How to set avatar with php code

Hello everyone,

I am look for a way to set an user avatar through a php code, is there any function like set_user_avatar() ?

I have already a code that generate an image and allow the user to download it.

header(‘Content-Type: image/png’);
imagepng($avatar);

But i would like that instead of downloading it, it upload that image as user avatar.

Thanks to everyone for the support.