Android touch event raw input processing

What is the nature of touch handling for android? Is it device specific as different displays are used across devices? I am trying to find where exactly in the massive mess that is aosp I should look to find the code relevant to touch/gesture detection. Currently really frustrated with my nexus 9 as the touch detection is ****e. I turned on pointer mapping in the developer options and it appears that the moment you touch the display it tracks a point and waits to see if its a swipe or single touch. The travel needed to tell it that you are swiping is very substantial and it only seems to track 2 points for this large travel. The reason this is frustrating is that when you are writing with a stylus or what not, every letter must start with a straight line segment as it detects that you are just touching the display vs swiping. Handwriting degrades and writing small curves becomes nearly impossible. I would like to take a look at the code that handles this but can't seem to find an easy way to browse aosp. Don't even know if at this point it is a fault of the android system, the kernel, or just a hardware limitation. I appreciate any assistance