fix: Re-apply upstream PRs #1005, #1010, #1003

Re-applies changes that were accidentally discarded during a prior
dry-run cherry-pick reset (git checkout -- .).

- PR #1005: Use HalPowerManager for battery percentage (uint16_t return
  type, remove Battery.h, update theme files)
- PR #1010: Fix dangling pointer in onGoToReader()
- PR #1003: Render image placeholders while waiting for decode (adds
  isCached, renderPlaceholder, renderTextOnly, countUncachedImages,
  renderImagePlaceholders)

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

lib/Epub/Epub/Page.cpp

@@ -61,6 +61,49 @@ std::unique_ptr<PageImage> PageImage::deserialize(FsFile& file) {
   return std::unique_ptr<PageImage>(new PageImage(std::move(ib), xPos, yPos));
 }
 
+bool PageImage::isCached() const { return imageBlock->isCached(); }
+
+void PageImage::renderPlaceholder(GfxRenderer& renderer, const int xOffset, const int yOffset) const {
+  int x = xPos + xOffset;
+  int y = yPos + yOffset;
+  int w = imageBlock->getWidth();
+  int h = imageBlock->getHeight();
+  renderer.fillRect(x, y, w, h, true);
+  if (w > 2 && h > 2) {
+    renderer.fillRect(x + 1, y + 1, w - 2, h - 2, false);
+  }
+}
+
+void Page::renderTextOnly(GfxRenderer& renderer, const int fontId, const int xOffset, const int yOffset) const {
+  for (auto& element : elements) {
+    if (element->getTag() == TAG_PageLine) {
+      element->render(renderer, fontId, xOffset, yOffset);
+    }
+  }
+}
+
+int Page::countUncachedImages() const {
+  int count = 0;
+  for (auto& element : elements) {
+    if (element->getTag() == TAG_PageImage) {
+      auto* img = static_cast<PageImage*>(element.get());
+      if (!img->isCached()) {
+        count++;
+      }
+    }
+  }
+  return count;
+}
+
+void Page::renderImagePlaceholders(GfxRenderer& renderer, const int xOffset, const int yOffset) const {
+  for (auto& element : elements) {
+    if (element->getTag() == TAG_PageImage) {
+      auto* img = static_cast<PageImage*>(element.get());
+      img->renderPlaceholder(renderer, xOffset, yOffset);
+    }
+  }
+}
+
 // ---------------------------------------------------------------------------
 // PageTableRow
 // ---------------------------------------------------------------------------

lib/Epub/Epub/Page.h

@@ -80,6 +80,8 @@ class PageImage final : public PageElement {
   void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) override;
   bool serialize(FsFile& file) override;
   PageElementTag getTag() const override { return TAG_PageImage; }
+  bool isCached() const;
+  void renderPlaceholder(GfxRenderer& renderer, int xOffset, int yOffset) const;
   static std::unique_ptr<PageImage> deserialize(FsFile& file);
 
   // Helper to get image block dimensions (needed for bounding box calculation)
@@ -104,4 +106,8 @@ class Page {
   // Returns true if page has images and fills out the bounding box coordinates.
   // If no images, returns false.
   bool getImageBoundingBox(int& outX, int& outY, int& outWidth, int& outHeight) const;
+
+  void renderTextOnly(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) const;
+  int countUncachedImages() const;
+  void renderImagePlaceholders(GfxRenderer& renderer, int xOffset, int yOffset) const;
 };

lib/Epub/Epub/blocks/ImageBlock.cpp

@@ -93,6 +93,11 @@ bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x,
 
 }  // namespace
 
+bool ImageBlock::isCached() const {
+  std::string cachePath = getCachePath(imagePath);
+  return Storage.exists(cachePath.c_str());
+}
+
 void ImageBlock::render(GfxRenderer& renderer, const int x, const int y) {
   LOG_DBG("IMG", "Rendering image at %d,%d: %s (%dx%d)", x, y, imagePath.c_str(), width, height);
 

lib/Epub/Epub/blocks/ImageBlock.h

@@ -16,6 +16,7 @@ class ImageBlock final : public Block {
   int16_t getHeight() const { return height; }
 
   bool imageExists() const;
+  bool isCached() const;
 
   BlockType getType() override { return IMAGE_BLOCK; }
   bool isEmpty() override { return false; }

lib/Epub/Epub/converters/PngToFramebufferConverter.cpp

@@ -90,6 +90,32 @@ int32_t pngSeekWithHandle(PNGFILE* pFile, int32_t pos) {
 constexpr size_t PNG_DECODER_APPROX_SIZE = 44 * 1024;                          // ~42 KB + overhead
 constexpr size_t MIN_FREE_HEAP_FOR_PNG = PNG_DECODER_APPROX_SIZE + 16 * 1024;  // decoder + 16 KB headroom
 
+// PNGdec keeps TWO scanlines in its internal ucPixels buffer (current + previous)
+// and each scanline includes a leading filter byte.
+// Required storage is therefore approximately: 2 * (pitch + 1) + alignment slack.
+// If PNG_MAX_BUFFERED_PIXELS is smaller than this requirement for a given image,
+// PNGdec can overrun its internal buffer before our draw callback executes.
+int bytesPerPixelFromType(int pixelType) {
+  switch (pixelType) {
+    case PNG_PIXEL_TRUECOLOR:
+      return 3;
+    case PNG_PIXEL_GRAY_ALPHA:
+      return 2;
+    case PNG_PIXEL_TRUECOLOR_ALPHA:
+      return 4;
+    case PNG_PIXEL_GRAYSCALE:
+    case PNG_PIXEL_INDEXED:
+    default:
+      return 1;
+  }
+}
+
+int requiredPngInternalBufferBytes(int srcWidth, int pixelType) {
+  // +1 filter byte per scanline, *2 for current+previous lines, +32 for alignment margin.
+  int pitch = srcWidth * bytesPerPixelFromType(pixelType);
+  return ((pitch + 1) * 2) + 32;
+}
+
 // Convert entire source line to grayscale with alpha blending to white background.
 // For indexed PNGs with tRNS chunk, alpha values are stored at palette[768] onwards.
 // Processing the whole line at once improves cache locality and reduces per-pixel overhead.
@@ -304,6 +330,18 @@ bool PngToFramebufferConverter::decodeToFramebuffer(const std::string& imagePath
   LOG_DBG("PNG", "PNG %dx%d -> %dx%d (scale %.2f), bpp: %d", ctx.srcWidth, ctx.srcHeight, ctx.dstWidth, ctx.dstHeight,
           ctx.scale, png->getBpp());
 
