
+    if (++settingsRead >= fileSettingsCount) break;
   } while (false);
 
   inputFile.close();

src/CrossPointSettings.h

@@ -21,6 +21,13 @@ class CrossPointSettings {
   // Status bar display type enum
   enum STATUS_BAR_MODE { NONE = 0, NO_PROGRESS = 1, FULL = 2 };
 
+  enum ORIENTATION {
+    PORTRAIT = 0,      // 480x800 logical coordinates (current default)
+    LANDSCAPE_CW = 1,  // 800x480 logical coordinates, rotated 180° (swap top/bottom)
+    INVERTED = 2,      // 480x800 logical coordinates, inverted
+    LANDSCAPE_CCW = 3  // 800x480 logical coordinates, native panel orientation
+  };
+
   // Sleep screen settings
   uint8_t sleepScreen = DARK;
   // Status bar settings
@@ -29,6 +36,9 @@ class CrossPointSettings {
   uint8_t extraParagraphSpacing = 1;
   // Duration of the power button press
   uint8_t shortPwrBtn = 0;
+  // EPUB reading orientation settings
+  // 0 = portrait (default), 1 = landscape clockwise, 2 = inverted, 3 = landscape counter-clockwise
+  uint8_t orientation = PORTRAIT;
 
   ~CrossPointSettings() = default;
 

src/activities/boot_sleep/BootActivity.cpp

@@ -8,11 +8,11 @@
 void BootActivity::onEnter() {
   Activity::onEnter();
 
-  const auto pageWidth = GfxRenderer::getScreenWidth();
+  const auto pageWidth = renderer.getScreenWidth();
-  const auto pageHeight = GfxRenderer::getScreenHeight();
+  const auto pageHeight = renderer.getScreenHeight();
 
   renderer.clearScreen();
-  renderer.drawImage(CrossLarge, (pageWidth - 128) / 2, (pageHeight - 128) / 2, 128, 128);
+  renderer.drawImage(CrossLarge, (pageWidth + 128) / 2, (pageHeight - 128) / 2, 128, 128);
   renderer.drawCenteredText(UI_FONT_ID, pageHeight / 2 + 70, "CrossPoint", true, BOLD);
   renderer.drawCenteredText(SMALL_FONT_ID, pageHeight / 2 + 95, "BOOTING");
   renderer.drawCenteredText(SMALL_FONT_ID, pageHeight - 30, CROSSPOINT_VERSION);

src/activities/boot_sleep/SleepActivity.cpp

@@ -112,7 +112,7 @@ void SleepActivity::renderDefaultSleepScreen() const {
   const auto pageHeight = renderer.getScreenHeight();
 
   renderer.clearScreen();
-  renderer.drawImage(CrossLarge, (pageWidth - 128) / 2, (pageHeight - 128) / 2, 128, 128);
+  renderer.drawImage(CrossLarge, (pageWidth + 128) / 2, (pageHeight - 128) / 2, 128, 128);
   renderer.drawCenteredText(UI_FONT_ID, pageHeight / 2 + 70, "CrossPoint", true, BOLD);
   renderer.drawCenteredText(SMALL_FONT_ID, pageHeight / 2 + 95, "SLEEPING");
 

src/activities/reader/EpubReaderActivity.cpp

@@ -16,10 +16,8 @@ constexpr int pagesPerRefresh = 15;
 constexpr unsigned long skipChapterMs = 700;
 constexpr unsigned long goHomeMs = 1000;
 constexpr float lineCompression = 0.95f;
-constexpr int marginTop = 8;
+constexpr int horizontalPadding = 5;
-constexpr int marginRight = 10;
+constexpr int statusBarMargin = 19;
-constexpr int marginBottom = 22;
-constexpr int marginLeft = 10;
 }  // namespace
 
 void EpubReaderActivity::taskTrampoline(void* param) {
@@ -34,6 +32,24 @@ void EpubReaderActivity::onEnter() {
     return;
   }
 
