Applay striped buffer approach to save memory

lib/hal/HalDisplay.cpp

@@ -97,6 +97,13 @@ void HalDisplay::cleanupGrayscaleBuffers(const uint8_t* bwBuffer) { einkDisplay.
 
 void HalDisplay::displayGrayBuffer(bool turnOffScreen) { einkDisplay.displayGrayBuffer(turnOffScreen); }
 
+void HalDisplay::writeGrayscalePlaneStrip(bool lsbPlane, const uint8_t* rows, uint16_t yStart, uint16_t numRows) {
+  einkDisplay.writeGrayscalePlaneStrip(lsbPlane ? EInkDisplay::GRAY_PLANE_LSB : EInkDisplay::GRAY_PLANE_MSB, rows,
+                                       yStart, numRows);
+}
+
+bool HalDisplay::supportsStripGrayscale() const { return einkDisplay.supportsStripGrayscale(); }
+
 uint16_t HalDisplay::getDisplayWidth() const { return einkDisplay.getDisplayWidth(); }
 
 uint16_t HalDisplay::getDisplayHeight() const { return einkDisplay.getDisplayHeight(); }

lib/hal/HalDisplay.h

@@ -55,6 +55,12 @@ class HalDisplay {
 
   void displayGrayBuffer(bool turnOffScreen = false);
 
+  // Tiled grayscale: stream one band of a plane (lsbPlane selects LSB/MSB RAM)
+  // straight to the controller; supportsStripGrayscale() gates the path. See
+  // EInkDisplay::writeGrayscalePlaneStrip.
+  void writeGrayscalePlaneStrip(bool lsbPlane, const uint8_t* rows, uint16_t yStart, uint16_t numRows);
+  bool supportsStripGrayscale() const;
+
   // Runtime geometry passthrough
   uint16_t getDisplayWidth() const;
   uint16_t getDisplayHeight() const;