feat: UI themes, Lyra (#528)

## Summary

### What is the goal of this PR?

- Visual UI overhaul
- UI theme selection

### What changes are included?

- Added a setting "UI Theme": Classic, Lyra
- The classic theme is the current Crosspoint theme
- The Lyra theme implements these mockups:
https://www.figma.com/design/UhxoV4DgUnfrDQgMPPTXog/Lyra-Theme?node-id=2003-7596&t=4CSOZqf0n9uQMxDt-0
by Discord users yagofarias, ruby and gan_shu
- New functions in GFXRenderer to render rounded rectangles, greyscale
fills (using dithering) and thick lines
- Basic UI components are factored into BaseTheme methods which can be
overridden by each additional theme. Methods that are not overridden
will fallback to BaseTheme behavior. This means any new
features/components in CrossPoint only need to be developed for the
"Classic" BaseTheme.
- Additional themes can easily be developed by the community using this
foundation

![IMG_7649
Medium](https://github.com/user-attachments/assets/b516f5a9-2636-4565-acff-91a25b93b39b)
![IMG_7746
Medium](https://github.com/user-attachments/assets/def41810-ab6e-4952-b40f-b9ce7d62bea8)
![IMG_7651
Medium](https://github.com/user-attachments/assets/518a9a6d-107a-4be3-9533-43a2b64b944b)



## Additional Context

- Only the Home, Library and main Settings screens have been implemented
so far, this will be extended to the transfer screens and chapter
selection screen later on, but we need to get the ball rolling somehow
:)
- Loading extra covers on the home screen in the Lyra theme takes a
little more time (about 2 seconds), I added a loading bar popup (reusing
the Indexing progress bar from the reader view, factored into a neat UI
component) but the popup adds ~400ms to the loading time.
- ~~Home screen thumbnails will need to be generated separately for each
theme, because they are displayed in different sizes. Because we're
using dithering, displaying a thumb with the wrong size causes the
picture to look janky or dark as it does on the screenshots above. No
worries this will be fixed in a future PR.~~ Thumbs are now generated
with a size parameter
- UI Icons will need to be implemented in a future PR.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**PARTIALLY**_
This is not a vibe coded PR. Copilot was used for autocompletion to save
time but I reviewed, understood and edited all generated code.

---------

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

lib/Epub/Epub.cpp

@@ -513,11 +513,12 @@ bool Epub::generateCoverBmp(bool cropped) const {
   return false;
 }
 
-std::string Epub::getThumbBmpPath() const { return cachePath + "/thumb.bmp"; }
+std::string Epub::getThumbBmpPath() const { return cachePath + "/thumb_[HEIGHT].bmp"; }
+std::string Epub::getThumbBmpPath(int height) const { return cachePath + "/thumb_" + std::to_string(height) + ".bmp"; }
 
-bool Epub::generateThumbBmp() const {
+bool Epub::generateThumbBmp(int height) const {
   // Already generated, return true
-  if (SdMan.exists(getThumbBmpPath().c_str())) {
+  if (SdMan.exists(getThumbBmpPath(height).c_str())) {
     return true;
   }
 
@@ -529,11 +530,8 @@ bool Epub::generateThumbBmp() const {
   const auto coverImageHref = bookMetadataCache->coreMetadata.coverItemHref;
   if (coverImageHref.empty()) {
     Serial.printf("[%lu] [EBP] No known cover image for thumbnail\n", millis());
-    return false;
-  }
-
-  if (coverImageHref.substr(coverImageHref.length() - 4) == ".jpg" ||
-      coverImageHref.substr(coverImageHref.length() - 5) == ".jpeg") {
+  } else if (coverImageHref.substr(coverImageHref.length() - 4) == ".jpg" ||
+             coverImageHref.substr(coverImageHref.length() - 5) == ".jpeg") {
     Serial.printf("[%lu] [EBP] Generating thumb BMP from JPG cover image\n", millis());
     const auto coverJpgTempPath = getCachePath() + "/.cover.jpg";
 
