Recognizing tap and other common gestures

Unlike the Event Listeners described in the previous recipe, gestures require a two-step process:

1. Gather movement data
2. Analyze the data to determine whether it matches a known gesture

Step 1 begins when the user touches the screen, which fires the onTouchEvent() callback with the movement data sent in a MotionEvent object. Fortunately, Android makes step 2, analyzing the data, easier with the GestureDetector class, which detects the following gestures:

• onTouchEvent()
• onDown()
• onFling()
• onLongPress()
• onScroll()
• onShowPress()
• onDoubleTap()
• onDoubleTapEvent()
• onSingleTapConfirmed()

This recipe will demonstrate using GestureDetector.SimpleOnGestureListener to recognize the touch and double tap gestures.

Getting ready

Create a new project in Android Studio and call it CommonGestureDetector. Use the default Phone & Tablet options and select Empty Activity when prompted for the Activity Type.

How to do it...

We will be using the activity itself to detect gestures, so...