+  const int pixelType = png->getPixelType();
+  const int requiredInternal = requiredPngInternalBufferBytes(ctx.srcWidth, pixelType);
+  if (requiredInternal > PNG_MAX_BUFFERED_PIXELS) {
+    LOG_ERR("PNG",
+            "PNG row buffer too small: need %d bytes for width=%d type=%d, configured PNG_MAX_BUFFERED_PIXELS=%d",
+            requiredInternal, ctx.srcWidth, pixelType, PNG_MAX_BUFFERED_PIXELS);
+    LOG_ERR("PNG", "Aborting decode to avoid PNGdec internal buffer overflow");
+    png->close();
+    delete png;
+    return false;
+  }
+
   if (png->getBpp() != 8) {
     warnUnsupportedFeature("bit depth (" + std::to_string(png->getBpp()) + "bpp)", imagePath);
   }

lib/Epub/Epub/css/CssParser.cpp

@@ -295,6 +295,9 @@ void CssParser::parseDeclarationIntoStyle(const std::string& decl, CssStyle& sty
       style.defined.paddingTop = style.defined.paddingRight = style.defined.paddingBottom = style.defined.paddingLeft =
           1;
     }
+  } else if (propNameBuf == "height") {
+    style.imageHeight = interpretLength(propValueBuf);
+    style.defined.imageHeight = 1;
   } else if (propNameBuf == "width") {
     style.width = interpretLength(propValueBuf);
     style.defined.width = 1;
@@ -565,7 +568,7 @@ CssStyle CssParser::parseInlineStyle(const std::string& styleValue) { return par
 // Cache serialization
 
 // Cache format version - increment when format changes
-constexpr uint8_t CSS_CACHE_VERSION = 2;
+constexpr uint8_t CSS_CACHE_VERSION = 3;
 constexpr char rulesCache[] = "/css_rules.cache";
 
 bool CssParser::hasCache() const { return Storage.exists((cachePath + rulesCache).c_str()); }
@@ -616,6 +619,8 @@ bool CssParser::saveToCache() const {
     writeLength(style.paddingBottom);
     writeLength(style.paddingLeft);
     writeLength(style.paddingRight);
+    writeLength(style.imageHeight);
+    writeLength(style.width);
 
     // Write defined flags as uint16_t
     uint16_t definedBits = 0;
@@ -632,6 +637,8 @@ bool CssParser::saveToCache() const {
     if (style.defined.paddingBottom) definedBits |= 1 << 10;
     if (style.defined.paddingLeft) definedBits |= 1 << 11;
     if (style.defined.paddingRight) definedBits |= 1 << 12;
+    if (style.defined.width) definedBits |= 1 << 13;
+    if (style.defined.imageHeight) definedBits |= 1 << 14;
     file.write(reinterpret_cast<const uint8_t*>(&definedBits), sizeof(definedBits));
   }
 
@@ -733,7 +740,8 @@ bool CssParser::loadFromCache() {
 
     if (!readLength(style.textIndent) || !readLength(style.marginTop) || !readLength(style.marginBottom) ||
         !readLength(style.marginLeft) || !readLength(style.marginRight) || !readLength(style.paddingTop) ||
-        !readLength(style.paddingBottom) || !readLength(style.paddingLeft) || !readLength(style.paddingRight)) {
+        !readLength(style.paddingBottom) || !readLength(style.paddingLeft) || !readLength(style.paddingRight) ||
+        !readLength(style.imageHeight) || !readLength(style.width)) {
       rulesBySelector_.clear();
       file.close();
       return false;
@@ -759,6 +767,8 @@ bool CssParser::loadFromCache() {
     style.defined.paddingBottom = (definedBits & 1 << 10) != 0;
     style.defined.paddingLeft = (definedBits & 1 << 11) != 0;
     style.defined.paddingRight = (definedBits & 1 << 12) != 0;
+    style.defined.width = (definedBits & 1 << 13) != 0;
+    style.defined.imageHeight = (definedBits & 1 << 14) != 0;
 
     rulesBySelector_[selector] = style;
   }

lib/Epub/Epub/css/CssStyle.h

@@ -70,6 +70,7 @@ struct CssPropertyFlags {
   uint16_t paddingLeft : 1;
   uint16_t paddingRight : 1;
   uint16_t width : 1;
+  uint16_t imageHeight : 1;
 
   CssPropertyFlags()
       : textAlign(0),
@@ -85,18 +86,20 @@ struct CssPropertyFlags {
         paddingBottom(0),
         paddingLeft(0),
         paddingRight(0),
-        width(0) {}
+        width(0),
+        imageHeight(0) {}
 
   [[nodiscard]] bool anySet() const {
     return textAlign || fontStyle || fontWeight || textDecoration || textIndent || marginTop || marginBottom ||
-           marginLeft || marginRight || paddingTop || paddingBottom || paddingLeft || paddingRight || width;
+           marginLeft || marginRight || paddingTop || paddingBottom || paddingLeft || paddingRight || width ||
+           imageHeight;
   }
 
   void clearAll() {
     textAlign = fontStyle = fontWeight = textDecoration = textIndent = 0;
     marginTop = marginBottom = marginLeft = marginRight = 0;
     paddingTop = paddingBottom = paddingLeft = paddingRight = 0;
-    width = 0;
+    width = imageHeight = 0;
   }
 };
 
@@ -118,7 +121,8 @@ struct CssStyle {
   CssLength paddingBottom;  // Padding after
   CssLength paddingLeft;    // Padding left
   CssLength paddingRight;   // Padding right
-  CssLength width;          // Element width (used for table columns/cells)
+  CssLength width;          // Element width (used for table columns/cells and image sizing)
+  CssLength imageHeight;    // Height for img (e.g. 2em) -- width derived from aspect ratio when only height set
 
   CssPropertyFlags defined;  // Tracks which properties were explicitly set
 
@@ -181,6 +185,10 @@ struct CssStyle {
       width = base.width;
       defined.width = 1;
     }
+    if (base.hasImageHeight()) {
+      imageHeight = base.imageHeight;
+      defined.imageHeight = 1;
+    }
   }
 
   [[nodiscard]] bool hasTextAlign() const { return defined.textAlign; }
@@ -197,6 +205,7 @@ struct CssStyle {
   [[nodiscard]] bool hasPaddingLeft() const { return defined.paddingLeft; }
   [[nodiscard]] bool hasPaddingRight() const { return defined.paddingRight; }
   [[nodiscard]] bool hasWidth() const { return defined.width; }
+  [[nodiscard]] bool hasImageHeight() const { return defined.imageHeight; }
 
   void reset() {
     textAlign = CssTextAlign::Left;
@@ -207,6 +216,7 @@ struct CssStyle {
     marginTop = marginBottom = marginLeft = marginRight = CssLength{};
     paddingTop = paddingBottom = paddingLeft = paddingRight = CssLength{};
     width = CssLength{};
+    imageHeight = CssLength{};
     defined.clearAll();
   }
 };

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp

@@ -418,7 +418,47 @@ void XMLCALL ChapterHtmlSlimParser::startElement(void* userData, const XML_Char*
               if (decoder->getDimensions(cachedImagePath, dims)) {
                 LOG_DBG("EHP", "Image dimensions: %dx%d", dims.width, dims.height);
 
