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
17package com.android.car.radio;
18
19import android.animation.ValueAnimator;
20import android.content.Context;
21import android.support.v7.widget.LinearLayoutManager;
22import android.support.v7.widget.RecyclerView;
23import android.view.View;
24
25import 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 */
32public 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