android - StaggeredGridLayoutManager和移动项

我创建了一个非常简单的项目，通过recyclerview显示了28张带有StaggeredGridLayoutManager的图像。但是当我滚动recyclerview时，它会例如从左向右移动项目或交换左右列。

代码:

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;


public class MainActivity extends Activity {


    String mImageDir;
    private RecyclerView mRecyclerView;
    private StaggeredGridLayoutManager mLayoutManager;



    MyRecyclerAdapter myRecyclerAdapter;
    List<ImageModel> mImageList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = (RecyclerView)findViewById(R.id.recyclerview_rootview);
        mLayoutManager = new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL);
        mLayoutManager.setGapStrategy(StaggeredGridLayoutManager.GAP_HANDLING_MOVE_ITEMS_BETWEEN_SPANS);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setHasFixedSize(false);
        mImageList = new ArrayList<ImageModel>();
        for (int i = 1; i < 29 ; i++) {
            ImageModel img = new ImageModel();
            img.setTitle("Image No " + i);
            int drawableResourceId = this.getResources().getIdentifier("image"+String.valueOf(i), "drawable", this.getPackageName());
            img.setResId(drawableResourceId);
            mImageList.add(img);

        }
        myRecyclerAdapter = new MyRecyclerAdapter(MainActivity.this,mImageList);
        mRecyclerView.setAdapter(myRecyclerAdapter);

    }

}

和适配器:

public class MyRecyclerAdapter extends RecyclerView.Adapter<MyRecyclerAdapter.ViewHolder> {


    private List<ImageModel> mItems;
    Context mContext;

    public MyRecyclerAdapter(Context context,List<ImageModel> objects) {
        mContext = context;
        mItems = objects;

    }

    static class ViewHolder extends RecyclerView.ViewHolder{
        public  ImageView mImageView;
        public  TextView mTextView;
        public View rootView;
        public ViewHolder(View itemView) {
            super(itemView);
            rootView = itemView;
            mImageView =(ImageView)itemView.findViewById(R.id.image);
            mTextView =(TextView)itemView.findViewById(R.id.title);
        }
    }

    @Override
    public int getItemCount() {

        return mItems.size();
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {

        ImageModel item = mItems.get(position);
        Picasso.with(mContext).load(item.getResId()).into(holder.mImageView);
        holder.mTextView.setText(item.getTitle());
    }


    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int arg1) {
        LayoutInflater inflater =
                (LayoutInflater) mContext.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        View convertView = inflater.inflate(R.layout.item, parent, false);
        return new ViewHolder(convertView);

    }

}

和一个样本移动项:

http://i.imgur.com/FUapm2K.gif?1

如果您播放(上下滚动)，则可以发现更多有趣的动画:-)

如何防止这种情况发生并具有稳定的布局(如普通的ListView)？

编辑

@Override
public void onBindViewHolder(ViewHolder holder, int position) {

    ImageModel item = mItems.get(position);
    RelativeLayout.LayoutParams rlp = (RelativeLayout.LayoutParams)holder.mImageView.getLayoutParams();
    float ratio = item.getHeight()/item.getWidth();
    rlp.height = (int)(rlp.width * ratio);
    holder.mImageView.setLayoutParams(rlp);
    Picasso.with(mContext).load(item.getResId()).into(holder.mImageView);
    holder.mTextView.setText(item.getTitle());
}

最佳答案

发生这种情况是因为SGLM不保留有关 View 的任何w/h信息。因此，每次View反弹时，加载图像时，它都会先获得占位符的大小，然后再获得最终的大小。

加载具有不同尺寸(而不是占位符)的实际图像会触发新的布局请求，并且在该布局请求期间，SGLM会检测到UI中存在空白(或某些项目带有较高的位置，而该项目位于带有较低位置的下方)位置)，从而重新排序带有动画的项目。

您可以通过将占位符图像设置为实际图像的尺寸来避免这种情况。如果您没有时间，可以在第一次加载图像后保存它们，并在下一个onBind调用中使用它。

关于android - StaggeredGridLayoutManager和移动项，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/27636999/