+  // Configure screen orientation based on settings
+  switch (SETTINGS.orientation) {
+    case CrossPointSettings::ORIENTATION::PORTRAIT:
+      renderer.setOrientation(GfxRenderer::Orientation::Portrait);
+      break;
+    case CrossPointSettings::ORIENTATION::LANDSCAPE_CW:
+      renderer.setOrientation(GfxRenderer::Orientation::LandscapeClockwise);
+      break;
+    case CrossPointSettings::ORIENTATION::INVERTED:
+      renderer.setOrientation(GfxRenderer::Orientation::PortraitInverted);
+      break;
+    case CrossPointSettings::ORIENTATION::LANDSCAPE_CCW:
+      renderer.setOrientation(GfxRenderer::Orientation::LandscapeCounterClockwise);
+      break;
+    default:
+      break;
+  }
+
   renderingMutex = xSemaphoreCreateMutex();
 
   epub->setupCacheDir();
@@ -67,6 +83,9 @@ void EpubReaderActivity::onEnter() {
 void EpubReaderActivity::onExit() {
   ActivityWithSubactivity::onExit();
 
+  // Reset orientation back to portrait for the rest of the UI
+  renderer.setOrientation(GfxRenderer::Orientation::Portrait);
+
   // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
   if (displayTaskHandle) {
@@ -219,12 +238,24 @@ void EpubReaderActivity::renderScreen() {
     return;
   }
 
+  // Apply screen viewable areas and additional padding
+  int orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft;
+  renderer.getOrientedViewableTRBL(&orientedMarginTop, &orientedMarginRight, &orientedMarginBottom,
+                                   &orientedMarginLeft);
+  orientedMarginLeft += horizontalPadding;
+  orientedMarginRight += horizontalPadding;
+  orientedMarginBottom += statusBarMargin;
+
   if (!section) {
     const auto filepath = epub->getSpineItem(currentSpineIndex).href;
     Serial.printf("[%lu] [ERS] Loading file: %s, index: %d\n", millis(), filepath.c_str(), currentSpineIndex);
     section = std::unique_ptr<Section>(new Section(epub, currentSpineIndex, renderer));
-    if (!section->loadCacheMetadata(READER_FONT_ID, lineCompression, marginTop, marginRight, marginBottom, marginLeft,
+
-                                    SETTINGS.extraParagraphSpacing)) {
+    const auto viewportWidth = renderer.getScreenWidth() - orientedMarginLeft - orientedMarginRight;
+    const auto viewportHeight = renderer.getScreenHeight() - orientedMarginTop - orientedMarginBottom;
+
+    if (!section->loadCacheMetadata(READER_FONT_ID, lineCompression, SETTINGS.extraParagraphSpacing, viewportWidth,
+                                    viewportHeight)) {
       Serial.printf("[%lu] [ERS] Cache not found, building...\n", millis());
 
       // Progress bar dimensions
@@ -236,8 +267,8 @@ void EpubReaderActivity::renderScreen() {
       const int boxWidthNoBar = textWidth + boxMargin * 2;
       const int boxHeightWithBar = renderer.getLineHeight(READER_FONT_ID) + barHeight + boxMargin * 3;
       const int boxHeightNoBar = renderer.getLineHeight(READER_FONT_ID) + boxMargin * 2;
-      const int boxXWithBar = (GfxRenderer::getScreenWidth() - boxWidthWithBar) / 2;
+      const int boxXWithBar = (renderer.getScreenWidth() - boxWidthWithBar) / 2;
-      const int boxXNoBar = (GfxRenderer::getScreenWidth() - boxWidthNoBar) / 2;
+      const int boxXNoBar = (renderer.getScreenWidth() - boxWidthNoBar) / 2;
       constexpr int boxY = 50;
       const int barX = boxXWithBar + (boxWidthWithBar - barWidth) / 2;
       const int barY = boxY + renderer.getLineHeight(READER_FONT_ID) + boxMargin * 2;
@@ -254,8 +285,7 @@ void EpubReaderActivity::renderScreen() {
       section->setupCacheDir();
 
