Swipe Direction in ViewPager

Question

I have an Android app that uses ViewPager and FragmentStatePagerAdapter. I however need to add a new feature in which I have to know the swipe direction to move from one fragment view to another, left or right. (i.e, when I swipe left, I would do one thing, and when I swipe right I would do something else).

Please note, I do not need the events to happen AFTER the swipe is over. I have to do those events as the swipe occurs. I thought of using setOnPageChangeListener() but it does not tell me swipe direction. Can you advise me please on how to figure out swipe direction?

Thanks.

Answer 1

I ran into this issue and need to know the direction of the swipe as it was happening in order to prevent swiping in a certain direction. Here is how I solved my problem, hopefully it is helpful to someone. I found all of the previous examples inefficient for what I needed.

If you subclass your ViewPager, you can respond to the onInterceptTouchEvent(MotionEvent event) and onTouchEvent(MotionEvent event) methods of the ViewPager

@Override public boolean onInterceptTouchEvent(MotionEvent event) {     boolean wasSwipeToRight = this.wasSwipeToRightEvent(event));     // Do what you want here with left/right swipe      return super.onInterceptTouchEvent(event); }  @Override public boolean onTouchEvent(MotionEvent event) {     boolean wasSwipeToRight = this.wasSwipeToRightEvent(event));     // Do what you want here with left/right swipe      return super.onTouchEvent(event); } 

Here is the method which is called to determine the direction of the event.

// Stores the starting X position of the ACTION_DOWN event float downX;  /**  * Checks the X position value of the event and compares it to  * previous MotionEvents. Returns a true/false value based on if the   * event was an swipe to the right or a swipe to the left.  *  * @param event -   Motion Event triggered by the ViewPager  * @return      -   True if the swipe was from left to right. False otherwise  */ private boolean wasSwipeToRightEvent(MotionEvent event){     switch (event.getAction()) {         case MotionEvent.ACTION_DOWN:             downX = event.getX();             return false;          case MotionEvent.ACTION_MOVE:         case MotionEvent.ACTION_UP:             return downX - event.getX() > 0;          default:             return false;     } }