@@ -549,14 +547,14 @@ bool Epub::generateThumbBmp() const {
     }
 
     FsFile thumbBmp;
-    if (!SdMan.openFileForWrite("EBP", getThumbBmpPath(), thumbBmp)) {
+    if (!SdMan.openFileForWrite("EBP", getThumbBmpPath(height), thumbBmp)) {
       coverJpg.close();
       return false;
     }
     // Use smaller target size for Continue Reading card (half of screen: 240x400)
     // Generate 1-bit BMP for fast home screen rendering (no gray passes needed)
-    constexpr int THUMB_TARGET_WIDTH = 240;
-    constexpr int THUMB_TARGET_HEIGHT = 400;
+    int THUMB_TARGET_WIDTH = height * 0.6;
+    int THUMB_TARGET_HEIGHT = height;
     const bool success = JpegToBmpConverter::jpegFileTo1BitBmpStreamWithSize(coverJpg, thumbBmp, THUMB_TARGET_WIDTH,
                                                                              THUMB_TARGET_HEIGHT);
     coverJpg.close();
@@ -565,7 +563,7 @@ bool Epub::generateThumbBmp() const {
 
     if (!success) {
       Serial.printf("[%lu] [EBP] Failed to generate thumb BMP from JPG cover image\n", millis());
-      SdMan.remove(getThumbBmpPath().c_str());
+      SdMan.remove(getThumbBmpPath(height).c_str());
     }
     Serial.printf("[%lu] [EBP] Generated thumb BMP from JPG cover image, success: %s\n", millis(),
                   success ? "yes" : "no");
@@ -574,6 +572,10 @@ bool Epub::generateThumbBmp() const {
     Serial.printf("[%lu] [EBP] Cover image is not a JPG, skipping thumbnail\n", millis());
   }
 
+  // Write an empty bmp file to avoid generation attempts in the future
+  FsFile thumbBmp;
+  SdMan.openFileForWrite("EBP", getThumbBmpPath(height), thumbBmp);
+  thumbBmp.close();
   return false;
 }
 

lib/Epub/Epub.h

@@ -56,7 +56,8 @@ class Epub {
   std::string getCoverBmpPath(bool cropped = false) const;
   bool generateCoverBmp(bool cropped = false) const;
   std::string getThumbBmpPath() const;
-  bool generateThumbBmp() const;
+  std::string getThumbBmpPath(int height) const;
+  bool generateThumbBmp(int height) const;
   uint8_t* readItemContentsToBytes(const std::string& itemHref, size_t* size = nullptr,
                                    bool trailingNullByte = false) const;
   bool readItemContentsToStream(const std::string& itemHref, Print& out, size_t chunkSize) const;

lib/GfxRenderer/GfxRenderer.cpp

@@ -130,6 +130,12 @@ void GfxRenderer::drawLine(int x1, int y1, int x2, int y2, const bool state) con
   }
 }
 
+void GfxRenderer::drawLine(int x1, int y1, int x2, int y2, const int lineWidth, const bool state) const {
+  for (int i = 0; i < lineWidth; i++) {
+    drawLine(x1, y1 + i, x2, y2 + i, state);
+  }
+}
+
 void GfxRenderer::drawRect(const int x, const int y, const int width, const int height, const bool state) const {
   drawLine(x, y, x + width - 1, y, state);
   drawLine(x + width - 1, y, x + width - 1, y + height - 1, state);
@@ -137,12 +143,215 @@ void GfxRenderer::drawRect(const int x, const int y, const int width, const int
   drawLine(x, y, x, y + height - 1, state);
 }
 