-                // Scale to fit viewport while maintaining aspect ratio
+                int displayWidth = 0;
+                int displayHeight = 0;
+                const float emSize =
+                    static_cast<float>(self->renderer.getLineHeight(self->fontId)) * self->lineCompression;
+                CssStyle imgStyle = self->cssParser ? self->cssParser->resolveStyle("img", classAttr) : CssStyle{};
+                if (!styleAttr.empty()) {
+                  imgStyle.applyOver(CssParser::parseInlineStyle(styleAttr));
+                }
+                const bool hasCssHeight = imgStyle.hasImageHeight();
+                const bool hasCssWidth = imgStyle.hasWidth();
+
+                if (hasCssHeight && dims.width > 0 && dims.height > 0) {
+                  displayHeight = static_cast<int>(
+                      imgStyle.imageHeight.toPixels(emSize, static_cast<float>(self->viewportHeight)) + 0.5f);
+                  if (displayHeight < 1) displayHeight = 1;
+                  displayWidth =
+                      static_cast<int>(displayHeight * (static_cast<float>(dims.width) / dims.height) + 0.5f);
+                  if (displayWidth > self->viewportWidth) {
+                    displayWidth = self->viewportWidth;
+                    displayHeight =
+                        static_cast<int>(displayWidth * (static_cast<float>(dims.height) / dims.width) + 0.5f);
+                    if (displayHeight < 1) displayHeight = 1;
+                  }
+                  if (displayWidth < 1) displayWidth = 1;
+                  LOG_DBG("EHP", "Display size from CSS height: %dx%d", displayWidth, displayHeight);
+                } else if (hasCssWidth && !hasCssHeight && dims.width > 0 && dims.height > 0) {
+                  displayWidth = static_cast<int>(
+                      imgStyle.width.toPixels(emSize, static_cast<float>(self->viewportWidth)) + 0.5f);
+                  if (displayWidth > self->viewportWidth) displayWidth = self->viewportWidth;
+                  if (displayWidth < 1) displayWidth = 1;
+                  displayHeight =
+                      static_cast<int>(displayWidth * (static_cast<float>(dims.height) / dims.width) + 0.5f);
+                  if (displayHeight > self->viewportHeight) {
+                    displayHeight = self->viewportHeight;
+                    displayWidth =
+                        static_cast<int>(displayHeight * (static_cast<float>(dims.width) / dims.height) + 0.5f);
+                    if (displayWidth < 1) displayWidth = 1;
+                  }
+                  if (displayHeight < 1) displayHeight = 1;
+                  LOG_DBG("EHP", "Display size from CSS width: %dx%d", displayWidth, displayHeight);
+                } else {
                   int maxWidth = self->viewportWidth;
                   int maxHeight = self->viewportHeight;
                   float scaleX = (dims.width > maxWidth) ? (float)maxWidth / dims.width : 1.0f;
@@ -426,10 +466,10 @@ void XMLCALL ChapterHtmlSlimParser::startElement(void* userData, const XML_Char*
                   float scale = (scaleX < scaleY) ? scaleX : scaleY;
                   if (scale > 1.0f) scale = 1.0f;
 
-                int displayWidth = (int)(dims.width * scale);
-                int displayHeight = (int)(dims.height * scale);
-
+                  displayWidth = (int)(dims.width * scale);
+                  displayHeight = (int)(dims.height * scale);
                   LOG_DBG("EHP", "Display size: %dx%d (scale %.2f)", displayWidth, displayHeight, scale);
+                }
 
                 // Create page for image - only break if image won't fit remaining space
                 if (self->currentPage && !self->currentPage->elements.empty() &&

lib/GfxRenderer/GfxRenderer.cpp

@@ -59,6 +59,130 @@ static inline void rotateCoordinates(const GfxRenderer::Orientation orientation,
   }
 }
 
+enum class TextRotation { None, Rotated90CW, Rotated90CCW };
+
+// Shared glyph rendering logic for normal and rotated text.
+// Coordinate mapping and cursor advance direction are selected at compile time via the template parameter.
+template <TextRotation rotation>
+static void renderCharImpl(const GfxRenderer& renderer, GfxRenderer::RenderMode renderMode,
+                           const EpdFontFamily& fontFamily, const uint32_t cp, int* cursorX, int* cursorY,
+                           const bool pixelState, const EpdFontFamily::Style style) {
+  const EpdGlyph* glyph = fontFamily.getGlyph(cp, style);
+  if (!glyph) {
+    glyph = fontFamily.getGlyph(REPLACEMENT_GLYPH, style);
+  }
+
+  if (!glyph) {
+    LOG_ERR("GFX", "No glyph for codepoint %d", cp);
+    return;
+  }
+
+  const EpdFontData* fontData = fontFamily.getData(style);
+  const bool is2Bit = fontData->is2Bit;
+  const uint8_t width = glyph->width;
+  const uint8_t height = glyph->height;
+  const int left = glyph->left;
+  const int top = glyph->top;
+
+  const uint8_t* bitmap = renderer.getGlyphBitmap(fontData, glyph);
+
+  if (bitmap != nullptr) {
+    int outerBase, innerBase;
+    if constexpr (rotation == TextRotation::Rotated90CW) {
+      outerBase = *cursorX + fontData->ascender - top;  // screenX = outerBase + glyphY
+      innerBase = *cursorY - left;                      // screenY = innerBase - glyphX
+    } else if constexpr (rotation == TextRotation::Rotated90CCW) {
+      outerBase = *cursorX + fontData->advanceY - 1 - fontData->ascender + top;  // screenX = outerBase - glyphY
+      innerBase = *cursorY + left;                                               // screenY = innerBase + glyphX
+    } else {
+      outerBase = *cursorY - top;   // screenY = outerBase + glyphY
+      innerBase = *cursorX + left;  // screenX = innerBase + glyphX
+    }
+
+    if (is2Bit) {
+      int pixelPosition = 0;
+      for (int glyphY = 0; glyphY < height; glyphY++) {
+        int outerCoord;
+        if constexpr (rotation == TextRotation::Rotated90CCW) {
+          outerCoord = outerBase - glyphY;
+        } else {
+          outerCoord = outerBase + glyphY;
+        }
+        for (int glyphX = 0; glyphX < width; glyphX++, pixelPosition++) {
+          int screenX, screenY;
+          if constexpr (rotation == TextRotation::Rotated90CW) {
+            screenX = outerCoord;
+            screenY = innerBase - glyphX;
+          } else if constexpr (rotation == TextRotation::Rotated90CCW) {
+            screenX = outerCoord;
+            screenY = innerBase + glyphX;
+          } else {
+            screenX = innerBase + glyphX;
+            screenY = outerCoord;
+          }
+
+          const uint8_t byte = bitmap[pixelPosition >> 2];
+          const uint8_t bit_index = (3 - (pixelPosition & 3)) * 2;
+          // the direct bit from the font is 0 -> white, 1 -> light gray, 2 -> dark gray, 3 -> black
+          // we swap this to better match the way images and screen think about colors:
+          // 0 -> black, 1 -> dark grey, 2 -> light grey, 3 -> white
+          const uint8_t bmpVal = 3 - ((byte >> bit_index) & 0x3);
+
+          if (renderMode == GfxRenderer::BW && bmpVal < 3) {
+            // Black (also paints over the grays in BW mode)
+            renderer.drawPixel(screenX, screenY, pixelState);
+          } else if (renderMode == GfxRenderer::GRAYSCALE_MSB && (bmpVal == 1 || bmpVal == 2)) {
+            // Light gray (also mark the MSB if it's going to be a dark gray too)
+            // We have to flag pixels in reverse for the gray buffers, as 0 leave alone, 1 update
+            renderer.drawPixel(screenX, screenY, false);
+          } else if (renderMode == GfxRenderer::GRAYSCALE_LSB && bmpVal == 1) {
+            // Dark gray
+            renderer.drawPixel(screenX, screenY, false);
+          }
+        }
+      }
+    } else {
+      int pixelPosition = 0;
+      for (int glyphY = 0; glyphY < height; glyphY++) {
+        int outerCoord;
+        if constexpr (rotation == TextRotation::Rotated90CCW) {
+          outerCoord = outerBase - glyphY;
+        } else {
+          outerCoord = outerBase + glyphY;
+        }
+        for (int glyphX = 0; glyphX < width; glyphX++, pixelPosition++) {
+          int screenX, screenY;
+          if constexpr (rotation == TextRotation::Rotated90CW) {
+            screenX = outerCoord;
+            screenY = innerBase - glyphX;
+          } else if constexpr (rotation == TextRotation::Rotated90CCW) {
+            screenX = outerCoord;
+            screenY = innerBase + glyphX;
+          } else {
+            screenX = innerBase + glyphX;
+            screenY = outerCoord;
+          }
+
+          const uint8_t byte = bitmap[pixelPosition >> 3];
+          const uint8_t bit_index = 7 - (pixelPosition & 7);
+
+          if ((byte >> bit_index) & 1) {
+            renderer.drawPixel(screenX, screenY, pixelState);
+          }
+        }
+      }
+    }
+  }
+
+  if constexpr (rotation == TextRotation::Rotated90CW) {
+    *cursorY -= glyph->advanceX;
+  } else if constexpr (rotation == TextRotation::Rotated90CCW) {
+    *cursorY += glyph->advanceX;
+  } else {
+    *cursorX += glyph->advanceX;
+  }
+}
+
 // IMPORTANT: This function is in critical rendering path and is called for every pixel. Please keep it as simple and
 // efficient as possible.
 void GfxRenderer::drawPixel(const int x, const int y, const bool state) const {
@@ -115,7 +239,7 @@ void GfxRenderer::drawCenteredText(const int fontId, const int y, const char* te
 
