83 lines
2.6 KiB
Java
83 lines
2.6 KiB
Java
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.setupwizardlib.template;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import android.util.Log;
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import android.widget.AbsListView;
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import android.widget.ListAdapter;
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import android.widget.ListView;
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import com.android.setupwizardlib.template.RequireScrollMixin.ScrollHandlingDelegate;
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/**
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* {@link ScrollHandlingDelegate} which analyzes scroll events from {@link ListView} and notifies
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* {@link RequireScrollMixin} about scrollability changes.
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*/
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public class ListViewScrollHandlingDelegate
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implements ScrollHandlingDelegate, AbsListView.OnScrollListener {
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private static final String TAG = "ListViewDelegate";
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private static final int SCROLL_DURATION = 500;
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@NonNull private final RequireScrollMixin requireScrollMixin;
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@Nullable private final ListView listView;
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public ListViewScrollHandlingDelegate(
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@NonNull RequireScrollMixin requireScrollMixin, @Nullable ListView listView) {
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this.requireScrollMixin = requireScrollMixin;
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this.listView = listView;
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}
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@Override
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public void startListening() {
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if (listView != null) {
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listView.setOnScrollListener(this);
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final ListAdapter adapter = listView.getAdapter();
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if (listView.getLastVisiblePosition() < adapter.getCount()) {
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requireScrollMixin.notifyScrollabilityChange(true);
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}
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} else {
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Log.w(TAG, "Cannot require scroll. List view is null");
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}
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}
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@Override
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public void pageScrollDown() {
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if (listView != null) {
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final int height = listView.getHeight();
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listView.smoothScrollBy(height, SCROLL_DURATION);
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}
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}
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@Override
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public void onScrollStateChanged(AbsListView view, int scrollState) {}
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@Override
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public void onScroll(
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AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
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if (firstVisibleItem + visibleItemCount >= totalItemCount) {
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requireScrollMixin.notifyScrollabilityChange(false);
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} else {
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requireScrollMixin.notifyScrollabilityChange(true);
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}
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}
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}
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