i want to alter the contents of my computer screen..

i am flying blind on this..
what steps must i take?

..

i have thought to use a series of javascript libraries to utilise the browser as a windowed screen,
and simply manipulate from there,
but this introduces a great deal of overhead

can i get to the primary screen?
how do i manipulate what is being shown to me pixel by pixel?

currently i am seeing a resolution of 1280x720 on my computer screen,
many different things are running to fill up my screen right now: a browser, a couple terminals, vlc..

how can i tell pixel 34,17 of what i am seeing right now to swap values with the pixel at 117,334?

Are you already familiar with the contents of the section titled "Pixels and Colors" in this article?

yeah, i wanted to remain platform agnostic as i could

i was thinking about openGL as an option or SDL

just hoping someone might have some experience in this area

With OpenGL you can use glReadPixels() and glDrawPixels()

As far as SDL, check out this example code.