comprehension for non-programmers: evdev, uTouch, Multi-Touch

Hi everybody,

if you have a look at this diagram of the Linux graphics stack [1] can somebody point out, how uTouch respectively multi-touch is build up?
Is it a user-space component like libdrm that talks to the kernel-module evdev? Is it a kernel module?

I also created some other diagrams as well [2]. //Obviously I am not a programmer//, I'd simply like to better comprehend the software I am running (or will be running in the future).

I would like to get a better grasp of the handling of touchscreens nonetheless. No, I do not have a touchscreen.
I read about Wayland, recreated the entire Mesa 3D article and wrote about the free and open-source graphics drivers [3]. What about the INPUT?

While I am at it, I would also like to query, whether there is some API for the INPUT, analogue to OpenGL for rendering acceleration or OpenAL for sound. SDL?

Regards,
ScotXW

[1] https://commons.wikimedia.org/wiki/File:Linux_Graphics_Stack_2013.svg
[2] https://commons.wikimedia.org/wiki/User:ScotXW
[3] https://en.wikipedia.org/wiki/Free_and_open-source_device_drivers:_graphics