Decide wether scroll was user initiated or programmatically triggered?

Question

Some logic need to be executed in a HorizontalScrollView listener only if HorizontalScrollView was scrolled by user, and not me was who called horizontalScrollView.scrollBy(dx, 0); method at on other code part.

With flag - programmatic call was started, finished - can not really fix problem, because there is a small delay between scrollBy method call and triggering event handler. But in this time frame even user could touch and scroll HorizontalScrollView.

What approach would you suggest?

horizontalScrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {

        @Override
        public void onScrollChanged() {

            if (horizontalState == 0) {
                horizontalState = 2;
            }

            if (horizontalState == 2) {

                int d = ...;

                if (d != 0) {
                    userSettingRecycleView.scrollBy(d , 0);

                } else {
                    horizontalState = 0;
                }
            }
        }
    });

---

userSettingRecycleView.addOnScrollListener(new RecyclerView.OnScrollListener(){
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy){

                if (horizontalState == 1) {

                    super.onScrolled(recyclerView, dx, dy);
                    horizontalScrollView.scrollBy(dx, 0);
                }
            }

            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);

                if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {

                    ItemUserSettingRatingActivity.horizontalState = 1;
                }

                if (newState == RecyclerView.SCROLL_STATE_IDLE || newState == RecyclerView.SCROLL_STATE_SETTLING) {
                    ItemUserSettingRatingActivity.horizontalState = 0;
                }
            }
        });

Answer 1

I would suggest to disable user touches in range between your programm scrool events. That is, use those classes to create your custom HorisontalScrollView and to enable/disable taps' catch in a programm way.