 void GfxRenderer::drawText(const int fontId, const int x, const int y, const char* text, const bool black,
                            const EpdFontFamily::Style style) const {
-  const int yPos = y + getFontAscenderSize(fontId);
+  int yPos = y + getFontAscenderSize(fontId);
   int xpos = x;
 
   // cannot draw a NULL / empty string
@@ -824,7 +948,8 @@ int GfxRenderer::getSpaceWidth(const int fontId, const EpdFontFamily::Style styl
     return 0;
   }
 
-  return fontIt->second.getGlyph(' ', style)->advanceX;
+  const EpdGlyph* spaceGlyph = fontIt->second.getGlyph(' ', style);
+  return spaceGlyph ? spaceGlyph->advanceX : 0;
 }
 
 int GfxRenderer::getTextAdvanceX(const int fontId, const char* text, const EpdFontFamily::Style style) const {
@@ -838,7 +963,9 @@ int GfxRenderer::getTextAdvanceX(const int fontId, const char* text, const EpdFo
   int width = 0;
   const auto& font = fontIt->second;
   while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text)))) {
-    width += font.getGlyph(cp, style)->advanceX;
+    const EpdGlyph* glyph = font.getGlyph(cp, style);
+    if (!glyph) glyph = font.getGlyph(REPLACEMENT_GLYPH, style);
+    if (glyph) width += glyph->advanceX;
   }
   return width;
 }
@@ -887,68 +1014,12 @@ void GfxRenderer::drawTextRotated90CW(const int fontId, const int x, const int y
 
   const auto& font = fontIt->second;
 
-  // For 90° clockwise rotation:
-  // Original (glyphX, glyphY) -> Rotated (glyphY, -glyphX)
-  // Text reads from bottom to top
-
-  int yPos = y;  // Current Y position (decreases as we draw characters)
+  int xPos = x;
+  int yPos = y;
 
   uint32_t cp;
   while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text)))) {
-    const EpdGlyph* glyph = font.getGlyph(cp, style);
-    if (!glyph) {
-      glyph = font.getGlyph(REPLACEMENT_GLYPH, style);
-    }
-    if (!glyph) {
-      continue;
-    }
-
-    const EpdFontData* fontData = font.getData(style);
-    const int is2Bit = fontData->is2Bit;
-    const uint8_t width = glyph->width;
-    const uint8_t height = glyph->height;
-    const int left = glyph->left;
-    const int top = glyph->top;
-
-    const uint8_t* bitmap = getGlyphBitmap(fontData, glyph);
-
-    if (bitmap != nullptr) {
-      for (int glyphY = 0; glyphY < height; glyphY++) {
-        for (int glyphX = 0; glyphX < width; glyphX++) {
-          const int pixelPosition = glyphY * width + glyphX;
-
-          // 90° clockwise rotation transformation:
-          // screenX = x + (ascender - top + glyphY)
-          // screenY = yPos - (left + glyphX)
-          const int screenX = x + (fontData->ascender - top + glyphY);
-          const int screenY = yPos - left - glyphX;
-
-          if (is2Bit) {
-            const uint8_t byte = bitmap[pixelPosition / 4];
-            const uint8_t bit_index = (3 - pixelPosition % 4) * 2;
-            const uint8_t bmpVal = 3 - (byte >> bit_index) & 0x3;
-
-            if (renderMode == BW && bmpVal < 3) {
-              drawPixel(screenX, screenY, black);
-            } else if (renderMode == GRAYSCALE_MSB && (bmpVal == 1 || bmpVal == 2)) {
-              drawPixel(screenX, screenY, false);
-            } else if (renderMode == GRAYSCALE_LSB && bmpVal == 1) {
-              drawPixel(screenX, screenY, false);
-            }
-          } else {
-            const uint8_t byte = bitmap[pixelPosition / 8];
-            const uint8_t bit_index = 7 - (pixelPosition % 8);
-
-            if ((byte >> bit_index) & 1) {
-              drawPixel(screenX, screenY, black);
-            }
-          }
-        }
-      }
-    }
-
-    // Move to next character position (going up, so decrease Y)
-    yPos -= glyph->advanceX;
+    renderCharImpl<TextRotation::Rotated90CW>(*this, renderMode, font, cp, &xPos, &yPos, black, style);
   }
 }
 
@@ -959,77 +1030,20 @@ void GfxRenderer::drawTextRotated90CCW(const int fontId, const int x, const int
     return;
   }
 
-  if (fontMap.count(fontId) == 0) {
+  const auto fontIt = fontMap.find(fontId);
+  if (fontIt == fontMap.end()) {
     LOG_ERR("GFX", "Font %d not found", fontId);
     return;
   }
-  const auto font = fontMap.at(fontId);
 
-  // For 90° counter-clockwise rotation:
-  // Mirror of CW: glyphY maps to -X direction, glyphX maps to +Y direction
-  // Text reads from top to bottom
+  const auto& font = fontIt->second;
 
