自定义 Horizo​​ntalScrollView 适配器 RecyclerView

Question

我正在尝试使用RecyclerView 创建一个HorizontalScrollView，我的适配器带有FirebaseAdapter 和我的onCreateViewHolder、onDataChanged 及其onBindViewHolder，我想补充一下我的RecyclerView 是这样的Image，类似于，用户只会看到 3 个项目，并且居中缩放/更大，有人告诉我必须覆盖 getItemViewType，但我不知道如何，可以你指导怎么做？

为了让它表现得像 HorizontalScrollView，我添加了一个 CustomLinearLayout，如下所示：

LinearLayoutManager layoutManager = 
new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
rv.setLayoutManager(layoutManager);

我希望它显示的是这样的（每个空白矩形都是一个项目）：

对于那些不懂的人

我已经有一个RecyclerView，它的行为类似于HorizontalScrollView 但是我无法进行自定义，以便像上面的图片一样显示它。

Answer 1

实际上这是一个流行的实现方式，因此该解决方案已经存在于 GitHub 上 - https://github.com/yarolegovich/DiscreteScrollView。它是高度可定制的，因此您可以根据自己的需求和指标进行调整。这是该库中的一个示例：

Answer 2

我遇到过类似的情况，但我将其从 recylerview 更改为 ViewPager 进行了修复，它更流畅，性能更好 首先，您将使用边距和填充的 xml 布局，它由 4 个类组成，其中包括用于所需动画的阴影变换、用于寻呼机适配器的 cardFragmentPagerAdapter、用于卡片高度的接口 cardAdapter 和用于布局外观的 cardFragment

<android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="130dp"
        android:layout_alignParentBottom="true"
        android:clipToPadding="false"
        android:overScrollMode="never"
        android:paddingEnd="80dp"
        android:paddingLeft="80dp"
        android:paddingRight="80dp"
        android:paddingStart="80dp" />

然后你将设置viewpager的边距

int margin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 10 * 2,
            getResources().getDisplayMetrics());

    viewPager.setPageMargin(-margin);
    viewPager.setClipChildren(false);

然后您将适配器设置为 viewpager 及其负责动画的阴影变换

pagerAdapter = new CardFragmentPagerAdapter(getSupportFragmentManager(),
                                    dpToPixels(2, JobMapActivity.this),
                                    titlesCard, catIconCard, catNameCard, startDateCard, startTimeCard);
                            viewPager.setAdapter(pagerAdapter);
                            viewPager.setOffscreenPageLimit(3);
                            ShadowTransformer fragmentCardShadowTransformer = new ShadowTransformer(viewPager, pagerAdapter);
                            fragmentCardShadowTransformer.enableScaling(true);
                            viewPager.setPageTransformer(false, fragmentCardShadowTransformer);

您的 CardFragmentPagerAdapter 代码是

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v7.widget.CardView;
import android.util.SparseArray;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.List;
public class CardFragmentPagerAdapter extends FragmentStatePagerAdapter implements CardAdapter {

private List<CardFragment> fragments;
SparseArray<Fragment> registeredFragments = new SparseArray<>();
private float baseElevation;
ArrayList<String> titles, icons, names, dates, times;

public CardFragmentPagerAdapter(FragmentManager fm, float baseElevation,
                                ArrayList<String> title, ArrayList<String> icon,
                                ArrayList<String> name, ArrayList<String> startDate,
                                ArrayList<String> startTime) {
    super(fm);
    fragments = new ArrayList<>();
    this.baseElevation = baseElevation;
    titles = title;
    icons = icon;
    names = name;
    dates = startDate;
    times = startTime;
    for (int i = 0; i < titles.size(); i++) {
        addCardFragment(new CardFragment());
    }
}

@Override
public float getBaseElevation() {
    return baseElevation;
}

@Override
public CardView getCardViewAt(int position) {
    return fragments.get(position).getCardView();
}

