Feature/cover crop mode (#225)

Added a setting to select `fit` or `crop` for cover image on sleep
screen.

Might add a `expand` feature in the future that does not crop but rather
fills the blank space with a mirror of the image.

---------

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

lib/GfxRenderer/Bitmap.cpp

@@ -250,34 +250,29 @@ BmpReaderError Bitmap::parseHeaders() {
     delete[] errorNextRow;
     errorCurRow = new int16_t[width + 2]();  // +2 for boundary handling
     errorNextRow = new int16_t[width + 2]();
-    lastRowY = -1;
+    prevRowY = -1;
   }
 
   return BmpReaderError::Ok;
 }
 
 // packed 2bpp output, 0 = black, 1 = dark gray, 2 = light gray, 3 = white
-BmpReaderError Bitmap::readRow(uint8_t* data, uint8_t* rowBuffer, int rowY) const {
+BmpReaderError Bitmap::readNextRow(uint8_t* data, uint8_t* rowBuffer) const {
   // Note: rowBuffer should be pre-allocated by the caller to size 'rowBytes'
   if (file.read(rowBuffer, rowBytes) != rowBytes) return BmpReaderError::ShortReadRow;
 
   // Handle Floyd-Steinberg error buffer progression
   const bool useFS = USE_FLOYD_STEINBERG && errorCurRow && errorNextRow;
   if (useFS) {
-    // Check if we need to advance to next row (or reset if jumping)
-    if (rowY != lastRowY + 1 && rowY != 0) {
-      // Non-sequential row access - reset error buffers
-      memset(errorCurRow, 0, (width + 2) * sizeof(int16_t));
-      memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
-    } else if (rowY > 0) {
+    if (prevRowY != -1) {
       // Sequential access - swap buffers
       int16_t* temp = errorCurRow;
       errorCurRow = errorNextRow;
       errorNextRow = temp;
       memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
     }
-    lastRowY = rowY;
   }
+  prevRowY += 1;
 
   uint8_t* outPtr = data;
   uint8_t currentOutByte = 0;
@@ -292,7 +287,7 @@ BmpReaderError Bitmap::readRow(uint8_t* data, uint8_t* rowBuffer, int rowY) cons
       color = quantizeFloydSteinberg(lum, currentX, width, errorCurRow, errorNextRow, false);
     } else {
       // Simple quantization or noise dithering
-      color = quantize(lum, currentX, rowY);
+      color = quantize(lum, currentX, prevRowY);
     }
     currentOutByte |= (color << bitShift);
     if (bitShift == 0) {
@@ -365,7 +360,7 @@ BmpReaderError Bitmap::rewindToData() const {
   if (USE_FLOYD_STEINBERG && errorCurRow && errorNextRow) {
     memset(errorCurRow, 0, (width + 2) * sizeof(int16_t));
     memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
-    lastRowY = -1;
+    prevRowY = -1;
   }
 
   return BmpReaderError::Ok;

lib/GfxRenderer/Bitmap.h

@@ -31,7 +31,7 @@ class Bitmap {
   explicit Bitmap(FsFile& file) : file(file) {}
   ~Bitmap();
   BmpReaderError parseHeaders();
-  BmpReaderError readRow(uint8_t* data, uint8_t* rowBuffer, int rowY) const;
+  BmpReaderError readNextRow(uint8_t* data, uint8_t* rowBuffer) const;
   BmpReaderError rewindToData() const;
   int getWidth() const { return width; }
   int getHeight() const { return height; }
@@ -55,5 +55,5 @@ class Bitmap {
   // Floyd-Steinberg dithering state (mutable for const methods)
   mutable int16_t* errorCurRow = nullptr;
   mutable int16_t* errorNextRow = nullptr;
-  mutable int lastRowY = -1;  // Track row progression for error propagation
+  mutable int prevRowY = -1;  // Track row progression for error propagation
 };

lib/GfxRenderer/GfxRenderer.cpp

@@ -152,18 +152,24 @@ void GfxRenderer::drawImage(const uint8_t bitmap[], const int x, const int y, co
   einkDisplay.drawImage(bitmap, rotatedX, rotatedY, width, height);
 }
 
