/**
   * @fn begin
   * @brief Init function, initialize some parameters displayed on the screen, and enable display
   * @return Error code
   */
  int16_t begin();
  
  /**
   * @fn drawPixel
   * @brief Draw point function, draw a point on the screen
   * @param x x-coordinate
   * @param y y-coordinate
   * @param color pixel color
   */
  void drawPixel(int16_t x, int16_t y, uint16_t color);
  
  /**
   * @fn fillScreen
   * @brief Fill screen with a color
   * @param color data in RGB565 format
   */
  void fillScreen(uint16_t color);    
  
  /**
   * @fn drawHLine
   * @brief Draw a horizontal line with the starting point（x，y）
   * @param x The coordinate of the starting point x on the x axis. Take the top left corner of the screen as the origin. 
   * @param y The coordinate of the starting point y on the y axis
   * @param width The line width
   * @param color The line color
   */
  void drawHLine(int16_t x, int16_t y, int16_t width, uint16_t color);

  /**
   * @fn drawVLine
   * @brief Draw a vertical line with the starting point（x，y）
   * @param x The coordinate of the starting point x on the x axis. Take the top left corner of the screen as the origin.
   * @param y The coordinate of the starting point y on the y axis 
   * @param width  The line width
   * @param color  The line color
   */
  void drawVLine(int16_t x, int16_t y, int16_t height, uint16_t color);