+// Border is inside the rectangle
+void GfxRenderer::drawRect(const int x, const int y, const int width, const int height, const int lineWidth,
+                           const bool state) const {
+  for (int i = 0; i < lineWidth; i++) {
+    drawLine(x + i, y + i, x + width - i, y + i, state);
+    drawLine(x + width - i, y + i, x + width - i, y + height - i, state);
+    drawLine(x + width - i, y + height - i, x + i, y + height - i, state);
+    drawLine(x + i, y + height - i, x + i, y + i, state);
+  }
+}
+
+void GfxRenderer::drawArc(const int maxRadius, const int cx, const int cy, const int xDir, const int yDir,
+                          const int lineWidth, const bool state) const {
+  const int stroke = std::min(lineWidth, maxRadius);
+  const int innerRadius = std::max(maxRadius - stroke, 0);
+  const int outerRadiusSq = maxRadius * maxRadius;
+  const int innerRadiusSq = innerRadius * innerRadius;
+  for (int dy = 0; dy <= maxRadius; ++dy) {
+    for (int dx = 0; dx <= maxRadius; ++dx) {
+      const int distSq = dx * dx + dy * dy;
+      if (distSq > outerRadiusSq || distSq < innerRadiusSq) {
+        continue;
+      }
+      const int px = cx + xDir * dx;
+      const int py = cy + yDir * dy;
+      drawPixel(px, py, state);
+    }
+  }
+};
+
+// Border is inside the rectangle, rounded corners
+void GfxRenderer::drawRoundedRect(const int x, const int y, const int width, const int height, const int lineWidth,
+                                  const int cornerRadius, bool state) const {
+  drawRoundedRect(x, y, width, height, lineWidth, cornerRadius, true, true, true, true, state);
+}
+
+// Border is inside the rectangle, rounded corners
+void GfxRenderer::drawRoundedRect(const int x, const int y, const int width, const int height, const int lineWidth,
+                                  const int cornerRadius, bool roundTopLeft, bool roundTopRight, bool roundBottomLeft,
+                                  bool roundBottomRight, bool state) const {
+  if (lineWidth <= 0 || width <= 0 || height <= 0) {
+    return;
+  }
+
+  const int maxRadius = std::min({cornerRadius, width / 2, height / 2});
+  if (maxRadius <= 0) {
+    drawRect(x, y, width, height, lineWidth, state);
+    return;
+  }
+
+  const int stroke = std::min(lineWidth, maxRadius);
+  const int right = x + width - 1;
+  const int bottom = y + height - 1;
+
+  const int horizontalWidth = width - 2 * maxRadius;
+  if (horizontalWidth > 0) {
+    if (roundTopLeft || roundTopRight) {
+      fillRect(x + maxRadius, y, horizontalWidth, stroke, state);
+    }
+    if (roundBottomLeft || roundBottomRight) {
+      fillRect(x + maxRadius, bottom - stroke + 1, horizontalWidth, stroke, state);
+    }
+  }
+
+  const int verticalHeight = height - 2 * maxRadius;
+  if (verticalHeight > 0) {
+    if (roundTopLeft || roundBottomLeft) {
+      fillRect(x, y + maxRadius, stroke, verticalHeight, state);
+    }
+    if (roundTopRight || roundBottomRight) {
+      fillRect(right - stroke + 1, y + maxRadius, stroke, verticalHeight, state);
+    }
+  }
+
+  if (roundTopLeft) {
+    drawArc(maxRadius, x + maxRadius, y + maxRadius, -1, -1, lineWidth, state);
+  }
+  if (roundTopRight) {
+    drawArc(maxRadius, right - maxRadius, y + maxRadius, 1, -1, lineWidth, state);
+  }
+  if (roundBottomRight) {
+    drawArc(maxRadius, right - maxRadius, bottom - maxRadius, 1, 1, lineWidth, state);
+  }
+  if (roundBottomLeft) {
+    drawArc(maxRadius, x + maxRadius, bottom - maxRadius, -1, 1, lineWidth, state);
+  }
+}
+
 void GfxRenderer::fillRect(const int x, const int y, const int width, const int height, const bool state) const {
   for (int fillY = y; fillY < y + height; fillY++) {
     drawLine(x, fillY, x + width - 1, fillY, state);
   }
 }
 
