How to know viewpager is scroll left or right?

Question

I am using ViewPager (support library). I want to know every time the ViewPager change the visible page, it is scrolling left or right.

Please give me a solution. An

Answer 1

Apologies - had to edit the answer as I found a bug. Here is improved solution:

The solution compares current page index with one previously selected (previousPageIndex)

newPageIndex represents the page which is about to be scrolled to.

Condition (positionOffset == 0) compares if the scroll finished

private int previousPageIndex = 0;
private int newPageIndex = -1;

private final int MOVE_DIRECTION_NONE = 0;
private final int MOVE_DIRECTION_LEFT = 1;
private final int MOVE_DIRECTION_RIGHT = 2;

private int moveDirection = MOVE_DIRECTION_NONE;


@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    super.onPageScrolled(position, positionOffset, positionOffsetPixels);

    if (moveDirection == MOVE_DIRECTION_NONE) {
        if (previousPageIndex  == position){
            moveDirection = MOVE_DIRECTION_LEFT;
            if (newPageIndex == -1) newPageIndex = previousPageIndex + 1;
        }  else {
            moveDirection = MOVE_DIRECTION_RIGHT;
            if (newPageIndex == -1) newPageIndex = previousPageIndex - 1;
        }
    }

    if (positionOffset == 0) {
        System.out.println("Reseting");
        previousPageIndex = position;
        moveDirection = MOVE_DIRECTION_NONE;
        newPageIndex = -1;
    }

    switch (moveDirection) {
        case MOVE_DIRECTION_LEFT:
            if (onPageChangingHandler != null) onPageChangingHandler.pageChanging(previousPageIndex, newPageIndex, positionOffset);
            System.out.println("Sliding Left | Previous index: " + previousPageIndex + " | New Index: " + newPageIndex + " | offset: " + positionOffset  + " | Position: " + position);
            break;
        case MOVE_DIRECTION_RIGHT:
            if (onPageChangingHandler != null) onPageChangingHandler.pageChanging(newPageIndex, previousPageIndex, positionOffset);
            System.out.println("Sliding Right | Previous index: " + previousPageIndex + " | New Index: " + newPageIndex + " | offset: " + positionOffset + " | Position: " + position);
            break;
        case MOVE_DIRECTION_NONE:
            System.out.println("Moving NONE");
            break;
    }
}