       // Setup callback - only called for chapters >= 50KB, redraws with progress bar
-      auto progressSetup = [this, boxXWithBar, boxWidthWithBar, boxHeightWithBar, boxMargin, barX, barY, barWidth,
+      auto progressSetup = [this, boxXWithBar, boxWidthWithBar, boxHeightWithBar, barX, barY] {
-                            barHeight]() {
         renderer.fillRect(boxXWithBar, boxY, boxWidthWithBar, boxHeightWithBar, false);
         renderer.drawText(READER_FONT_ID, boxXWithBar + boxMargin, boxY + boxMargin, "Indexing...");
         renderer.drawRect(boxXWithBar + 5, boxY + 5, boxWidthWithBar - 10, boxHeightWithBar - 10);
@@ -270,8 +300,8 @@ void EpubReaderActivity::renderScreen() {
         renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
       };
 
-      if (!section->persistPageDataToSD(READER_FONT_ID, lineCompression, marginTop, marginRight, marginBottom,
+      if (!section->persistPageDataToSD(READER_FONT_ID, lineCompression, SETTINGS.extraParagraphSpacing, viewportWidth,
-                                        marginLeft, SETTINGS.extraParagraphSpacing, progressSetup, progressCallback)) {
+                                        viewportHeight, progressSetup, progressCallback)) {
         Serial.printf("[%lu] [ERS] Failed to persist page data to SD\n", millis());
         section.reset();
         return;
@@ -292,7 +322,7 @@ void EpubReaderActivity::renderScreen() {
   if (section->pageCount == 0) {
     Serial.printf("[%lu] [ERS] No pages to render\n", millis());
     renderer.drawCenteredText(READER_FONT_ID, 300, "Empty chapter", true, BOLD);
-    renderStatusBar();
+    renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
     renderer.displayBuffer();
     return;
   }
@@ -300,7 +330,7 @@ void EpubReaderActivity::renderScreen() {
   if (section->currentPage < 0 || section->currentPage >= section->pageCount) {
     Serial.printf("[%lu] [ERS] Page out of bounds: %d (max %d)\n", millis(), section->currentPage, section->pageCount);
     renderer.drawCenteredText(READER_FONT_ID, 300, "Out of bounds", true, BOLD);
-    renderStatusBar();
+    renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
     renderer.displayBuffer();
     return;
   }
@@ -314,7 +344,7 @@ void EpubReaderActivity::renderScreen() {
       return renderScreen();
     }
     const auto start = millis();
-    renderContents(std::move(p));
+    renderContents(std::move(p), orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
     Serial.printf("[%lu] [ERS] Rendered page in %dms\n", millis(), millis() - start);
   }
 
@@ -330,9 +360,11 @@ void EpubReaderActivity::renderScreen() {
   }
 }
 
-void EpubReaderActivity::renderContents(std::unique_ptr<Page> page) {
+void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int orientedMarginTop,
-  page->render(renderer, READER_FONT_ID);
+                                        const int orientedMarginRight, const int orientedMarginBottom,
-  renderStatusBar();
+                                        const int orientedMarginLeft) {
+  page->render(renderer, READER_FONT_ID, orientedMarginLeft, orientedMarginTop);
+  renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
   if (pagesUntilFullRefresh <= 1) {
     renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
     pagesUntilFullRefresh = pagesPerRefresh;
@@ -349,13 +381,13 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page) {
   {
     renderer.clearScreen(0x00);
     renderer.setRenderMode(GfxRenderer::GRAYSCALE_LSB);
-    page->render(renderer, READER_FONT_ID);
+    page->render(renderer, READER_FONT_ID, orientedMarginLeft, orientedMarginTop);
     renderer.copyGrayscaleLsbBuffers();
 
     // Render and copy to MSB buffer
     renderer.clearScreen(0x00);
     renderer.setRenderMode(GfxRenderer::GRAYSCALE_MSB);
-    page->render(renderer, READER_FONT_ID);
+    page->render(renderer, READER_FONT_ID, orientedMarginLeft, orientedMarginTop);
     renderer.copyGrayscaleMsbBuffers();
 
     // display grayscale part
@@ -367,7 +399,8 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page) {
   renderer.restoreBwBuffer();
 }
 
-void EpubReaderActivity::renderStatusBar() const {
+void EpubReaderActivity::renderStatusBar(const int orientedMarginRight, const int orientedMarginBottom,
+                                         const int orientedMarginLeft) const {
   // determine visible status bar elements
   const bool showProgress = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;
   const bool showBattery = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::NO_PROGRESS ||
@@ -375,8 +408,9 @@ void EpubReaderActivity::renderStatusBar() const {
   const bool showChapterTitle = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::NO_PROGRESS ||
                                 SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;
 
