Java Code Examples for androidx.recyclerview.widget.GridLayoutManager#findLastVisibleItemPosition()

public void refreshSelection() {
    GridLayoutManager layoutManager = (GridLayoutManager) mRecyclerView.getLayoutManager();
    int first = layoutManager.findFirstVisibleItemPosition();
    int last = layoutManager.findLastVisibleItemPosition();
    if (first == -1 || last == -1) {
        return;
    }
    Cursor cursor = getCursor();
    for (int i = first; i <= last; i++) {
        RecyclerView.ViewHolder holder = mRecyclerView.findViewHolderForAdapterPosition(first);
        if (holder instanceof MediaViewHolder) {
            if (cursor.moveToPosition(i)) {
                setCheckStatus(Item.valueOf(cursor), ((MediaViewHolder) holder).mMediaGrid);
            }
        }
    }
}
 

/**
 * Checks if the user started this activity by pressing the back button on another main activity.
 * If so it runs the show animation for the activity's icon, text and visual elements.
 */
public void checkIsBackFromMainActivity() {
    if (isTransitioned) {
        GridLayoutManager manager = (GridLayoutManager) mRecyclerView.getLayoutManager();
        final int DELAY_BETWEEN = 50;
        int firstVisibleItemPosition = manager.findFirstVisibleItemPosition();
        int lastVisibleItemPosition = manager.findLastVisibleItemPosition();

        int startPositionCol = AnimationService.getColumnPosFromIndex(firstVisibleItemPosition, mRecyclerView);
        int startPositionRow = AnimationService.getRowPosFromIndex(firstVisibleItemPosition, mRecyclerView);

        // Show the Activity Icon and Text
        AnimationService.startAlphaRevealAnimation(mCircleIconWrapper);
        AnimationService.startAlphaRevealAnimation(mTitleView);

        // Fake fill the RecyclerViews with children again
        for (int i = firstVisibleItemPosition; i <= lastVisibleItemPosition; i++) {
            final View mView = mRecyclerView.getChildAt(i - firstVisibleItemPosition);

            int positionColumnDistance = Math.abs(AnimationService.getColumnPosFromIndex(i, mRecyclerView) - startPositionCol);
            int positionRowDistance = Math.abs(AnimationService.getRowPosFromIndex(i, mRecyclerView) - startPositionRow);
            int delay = (positionColumnDistance + positionRowDistance) * DELAY_BETWEEN;

            //int delay = (i - firstVisibleItemPosition) * DELAY_BETWEEN;
            if (mView != null) {
                AnimationService.startAlphaRevealAnimation(delay, mView, mAdapter instanceof StreamsAdapter);
            }
        }
        isTransitioned = false;
    }
}
 

public void checkForNewElements(RecyclerView recyclerView) {
    int currentOffset = mLazyFetchingActivity.getCurrentOffset();
    int maxElementsToFetchTotal = mLazyFetchingActivity.getMaxElementsToFetch();

    // If the task has already been run, make a new task as a task can only be run once.
    if (getElementsTask.getStatus() == AsyncTask.Status.FINISHED) {
        getElementsTask = new GetVisualElementsTask<>(mLazyFetchingActivity);
    }

    // Only bother to check if we need to fetch more game objects if we are not already in the process of doing so.
    if (getElementsTask.getStatus() != AsyncTask.Status.RUNNING && currentOffset < maxElementsToFetchTotal) {
        GridLayoutManager lm = (GridLayoutManager) recyclerView.getLayoutManager();
        RecyclerView.Adapter mAdapter = recyclerView.getAdapter();
        if (mAdapter == null) {
            return;
        }

        int lastViewPosition = lm.findLastVisibleItemPosition();
        int spanCount = lm.getSpanCount();
        int itemCount = mAdapter.getItemCount();
        final double FETCH_WHEN_BELOW_FIVE = 5;
        final double NUMBER_OF_ROWS = Math.ceil(itemCount / (spanCount * 1.0)); // Round UP to the nearest Integer
        final double LAST_ROW_VISIBLE = Math.ceil(lastViewPosition / (spanCount * 1.0)); // Round UP to the nearest Integer

