Most applications tend to only listen for a simple touch gesture, perhaps the odd app with listen for a swipe or fling... what if you had an application that in a single view had to handle (for example) all the following views.
- Tap
- Double Tap
- 2 finger Tap
- 2 finger double tap
- 3 finger tap
- Pinch
- 1 finger down, second finger tap.
- 1 finger scroll (dragging and fling)
- 2 finger scroll (dragging and fling)
- 3 finger scroll (dragging and fling)
- tap and a half (basically tap, then finger down again)
That right, what if you wanted to emulate all the gesture of a touch-pad on your android screen? Google does provide some classes that you can use but they only handle frequently used gestures. Google provides a demo on complex gesture handling but this only allows you to create a database of gestures (with just one finger) and match against it. A lot of the 2 and 3 finger taps and gestures are not catered for.
Explanation of the code on how to detect one finger, two finger and pinch can be found on my blog in the article Android: Detecting a Pinch Gesture.