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