Building Android UIs with Custom Views

Detecting gestures

Let's change the code we've been building to use GestureDetector. We'll also use a Scroller implementation to scroll smoothly between values. We can modify the constructor to create the Scroller object and the GestureDetector with an implementation of a GestureDetector.OnGestureListener:

private GestureDetector gestureListener; 
private Scroller angleScroller; 
 
public CircularActivityIndicator(Context context, AttributeSet attributeSet) { 
    super(context, attributeSet); 
 
    ... 
     
    selectedAngle = 280; 
    pressed = false; 
 
    angleScroller = new Scroller(context, null, true); 
    angleScroller.setFinalX(selectedAngle); 
 
    gestureListener = new GestureDetector(context, new GestureDetector.OnGestureListener() { boolean processed; @Override public ...