Correct way to implement 2d tiled map on Kivy

Question

I'm learning to use Kivy and for this I'm trying to create a 2d game. So, I'm using Map Editor to generate a tmx file and load it on Kivy using this tutorial. However, this tutorial is for a static maps. I need a code, where my main character will be always on the middle of the screen. Obviously, for performance issues, this code must load the map in real time, for example: If the main player moves to the north, the south tile must be subtracted by one and the north tile must be added by one. What I have to change on the Character().onKeyDown() method to load new tiles and display them?