+static constexpr uint8_t bayer4x4[4][4] = {
+    {0, 8, 2, 10},
+    {12, 4, 14, 6},
+    {3, 11, 1, 9},
+    {15, 7, 13, 5},
+};
+static constexpr int matrixSize = 4;
+static constexpr int matrixLevels = matrixSize * matrixSize;
+
+void GfxRenderer::drawPixelDither(const int x, const int y, Color color) const {
+  if (color == Color::Clear) {
+  } else if (color == Color::Black) {
+    drawPixel(x, y, true);
+  } else if (color == Color::White) {
+    drawPixel(x, y, false);
+  } else {
+    // Use dithering
+    const int greyLevel = static_cast<int>(color) - 1;  // 0-15
+    const int normalizedGrey = (greyLevel * 255) / (matrixLevels - 1);
+    const int clampedGrey = std::max(0, std::min(normalizedGrey, 255));
+    const int threshold = (clampedGrey * (matrixLevels + 1)) / 256;
+
+    const int matrixX = x & (matrixSize - 1);
+    const int matrixY = y & (matrixSize - 1);
+    const uint8_t patternValue = bayer4x4[matrixY][matrixX];
+    const bool black = patternValue < threshold;
+    drawPixel(x, y, black);
+  }
+}
+
+// Use Bayer matrix 4x4 dithering to fill the rectangle with a grey level
+void GfxRenderer::fillRectDither(const int x, const int y, const int width, const int height, Color color) const {
+  if (color == Color::Clear) {
+  } else if (color == Color::Black) {
+    fillRect(x, y, width, height, true);
+  } else if (color == Color::White) {
+    fillRect(x, y, width, height, false);
+  } else {
+    for (int fillY = y; fillY < y + height; fillY++) {
+      for (int fillX = x; fillX < x + width; fillX++) {
+        drawPixelDither(fillX, fillY, color);
+      }
+    }
+  }
+}
+
+void GfxRenderer::fillArc(const int maxRadius, const int cx, const int cy, const int xDir, const int yDir,
+                          Color color) const {
+  const int radiusSq = maxRadius * maxRadius;
+  for (int dy = 0; dy <= maxRadius; ++dy) {
+    for (int dx = 0; dx <= maxRadius; ++dx) {
+      const int distSq = dx * dx + dy * dy;
+      const int px = cx + xDir * dx;
+      const int py = cy + yDir * dy;
+      if (distSq <= radiusSq) {
+        drawPixelDither(px, py, color);
+      }
+    }
+  }
+}
+
+void GfxRenderer::fillRoundedRect(const int x, const int y, const int width, const int height, const int cornerRadius,
+                                  const Color color) const {
+  fillRoundedRect(x, y, width, height, cornerRadius, true, true, true, true, color);
+}
+
+void GfxRenderer::fillRoundedRect(const int x, const int y, const int width, const int height, const int cornerRadius,
+                                  bool roundTopLeft, bool roundTopRight, bool roundBottomLeft, bool roundBottomRight,
+                                  const Color color) const {
+  if (width <= 0 || height <= 0) {
+    return;
+  }
+
+  const int maxRadius = std::min({cornerRadius, width / 2, height / 2});
+  if (maxRadius <= 0) {
+    fillRectDither(x, y, width, height, color);
+    return;
+  }
+
+  const int horizontalWidth = width - 2 * maxRadius;
+  if (horizontalWidth > 0) {
+    fillRectDither(x + maxRadius + 1, y, horizontalWidth - 2, height, color);
+  }
+
+  const int verticalHeight = height - 2 * maxRadius - 2;
+  if (verticalHeight > 0) {
+    fillRectDither(x, y + maxRadius + 1, maxRadius + 1, verticalHeight, color);
+    fillRectDither(x + width - maxRadius - 1, y + maxRadius + 1, maxRadius + 1, verticalHeight, color);
+  }
+
+  if (roundTopLeft) {
+    fillArc(maxRadius, x + maxRadius, y + maxRadius, -1, -1, color);
+  } else {
+    fillRectDither(x, y, maxRadius + 1, maxRadius + 1, color);
+  }
+
+  if (roundTopRight) {
+    fillArc(maxRadius, x + width - maxRadius - 1, y + maxRadius, 1, -1, color);
+  } else {
+    fillRectDither(x + width - maxRadius - 1, y, maxRadius + 1, maxRadius + 1, color);
+  }
+
+  if (roundBottomRight) {
+    fillArc(maxRadius, x + width - maxRadius - 1, y + height - maxRadius - 1, 1, 1, color);
+  } else {
+    fillRectDither(x + width - maxRadius - 1, y + height - maxRadius - 1, maxRadius + 1, maxRadius + 1, color);
+  }
+
+  if (roundBottomLeft) {
+    fillArc(maxRadius, x + maxRadius, y + height - maxRadius - 1, -1, 1, color);
+  } else {
+    fillRectDither(x, y + height - maxRadius - 1, maxRadius + 1, maxRadius + 1, color);
+  }
+}
+
 void GfxRenderer::drawImage(const uint8_t bitmap[], const int x, const int y, const int width, const int height) const {
   int rotatedX = 0;
   int rotatedY = 0;
@@ -166,6 +375,10 @@ void GfxRenderer::drawImage(const uint8_t bitmap[], const int x, const int y, co
   display.drawImage(bitmap, rotatedX, rotatedY, width, height);
 }
 
