Android Application Development Cookbook - Second Edition

Recognizing tap and other common gestures

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

• Gather the movement data
• 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 the GestureDetector.SimpleOnGestureListener to recognize the touch and double tap gestures.

Getting ...