Waveshare E-Ink 4.2 inch library usage


I want to know how to properly use the following functions in E-Ink GitHub library here: e-Paper/epd4in2b.cpp at master · waveshare/e-Paper · GitHub

  • void SetPartialWindow(char* frame_buffer, int x, int y, int w, int l);
  • void Set_4GrayDisplay( char *Image, int x, int y, int w, int l);

For updating a regular image I convert the image to one bitmap byte array and copy the values over to the library and us the function DisplayFrame(char* frame_buffer); to display the image. Not sure if I should use the same process with reduced dimensions for the two methods mentioned above.