-  const int advanceY = font.getData(style)->advanceY;
-  const int ascender = font.getData(style)->ascender;
-
-  int yPos = y;  // Current Y position (increases as we draw characters)
+  int xPos = x;
+  int yPos = y;
 
   uint32_t cp;
   while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text)))) {
-    const EpdGlyph* glyph = font.getGlyph(cp, style);
-    if (!glyph) {
-      glyph = font.getGlyph(REPLACEMENT_GLYPH, style);
-    }
-    if (!glyph) {
-      continue;
-    }
-
-    const int is2Bit = font.getData(style)->is2Bit;
-    const uint32_t offset = glyph->dataOffset;
-    const uint8_t width = glyph->width;
-    const uint8_t height = glyph->height;
-    const int left = glyph->left;
-    const int top = glyph->top;
-
-    const uint8_t* bitmap = &font.getData(style)->bitmap[offset];
-
-    if (bitmap != nullptr) {
-      for (int glyphY = 0; glyphY < height; glyphY++) {
-        for (int glyphX = 0; glyphX < width; glyphX++) {
-          const int pixelPosition = glyphY * width + glyphX;
-
-          // 90° counter-clockwise rotation transformation:
-          // screenX = mirrored CW X (right-to-left within advanceY span)
-          // screenY = yPos + (left + glyphX) (downward)
-          const int screenX = x + advanceY - 1 - (ascender - top + glyphY);
-          const int screenY = yPos + left + glyphX;
-
-          if (is2Bit) {
-            const uint8_t byte = bitmap[pixelPosition / 4];
-            const uint8_t bit_index = (3 - pixelPosition % 4) * 2;
-            const uint8_t bmpVal = 3 - (byte >> bit_index) & 0x3;
-
-            if (renderMode == BW && bmpVal < 3) {
-              drawPixel(screenX, screenY, black);
-            } else if (renderMode == GRAYSCALE_MSB && (bmpVal == 1 || bmpVal == 2)) {
-              drawPixel(screenX, screenY, false);
-            } else if (renderMode == GRAYSCALE_LSB && bmpVal == 1) {
-              drawPixel(screenX, screenY, false);
-            }
-          } else {
-            const uint8_t byte = bitmap[pixelPosition / 8];
-            const uint8_t bit_index = 7 - (pixelPosition % 8);
-
-            if ((byte >> bit_index) & 1) {
-              drawPixel(screenX, screenY, black);
-            }
-          }
-        }
-      }
-    }
-
-    // Move to next character position (going down, so increase Y)
-    yPos += glyph->advanceX;
+    renderCharImpl<TextRotation::Rotated90CCW>(*this, renderMode, font, cp, &xPos, &yPos, black, style);
   }
 }
 
@@ -1094,7 +1108,7 @@ bool GfxRenderer::storeBwBuffer() {
  * Uses chunked restoration to match chunked storage.
  */
 void GfxRenderer::restoreBwBuffer() {
-  // Check if any all chunks are allocated
+  // Check if all chunks are allocated
   bool missingChunks = false;
   for (const auto& bwBufferChunk : bwBufferChunks) {
     if (!bwBufferChunk) {
@@ -1109,13 +1123,6 @@ void GfxRenderer::restoreBwBuffer() {
   }
 
   for (size_t i = 0; i < BW_BUFFER_NUM_CHUNKS; i++) {
-    // Check if chunk is missing
-    if (!bwBufferChunks[i]) {
-      LOG_ERR("GFX", "!! BW buffer chunks not stored - this is likely a bug");
-      freeBwBufferChunks();
-      return;
-    }
-
     const size_t offset = i * BW_BUFFER_CHUNK_SIZE;
     memcpy(frameBuffer + offset, bwBufferChunks[i], BW_BUFFER_CHUNK_SIZE);
   }
@@ -1136,66 +1143,9 @@ void GfxRenderer::cleanupGrayscaleWithFrameBuffer() const {
   }
 }
 
-void GfxRenderer::renderChar(const EpdFontFamily& fontFamily, const uint32_t cp, int* x, const int* y,
-                             const bool pixelState, const EpdFontFamily::Style style) const {
-  const EpdGlyph* glyph = fontFamily.getGlyph(cp, style);
-  if (!glyph) {
-    glyph = fontFamily.getGlyph(REPLACEMENT_GLYPH, style);
-  }
-
-  // no glyph?
-  if (!glyph) {
-    LOG_ERR("GFX", "No glyph for codepoint %d", cp);
-    return;
-  }
-
-  const EpdFontData* fontData = fontFamily.getData(style);
-  const int is2Bit = fontData->is2Bit;
-  const uint8_t width = glyph->width;
-  const uint8_t height = glyph->height;
-  const int left = glyph->left;
-
-  const uint8_t* bitmap = getGlyphBitmap(fontData, glyph);
-
-  if (bitmap != nullptr) {
-    for (int glyphY = 0; glyphY < height; glyphY++) {
-      const int screenY = *y - glyph->top + glyphY;
-      for (int glyphX = 0; glyphX < width; glyphX++) {
-        const int pixelPosition = glyphY * width + glyphX;
-        const int screenX = *x + left + glyphX;
-
-        if (is2Bit) {
-          const uint8_t byte = bitmap[pixelPosition / 4];
-          const uint8_t bit_index = (3 - pixelPosition % 4) * 2;
-          // the direct bit from the font is 0 -> white, 1 -> light gray, 2 -> dark gray, 3 -> black
-          // we swap this to better match the way images and screen think about colors:
-          // 0 -> black, 1 -> dark grey, 2 -> light grey, 3 -> white
-          const uint8_t bmpVal = 3 - (byte >> bit_index) & 0x3;
-
-          if (renderMode == BW && bmpVal < 3) {
-            // Black (also paints over the grays in BW mode)
-            drawPixel(screenX, screenY, pixelState);
-          } else if (renderMode == GRAYSCALE_MSB && (bmpVal == 1 || bmpVal == 2)) {
-            // Light gray (also mark the MSB if it's going to be a dark gray too)
-            // We have to flag pixels in reverse for the gray buffers, as 0 leave alone, 1 update
-            drawPixel(screenX, screenY, false);
-          } else if (renderMode == GRAYSCALE_LSB && bmpVal == 1) {
-            // Dark gray
-            drawPixel(screenX, screenY, false);
-          }
-        } else {
-          const uint8_t byte = bitmap[pixelPosition / 8];
-          const uint8_t bit_index = 7 - (pixelPosition % 8);
-
-          if ((byte >> bit_index) & 1) {
-            drawPixel(screenX, screenY, pixelState);
-          }
-        }
-      }
-    }
-  }
-
-  *x += glyph->advanceX;
+void GfxRenderer::renderChar(const EpdFontFamily& fontFamily, uint32_t cp, int* x, int* y, bool pixelState,
+                             EpdFontFamily::Style style) const {
+  renderCharImpl<TextRotation::None>(*this, renderMode, fontFamily, cp, x, y, pixelState, style);
 }
 
 void GfxRenderer::getOrientedViewableTRBL(int* outTop, int* outRight, int* outBottom, int* outLeft) const {

lib/GfxRenderer/GfxRenderer.h

@@ -38,10 +38,9 @@ class GfxRenderer {
   uint8_t* bwBufferChunks[BW_BUFFER_NUM_CHUNKS] = {nullptr};
   std::map<int, EpdFontFamily> fontMap;
   FontDecompressor* fontDecompressor = nullptr;
-  void renderChar(const EpdFontFamily& fontFamily, uint32_t cp, int* x, const int* y, bool pixelState,
+  void renderChar(const EpdFontFamily& fontFamily, uint32_t cp, int* x, int* y, bool pixelState,
                   EpdFontFamily::Style style) const;
   void freeBwBufferChunks();
-  const uint8_t* getGlyphBitmap(const EpdFontData* fontData, const EpdGlyph* glyph) const;
   template <Color color>
   void drawPixelDither(int x, int y) const;
   template <Color color>
@@ -136,6 +135,9 @@ class GfxRenderer {
   void restoreBwBuffer();  // Restore and free the stored buffer
   void cleanupGrayscaleWithFrameBuffer() const;
 
