How can i simulate a spray like windows paint ? i think it create points random , what is your opinion?
Yes, I would say it colors random pixels within a certain radius of the selection point. There's also probably a time delay between the coloring of one pixel and the other, because machines today are fast enough to be able to color every possible pixel (As long as the radius is small) before you could let go of the mouse button.
Also, I think the algorithm that Paint uses can select a pixel to paint even if it already has been painted, since sometimes you can end up with a painted circle with a few unpainted pixels inside.