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      1 /*
      2  * Copyright (c) 2016, 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.android.car.radio;
     18 
     19 import android.animation.ValueAnimator;
     20 import android.content.Context;
     21 import android.support.v7.widget.LinearLayoutManager;
     22 import android.support.v7.widget.RecyclerView;
     23 import android.view.View;
     24 
     25 import androidx.car.widget.PagedListView;
     26 
     27 /**
     28  * Listener on the preset list that will add elevation on the container holding the current
     29  * playing radio station. This elevation will give the illusion of the preset list scrolling
     30  * under that container.
     31  */
     32 public class PresetListScrollListener extends RecyclerView.OnScrollListener {
     33     private static final int ANIMATION_DURATION_MS = 100;
     34 
     35     private final float mContainerElevation;
     36     private final View mCurrentRadioCardContainer;
     37     private final View mCurrentRadioCard;
     38     private final PagedListView mPresetList;
     39     private final ValueAnimator mRemoveElevationAnimator;
     40 
     41     public PresetListScrollListener(Context context, View container, View currentRadioCard,
     42             PagedListView presetList) {
     43         mPresetList = presetList;
     44         mCurrentRadioCardContainer = container.findViewById(R.id.preset_current_card_container);
     45         mCurrentRadioCard = currentRadioCard;
     46         mContainerElevation = context.getResources()
     47                 .getDimension(R.dimen.car_preset_container_elevation);
     48 
     49         mRemoveElevationAnimator = ValueAnimator.ofFloat(mContainerElevation, 0.f);
     50         mRemoveElevationAnimator
     51                 .setDuration(ANIMATION_DURATION_MS)
     52                 .addUpdateListener(animation -> mCurrentRadioCardContainer.setElevation(
     53                         (float) animation.getAnimatedValue()));
     54     }
     55 
     56     @Override
     57     public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
     58         if (mPresetList.getTranslationY() != 0.f) {
     59             return;
     60         }
     61 
     62         // The default LayoutManager for PagedListView is a LinearLayoutManager. Radio does
     63         // not change this.
     64         LinearLayoutManager layoutManager =
     65                 (LinearLayoutManager) recyclerView.getLayoutManager();
     66 
     67         if (layoutManager.findFirstCompletelyVisibleItemPosition() == 0) {
     68             // Animate the removal of the elevation so that it's not jarring.
     69             mRemoveElevationAnimator.start();
     70         } else {
     71             // No animation needed when adding the elevation because the scroll masks the adding
     72             // of the elevation.
     73             mCurrentRadioCardContainer.setElevation(mContainerElevation);
     74             mCurrentRadioCard.setTranslationZ(mContainerElevation);
     75         }
     76     }
     77 }
     78