1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.android.setupdesign.template; 18 19 import androidx.annotation.NonNull; 20 import androidx.annotation.Nullable; 21 import android.util.Log; 22 import android.widget.ScrollView; 23 import com.google.android.setupdesign.template.RequireScrollMixin.ScrollHandlingDelegate; 24 import com.google.android.setupdesign.view.BottomScrollView; 25 import com.google.android.setupdesign.view.BottomScrollView.BottomScrollListener; 26 27 /** 28 * {@link ScrollHandlingDelegate} which analyzes scroll events from {@link BottomScrollView} and 29 * notifies {@link RequireScrollMixin} about scrollability changes. 30 */ 31 public class ScrollViewScrollHandlingDelegate 32 implements ScrollHandlingDelegate, BottomScrollListener { 33 34 private static final String TAG = "ScrollViewDelegate"; 35 36 @NonNull private final RequireScrollMixin requireScrollMixin; 37 38 @Nullable private final BottomScrollView scrollView; 39 ScrollViewScrollHandlingDelegate( @onNull RequireScrollMixin requireScrollMixin, @Nullable ScrollView scrollView)40 public ScrollViewScrollHandlingDelegate( 41 @NonNull RequireScrollMixin requireScrollMixin, @Nullable ScrollView scrollView) { 42 this.requireScrollMixin = requireScrollMixin; 43 if (scrollView instanceof BottomScrollView) { 44 this.scrollView = (BottomScrollView) scrollView; 45 } else { 46 Log.w(TAG, "Cannot set non-BottomScrollView. Found=" + scrollView); 47 this.scrollView = null; 48 } 49 } 50 51 @Override onScrolledToBottom()52 public void onScrolledToBottom() { 53 requireScrollMixin.notifyScrollabilityChange(false); 54 } 55 56 @Override onRequiresScroll()57 public void onRequiresScroll() { 58 requireScrollMixin.notifyScrollabilityChange(true); 59 } 60 61 @Override startListening()62 public void startListening() { 63 if (scrollView != null) { 64 scrollView.setBottomScrollListener(this); 65 } else { 66 Log.w(TAG, "Cannot require scroll. Scroll view is null."); 67 } 68 } 69 70 @Override pageScrollDown()71 public void pageScrollDown() { 72 if (scrollView != null) { 73 scrollView.pageScroll(ScrollView.FOCUS_DOWN); 74 } 75 } 76 } 77