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时间：2016-08-23 11:39 来源：互联网作者：源码搜藏收藏

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源码类别：RecyclerViews
源码大小：未知
编码格式：gbk,utf8,不限
运行环境：php+mysql

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拖动选择回收站查看

这个库可以让你实现你的应用程序谷歌照片风格多选！你开始长按列表中的一个项目，然后拖动手指不放选择更多。

介绍

DragSelectRecyclerView与DragSelectRecyclerViewAdapter此库的两大类。他们一起工作，提供你所寻求的功能。

该库也将自动自动滚屏像谷歌照片。如果拖到RecyclerView的顶部，列表将滚动，反之亦然。

DragSelectRecyclerView

DragSelectRecyclerView取代了常规的RecyclerView在你的布局。它拦截触摸事件，当你告诉我们，如果选择模式被激活，并自动报告给您的适配器。

< com .afollestad.dragselectrecyclerview.DragSelectRecyclerView
         android : id = " @+id/list "
         android : layout_width = " match_parent "
         android : layout_height = " match_parent "
         android : scrollbars = " vertical " />

设置基本相同，因为这将是一个常规RecyclerView。您只需设置一个LayoutManager ，并RecyclerView.Adapter给它：

DragSelectRecyclerView list = (DragSelectRecyclerView) findViewById(R.id.list);
list.setLayoutManager(new GridLayoutManager(this, 3));
list.setAdapter(adapter);

这里唯一的主要区别是你需要的内部传递什么setAdapter()。这不可能是任何常规RecyclerView.Adapter，它必须是一个亚类的DragSelectRecyclerViewAdapter将在下文讨论。

DragSelectRecyclerViewAdapter

DragSelectRecyclerViewAdapter是一个RecyclerView.Adapter子类，DragSelectRecyclerView能够进行通信。它跟踪选定的指数-它可以让你改变它们，清除它们，聆听变化，如果选择某个索引检查。

基本适配器实现如下：

public class MainAdapter extends DragSelectRecyclerViewAdapter<MainAdapter.MainViewHolder> {

    public interface ClickListener {
        void onClick(int index);

        void onLongClick(int index);
    }

    private final ClickListener mCallback;

    // Constructor takes click listener callback
    protected MainAdapter(ClickListener callback) {
        super();
        mCallback = callback;
    }

    @Override
    public MainViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.griditem_main, parent, false);
        return new MainViewHolder(v);
    }

    @Override
    public void onBindViewHolder(MainViewHolder holder, int position) {
        super.onBindViewHolder(holder, position); // this line is important!

        // Sets position + 1 to a label view
        holder.label.setText(String.format("%d", position + 1));

        if (isIndexSelected(position)) {
            // Item is selected, change it somehow 
        } else {
            // Item is not selected, reset it to a non-selected state
        }
    }

    @Override
    protected boolean isIndexSelectable(int index) {
        // This method is OPTIONAL, returning false will prevent the item at the specified index from being selected.
        // Both initial selection, and drag selection.
        return true;
    }

    @Override
    public int getItemCount() {
        return 60;
    }

    public class MainViewHolder extends RecyclerView.ViewHolder
            implements View.OnClickListener, View.OnLongClickListener{

        public final TextView label;

        public MainViewHolder(View itemView) {
            super(itemView);
            this.label = (TextView) itemView.findViewById(R.id.label);
            this.itemView.setOnClickListener(this);
            this.itemView.setOnLongClickListener(this);
        }

        @Override
        public void onClick(View v) {
            // Forwards to the adapter's constructor callback
            if (mCallback != null) mCallback.onClick(getAdapterPosition());
        }

        @Override
        public boolean onLongClick(View v) {
            // Forwards to the adapter's constructor callback
            if (mCallback != null) mCallback.onLongClick(getAdapterPosition());
            return true;
        }
    }
}

你选择当选择一个项目（在做什么onBindViewHolder）。isIndexSelected(int)返回true或false。这里使用的点击监听执行将在下一节帮助。

用户激活，初始化拖动选择

除非你告诉它该库将不会启动选择模式。你希望用户能够积极它。在适配器的点击监听器实现上面设置将有助于这一点。

public class MainActivity extends AppCompatActivity implements
        MainAdapter.ClickListener, DragSelectRecyclerViewAdapter.SelectionListener {

    private DragSelectRecyclerView mList;
    private MainAdapter mAdapter;

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

        // Setup adapter and callbacks
        mAdapter = new MainAdapter(this);
        // Receives selection updates, recommended to set before restoreInstanceState() so initial reselection is received
        mAdapter.setSelectionListener(this);
        // Restore selected indices after Activity recreation
        mAdapter.restoreInstanceState(savedInstanceState);

        // Setup the RecyclerView
        mList = (DragSelectRecyclerView) findViewById(R.id.list);
        mList.setLayoutManager(new GridLayoutManager(this, getResources().getInteger(R.integer.grid_width)));
        mList.setAdapter(mAdapter);
    }

    @Override
    public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
        super.onSaveInstanceState(outState, outPersistentState);
        // Save selected indices to be restored after recreation
        mAdapter.saveInstanceState(outState);
    }

    @Override
    public void onClick(int index) {
        // Single click will select or deselect an item
        mAdapter.toggleSelected(index);
    }

    @Override
    public void onLongClick(int index) {
        // Long click initializes drag selection, and selects the initial item
        mList.setDragSelectActive(true, index);
    }

    @Override
    public void onDragSelectionChanged(int count) {
        // TODO Selection was changed, updating an indicator, e.g. a Toolbar or contextual action bar
    }
}

选择检索和修改

DragSelectRecyclerViewAdapter 包含了许多方法来帮助你！

//清除所有选定的指标

adapter.clearSelected();

//为选中（true）还是未选中的（假）设置一个指数

adapter.setSelected(index, true);

//如果选择了一个索引，取消选择它。否则，选择它。返回新的选择状态。

boolean selectedNow = adapter.toggleSelected(index);

//获取选定的指标数量

int count = adapter.getSelectedCount();

//获取所有选定的指数

Integer[] selectedItems = adapter.getSelectedIndices();

//检查是否选择了一个索引，在适配器子类有用

boolean selected = adapter.isIndexSelected(index);

//设置被通知的选择更改侦听器，在上面的部分中使用

adapter.setSelectionListener(listener);

//用于上面的方法，将保存指数捆绑

adapter.saveInstanceState(outState);

//上面部分中使用，恢复从包中选择指标

adapter.restoreInstanceState(inState);

自动滚屏

默认情况下，该库会自动滚动。在拖动选择，你的手指移动到列表的顶部会向上滚动。移动手指到列表的底部将向下滚动。

在顶部或底部的激活点的开始，该列表会慢慢滚动。你进入激活区越远，速度就越快滚动。

您可以禁用自动滚动，或者从你的布局XML改变激活热点：

< com .afollestad.dragselectrecyclerview.DragSelectRecyclerView
         android : id = " @+id/list "
         android : layout_width = " match_parent "
         android : layout_height = " match_parent "
         android : scrollbars = " vertical "
         app : dsrv_autoScrollEnabled = " true "
         app : dsrv_autoScrollHotspotHeight = " 56dp " />