        // If the Second to last or the last row is visible, then fetch more game objects.
        if (LAST_ROW_VISIBLE >= NUMBER_OF_ROWS - FETCH_WHEN_BELOW_FIVE) {
            getElementsTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
            mLazyFetchingActivity.startProgress();
        }
    }
}
 

private void checkLastItem() {
    GridLayoutManager layoutManager = (GridLayoutManager) binding.formRecycler.getLayoutManager();
    int lastVisiblePosition = layoutManager.findLastVisibleItemPosition();
    boolean shouldShowFab =
            lastVisiblePosition == dataEntryAdapter.getItemCount() - 1 ||
                    dataEntryAdapter.getItemViewType(lastVisiblePosition) == 17;
    animateFabButton(shouldShowFab);
}
 

@Override
public void onScrollStateChanged(int newState) {
    super.onScrollStateChanged(newState);
    if (newState == SCROLL_STATE_IDLE || newState == SCROLL_STATE_DRAGGING) {
        LayoutManager layoutManager = getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            GridLayoutManager linearManager = (GridLayoutManager) layoutManager;
            mFirstVisiblePosition = linearManager.findFirstVisibleItemPosition();
            mLastVisiblePosition = linearManager.findLastVisibleItemPosition();
        }
    }
}
 

@Override
public void onScrolled(int dx, int dy) {
    super.onScrolled(dx, dy);
    if (onRecyclerViewPreloadListener != null) {
        if (isEnabledLoadMore) {
            LayoutManager layoutManager = getLayoutManager();
            if (layoutManager == null) {
                throw new RuntimeException("LayoutManager is null,Please check it!");
            }
            Adapter adapter = getAdapter();
            if (adapter == null) {
                throw new RuntimeException("Adapter is null,Please check it!");
            }
            boolean isReachBottom = false;
            if (layoutManager instanceof GridLayoutManager) {
                GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
                int rowCount = adapter.getItemCount() / gridLayoutManager.getSpanCount();
                int lastVisibleRowPosition = gridLayoutManager.findLastVisibleItemPosition() / gridLayoutManager.getSpanCount();
                isReachBottom = (lastVisibleRowPosition >= rowCount - reachBottomRow);
            }

            if (!isReachBottom) {
                isInTheBottom = false;
            } else if (!isInTheBottom) {
                onRecyclerViewPreloadListener.onRecyclerViewPreloadMore();
                if (dy > 0) {
                    isInTheBottom = true;
                }
            } else {
                // 属于首次进入屏幕未滑动且内容未超过一屏，用于确保分页数设置过小导致内容不足二次上拉加载...
                if (dy == 0) {
                    isInTheBottom = false;
                }
            }
        }
    }
}
 

/**
 * Checks if the user started this activity by pressing the back button on another main activity.
 * If so it runs the show animation for the activity's icon, text and visual elements.
 */
public void checkIsBackFromMainActivity() {
    if (isTransitioned) {
        GridLayoutManager manager = (GridLayoutManager) mRecyclerView.getLayoutManager();
        final int DELAY_BETWEEN = 50;
        int firstVisibleItemPosition = manager.findFirstVisibleItemPosition();
        int lastVisibleItemPosition = manager.findLastVisibleItemPosition();

        int startPositionCol = AnimationService.getColumnPosFromIndex(firstVisibleItemPosition, mRecyclerView);
        int startPositionRow = AnimationService.getRowPosFromIndex(firstVisibleItemPosition, mRecyclerView);

        // Show the Activity Icon and Text
        AnimationService.startAlphaRevealAnimation(mCircleIconWrapper);
        AnimationService.startAlphaRevealAnimation(mTitleView);

        // Fake fill the RecyclerViews with children again
        for (int i = firstVisibleItemPosition; i <= lastVisibleItemPosition; i++) {
            final View mView = mRecyclerView.getChildAt(i - firstVisibleItemPosition);

            int positionColumnDistance = Math.abs(AnimationService.getColumnPosFromIndex(i, mRecyclerView) - startPositionCol);
            int positionRowDistance = Math.abs(AnimationService.getRowPosFromIndex(i, mRecyclerView) - startPositionRow);
            int delay = (positionColumnDistance + positionRowDistance) * DELAY_BETWEEN;

            //int delay = (i - firstVisibleItemPosition) * DELAY_BETWEEN;
            if (mView != null) {
                AnimationService.startAlphaRevealAnimation(delay, mView, mAdapter instanceof StreamsAdapter);
            }
        }
        isTransitioned = false;
    }
}
 

public void checkForNewElements(RecyclerView recyclerView) {
	int currentOffset = mLazyFetchingActivity.getCurrentOffset();
	int maxElementsToFetchTotal = mLazyFetchingActivity.getMaxElementsToFetch();

