RecyclerView的item使用属性动画。

recyclerview的item添加属性动画

1.配置使用Java8

在Moudule的build.gradle中

android {
    compileSdkVersion 24
    buildToolsVersion "24.0.2"
    compileOptions{ //添加
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    defaultConfig {
        applicationId "com.szlk.recyclerviewanimation"
        minSdkVersion 19
        targetSdkVersion 24
        versionCode 1
        versionName "1.0"
        jackOptions{
            enabled true   //启用jack编译器
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

2.Adapter代码

主要是在onBindViewHolder()方法中，直接给itemView中的子控件设置属性动画

public class RvAdapter extends RecyclerView.Adapter<RvAdapter.RvViewHolder> {
    private List<String> picUrl = new ArrayList<>();
    private Context context;

    private int mLastPosition = -1;

    public RvAdapter() {
    }

    public void setPicUrl(List<String> picUrl) {
        if (picUrl != null) {
            this.picUrl.clear();
            this.picUrl.addAll(picUrl);
            notifyDataSetChanged();
        }
    }

    @Override
    public RvViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        this.context = parent.getContext();
        View view = LayoutInflater.from(context).inflate(R.layout.item_layout, parent, false);
        RvViewHolder rvViewHolder = new RvViewHolder(view);
        rvViewHolder.setIsRecyclable(true);
        return rvViewHolder;
    }

    @Override
    public void onBindViewHolder(RvViewHolder holder, int position) {
        if (context == null) return;
        holder.iv.post(() ->
            Glide.with(context).load(picUrl.get(position))
                 .override(holder.iv.getMeasuredWidth(), holder.iv.getMeasuredHeight())
                 .centerCrop()
                 .into(holder.iv)
        );
        boolean b = Integer.compare(position,mLastPosition) < 0 ? true : false;
        addInAnimation(holder.itemView, b);
        mLastPosition = position;
    }

   /**
    *  将动画对象加入集合中  根据左右滑动加入不同 
    */
    private void addInAnimation(View view, boolean left) {
        List<Animator> list = new ArrayList<>();
        if (left) {
            list.add(ObjectAnimator.ofFloat(view, "translationX", -view.getMeasuredWidth() * 2, 0));
        } else {
            list.add(ObjectAnimator.ofFloat(view, "translationX", view.getMeasuredWidth() * 2, 0));
        }
        list.add(ObjectAnimator.ofFloat(view, "translationY", view.getMeasuredHeight() / 2, 0));
        list.add(ObjectAnimator.ofFloat(view, "alpha", 0, 1));
        list.add(ObjectAnimator.ofFloat(view, "scaleX", 0.25f, 1));
        list.add(ObjectAnimator.ofFloat(view, "scaleY", 0.25f, 1));
        startAnimation(list);
    }
    /**
     *  开启动画
     */
    private void startAnimation(List<Animator> list) {
        AnimatorSet animatorSet = new AnimatorSet();
        animatorSet.playTogether(list);
        animatorSet.setInterpolator(new DecelerateInterpolator());
        animatorSet.start();
    }

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

    class RvViewHolder extends RecyclerView.ViewHolder {
        private ImageView iv;

        public RvViewHolder(View itemView) {
            super(itemView);
            iv = (ImageView) itemView.findViewById(R.id.iv_item_layout);
        }
    }
}

3.Activity代码

尝试使用了Lambda

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        RecyclerView rv = (RecyclerView) findViewById(R.id.rv_activity);
        LinearLayoutManager manager = new LinearLayoutManager(MainActivity.this);
        manager.setOrientation(LinearLayoutManager.HORIZONTAL);
        rv.setLayoutManager(manager);
        rv.addItemDecoration(new RvItemDecoration(5));
        rv.setItemAnimator(new DefaultItemAnimator());
        RvAdapter adapter = new RvAdapter();
        rv.setAdapter(adapter);
        getPicList(adapter, "image/jpeg,image/png");
    }

    private void getPicList(RvAdapter adapter, String type) {
        Observable
                .just(type)
                .filter(s -> {//判断内存卡是否可以用
                    if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                        ToastUtils.show(MainActivity.this, "no sdCard");//已在主线程
                        return false;
                    }
                    return true;
                })
                .subscribeOn(AndroidSchedulers.mainThread())//切换到主线程 Toast
                .subscribeOn(Schedulers.io())//切换到io线程去执行查找图片路径
                .map(t -> {//拿到图片路径的集合
                      List<String> list = new ArrayList<>();
                      Uri imgUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                      ContentResolver contentResolver = MainActivity.this.getContentResolver();
                      //查找类型
                      String[] types = type.split(",");
                      String selection = MediaStore.Images.Media.MIME_TYPE + "=? or "
                             + MediaStore.Images.Media.MIME_TYPE + "=?";
                      //得到Cursor
                      Cursor cursor = contentResolver.query(imgUri, null, selection, types, MediaStore.Images.Media.DATE_MODIFIED);
                      while (cursor.moveToNext()) {
                           // 拿到每个图片的路径
                           String picPath = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
                           list.add(picPath);
                      }
                      cursor.close();
                      //将集合倒序
                      Collections.reverse(list);
                      return list;
                })
                .observeOn(AndroidSchedulers.mainThread())//切换到主线程
                .subscribe(adapter::setPicUrl);//将拿到的路径集合进行回调
    }
}