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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 androidx.recyclerview.widget.RecyclerView;
import android.util.Log;
import com.android.setupwizardlib.template.RequireScrollMixin.ScrollHandlingDelegate;
/**
* {@link ScrollHandlingDelegate} which analyzes scroll events from {@link RecyclerView} and
* notifies {@link RequireScrollMixin} about scrollability changes.
*/
public class RecyclerViewScrollHandlingDelegate implements ScrollHandlingDelegate {
private static final String TAG = "RVRequireScrollMixin";
@Nullable private final RecyclerView recyclerView;
@NonNull private final RequireScrollMixin requireScrollMixin;
public RecyclerViewScrollHandlingDelegate(
@NonNull RequireScrollMixin requireScrollMixin, @Nullable RecyclerView recyclerView) {
this.requireScrollMixin = requireScrollMixin;
this.recyclerView = recyclerView;
}
private boolean canScrollDown() {
if (recyclerView != null) {
// Compatibility implementation of View#canScrollVertically
final int offset = recyclerView.computeVerticalScrollOffset();
final int range =
recyclerView.computeVerticalScrollRange() - recyclerView.computeVerticalScrollExtent();
return range != 0 && offset < range - 1;
}
return false;
}
@Override
public void startListening() {
if (this.recyclerView != null) {
this.recyclerView.addOnScrollListener(
new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
requireScrollMixin.notifyScrollabilityChange(canScrollDown());
}
});
if (canScrollDown()) {
requireScrollMixin.notifyScrollabilityChange(true);
}
} else {
Log.w(TAG, "Cannot require scroll. Recycler view is null.");
}
}
@Override
public void pageScrollDown() {
if (recyclerView != null) {
final int height = recyclerView.getHeight();
recyclerView.smoothScrollBy(0, height);
}
}
}
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