-  // height variable shared by all elements
+  // Position status bar near the bottom of the logical screen, regardless of orientation
-  constexpr auto textY = 776;
+  const auto screenHeight = renderer.getScreenHeight();
+  const auto textY = screenHeight - orientedMarginBottom - 2;
   int percentageTextWidth = 0;
   int progressTextWidth = 0;
 
@@ -389,7 +423,7 @@ void EpubReaderActivity::renderStatusBar() const {
     const std::string progress = std::to_string(section->currentPage + 1) + "/" + std::to_string(section->pageCount) +
                                  "  " + std::to_string(bookProgress) + "%";
     progressTextWidth = renderer.getTextWidth(SMALL_FONT_ID, progress.c_str());
-    renderer.drawText(SMALL_FONT_ID, GfxRenderer::getScreenWidth() - marginRight - progressTextWidth, textY,
+    renderer.drawText(SMALL_FONT_ID, renderer.getScreenWidth() - orientedMarginRight - progressTextWidth, textY,
                       progress.c_str());
   }
 
@@ -398,13 +432,13 @@ void EpubReaderActivity::renderStatusBar() const {
     const uint16_t percentage = battery.readPercentage();
     const auto percentageText = std::to_string(percentage) + "%";
     percentageTextWidth = renderer.getTextWidth(SMALL_FONT_ID, percentageText.c_str());
-    renderer.drawText(SMALL_FONT_ID, 20 + marginLeft, textY, percentageText.c_str());
+    renderer.drawText(SMALL_FONT_ID, 20 + orientedMarginLeft, textY, percentageText.c_str());
 
     // 1 column on left, 2 columns on right, 5 columns of battery body
     constexpr int batteryWidth = 15;
     constexpr int batteryHeight = 10;
-    constexpr int x = marginLeft;
+    const int x = orientedMarginLeft;
-    constexpr int y = 783;
+    const int y = screenHeight - orientedMarginBottom + 5;
 
     // Top line
     renderer.drawLine(x, y, x + batteryWidth - 4, y);
@@ -429,9 +463,9 @@ void EpubReaderActivity::renderStatusBar() const {
   if (showChapterTitle) {
     // Centered chatper title text
     // Page width minus existing content with 30px padding on each side
-    const int titleMarginLeft = 20 + percentageTextWidth + 30 + marginLeft;
+    const int titleMarginLeft = 20 + percentageTextWidth + 30 + orientedMarginLeft;
-    const int titleMarginRight = progressTextWidth + 30 + marginRight;
+    const int titleMarginRight = progressTextWidth + 30 + orientedMarginRight;
-    const int availableTextWidth = GfxRenderer::getScreenWidth() - titleMarginLeft - titleMarginRight;
+    const int availableTextWidth = renderer.getScreenWidth() - titleMarginLeft - titleMarginRight;
     const int tocIndex = epub->getTocIndexForSpineIndex(currentSpineIndex);
 
     std::string title;

src/activities/reader/EpubReaderActivity.h

@@ -22,8 +22,9 @@ class EpubReaderActivity final : public ActivityWithSubactivity {
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
   void renderScreen();
-  void renderContents(std::unique_ptr<Page> p);
+  void renderContents(std::unique_ptr<Page> page, int orientedMarginTop, int orientedMarginRight,
-  void renderStatusBar() const;
+                      int orientedMarginBottom, int orientedMarginLeft);
+  void renderStatusBar(int orientedMarginRight, int orientedMarginBottom, int orientedMarginLeft) const;
 
  public:
   explicit EpubReaderActivity(GfxRenderer& renderer, InputManager& inputManager, std::unique_ptr<Epub> epub,

src/activities/reader/EpubReaderChapterSelectionActivity.cpp

@@ -7,10 +7,26 @@
 #include "config.h"
 
 namespace {
-constexpr int PAGE_ITEMS = 24;
+// Time threshold for treating a long press as a page-up/page-down
 constexpr int SKIP_PAGE_MS = 700;
 }  // namespace
 