+void GfxRenderer::drawIcon(const uint8_t bitmap[], const int x, const int y, const int width, const int height) const {
+  display.drawImage(bitmap, y, getScreenWidth() - width - x, height, width);
+}
+
 void GfxRenderer::drawBitmap(const Bitmap& bitmap, const int x, const int y, const int maxWidth, const int maxHeight,
                              const float cropX, const float cropY) const {
   // For 1-bit bitmaps, use optimized 1-bit rendering path (no crop support for 1-bit)
@@ -502,85 +715,6 @@ int GfxRenderer::getLineHeight(const int fontId) const {
   return fontMap.at(fontId).getData(EpdFontFamily::REGULAR)->advanceY;
 }
 
-void GfxRenderer::drawButtonHints(const int fontId, const char* btn1, const char* btn2, const char* btn3,
-                                  const char* btn4) {
-  const Orientation orig_orientation = getOrientation();
-  setOrientation(Orientation::Portrait);
-
-  const int pageHeight = getScreenHeight();
-  constexpr int buttonWidth = 106;
-  constexpr int buttonHeight = 40;
-  constexpr int buttonY = 40;     // Distance from bottom
-  constexpr int textYOffset = 7;  // Distance from top of button to text baseline
-  constexpr int buttonPositions[] = {25, 130, 245, 350};
-  const char* labels[] = {btn1, btn2, btn3, btn4};
-
-  for (int i = 0; i < 4; i++) {
-    // Only draw if the label is non-empty
-    if (labels[i] != nullptr && labels[i][0] != '\0') {
-      const int x = buttonPositions[i];
-      fillRect(x, pageHeight - buttonY, buttonWidth, buttonHeight, false);
-      drawRect(x, pageHeight - buttonY, buttonWidth, buttonHeight);
-      const int textWidth = getTextWidth(fontId, labels[i]);
-      const int textX = x + (buttonWidth - 1 - textWidth) / 2;
-      drawText(fontId, textX, pageHeight - buttonY + textYOffset, labels[i]);
-    }
-  }
-
-  setOrientation(orig_orientation);
-}
-
-void GfxRenderer::drawSideButtonHints(const int fontId, const char* topBtn, const char* bottomBtn) const {
-  const int screenWidth = getScreenWidth();
-  constexpr int buttonWidth = 40;   // Width on screen (height when rotated)
-  constexpr int buttonHeight = 80;  // Height on screen (width when rotated)
-  constexpr int buttonX = 5;        // Distance from right edge
-  // Position for the button group - buttons share a border so they're adjacent
-  constexpr int topButtonY = 345;  // Top button position
-
-  const char* labels[] = {topBtn, bottomBtn};
-
-  // Draw the shared border for both buttons as one unit
-  const int x = screenWidth - buttonX - buttonWidth;
-
-  // Draw top button outline (3 sides, bottom open)
-  if (topBtn != nullptr && topBtn[0] != '\0') {
-    drawLine(x, topButtonY, x + buttonWidth - 1, topButtonY);                                       // Top
-    drawLine(x, topButtonY, x, topButtonY + buttonHeight - 1);                                      // Left
-    drawLine(x + buttonWidth - 1, topButtonY, x + buttonWidth - 1, topButtonY + buttonHeight - 1);  // Right
-  }
-
-  // Draw shared middle border
-  if ((topBtn != nullptr && topBtn[0] != '\0') || (bottomBtn != nullptr && bottomBtn[0] != '\0')) {
-    drawLine(x, topButtonY + buttonHeight, x + buttonWidth - 1, topButtonY + buttonHeight);  // Shared border
-  }
-
-  // Draw bottom button outline (3 sides, top is shared)
-  if (bottomBtn != nullptr && bottomBtn[0] != '\0') {
-    drawLine(x, topButtonY + buttonHeight, x, topButtonY + 2 * buttonHeight - 1);  // Left
-    drawLine(x + buttonWidth - 1, topButtonY + buttonHeight, x + buttonWidth - 1,
-             topButtonY + 2 * buttonHeight - 1);                                                             // Right
-    drawLine(x, topButtonY + 2 * buttonHeight - 1, x + buttonWidth - 1, topButtonY + 2 * buttonHeight - 1);  // Bottom
-  }
-
-  // Draw text for each button
-  for (int i = 0; i < 2; i++) {
-    if (labels[i] != nullptr && labels[i][0] != '\0') {
-      const int y = topButtonY + i * buttonHeight;
-
-      // Draw rotated text centered in the button
-      const int textWidth = getTextWidth(fontId, labels[i]);
-      const int textHeight = getTextHeight(fontId);
-
-      // Center the rotated text in the button
-      const int textX = x + (buttonWidth - textHeight) / 2;
-      const int textY = y + (buttonHeight + textWidth) / 2;
-
-      drawTextRotated90CW(fontId, textX, textY, labels[i]);
-    }
-  }
-}
-
 int GfxRenderer::getTextHeight(const int fontId) const {
   if (fontMap.count(fontId) == 0) {
     Serial.printf("[%lu] [GFX] Font %d not found\n", millis(), fontId);