+  // Font helpers
+  const uint8_t* getGlyphBitmap(const EpdFontData* fontData, const EpdGlyph* glyph) const;
+
   // Low level functions
   uint8_t* getFrameBuffer() const;
   static size_t getBufferSize();

lib/hal/HalPowerManager.cpp

@@ -78,7 +78,7 @@ void HalPowerManager::startDeepSleep(HalGPIO& gpio) const {
   esp_deep_sleep_start();
 }
 
-int HalPowerManager::getBatteryPercentage() const {
+uint16_t HalPowerManager::getBatteryPercentage() const {
   static const BatteryMonitor battery = BatteryMonitor(BAT_GPIO0);
   return battery.readPercentage();
 }

lib/hal/HalPowerManager.h

@@ -28,7 +28,7 @@ class HalPowerManager {
   void startDeepSleep(HalGPIO& gpio) const;
 
   // Get battery percentage (range 0-100)
-  int getBatteryPercentage() const;
+  uint16_t getBatteryPercentage() const;
 
   // RAII lock to prevent low-power mode during critical work (e.g. rendering)
   class Lock {

platformio.ini

@@ -2,7 +2,7 @@
 default_envs = default
 
 [crosspoint]
-version = 1.0.0
+version = 1.1.1-rc
 
 [base]
 platform = espressif32 @ 6.12.0
@@ -31,9 +31,9 @@ build_flags =
   -std=gnu++2a
 # Enable UTF-8 long file names in SdFat
   -DUSE_UTF8_LONG_NAMES=1
-# Increase PNG scanline buffer to support up to 800px wide images
+# Increase PNG scanline buffer to support up to 2048px wide images
 # Default is (320*4+1)*2=2562, we need more for larger images
-  -DPNG_MAX_BUFFERED_PIXELS=6402
+  -DPNG_MAX_BUFFERED_PIXELS=16416
 
 build_unflags =
   -std=gnu++11

src/Battery.h

@@ -1,6 +0,0 @@
-#pragma once
-#include <BatteryMonitor.h>
-
-#define BAT_GPIO0 0  // Battery voltage
-
-static BatteryMonitor battery(BAT_GPIO0);

src/activities/boot_sleep/SleepActivity.cpp

@@ -21,6 +21,11 @@
 #include "util/BookSettings.h"
 #include "util/StringUtils.h"
 
+// Sleep cover refresh strategy when dithered letterbox fill is active:
+// 1 = Double FAST_REFRESH (clear to white, then render content -- avoids HALF_REFRESH crosstalk)
+// 0 = Standard HALF_REFRESH (original behavior)
+#define USE_SLEEP_DOUBLE_FAST_REFRESH 1
+
 namespace {
 
 // Number of source pixels along the image edge to average for the dominant color
@@ -74,37 +79,6 @@ uint8_t quantizeBayerDither(int gray, int x, int y) {
   }
 }
 
-// Check whether a gray value would produce a dithered mix that crosses the
-// level-2 / level-3 boundary.  This is the ONLY boundary where some dithered
-// pixels are BLACK (level ≤ 2) and others are WHITE (level 3) in the BW pass,
-// creating a high-frequency checkerboard that causes e-ink display crosstalk
-// and washes out adjacent content during HALF_REFRESH.
-// Gray values 171-254 produce a level-2/level-3 mix via Bayer dithering.
-bool bayerCrossesBwBoundary(uint8_t gray) { return gray > 170 && gray < 255; }
-
-// Hash-based block dithering for BW-boundary gray values (171-254).
-// Each blockSize×blockSize pixel block gets a single uniform level (2 or 3),
-// determined by a deterministic spatial hash.  The proportion of level-3 blocks
-// approximates the target gray.  Unlike Bayer, the pattern is irregular
-// (noise-like), making it much less visually obvious at the same block size.
-// The hash is purely spatial (depends only on x, y, blockSize) so it produces
-// identical levels across BW, LSB, and MSB render passes.
-static constexpr int BW_DITHER_BLOCK = 2;
-
-uint8_t hashBlockDither(uint8_t avg, int x, int y) {
-  const int bx = x / BW_DITHER_BLOCK;
-  const int by = y / BW_DITHER_BLOCK;
-  // Fast mixing hash (splitmix32-inspired)
-  uint32_t h = (uint32_t)bx * 2654435761u ^ (uint32_t)by * 2246822519u;
-  h ^= h >> 16;
-  h *= 0x45d9f3bu;
-  h ^= h >> 16;
-  // Proportion of level-3 blocks needed to approximate the target gray
-  const float ratio = (avg - 170.0f) / 85.0f;
-  const uint32_t threshold = (uint32_t)(ratio * 4294967295.0f);
-  return (h < threshold) ? 3 : 2;
-}
-
 // --- Edge average cache ---
 // Caches the computed edge averages alongside the cover BMP so we don't rescan on every sleep.
 constexpr uint8_t EDGE_CACHE_VERSION = 2;
@@ -278,19 +252,6 @@ void drawLetterboxFill(GfxRenderer& renderer, const LetterboxFillData& data, uin
 
   const bool isSolid = (fillMode == CrossPointSettings::SLEEP_SCREEN_LETTERBOX_FILL::LETTERBOX_SOLID);
 
-  // For DITHERED mode with gray values in 171-254 (the level-2/level-3 BW boundary):
-  // Pixel-level Bayer dithering creates a regular high-frequency checkerboard in
-  // the BW pass that causes e-ink display crosstalk during HALF_REFRESH.
-  //
-  // Solution: HASH-BASED BLOCK DITHERING.  Each 2x2 pixel block gets a single
-  // level (2 or 3) determined by a spatial hash, with the proportion of level-3
-  // blocks tuned to approximate the target gray.  The 2px minimum run avoids BW
-  // crosstalk, and the irregular hash pattern is much less visible than a regular
-  // Bayer grid at the same block size.
-  const bool hashA = !isSolid && bayerCrossesBwBoundary(data.avgA);
-  const bool hashB = !isSolid && bayerCrossesBwBoundary(data.avgB);
-
-  // For solid mode: snap to nearest e-ink level
   const uint8_t levelA = isSolid ? snapToEinkLevel(data.avgA) / 85 : 0;
   const uint8_t levelB = isSolid ? snapToEinkLevel(data.avgB) / 85 : 0;
 
