How does Android detect events? I'm not asking about implementing different handlers for events, but the logic on decide the event types. For example, when the user performs a swipe on the screen, where the Android SDK detects that this is a swipe event instead of a scroll event or other events? Thanks in advance!
Touch events are typically interpreted by a GestureDetector. Typically, touch events are handled by a View by simply passing them to a GestureDetector. The GestureDetector detects when there is some particular gesture (tap, fling, etc.) by analyzing the recent history of touch events. The GestureDetector then notifies one of the registered listeners (often a subclass of SimpleOnGestureListener).
It's up to the listener to decide what the semantic meaning is of the gesture. For instance, a ScrollView will set an OnGestureListener that reacts to a fling event by scrolling rapidly. A custom view might react to a fling by deleting some object from the view.