lib/GfxRenderer/GfxRenderer.h

@@ -7,6 +7,10 @@
 
 #include "Bitmap.h"
 
+// Color representation: uint8_t mapped to 4x4 Bayer matrix dithering levels
+// 0 = transparent, 1-16 = gray levels (white to black)
+enum Color : uint8_t { Clear = 0x00, White = 0x01, LightGray = 0x05, DarkGray = 0x0A, Black = 0x10 };
+
 class GfxRenderer {
  public:
   enum RenderMode { BW, GRAYSCALE_LSB, GRAYSCALE_MSB };
@@ -34,6 +38,8 @@ class GfxRenderer {
                   EpdFontFamily::Style style) const;
   void freeBwBufferChunks();
   void rotateCoordinates(int x, int y, int* rotatedX, int* rotatedY) const;
+  void drawPixelDither(int x, int y, Color color) const;
+  void fillArc(int maxRadius, int cx, int cy, int xDir, int yDir, Color color) const;
 
  public:
   explicit GfxRenderer(HalDisplay& halDisplay) : display(halDisplay), renderMode(BW), orientation(Portrait) {}
@@ -63,9 +69,20 @@ class GfxRenderer {
   // Drawing
   void drawPixel(int x, int y, bool state = true) const;
   void drawLine(int x1, int y1, int x2, int y2, bool state = true) const;
+  void drawLine(int x1, int y1, int x2, int y2, int lineWidth, bool state) const;
+  void drawArc(int maxRadius, int cx, int cy, int xDir, int yDir, int lineWidth, bool state) const;
   void drawRect(int x, int y, int width, int height, bool state = true) const;
+  void drawRect(int x, int y, int width, int height, int lineWidth, bool state) const;
+  void drawRoundedRect(int x, int y, int width, int height, int lineWidth, int cornerRadius, bool state) const;
+  void drawRoundedRect(int x, int y, int width, int height, int lineWidth, int cornerRadius, bool roundTopLeft,
+                       bool roundTopRight, bool roundBottomLeft, bool roundBottomRight, bool state) const;
   void fillRect(int x, int y, int width, int height, bool state = true) const;
+  void fillRectDither(int x, int y, int width, int height, Color color) const;
+  void fillRoundedRect(int x, int y, int width, int height, int cornerRadius, Color color) const;
+  void fillRoundedRect(int x, int y, int width, int height, int cornerRadius, bool roundTopLeft, bool roundTopRight,
+                       bool roundBottomLeft, bool roundBottomRight, Color color) const;
   void drawImage(const uint8_t bitmap[], int x, int y, int width, int height) const;
+  void drawIcon(const uint8_t bitmap[], int x, int y, int width, int height) const;
   void drawBitmap(const Bitmap& bitmap, int x, int y, int maxWidth, int maxHeight, float cropX = 0,
                   float cropY = 0) const;
   void drawBitmap1Bit(const Bitmap& bitmap, int x, int y, int maxWidth, int maxHeight) const;
@@ -84,17 +101,11 @@ class GfxRenderer {
   std::string truncatedText(int fontId, const char* text, int maxWidth,
                             EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
 
