How do I change color to a sprite?

Hello everyone!

Ok so, I have a square. A color X one. I want to change its color to color Y, without having to create a different animation with the exact square with color Y. And if it's possible, I want it to transform from color X to color Y like a loading bar, starting from the left, and going to the right. Something like in the attached picture. I repeat, I don't want to create different animations for every transformation from color X to color Y...

You can adjust a sprites hue with webGL (This wont work on black though)

If the effect you want to achieve is exactly as described I would simply use two square sprites and adjust the width values of the red one.

Ok, thank you... I'll try it later, if I have any more question I'll post here