RecyclerView smoothScroll to position in the center. android
Improvements to the answer - there is no need to override the LinearLayoutManager
From the previous answer:
public class CenterSmoothScroller extends LinearSmoothScroller {
public CenterSmoothScroller(Context context) {
super(context);
}
@Override
public int calculateDtToFit(int viewStart, int viewEnd, int boxStart, int boxEnd, int snapPreference) {
return (boxStart + (boxEnd - boxStart) / 2) - (viewStart + (viewEnd - viewStart) / 2);
}
}
Here how to use it:
RecyclerView.LayoutManager lm = new GridLayoutManager(...): // or whatever layout manager you need
...
RecyclerView.SmoothScroller smoothScroller = new CenterSmoothScroller(recyclerView.getContext());
smoothScroller.setTargetPosition(position);
lm.startSmoothScroll(smoothScroller);
Yes it's possible.
By implementing RecyclerView.SmoothScroller
's method onTargetFound(View, State, Action)
.
/**
* Called when the target position is laid out. This is the last callback SmoothScroller
* will receive and it should update the provided {@link Action} to define the scroll
* details towards the target view.
* @param targetView The view element which render the target position.
* @param state Transient state of RecyclerView
* @param action Action instance that you should update to define final scroll action
* towards the targetView
*/
abstract protected void onTargetFound(View targetView, State state, Action action);
Specifically in LinearLayoutManager
with LinearSmoothScroller
:
public class CenterLayoutManager extends LinearLayoutManager {
public CenterLayoutManager(Context context) {
super(context);
}
public CenterLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
public CenterLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {
RecyclerView.SmoothScroller smoothScroller = new CenterSmoothScroller(recyclerView.getContext());
smoothScroller.setTargetPosition(position);
startSmoothScroll(smoothScroller);
}
private static class CenterSmoothScroller extends LinearSmoothScroller {
CenterSmoothScroller(Context context) {
super(context);
}
@Override
public int calculateDtToFit(int viewStart, int viewEnd, int boxStart, int boxEnd, int snapPreference) {
return (boxStart + (boxEnd - boxStart) / 2) - (viewStart + (viewEnd - viewStart) / 2);
}
}
}