@Override
public int getCount() {
    return fragments.size();
}

@Override
public Fragment getItem(int position) {
    return CardFragment.getInstance(position, titles.get(position),
            icons.get(position), names.get(position), dates.get(position), times.get(position));
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    super.destroyItem(container, position, object);
    registeredFragments.remove(position);
}

public void addCardFragment(CardFragment fragment) {
    fragments.add(fragment);
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    Object fragment = super.instantiateItem(container, position);
    Fragment fragment2 = (Fragment) super.instantiateItem(container, position);
    fragments.set(position, (CardFragment) fragment);
    registeredFragments.put(position, fragment2);
    return fragment;
}

public String getRegisteredFragment(int position) {
    return fragments.get(position).getTitle();
}


@Override
public int getItemPosition(Object object) {
    return POSITION_NONE;
}

}

cardAdapter 是海拔的接口

    import android.support.v7.widget.CardView;

public interface CardAdapter {

    int MAX_ELEVATION_FACTOR = 8;

    float getBaseElevation();

    CardView getCardViewAt(int position);

    int getCount();
}

你的阴影变换类是

  import android.support.v4.view.ViewPager;
import android.support.v7.widget.CardView;
import android.view.View;

import com.foksart.greatskillsfixers.adapters.CardAdapter;

public class ShadowTransformer implements ViewPager.OnPageChangeListener, ViewPager.PageTransformer {

    private ViewPager viewPager;
    private CardAdapter cardAdapter;
    private float lastOffset;
    private boolean scalingEnabled;

    public ShadowTransformer(ViewPager viewPager, CardAdapter adapter) {
        this.viewPager = viewPager;
        viewPager.addOnPageChangeListener(this);
        cardAdapter = adapter;
    }

    public void enableScaling(boolean enable) {
        if (scalingEnabled && !enable) {
            // shrink main card
            CardView currentCard = cardAdapter.getCardViewAt(viewPager.getCurrentItem());
            if (currentCard != null) {
                currentCard.animate().scaleY(.9f);
//                currentCard.animate().scaleX(.9f);
            }
        }else if(!scalingEnabled && enable){
            // grow main card
            CardView currentCard = cardAdapter.getCardViewAt(viewPager.getCurrentItem());
            if (currentCard != null) {
                //enlarge the current item
                currentCard.animate().scaleY(1.3f);
//                currentCard.animate().scaleX(1.3f);
            }
        }
        scalingEnabled = enable;
    }

    @Override
    public void transformPage(View page, float position) {

    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        int realCurrentPosition;
        int nextPosition;
        float baseElevation = cardAdapter.getBaseElevation();
        float realOffset;
        boolean goingLeft = lastOffset > positionOffset;

        // If we're going backwards, onPageScrolled receives the last position
        // instead of the current one
        if (goingLeft) {
            realCurrentPosition = position + 1;
            nextPosition = position;
            realOffset = 1 - positionOffset;
        } else {
            nextPosition = position + 1;
            realCurrentPosition = position;
            realOffset = positionOffset;
        }

        // Avoid crash on overscroll
        if (nextPosition > cardAdapter.getCount() - 1
                || realCurrentPosition > cardAdapter.getCount() - 1) {
            return;
        }

        CardView currentCard = cardAdapter.getCardViewAt(realCurrentPosition);

        // This might be null if a fragment is being used
        // and the views weren't created yet
        if (currentCard != null) {
            if (scalingEnabled) {
                currentCard.setScaleX((float) (1 + 0.1 * (1 - realOffset)));
                currentCard.setScaleY((float) (1 + 0.1 * (1 - realOffset)));
            }
            currentCard.setCardElevation((baseElevation + baseElevation
                    * (CardAdapter.MAX_ELEVATION_FACTOR - 1) * (1 - realOffset)));
        }

        CardView nextCard = cardAdapter.getCardViewAt(nextPosition);

