feat: enhance display handling with EInkDisplayHandler class and update DisplayHandler interface

main/display/display.h

@@ -12,18 +12,22 @@ public:
   DisplayHandler(
     EventGroupHandle_t system_event_group
   ) : _system_event_group(system_event_group) { }
-  ~DisplayHandler();
+  virtual ~DisplayHandler();
   
   // required to be called by inheriting class after SPI device is created
   // set set_display_ready to false if further initialization is needed before marking display ready
-  void init_devices(bool set_display_ready = true);
+  virtual void init_devices(bool set_display_ready = true);
+
+protected:
+  // Allow derived classes to access touch handle
+  esp_lcd_touch_handle_t get_touch_handle() const { return _tp_handle; }
 
   void epd_write_cmd(uint8_t cmd);
   void epd_write_data(uint8_t data);
 
   void epd_write_cmd_with_data(uint8_t cmd, const uint8_t* data, size_t data_len);
 
-private:
+protected:
   SemaphoreHandle_t _spi_mutex = xSemaphoreCreateMutex();
   spi_device_handle_t _spi = nullptr;
   EventGroupHandle_t _system_event_group = nullptr;

main/display/eink_display_handler.h

@@ -0,0 +1,58 @@
+#pragma once
+#include "display/display.h"
+#include "lvgl.h"
+#include "esp_lvgl_port.h"
+#include "freertos/semphr.h"
+
+// Refresh mode configuration
+#define PARTIAL_REFRESH_THRESHOLD 10  // Full refresh every N partial refreshes
+#define DISPLAY_WIDTH 800
+#define DISPLAY_HEIGHT 480
+#define DISPLAY_BUFFER_SIZE ((DISPLAY_WIDTH * DISPLAY_HEIGHT) / 8)  // 1-bit per pixel
+
+class EInkDisplayHandler : public DisplayHandler {
+public:
+  EInkDisplayHandler(EventGroupHandle_t system_event_group);
+  virtual ~EInkDisplayHandler();
+
+  void init();
+  void start_touch_task();
+
+  // Request a full refresh on next flush
+  void request_full_refresh();
+
+  // Check if display is busy (refreshing)
+  bool is_busy() const;
+
+private:
+  // LVGL display and input device handles
+  lv_display_t* _lvgl_display = nullptr;
+  lv_indev_t* _lvgl_touch_indev = nullptr;
+
+  // Framebuffer
+  uint8_t* _framebuffer = nullptr;
+  bool _framebuffer_in_psram = false;
+
+  // Refresh tracking
+  uint32_t _partial_refresh_count = 0;
+  bool _force_full_refresh = false;
+  SemaphoreHandle_t _refresh_mutex = nullptr;
+
+  // Touch task
+  TaskHandle_t _touch_task_handle = nullptr;
+
+  // LVGL callbacks
+  static void _lvgl_flush_cb(lv_display_t* disp, const lv_area_t* area, uint8_t* px_map);
+  static void _lvgl_touch_read_cb(lv_indev_t* indev, lv_indev_data_t* data);
+
+  // Display operations
+  void _perform_full_refresh(const uint8_t* framebuffer);
+  void _perform_partial_refresh(const uint8_t* framebuffer);
+  void _wait_for_busy();
+
+  // Touch task
+  static void _touch_task(void* param);
+
+  // Helper to convert LVGL 1-bit buffer to e-paper format
+  void _convert_buffer_to_epaper(const uint8_t* lvgl_buf, uint8_t* epd_buf, size_t size);
+};