sp9mrn:
You have to delete previous values first. Good way is save old values and print it using background colour just before printing new values.
If your TFT is fast enough You can clear display instead.
You can also print rectangle in badkground color - deleting old values.
In my opinion printing saved old values is best way - I 'm usin'g it.I heard about "XOR way" but dont know it.
MAc
XOR can only work if your display supports reading as well as writing the framebuffer memory - a lot don't.