android - tag - gtm console

Cómo implementar el desplazamiento sin fin usando StaggeredLayoutManager

Question

Ya intenté implementar el desplazamiento sin fin para LinearLayoutManager y fue exitoso e intenté copiar la implementación de LinearLayoutManager en StaggeredGridLayoutManager pero no funciona.

Solo quiero obtener el primer objeto visible.

en LinearLayoutManager:

int firstVisibleItem = linearLayoutManager.findFirstVisibleItemPosition(int);

pero en StaggeredGridLayoutManager es:

int firstVisibleItem = staggeredGridLayoutManager.findFirstVisibleItemPositions(int[])

¿Cómo obtener el primer objeto visible usando (int) no (int [])?

¿Hay algún buen enfoque / implementación sobre esto?

Gracias por adelantado.

Answer 1

Esta es mi implementación de un ScrollListener .

Aquí está mi código para implementar el ScrollListener :

private EndlessScrollListener scrollListener =
new EndlessScrollListener(new EndlessScrollListener.RefreshList() {
@Override public void onRefresh(int pageNumber) {
//Here you can execute server connection or anything else to update data and present with Recycler view
// Notice: It is sync method
}
});
recyclerView.addOnScrollListener(scrollListener);

ScrollListener personalizada ScrollListener :

class EndlessScrollListener extends RecyclerView.OnScrollListener {
private boolean isLoading;
private boolean hasMorePages;
private int pageNumber = 0;
private RefreshList refreshList;
private boolean isRefreshing;
private int pastVisibleItems;
public EndlessScrollListener(RefreshList refreshList) {
this.isLoading = false;
this.hasMorePages = true;
this.refreshList = refreshList;
}
@Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
StaggeredGridLayoutManager manager =
(StaggeredGridLayoutManager) recyclerView.getLayoutManager();
int visibleItemCount = manager.getChildCount();
int totalItemCount = manager.getItemCount();
int[] firstVisibleItems = manager.findFirstVisibleItemPositions(null);
if (firstVisibleItems != null && firstVisibleItems.length > 0) {
pastVisibleItems = firstVisibleItems[0];
}
if ((visibleItemCount + pastVisibleItems) >= totalItemCount && !isLoading) {
isLoading = true;
if (hasMorePages && !isRefreshing) {
isRefreshing = true;
new Handler().postDelayed(new Runnable() {
@Override public void run() {
refreshList.onRefresh(pageNumber);
}
}, 200);
}
} else {
isLoading = false;
}
}
public void noMorePages() {
this.hasMorePages = false;
}
public void notifyMorePages() {
isRefreshing = false;
pageNumber = pageNumber + 1;
}
public interface RefreshList {
void onRefresh(int pageNumber);
}
}

Answer 2

Lo tengo funcionando:

Puede usar uno de los dos métodos en el StaggeredGridLayoutManager:

1. findFirstVisibleItemPositions(int[])
2. findFirstCompletelyVisibleItemPositions(int[])

Pase una matriz int vacía que se inicializará con las posiciones y use la que tenga sentido para usted.

private boolean loading = true;
private int pastVisibleItems, visibleItemCount, totalItemCount;
mRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener({
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
visibleItemCount = mLayoutManager.getChildCount();
totalItemCount = mLayoutManager.getItemCount();
int[] firstVisibleItems = null;
firstVisibleItems = mLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
if(firstVisibleItems != null && firstVisibleItems.length > 0) {
pastVisibleItems = firstVisibleItems[0];
}
if (loading) {
if ((visibleItemCount + pastVisibleItems) >= totalItemCount) {
loading = false;
Log.d("tag", "LOAD NEXT ITEM");
}
}
}
});

Answer 3

Para implementar EndlessRecyclerOnScrollListener primero cree la clase java EndlessRecyclerOnScrollListener

 import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener {
public static String TAG = EndlessRecyclerOnScrollListener.class.getSimpleName();
private int scrolledDistance = 0;
private boolean controlsVisible = false;
private boolean loading = true; // True if we are still waiting for the last set of data to load.
private int visibleThreshold = 5; // The minimum amount of items to have below your current scroll position before loading more.
private int pastVisibleItems, visibleItemCount, totalItemCount;
private int current_page = 1;
private StaggeredGridLayoutManager mStaggeredGridLayoutManager;
public EndlessRecyclerOnScrollListener(StaggeredGridLayoutManager staggeredGridLayoutManager) {
this.mStaggeredGridLayoutManager = staggeredGridLayoutManager;
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
visibleItemCount = recyclerView.getChildCount();
totalItemCount = mStaggeredGridLayoutManager.getItemCount();
//firstVisibleItem = mStaggeredGridLayoutManager.findFirstVisibleItemPosition();
int[] firstVisibleItems = null;
firstVisibleItems = mStaggeredGridLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
if (firstVisibleItems != null && firstVisibleItems.length > 0) {
pastVisibleItems = firstVisibleItems[0];
}
if (loading) {
if ((visibleItemCount + pastVisibleItems) >= totalItemCount) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading && (totalItemCount - visibleItemCount)
<= (pastVisibleItems + visibleThreshold)) {
// End has been reached
// Do something
current_page++;
onLoadMore(current_page);
loading = true;
}
if (scrolledDistance > 1 && controlsVisible) {
controlsVisible = false;
scrolledDistance = 0;
} else if (scrolledDistance < -1 && !controlsVisible) {
controlsVisible = true;
scrolledDistance = 0;
}
if ((controlsVisible && dy > 0) || (!controlsVisible && dy < 0)) {
scrolledDistance += dy;
}
}
public abstract void onLoadMore(int current_page);
;
}

Luego, en su actividad o fragmento (este ejemplo es para fragmento) use el siguiente código

 RecyclerView mRecyclerView;
StaggeredGridLayoutManager mStaggeredGridLayoutManager;
private RecyclerView.Adapter adapter;
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle saveInstanceState) {
View v = inflater.inflate(R.layout.notices_layout, container, false);
mRecyclerView = (RecyclerView) v.findViewById(R.id.listaNoticias);
mStaggeredGridLayoutManager = new StaggeredGridLayoutManager(
2, //number of grid columns
GridLayoutManager.VERTICAL);
//Sets the gap handling strategy for StaggeredGridLayoutManager
mStaggeredGridLayoutManager.setGapStrategy(StaggeredGridLayoutManager.GAP_HANDLING_NONE);
mRecyclerView.setLayoutManager(mStaggeredGridLayoutManager);
//initializing our adapter
adapter = new MyAdapter(list, getContext());
//Adding adapter to recyclerview
mRecyclerView.setAdapter(adapter);
mRecyclerView.setOnScrollListener(new EndlessRecyclerOnScrollListener(mStaggeredGridLayoutManager) {
@Override
public void onLoadMore(int current_page) {
// do something...
getData(current_page);
}
});
return v;
}

Answer 4

int mSpanCount = 2;
int[] into = new int[mSpanCount];
int firstVisibleItem = staggeredGridLayoutManager.findFirstVisibleItemPositions(into)[0];