        // We might be scrolling fast enough so that the next (or previous) card
        // was already destroyed or a fragment might not have been created yet
        if (nextCard != null) {
            if (scalingEnabled) {
                nextCard.setScaleX((float) (1 + 0.1 * (realOffset)));
                nextCard.setScaleY((float) (1 + 0.1 * (realOffset)));
            }
            nextCard.setCardElevation((baseElevation + baseElevation
                    * (CardAdapter.MAX_ELEVATION_FACTOR - 1) * (realOffset)));
        }

        lastOffset = positionOffset;
    }

    @Override
    public void onPageSelected(int position) {

    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }
}

用于布局的 cardFragment

    import android.graphics.Color;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.CardView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.bumptech.glide.Glide;
import com.foksart.greatskillsfixers.ActivityClasses.JobMapActivity;
import com.foksart.greatskillsfixers.R;


public class CardFragment extends Fragment {

    private CardView cardView;
    int position;
    String title, icon, name, date, time;

    public static Fragment getInstance(int position, String title,
                                       String icon, String name,
                                       String date, String time) {
        CardFragment f = new CardFragment();
        Bundle args = new Bundle();
        args.putInt("position", position);
        args.putString("title", title);
        args.putString("icon", icon);
        args.putString("name", name);
        args.putString("date", date);
        args.putString("time", time);

        f.setArguments(args);
        return f;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.card_map_item, container, false);
        cardView = view.findViewById(R.id.cardView);
        cardView.setMaxCardElevation(cardView.getCardElevation() * CardAdapter.MAX_ELEVATION_FACTOR);
        TextView jobTitle = view.findViewById(R.id.jobTitle);
        jobTitle.setText(title);

        ImageView catIcon = view.findViewById(R.id.catIcon);
        Glide.with(getActivity()).load(icon).into(catIcon);
        catIcon.setColorFilter(Color.parseColor("#969798"));

        TextView catName = view.findViewById(R.id.catName);
        catName.setText(name);

        TextView Date = view.findViewById(R.id.Date);
        Date.setText(date);

        TextView Time = view.findViewById(R.id.Time);
        Time.setText(time);

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ((JobMapActivity)getActivity()).viewPagerClick(position);
            }
        });

        return view;
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        position = getArguments().getInt("position");
        title = getArguments().getString("title");
        icon = getArguments().getString("icon");
        name = getArguments().getString("name");
        date = getArguments().getString("date");
        time = getArguments().getString("time");
    }

    public CardView getCardView() {
        return cardView;
    }


    public String getTitle(){return title;}

Answer 3

请尝试看看这是否有帮助。

public class MainActivity extends AppCompatActivity {


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    List<String>texts = new ArrayList<>();
    texts.add("test 1");
    texts.add("test 2");
    texts.add("test 3");
    texts.add("test 4");
    texts.add("test 5");

    LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

    RecyclerView myList = (RecyclerView) findViewById(R.id.RV);
    myList.setLayoutManager(layoutManager);
    myList.setAdapter(new TestAdapter(texts));

}


 class TestAdapter extends RecyclerView.Adapter<TestAdapter.MyViewHolder> {

    private List<String> TextsList;

    public class MyViewHolder extends RecyclerView.ViewHolder {
         public TextView title;

         public MyViewHolder(View view) {
             super(view);
             title = (TextView) view.findViewById(R.id.title);
         }
     }


     public class MyBigViewHolder extends RecyclerView.ViewHolder {
         public TextView title;

         public MyBigViewHolder(View view) {
             super(view);
             title = (TextView) view.findViewById(R.id.title);
         }
     }


    public TestAdapter(List<String> textsList) {
        this.TextsList = textsList;
    }

     @Override
     public int getItemViewType(int position) {
         // Just as an example, return 0 or 2 depending on position
         // Note that unlike in ListView adapters, types don't have to be contiguous
         return position % 2 * 3;
     }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = null;
            if(viewType == 0) {
                itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.movie_list_row_2, parent, false);
            }else{
                itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.movie_list_row, parent, false);
            }

        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        String text = TextsList.get(position);
        holder.title.setText(text);
    }

    @Override
    public int getItemCount() {
        return TextsList.size();
    }
}

}