+int EpubReaderChapterSelectionActivity::getPageItems() const {
+  // Layout constants used in renderScreen
+  constexpr int startY = 60;
+  constexpr int lineHeight = 30;
+
+  const int screenHeight = renderer.getScreenHeight();
+  const int availableHeight = screenHeight - startY;
+  int items = availableHeight / lineHeight;
+
+  // Ensure we always have at least one item per page to avoid division by zero
+  if (items < 1) {
+    items = 1;
+  }
+  return items;
+}
+
 void EpubReaderChapterSelectionActivity::taskTrampoline(void* param) {
   auto* self = static_cast<EpubReaderChapterSelectionActivity*>(param);
   self->displayTaskLoop();
@@ -56,6 +72,7 @@ void EpubReaderChapterSelectionActivity::loop() {
       inputManager.wasReleased(InputManager::BTN_DOWN) || inputManager.wasReleased(InputManager::BTN_RIGHT);
 
   const bool skipPage = inputManager.getHeldTime() > SKIP_PAGE_MS;
+  const int pageItems = getPageItems();
 
   if (inputManager.wasReleased(InputManager::BTN_CONFIRM)) {
     onSelectSpineIndex(selectorIndex);
@@ -64,14 +81,14 @@ void EpubReaderChapterSelectionActivity::loop() {
   } else if (prevReleased) {
     if (skipPage) {
       selectorIndex =
-          ((selectorIndex / PAGE_ITEMS - 1) * PAGE_ITEMS + epub->getSpineItemsCount()) % epub->getSpineItemsCount();
+          ((selectorIndex / pageItems - 1) * pageItems + epub->getSpineItemsCount()) % epub->getSpineItemsCount();
     } else {
       selectorIndex = (selectorIndex + epub->getSpineItemsCount() - 1) % epub->getSpineItemsCount();
     }
     updateRequired = true;
   } else if (nextReleased) {
     if (skipPage) {
-      selectorIndex = ((selectorIndex / PAGE_ITEMS + 1) * PAGE_ITEMS) % epub->getSpineItemsCount();
+      selectorIndex = ((selectorIndex / pageItems + 1) * pageItems) % epub->getSpineItemsCount();
     } else {
       selectorIndex = (selectorIndex + 1) % epub->getSpineItemsCount();
     }
@@ -95,17 +112,18 @@ void EpubReaderChapterSelectionActivity::renderScreen() {
   renderer.clearScreen();
 
   const auto pageWidth = renderer.getScreenWidth();
+  const int pageItems = getPageItems();
   renderer.drawCenteredText(READER_FONT_ID, 10, "Select Chapter", true, BOLD);
 
-  const auto pageStartIndex = selectorIndex / PAGE_ITEMS * PAGE_ITEMS;
+  const auto pageStartIndex = selectorIndex / pageItems * pageItems;
-  renderer.fillRect(0, 60 + (selectorIndex % PAGE_ITEMS) * 30 + 2, pageWidth - 1, 30);
+  renderer.fillRect(0, 60 + (selectorIndex % pageItems) * 30 + 2, pageWidth - 1, 30);
-  for (int i = pageStartIndex; i < epub->getSpineItemsCount() && i < pageStartIndex + PAGE_ITEMS; i++) {
+  for (int i = pageStartIndex; i < epub->getSpineItemsCount() && i < pageStartIndex + pageItems; i++) {
     const int tocIndex = epub->getTocIndexForSpineIndex(i);
     if (tocIndex == -1) {
-      renderer.drawText(UI_FONT_ID, 20, 60 + (i % PAGE_ITEMS) * 30, "Unnamed", i != selectorIndex);
+      renderer.drawText(UI_FONT_ID, 20, 60 + (i % pageItems) * 30, "Unnamed", i != selectorIndex);
     } else {
       auto item = epub->getTocItem(tocIndex);
-      renderer.drawText(UI_FONT_ID, 20 + (item.level - 1) * 15, 60 + (i % PAGE_ITEMS) * 30, item.title.c_str(),
+      renderer.drawText(UI_FONT_ID, 20 + (item.level - 1) * 15, 60 + (i % pageItems) * 30, item.title.c_str(),
                         i != selectorIndex);
     }
   }

src/activities/reader/EpubReaderChapterSelectionActivity.h

@@ -18,6 +18,10 @@ class EpubReaderChapterSelectionActivity final : public Activity {
   const std::function<void()> onGoBack;
   const std::function<void(int newSpineIndex)> onSelectSpineIndex;
 
