| /* |
| * 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); |
| } |
| } |
| } |