-  // UI Components
-  void drawButtonHints(int fontId, const char* btn1, const char* btn2, const char* btn3, const char* btn4);
-  void drawSideButtonHints(int fontId, const char* topBtn, const char* bottomBtn) const;
-
- private:
   // Helper for drawing rotated text (90 degrees clockwise, for side buttons)
   void drawTextRotated90CW(int fontId, int x, int y, const char* text, bool black = true,
                            EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
   int getTextHeight(int fontId) const;
 
- public:
   // Grayscale functions
   void setRenderMode(const RenderMode mode) { this->renderMode = mode; }
   void copyGrayscaleLsbBuffers() const;

lib/Xtc/Xtc.cpp

@@ -301,11 +301,12 @@ bool Xtc::generateCoverBmp() const {
   return true;
 }
 
-std::string Xtc::getThumbBmpPath() const { return cachePath + "/thumb.bmp"; }
+std::string Xtc::getThumbBmpPath() const { return cachePath + "/thumb_[HEIGHT].bmp"; }
+std::string Xtc::getThumbBmpPath(int height) const { return cachePath + "/thumb_" + std::to_string(height) + ".bmp"; }
 
-bool Xtc::generateThumbBmp() const {
+bool Xtc::generateThumbBmp(int height) const {
   // Already generated
-  if (SdMan.exists(getThumbBmpPath().c_str())) {
+  if (SdMan.exists(getThumbBmpPath(height).c_str())) {
     return true;
   }
 
@@ -333,8 +334,8 @@ bool Xtc::generateThumbBmp() const {
   const uint8_t bitDepth = parser->getBitDepth();
 
   // Calculate target dimensions for thumbnail (fit within 240x400 Continue Reading card)
-  constexpr int THUMB_TARGET_WIDTH = 240;
-  constexpr int THUMB_TARGET_HEIGHT = 400;
+  int THUMB_TARGET_WIDTH = height * 0.6;
+  int THUMB_TARGET_HEIGHT = height;
 
   // Calculate scale factor
   float scaleX = static_cast<float>(THUMB_TARGET_WIDTH) / pageInfo.width;
@@ -348,7 +349,7 @@ bool Xtc::generateThumbBmp() const {
     if (generateCoverBmp()) {
       FsFile src, dst;
       if (SdMan.openFileForRead("XTC", getCoverBmpPath(), src)) {
-        if (SdMan.openFileForWrite("XTC", getThumbBmpPath(), dst)) {
+        if (SdMan.openFileForWrite("XTC", getThumbBmpPath(height), dst)) {
           uint8_t buffer[512];
           while (src.available()) {
             size_t bytesRead = src.read(buffer, sizeof(buffer));
@@ -359,7 +360,7 @@ bool Xtc::generateThumbBmp() const {
         src.close();
       }
       Serial.printf("[%lu] [XTC] Copied cover to thumb (no scaling needed)\n", millis());
-      return SdMan.exists(getThumbBmpPath().c_str());
+      return SdMan.exists(getThumbBmpPath(height).c_str());
     }
     return false;
   }
@@ -393,7 +394,7 @@ bool Xtc::generateThumbBmp() const {
 
   // Create thumbnail BMP file - use 1-bit format for fast home screen rendering (no gray passes)
   FsFile thumbBmp;
-  if (!SdMan.openFileForWrite("XTC", getThumbBmpPath(), thumbBmp)) {
+  if (!SdMan.openFileForWrite("XTC", getThumbBmpPath(height), thumbBmp)) {
     Serial.printf("[%lu] [XTC] Failed to create thumb BMP file\n", millis());
     free(pageBuffer);
     return false;
@@ -558,7 +559,7 @@ bool Xtc::generateThumbBmp() const {
   free(pageBuffer);
 
   Serial.printf("[%lu] [XTC] Generated thumb BMP (%dx%d): %s\n", millis(), thumbWidth, thumbHeight,
-                getThumbBmpPath().c_str());
+                getThumbBmpPath(height).c_str());
   return true;
 }
 

lib/Xtc/Xtc.h

@@ -65,7 +65,8 @@ class Xtc {
   bool generateCoverBmp() const;
   // Thumbnail support (for Continue Reading card)
   std::string getThumbBmpPath() const;
-  bool generateThumbBmp() const;
+  std::string getThumbBmpPath(int height) const;
+  bool generateThumbBmp(int height) const;
 
   // Page access
   uint32_t getPageCount() const;