@@ -298,13 +259,7 @@ void drawLetterboxFill(GfxRenderer& renderer, const LetterboxFillData& data, uin
     if (data.letterboxA > 0) {
       for (int y = 0; y < data.letterboxA; y++)
         for (int x = 0; x < renderer.getScreenWidth(); x++) {
-          uint8_t lv;
-          if (isSolid)
-            lv = levelA;
-          else if (hashA)
-            lv = hashBlockDither(data.avgA, x, y);
-          else
-            lv = quantizeBayerDither(data.avgA, x, y);
+          const uint8_t lv = isSolid ? levelA : quantizeBayerDither(data.avgA, x, y);
           renderer.drawPixelGray(x, y, lv);
         }
     }
@@ -312,13 +267,7 @@ void drawLetterboxFill(GfxRenderer& renderer, const LetterboxFillData& data, uin
       const int start = renderer.getScreenHeight() - data.letterboxB;
       for (int y = start; y < renderer.getScreenHeight(); y++)
         for (int x = 0; x < renderer.getScreenWidth(); x++) {
-          uint8_t lv;
-          if (isSolid)
-            lv = levelB;
-          else if (hashB)
-            lv = hashBlockDither(data.avgB, x, y);
-          else
-            lv = quantizeBayerDither(data.avgB, x, y);
+          const uint8_t lv = isSolid ? levelB : quantizeBayerDither(data.avgB, x, y);
           renderer.drawPixelGray(x, y, lv);
         }
     }
@@ -326,13 +275,7 @@ void drawLetterboxFill(GfxRenderer& renderer, const LetterboxFillData& data, uin
     if (data.letterboxA > 0) {
       for (int x = 0; x < data.letterboxA; x++)
         for (int y = 0; y < renderer.getScreenHeight(); y++) {
-          uint8_t lv;
-          if (isSolid)
-            lv = levelA;
-          else if (hashA)
-            lv = hashBlockDither(data.avgA, x, y);
-          else
-            lv = quantizeBayerDither(data.avgA, x, y);
+          const uint8_t lv = isSolid ? levelA : quantizeBayerDither(data.avgA, x, y);
           renderer.drawPixelGray(x, y, lv);
         }
     }
@@ -340,13 +283,7 @@ void drawLetterboxFill(GfxRenderer& renderer, const LetterboxFillData& data, uin
       const int start = renderer.getScreenWidth() - data.letterboxB;
       for (int x = start; x < renderer.getScreenWidth(); x++)
         for (int y = 0; y < renderer.getScreenHeight(); y++) {
-          uint8_t lv;
-          if (isSolid)
-            lv = levelB;
-          else if (hashB)
-            lv = hashBlockDither(data.avgB, x, y);
-          else
-            lv = quantizeBayerDither(data.avgB, x, y);
+          const uint8_t lv = isSolid ? levelB : quantizeBayerDither(data.avgB, x, y);
           renderer.drawPixelGray(x, y, lv);
         }
     }
@@ -543,35 +480,47 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap, const std::str
   const bool hasGreyscale = bitmap.hasGreyscale() &&
                             SETTINGS.sleepScreenCoverFilter == CrossPointSettings::SLEEP_SCREEN_COVER_FILTER::NO_FILTER;
 
-  // Draw letterbox fill (BW pass)
-  if (fillData.valid) {
-    drawLetterboxFill(renderer, fillData, fillMode);
-  }
+  const bool isInverted =
+      SETTINGS.sleepScreenCoverFilter == CrossPointSettings::SLEEP_SCREEN_COVER_FILTER::INVERTED_BLACK_AND_WHITE;
 
+#if USE_SLEEP_DOUBLE_FAST_REFRESH
+  const bool useDoubleFast =
+      fillData.valid && fillMode == CrossPointSettings::SLEEP_SCREEN_LETTERBOX_FILL::LETTERBOX_DITHERED;
+#else
+  const bool useDoubleFast = false;
+#endif
+
+  if (useDoubleFast) {
+    // Double FAST_REFRESH technique: avoids HALF_REFRESH crosstalk with dithered letterbox.
+    // Pass 1: clear to white baseline
+    renderer.clearScreen();
+    renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+
+    // Pass 2: render actual content and display
+    if (fillData.valid) drawLetterboxFill(renderer, fillData, fillMode);
     renderer.drawBitmap(bitmap, x, y, pageWidth, pageHeight, cropX, cropY);
-
-  if (SETTINGS.sleepScreenCoverFilter == CrossPointSettings::SLEEP_SCREEN_COVER_FILTER::INVERTED_BLACK_AND_WHITE) {
-    renderer.invertScreen();
-  }
-
+    if (isInverted) renderer.invertScreen();
+    renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+  } else {
+    // Standard path: single HALF_REFRESH
+    if (fillData.valid) drawLetterboxFill(renderer, fillData, fillMode);
+    renderer.drawBitmap(bitmap, x, y, pageWidth, pageHeight, cropX, cropY);
+    if (isInverted) renderer.invertScreen();
     renderer.displayBuffer(HalDisplay::HALF_REFRESH);
+  }
 
   if (hasGreyscale) {
     bitmap.rewindToData();
     renderer.clearScreen(0x00);
     renderer.setRenderMode(GfxRenderer::GRAYSCALE_LSB);
-    if (fillData.valid) {
-      drawLetterboxFill(renderer, fillData, fillMode);
-    }
+    if (fillData.valid) drawLetterboxFill(renderer, fillData, fillMode);
     renderer.drawBitmap(bitmap, x, y, pageWidth, pageHeight, cropX, cropY);
     renderer.copyGrayscaleLsbBuffers();
 
     bitmap.rewindToData();
     renderer.clearScreen(0x00);
     renderer.setRenderMode(GfxRenderer::GRAYSCALE_MSB);
-    if (fillData.valid) {
-      drawLetterboxFill(renderer, fillData, fillMode);
-    }
+    if (fillData.valid) drawLetterboxFill(renderer, fillData, fillMode);
     renderer.drawBitmap(bitmap, x, y, pageWidth, pageHeight, cropX, cropY);
     renderer.copyGrayscaleMsbBuffers();
 

src/activities/home/HomeActivity.cpp

@@ -13,7 +13,6 @@
 #include <cstring>
 #include <vector>
 
-#include "Battery.h"
 #include "CrossPointSettings.h"
 #include "CrossPointState.h"
 #include "MappedInputManager.h"

src/activities/reader/EpubReaderActivity.cpp

@@ -22,11 +22,6 @@
 #include "util/BookmarkStore.h"
 #include "util/Dictionary.h"
 
-// Image refresh optimization strategy:
-// 0 = Use double FAST_REFRESH technique (default, feels snappier)
-// 1 = Use displayWindow() for partial refresh (experimental)
-#define USE_IMAGE_DOUBLE_FAST_REFRESH 0
-
 namespace {
 // pagesPerRefresh now comes from SETTINGS.getRefreshFrequency()
 constexpr unsigned long skipChapterMs = 700;
@@ -1022,13 +1017,16 @@ void EpubReaderActivity::saveProgress(int spineIndex, int currentPage, int pageC
 void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int orientedMarginTop,
                                         const int orientedMarginRight, const int orientedMarginBottom,
                                         const int orientedMarginLeft) {
-  // Determine if this page needs special image handling
-  bool pageHasImages = page->hasImages();
-  bool useAntiAliasing = SETTINGS.textAntiAliasing;
+  // Force special handling for pages with images when anti-aliasing is on
+  bool imagePageWithAA = page->hasImages() && SETTINGS.textAntiAliasing;
 