+  // Number of items that fit on a page, derived from logical screen height.
+  // This adapts automatically when switching between portrait and landscape.
+  int getPageItems() const;
+
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
   void renderScreen();

src/activities/reader/FileSelectionActivity.cpp

@@ -158,7 +158,7 @@ void FileSelectionActivity::displayTaskLoop() {
 void FileSelectionActivity::render() const {
   renderer.clearScreen();
 
-  const auto pageWidth = GfxRenderer::getScreenWidth();
+  const auto pageWidth = renderer.getScreenWidth();
   renderer.drawCenteredText(READER_FONT_ID, 10, "Books", true, BOLD);
 
   // Help text

src/activities/settings/SettingsActivity.cpp

@@ -9,13 +9,17 @@
 
 // Define the static settings list
 namespace {
-constexpr int settingsCount = 5;
+constexpr int settingsCount = 6;
 const SettingInfo settingsList[settingsCount] = {
     // Should match with SLEEP_SCREEN_MODE
     {"Sleep Screen", SettingType::ENUM, &CrossPointSettings::sleepScreen, {"Dark", "Light", "Custom", "Cover"}},
     {"Status Bar", SettingType::ENUM, &CrossPointSettings::statusBar, {"None", "No Progress", "Full"}},
     {"Extra Paragraph Spacing", SettingType::TOGGLE, &CrossPointSettings::extraParagraphSpacing, {}},
     {"Short Power Button Click", SettingType::TOGGLE, &CrossPointSettings::shortPwrBtn, {}},
+    {"Reading Orientation",
+     SettingType::ENUM,
+     &CrossPointSettings::orientation,
+     {"Portrait", "Landscape CW", "Inverted", "Landscape CCW"}},
     {"Check for updates", SettingType::ACTION, nullptr, {}},
 };
 }  // namespace
@@ -139,8 +143,8 @@ void SettingsActivity::displayTaskLoop() {
 void SettingsActivity::render() const {
   renderer.clearScreen();
 
-  const auto pageWidth = GfxRenderer::getScreenWidth();
+  const auto pageWidth = renderer.getScreenWidth();
-  const auto pageHeight = GfxRenderer::getScreenHeight();
+  const auto pageHeight = renderer.getScreenHeight();
 
   // Draw header
   renderer.drawCenteredText(READER_FONT_ID, 10, "Settings", true, BOLD);

src/activities/util/FullScreenMessageActivity.cpp

@@ -8,7 +8,7 @@ void FullScreenMessageActivity::onEnter() {
   Activity::onEnter();
 
   const auto height = renderer.getLineHeight(UI_FONT_ID);
-  const auto top = (GfxRenderer::getScreenHeight() - height) / 2;
+  const auto top = (renderer.getScreenHeight() - height) / 2;
 
   renderer.clearScreen();
   renderer.drawCenteredText(UI_FONT_ID, top, text.c_str(), true, style);

src/activities/util/KeyboardEntryActivity.cpp

@@ -235,7 +235,7 @@ void KeyboardEntryActivity::loop() {
 }
 
 void KeyboardEntryActivity::render() const {
-  const auto pageWidth = GfxRenderer::getScreenWidth();
+  const auto pageWidth = renderer.getScreenWidth();
 
   renderer.clearScreen();
 
@@ -329,7 +329,7 @@ void KeyboardEntryActivity::render() const {
   }
 
   // Draw help text at absolute bottom of screen (consistent with other screens)
-  const auto pageHeight = GfxRenderer::getScreenHeight();
+  const auto pageHeight = renderer.getScreenHeight();
   renderer.drawText(SMALL_FONT_ID, 10, pageHeight - 30, "Navigate: D-pad | Select: OK | Cancel: BACK");
   renderer.displayBuffer();
 }