67 lines
2.4 KiB
Java
67 lines
2.4 KiB
Java
/* Copyright 2017 Andrew Dawson
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*
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* This file is part of Tusky.
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*
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* Tusky is free software: you can redistribute it and/or modify it under the terms of the GNU
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* Lesser General Public License as published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
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* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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* General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License along with Tusky. If
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* not, see <http://www.gnu.org/licenses/>. */
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package com.keylesspalace.tusky;
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import android.support.v7.widget.LinearLayoutManager;
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import android.support.v7.widget.RecyclerView;
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abstract class EndlessOnScrollListener extends RecyclerView.OnScrollListener {
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private static final int VISIBLE_THRESHOLD = 15;
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private int currentPage;
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private int previousTotalItemCount;
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private boolean loading;
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private int startingPageIndex;
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private LinearLayoutManager layoutManager;
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EndlessOnScrollListener(LinearLayoutManager layoutManager) {
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this.layoutManager = layoutManager;
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currentPage = 0;
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previousTotalItemCount = 0;
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loading = true;
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startingPageIndex = 0;
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}
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@Override
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public void onScrolled(RecyclerView view, int dx, int dy) {
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int totalItemCount = layoutManager.getItemCount();
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int lastVisibleItemPosition = layoutManager.findLastVisibleItemPosition();
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if (totalItemCount < previousTotalItemCount) {
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currentPage = startingPageIndex;
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previousTotalItemCount = totalItemCount;
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if (totalItemCount == 0) {
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loading = true;
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}
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}
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if (loading && totalItemCount > previousTotalItemCount) {
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loading = false;
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previousTotalItemCount = totalItemCount;
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}
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if (!loading && lastVisibleItemPosition + VISIBLE_THRESHOLD > totalItemCount) {
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currentPage++;
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onLoadMore(currentPage, totalItemCount, view);
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loading = true;
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}
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}
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void reset() {
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currentPage = startingPageIndex;
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previousTotalItemCount = 0;
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loading = true;
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}
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public abstract void onLoadMore(int page, int totalItemsCount, RecyclerView view);
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}
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