	// If the task has already been run, make a new task as a task can only be run once.
	if(getElementsTask.getStatus() == AsyncTask.Status.FINISHED) {
		getElementsTask = new GetVisualElementsTask<>();
	}

	// Only bother to check if we need to fetch more game objects if we are not already in the process of doing so.
	if(getElementsTask.getStatus() != AsyncTask.Status.RUNNING && currentOffset < maxElementsToFetchTotal) {
		GridLayoutManager lm = (GridLayoutManager) recyclerView.getLayoutManager();
		RecyclerView.Adapter mAdapter = recyclerView.getAdapter();
		if (mAdapter == null ){
			return;
		}

		int lastViewPosition = lm.findLastVisibleItemPosition();
		int spanCount = lm.getSpanCount();
		int itemCount = mAdapter.getItemCount();
		final double FETCH_WHEN_BELOW_FIVE = 5;
		final double NUMBER_OF_ROWS = Math.ceil(itemCount / (spanCount * 1.0)); // Round UP to the nearest Integer
		final double LAST_ROW_VISIBLE = Math.ceil(lastViewPosition/(spanCount * 1.0)); // Round UP to the nearest Integer

		// If the Second to last or the last row is visible, then fetch more game objects.
		if(LAST_ROW_VISIBLE >= NUMBER_OF_ROWS - FETCH_WHEN_BELOW_FIVE) {
			getElementsTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, mLazyFetchingActivity);
			mLazyFetchingActivity.startProgress();
		}
	}
}
 

private void scroll_load_more_detection(RecyclerView recyclerView) {

        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();

        if (layoutManagerType == null) {
            if (layoutManager instanceof GridLayoutManager) {
                layoutManagerType = LAYOUT_MANAGER_TYPE.GRID;
            } else if (layoutManager instanceof StaggeredGridLayoutManager) {
                layoutManagerType = LAYOUT_MANAGER_TYPE.STAGGERED_GRID;
            } else if (layoutManager instanceof LinearLayoutManager) {
                layoutManagerType = LAYOUT_MANAGER_TYPE.LINEAR;
            } else {
                throw new RuntimeException("Unsupported LayoutManager used. Valid ones are LinearLayoutManager, GridLayoutManager and StaggeredGridLayoutManager");
            }
        }

        mTotalItemCount = layoutManager.getItemCount();
        mVisibleItemCount = layoutManager.getChildCount();

        switch (layoutManagerType) {
            case LINEAR:
                mFirstVisibleItem = mRecyclerViewHelper.findFirstVisibleItemPosition();
                lastVisibleItemPosition = mRecyclerViewHelper.findLastVisibleItemPosition();
                break;
            case GRID:
                if (layoutManager instanceof GridLayoutManager) {
                    GridLayoutManager ly = (GridLayoutManager) layoutManager;
                    lastVisibleItemPosition = ly.findLastVisibleItemPosition();
                    mFirstVisibleItem = ly.findFirstVisibleItemPosition();
                }
                break;
            case STAGGERED_GRID:
                if (layoutManager instanceof StaggeredGridLayoutManager) {
                    StaggeredGridLayoutManager sy = (StaggeredGridLayoutManager) layoutManager;

                    if (mlastPositionsStaggeredGridLayout == null)
                        mlastPositionsStaggeredGridLayout = new int[sy.getSpanCount()];

                    sy.findLastVisibleItemPositions(mlastPositionsStaggeredGridLayout);
                    lastVisibleItemPosition = findMax(mlastPositionsStaggeredGridLayout);

                    sy.findFirstVisibleItemPositions(mlastPositionsStaggeredGridLayout);
                    mFirstVisibleItem = findMin(mlastPositionsStaggeredGridLayout);
                }
                break;
        }

        if (automaticLoadMoreEnabled) {

            if (mTotalItemCount > previousTotal) {
                automaticLoadMoreEnabled = false;
                previousTotal = mTotalItemCount;
            }
        }

        boolean bottomEdgeHit = (mTotalItemCount - mVisibleItemCount) <= mFirstVisibleItem;

        if (bottomEdgeHit) {
            if (mIsLoadMoreWidgetEnabled) {
                /**auto activate load more**/
                if (!automaticLoadMoreEnabled) {
                    onLoadMoreListener.loadMore(mRecyclerView.getAdapter().getItemCount(), lastVisibleItemPosition);
                    automaticLoadMoreEnabled = true;
                }
            }
            mAdapter.internalExecuteLoadingView();
            previousTotal = mTotalItemCount;
        }
    }