-  // Force half refresh for pages with images when anti-aliasing is on,
-  // as grayscale tones require half refresh to display correctly
-  bool forceFullRefresh = pageHasImages && useAntiAliasing;
+  if (page->countUncachedImages() > 0) {
+    page->renderTextOnly(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
+    page->renderImagePlaceholders(renderer, orientedMarginLeft, orientedMarginTop);
+    renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
+    renderer.displayBuffer();
+    renderer.clearScreen();
+  }
 
   page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
 
@@ -1048,42 +1046,26 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
   }
 
   renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
-
-  // Check if half-refresh is needed (either entering Reader or pages counter reached)
-  if (pagesUntilFullRefresh <= 1) {
-    renderer.displayBuffer(HalDisplay::HALF_REFRESH);
-    pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
-  } else if (forceFullRefresh) {
-    // OPTIMIZATION: For image pages with anti-aliasing, use fast double-refresh technique
-    // to reduce perceived lag. Only when pagesUntilFullRefresh > 1 (screen already clean).
+  if (imagePageWithAA) {
+    // Double FAST_REFRESH with selective image blanking (pablohc's technique):
+    // HALF_REFRESH sets particles too firmly for the grayscale LUT to adjust.
+    // Instead, blank only the image area and do two fast refreshes.
     int imgX, imgY, imgW, imgH;
     if (page->getImageBoundingBox(imgX, imgY, imgW, imgH)) {
-      int screenX = imgX + orientedMarginLeft;
-      int screenY = imgY + orientedMarginTop;
-      LOG_DBG("ERS", "Image page: fast double-refresh (page bbox: %d,%d %dx%d, screen: %d,%d %dx%d)", imgX, imgY, imgW,
-              imgH, screenX, screenY, imgW, imgH);
+      renderer.fillRect(imgX + orientedMarginLeft, imgY + orientedMarginTop, imgW, imgH, false);
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
 
-#if USE_IMAGE_DOUBLE_FAST_REFRESH == 0
-      // Method A: Fill blank area + two FAST_REFRESH operations
-      renderer.fillRect(screenX, screenY, imgW, imgH, false);
-      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
       page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
       renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
       renderer.displayBuffer(HalDisplay::FAST_REFRESH);
-#else
-      // Method B (experimental): Use displayWindow() for partial refresh
-      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
-      page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
-      renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
-      renderer.displayWindow(screenX, screenY, imgW, imgH, HalDisplay::FAST_REFRESH);
-#endif
     } else {
-      LOG_DBG("ERS", "Image page but no bbox, using standard half refresh");
       renderer.displayBuffer(HalDisplay::HALF_REFRESH);
     }
-    pagesUntilFullRefresh--;
+    // Double FAST_REFRESH handles ghosting for image pages; don't count toward full refresh cadence
+  } else if (pagesUntilFullRefresh <= 1) {
+    renderer.displayBuffer(HalDisplay::HALF_REFRESH);
+    pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
   } else {
-    // Normal page without images, or images without anti-aliasing
     renderer.displayBuffer();
     pagesUntilFullRefresh--;
   }

src/components/themes/BaseTheme.cpp

@@ -1,6 +1,7 @@
 #include "BaseTheme.h"
 
 #include <GfxRenderer.h>
+#include <HalPowerManager.h>
 #include <HalStorage.h>
 #include <Logging.h>
 #include <Utf8.h>
@@ -9,7 +10,6 @@
 #include <ctime>
 #include <string>
 
-#include "Battery.h"
 #include "CrossPointSettings.h"
 #include "I18n.h"
 #include "RecentBooksStore.h"
@@ -49,7 +49,7 @@ void drawBatteryIcon(const GfxRenderer& renderer, int x, int y, int battWidth, i
 
 void BaseTheme::drawBatteryLeft(const GfxRenderer& renderer, Rect rect, const bool showPercentage) const {
   // Left aligned: icon on left, percentage on right (reader mode)
-  const uint16_t percentage = battery.readPercentage();
+  const uint16_t percentage = powerManager.getBatteryPercentage();
   const int y = rect.y + 6;
 
   if (showPercentage) {
@@ -64,7 +64,7 @@ void BaseTheme::drawBatteryLeft(const GfxRenderer& renderer, Rect rect, const bo
 void BaseTheme::drawBatteryRight(const GfxRenderer& renderer, Rect rect, const bool showPercentage) const {
   // Right aligned: percentage on left, icon on right (UI headers)
   // rect.x is already positioned for the icon (drawHeader calculated it)
-  const uint16_t percentage = battery.readPercentage();
+  const uint16_t percentage = powerManager.getBatteryPercentage();
   const int y = rect.y + 6;
 
   if (showPercentage) {

src/components/themes/lyra/LyraTheme.cpp

@@ -1,6 +1,7 @@
 #include "LyraTheme.h"
 
 #include <GfxRenderer.h>
+#include <HalPowerManager.h>
 #include <HalStorage.h>
 #include <I18n.h>
 #include <Utf8.h>
@@ -10,7 +11,6 @@
 #include <string>
 #include <vector>
 
-#include "Battery.h"
 #include "CrossPointSettings.h"
 #include "RecentBooksStore.h"
 #include "components/UITheme.h"
@@ -88,7 +88,7 @@ const uint8_t* iconForName(UIIcon icon, int size) {
 
 void LyraTheme::drawBatteryLeft(const GfxRenderer& renderer, Rect rect, const bool showPercentage) const {
   // Left aligned: icon on left, percentage on right (reader mode)
-  const uint16_t percentage = battery.readPercentage();
+  const uint16_t percentage = powerManager.getBatteryPercentage();
   const int y = rect.y + 6;
   const int battWidth = LyraMetrics::values.batteryWidth;
 
@@ -125,7 +125,7 @@ void LyraTheme::drawBatteryLeft(const GfxRenderer& renderer, Rect rect, const bo
 
 void LyraTheme::drawBatteryRight(const GfxRenderer& renderer, Rect rect, const bool showPercentage) const {
   // Right aligned: percentage on left, icon on right (UI headers)
-  const uint16_t percentage = battery.readPercentage();
+  const uint16_t percentage = powerManager.getBatteryPercentage();
   const int y = rect.y + 6;
   const int battWidth = LyraMetrics::values.batteryWidth;
 

src/main.cpp

@@ -15,7 +15,6 @@
 #include <cstring>
 #include <ctime>
 
-#include "Battery.h"
 #include "CrossPointSettings.h"
 #include "CrossPointState.h"
 #include "KOReaderCredentialStore.h"
@@ -227,9 +226,9 @@ void onGoHome();
 void onGoToMyLibraryWithPath(const std::string& path);
 void onGoToRecentBooks();
 void onGoToReader(const std::string& initialEpubPath) {
+  const std::string bookPath = initialEpubPath;  // Copy before exitActivity() invalidates the reference
   exitActivity();
-  enterNewActivity(
-      new ReaderActivity(renderer, mappedInputManager, initialEpubPath, onGoHome, onGoToMyLibraryWithPath));
+  enterNewActivity(new ReaderActivity(renderer, mappedInputManager, bookPath, onGoHome, onGoToMyLibraryWithPath));
 }
 
 void onGoToFileTransfer() {