我正在尝试在 leanback GridLayoutManager(androidx.leanback.widget.GridLayoutManager)中找到第一个可见项目的位置。 我知道如何使用gridView.findFirstVisibleItemPosition()对于常规的androidx.recyclerview.widget.GridLayoutManager执行此操作。但是,对于leanback来说,它不起作用,并且在尝试访问androidx.leanback.widget 时出现错误“ 无法访问GridLayoutManager:它是public / package /”。它。谢谢。
答案 0 :(得分:0)
我无法找到原始问题的答案,但是我发现了类似的东西可以解决我的问题,并且可能对希望在leanback网格视图中找到位置的人有所帮助。
recyclerView?.clearOnScrollListeners()
recyclerView?.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
val focusedChild = recyclerView.layoutManager?.focusedChild
if (focusedChild != null) {
mScrolledPosition = recyclerView.getChildAdapterPosition(focusedChild)
}
}
})
答案 1 :(得分:0)
感谢mustafasevgi 我找到了找到第一个可见位置的方法:将下面的滚动侦听器添加到倾斜网格列表中,然后可以从中获取第一个可见位置
public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener
{
public static String TAG = "EndlessScrollListener";
private int previousTotal = 0; // The total number of items in the dataset after the last load
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.
int firstVisibleItem, visibleItemCount, totalItemCount;
private int currentPage = 1;
RecyclerViewPositionHelper mRecyclerViewHelper;
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
mRecyclerViewHelper = RecyclerViewPositionHelper.createHelper(recyclerView);
visibleItemCount = recyclerView.getChildCount();
totalItemCount = mRecyclerViewHelper.getItemCount();
firstVisibleItem = mRecyclerViewHelper.findFirstVisibleItemPosition();
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading && (totalItemCount - visibleItemCount)
<= (firstVisibleItem + visibleThreshold)) {
// End has been reached
// Do something
currentPage++;
onLoadMore(currentPage);
loading = true;
}
}
//Start loading
public abstract void onLoadMore(int currentPage);
}
和
public class RecyclerViewPositionHelper {
final RecyclerView recyclerView;
final RecyclerView.LayoutManager layoutManager;
RecyclerViewPositionHelper(RecyclerView recyclerView) {
this.recyclerView = recyclerView;
this.layoutManager = recyclerView.getLayoutManager();
}
public static RecyclerViewPositionHelper createHelper(RecyclerView recyclerView) {
if (recyclerView == null) {
throw new NullPointerException("Recycler View is null");
}
return new RecyclerViewPositionHelper(recyclerView);
}
/**
* Returns the adapter item count.
*
* @return The total number on items in a layout manager
*/
public int getItemCount() {
return layoutManager == null ? 0 : layoutManager.getItemCount();
}
/**
* Returns the adapter position of the first visible view. This position does not include
* adapter changes that were dispatched after the last layout pass.
*
* @return The adapter position of the first visible item or {@link RecyclerView#NO_POSITION} if
* there aren't any visible items.
*/
public int findFirstVisibleItemPosition() {
final View child = findOneVisibleChild(0, layoutManager.getChildCount(), false, true);
return child == null ? RecyclerView.NO_POSITION : recyclerView.getChildAdapterPosition(child);
}
/**
* Returns the adapter position of the first fully visible view. This position does not include
* adapter changes that were dispatched after the last layout pass.
*
* @return The adapter position of the first fully visible item or
* {@link RecyclerView#NO_POSITION} if there aren't any visible items.
*/
public int findFirstCompletelyVisibleItemPosition() {
final View child = findOneVisibleChild(0, layoutManager.getChildCount(), true, false);
return child == null ? RecyclerView.NO_POSITION : recyclerView.getChildAdapterPosition(child);
}
/**
* Returns the adapter position of the last visible view. This position does not include
* adapter changes that were dispatched after the last layout pass.
*
* @return The adapter position of the last visible view or {@link RecyclerView#NO_POSITION} if
* there aren't any visible items
*/
public int findLastVisibleItemPosition() {
final View child = findOneVisibleChild(layoutManager.getChildCount() - 1, -1, false, true);
return child == null ? RecyclerView.NO_POSITION : recyclerView.getChildAdapterPosition(child);
}
/**
* Returns the adapter position of the last fully visible view. This position does not include
* adapter changes that were dispatched after the last layout pass.
*
* @return The adapter position of the last fully visible view or
* {@link RecyclerView#NO_POSITION} if there aren't any visible items.
*/
public int findLastCompletelyVisibleItemPosition() {
final View child = findOneVisibleChild(layoutManager.getChildCount() - 1, -1, true, false);
return child == null ? RecyclerView.NO_POSITION : recyclerView.getChildAdapterPosition(child);
}
View findOneVisibleChild(int fromIndex, int toIndex, boolean completelyVisible,
boolean acceptPartiallyVisible) {
OrientationHelper helper;
if (layoutManager.canScrollVertically()) {
helper = OrientationHelper.createVerticalHelper(layoutManager);
} else {
helper = OrientationHelper.createHorizontalHelper(layoutManager);
}
final int start = helper.getStartAfterPadding();
final int end = helper.getEndAfterPadding();
final int next = toIndex > fromIndex ? 1 : -1;
View partiallyVisible = null;
for (int i = fromIndex; i != toIndex; i += next) {
final View child = layoutManager.getChildAt(i);
final int childStart = helper.getDecoratedStart(child);
final int childEnd = helper.getDecoratedEnd(child);
if (childStart < end && childEnd > start) {
if (completelyVisible) {
if (childStart >= start && childEnd <= end) {
return child;
} else if (acceptPartiallyVisible && partiallyVisible == null) {
partiallyVisible = child;
}
} else {
return child;
}
}
}
return partiallyVisible;
}
}