-void GfxRenderer::drawBitmap(const Bitmap& bitmap, const int x, const int y, const int maxWidth,
-                             const int maxHeight) const {
+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 {
   float scale = 1.0f;
   bool isScaled = false;
-  if (maxWidth > 0 && bitmap.getWidth() > maxWidth) {
-    scale = static_cast<float>(maxWidth) / static_cast<float>(bitmap.getWidth());
+  int cropPixX = std::floor(bitmap.getWidth() * cropX / 2.0f);
+  int cropPixY = std::floor(bitmap.getHeight() * cropY / 2.0f);
+  Serial.printf("[%lu] [GFX] Cropping %dx%d by %dx%d pix, is %s\n", millis(), bitmap.getWidth(), bitmap.getHeight(),
+                cropPixX, cropPixY, bitmap.isTopDown() ? "top-down" : "bottom-up");
+
+  if (maxWidth > 0 && (1.0f - cropX) * bitmap.getWidth() > maxWidth) {
+    scale = static_cast<float>(maxWidth) / static_cast<float>((1.0f - cropX) * bitmap.getWidth());
     isScaled = true;
   }
-  if (maxHeight > 0 && bitmap.getHeight() > maxHeight) {
-    scale = std::min(scale, static_cast<float>(maxHeight) / static_cast<float>(bitmap.getHeight()));
+  if (maxHeight > 0 && (1.0f - cropY) * bitmap.getHeight() > maxHeight) {
+    scale = std::min(scale, static_cast<float>(maxHeight) / static_cast<float>((1.0f - cropY) * bitmap.getHeight()));
     isScaled = true;
   }
+  Serial.printf("[%lu] [GFX] Scaling by %f - %s\n", millis(), scale, isScaled ? "scaled" : "not scaled");
 
   // Calculate output row size (2 bits per pixel, packed into bytes)
   // IMPORTANT: Use int, not uint8_t, to avoid overflow for images > 1020 pixels wide
@@ -178,29 +184,36 @@ void GfxRenderer::drawBitmap(const Bitmap& bitmap, const int x, const int y, con
     return;
   }
 
-  for (int bmpY = 0; bmpY < bitmap.getHeight(); bmpY++) {
+  for (int bmpY = 0; bmpY < (bitmap.getHeight() - cropPixY); bmpY++) {
     // The BMP's (0, 0) is the bottom-left corner (if the height is positive, top-left if negative).
     // Screen's (0, 0) is the top-left corner.
-    int screenY = y + (bitmap.isTopDown() ? bmpY : bitmap.getHeight() - 1 - bmpY);
+    int screenY = -cropPixY + (bitmap.isTopDown() ? bmpY : bitmap.getHeight() - 1 - bmpY);
     if (isScaled) {
       screenY = std::floor(screenY * scale);
     }
+    screenY += y;  // the offset should not be scaled
     if (screenY >= getScreenHeight()) {
       break;
     }
 
-    if (bitmap.readRow(outputRow, rowBytes, bmpY) != BmpReaderError::Ok) {
+    if (bitmap.readNextRow(outputRow, rowBytes) != BmpReaderError::Ok) {
       Serial.printf("[%lu] [GFX] Failed to read row %d from bitmap\n", millis(), bmpY);
       free(outputRow);
       free(rowBytes);
       return;
     }
 
-    for (int bmpX = 0; bmpX < bitmap.getWidth(); bmpX++) {
-      int screenX = x + bmpX;
+    if (bmpY < cropPixY) {
+      // Skip the row if it's outside the crop area
+      continue;
+    }
+
+    for (int bmpX = cropPixX; bmpX < bitmap.getWidth() - cropPixX; bmpX++) {
+      int screenX = bmpX - cropPixX;
       if (isScaled) {
         screenX = std::floor(screenX * scale);
       }
+      screenX += x;  // the offset should not be scaled
       if (screenX >= getScreenWidth()) {
         break;
       }

lib/GfxRenderer/GfxRenderer.h

@@ -66,7 +66,8 @@ class GfxRenderer {
   void drawRect(int x, int y, int width, int height, bool state = true) const;
   void fillRect(int x, int y, int width, int height, bool state = true) const;
   void drawImage(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) const;
+  void drawBitmap(const Bitmap& bitmap, int x, int y, int maxWidth, int maxHeight, float cropX = 0,
+                  float cropY = 0) const;
 
   // Text
   int getTextWidth(int fontId, const char* text, EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;