[feature] allow image and text fill

[eqn-group]

Hello, please take a look at swaylock or swaylock-effects and atleast allow some options like: 1- https://github.com/lokesh-krishna/dotfiles/blob/main/tokyo-night/config/swaylock/config 2- https://github.com/lokesh-krishna/dotfiles/blob/main/nord-v2/bin/lock.sh

I would love to use your tool, its better.