I'm trying to make a carousel-like view here using RecyclerView, I want the item to snap in the middle of the screen when scrolling, one item at a time. I've tried using recyclerView.setScrollingTouchSlop(RecyclerView.TOUCH_SLOP_PAGING);
but the view is still scrolling smoothly, I've also tried to implement my own logic using scroll listener like so:
recyclerView.setOnScrollListener(new OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
Log.v("Offset ", recyclerView.getWidth() + "");
if (newState == 0) {
try {
recyclerView.smoothScrollToPosition(layoutManager.findLastVisibleItemPosition());
recyclerView.scrollBy(20,0);
if (layoutManager.findLastVisibleItemPosition() >= recyclerView.getAdapter().getItemCount() - 1) {
Beam refresh = new Beam();
refresh.execute(createUrl());
}
} catch (Exception e) {
e.printStackTrace();
}
}
The swipe from right to left is working fine now, but not the other way around, what am I missing here ?
With LinearSnapHelper
, this is now very easy.
All you need to do is this:
SnapHelper helper = new LinearSnapHelper();
helper.attachToRecyclerView(recyclerView);
Update
Available since 25.1.0, PagerSnapHelper
can help achieve ViewPager
like effect. Use it as you would use the LinearSnapHelper
.
Old workaround:
If you wish for it to behave akin to the ViewPager
, try this instead:
LinearSnapHelper snapHelper = new LinearSnapHelper() {
@Override
public int findTargetSnapPosition(RecyclerView.LayoutManager layoutManager, int velocityX, int velocityY) {
View centerView = findSnapView(layoutManager);
if (centerView == null)
return RecyclerView.NO_POSITION;
int position = layoutManager.getPosition(centerView);
int targetPosition = -1;
if (layoutManager.canScrollHorizontally()) {
if (velocityX < 0) {
targetPosition = position - 1;
} else {
targetPosition = position + 1;
}
}
if (layoutManager.canScrollVertically()) {
if (velocityY < 0) {
targetPosition = position - 1;
} else {
targetPosition = position + 1;
}
}
final int firstItem = 0;
final int lastItem = layoutManager.getItemCount() - 1;
targetPosition = Math.min(lastItem, Math.max(targetPosition, firstItem));
return targetPosition;
}
};
snapHelper.attachToRecyclerView(recyclerView);
The implementation above just returns the position next to the current item (centered) based on the direction of the velocity, regardless of the magnitude.
The former one is a first party solution included in the Support Library version 24.2.0.
Meaning you have to add this to your app module's build.gradle
or update it.
compile "com.android.support:recyclerview-v7:24.2.0"