Screen Fading

[brokk]

Hello all,

My goal is to fade the sides of the screen from black, coming in more and more transparent.

One way of doing it is I made fading images and they were set on a showImg and always staying on borders of screen, adjusting it's height and width according to screen size.

Unfortunately, I think it somewhat lags.

Any suggestions?

I attached a picture with the idea I had in mind.
The black starts from the borders, and fades in.