not really sure what you mean by screen as you mentioned jacas robot class but also said, "only need what is currently displayed"  so are you talking about the whole desktop, or just your sketch window ?

I meant the whole deskop, like the print sreen button on the keyboard :)
I was adviced to make a transparent layer to spreed the whole size of the desktop and then sreenshot it. Since it's transparent i would get everything behind it. No idea how to do that in processing tough :)
Any ideas ?

not sure, i dont think you would get everything behind it if you use the build in save or saveFrame() function to save the processing screen to disk as it only writes the pixelarray into a file... similar with openGL i think.

In general i'm not trying to write it to a file i just want the pixels loaded in a bufferedImage object so i can do some processing on it.
You might be right about the background but its worth a try. Problem is i don't get the syntax of the openGL library of processing.
What I'm looking for is a code example that would use the class Sreenshot of openGL or any other way of capturing the sreen with OpenGl cause I'm sure it will be faster.
I've never worked with OpenGL and i realy need a faster sreen captureing algorithm then the java robot class can provide.
Thanks for the help :)

pretty sure you wont find it in the processing opengl library....
but lets see what others might suggest in this case, i never used anything beside the robot class for screen capturing.

 

Thanks. Anyways I'm still looking for a way to capture the desktop faster then the robot class can handle...

Do you want to capture an OpenGL sketch that runs in present mode ?

I think the OpenGL function that's might provide an answer would be glReadPixels.
However, i'm not sure that would be fastest than java Robot class.
Needs some testing there.

If you need to capture a fullscreen OpenGL rendering, i suggest using a third party program.
I have good result (like 120fps) with fraps for example.
Of course a free alternative would be nice.