使用ItemTouchHelper完成仿Inbox的滑動刪除

一、ItemTouchHelper介紹

This is a utility class to add swipe to dismiss and drag & drop support to RecyclerView.

It works with a RecyclerView and a Callback class, which configures what type of interactions are enabled and also receives events when user performs these actions.

itemTouchHelper是support:v7包中提供的一個工具來，使用來處理item的touch事件，主要為拖拽和側滑事件。

構造方法為：ItemTouchHelper(ItemTouchHelper.Callback callback)

其中需要傳入一個Callback對象。

Callback是一個抽象類，需要繼承去實現其中的方法，在v7包中已經有一個簡單的子類SimpleCallback可以直接使用。

構造方法為：SimpleCallback(int dragDirs, int swipeDirs)

  • dragDirs表示可以拖拽的方向

  • swipeDirs表示可以滑動的方向

值分別有：

  1. LEFT

  2. RIGHT

  3. START

  4. END

  5. UP

  6. DOWN

使用時必須重寫其中的onMove(RecyclerView recyclerView,ViewHolder viewHolder, ViewHolder target)和onSwiped(ViewHolder viewHolder, int direction)兩個方法。


ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {

@Override

public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {

//處理拖拽的事件

return false;

}

@Override

public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {

//處理側滑的事件

}

});

創建好ItemTouchHelper對象后，調用attachToRecyclerView(RecyclerView recyclerView)方法傳入需要操作的RecycleView。

二、實現仿Inbox的滑動操作

先看下效果：


RecycleViewSwipeDismiss.gif
  • 布局文件

activity_sample.xml




xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".SampleActivity">

android:id="@+id/rv_list"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:scrollbars="vertical"

tools:listitem="@layout/list_item_sample"/>

list_item_sample.xml






xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/rl_background"

android:layout_width="match_parent"

android:layout_height="wrap_content">

android:id="@+id/iv_done"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerVertical="true"

android:layout_marginLeft="16dp"

android:layout_marginStart="16dp"

android:src="@mipmap/bt_ic_done_white_24" />

android:id="@+id/iv_schedule"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentRight="true"

android:layout_centerVertical="true"

android:layout_marginEnd="16dp"

android:layout_marginRight="16dp"

android:src="@mipmap/bt_ic_schedule_white_24" />



android:id="@+id/ll_item"

android:layout_width="match_parent"

android:layout_height="64dp"

android:background="@android:color/white"

android:gravity="center_vertical"

android:orientation="vertical"

android:paddingLeft="16dp"

android:paddingRight="16dp">

android:id="@+id/tv_item"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:textAppearance="?android:attr/textAppearanceMedium"

tools:text="Item" />

android:layout_width="match_parent"

android:layout_height="1dp"

android:layout_below="@id/ll_item"

android:background="#B2B2b2" />
  • Activity中實現滑動操作

ViewHolder


static class ItemViewHolder extends RecyclerView.ViewHolder {

View vBackground; // 背景

View vItem;

TextView tvItem; // 滑動的view

ImageView ivDone;

ImageView ivSchedule;

public ItemViewHolder(View itemView) {

super(itemView);

vBackground = itemView.findViewById(R.id.rl_background);

vItem = itemView.findViewById(R.id.ll_item);

tvItem = (TextView) itemView.findViewById(R.id.tv_item);

ivDone = (ImageView) itemView.findViewById(R.id.iv_done);

ivSchedule = (ImageView) itemView.findViewById(R.id.iv_schedule);

}

}

SampleActivity.java


public class SampleActivity extends AppCompatActivity {

private RecyclerView rvList;

private SampleAdapter mSampleAdapter;

private ArrayList mData = new ArrayList<>();

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_sample);

initView();

}

private void initView() {

rvList = (RecyclerView) findViewById(R.id.rv_list);

LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);

linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);

rvList.setLayoutManager(linearLayoutManager);

for (int i = 0; i < 20; i++) {

mData.add("RecyclerView" + i);

}

mSampleAdapter = new SampleAdapter(this, mData);

rvList.setAdapter(mSampleAdapter);

// new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) 表示不可以拖拽，只可以在左右方向滑動

ItemTouchHelper itemTouchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {

@Override

public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {

// 不處理拖拽事件回調

return false;

}

@Override

public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {

// 處理滑動事件回調

final int pos = viewHolder.getAdapterPosition();

final String item = mData.get(pos);

mData.remove(pos);

mSampleAdapter.notifyItemRemoved(viewHolder.getAdapterPosition());

String text;

// 判斷方向，進行不同的操作

if (direction == ItemTouchHelper.RIGHT) {

text = "刪除一項";

} else {

text = "延遲一項";

}

Snackbar.make(viewHolder.itemView, text, Snackbar.LENGTH_LONG)

.setAction("撤銷", new View.OnClickListener() {

@Override

public void onClick(View v) {

mData.add(pos, item);

mSampleAdapter.notifyItemInserted(pos);

}

}).show();

}

@Override

public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {

// 釋放View時回調，清除背景顏色，隱藏圖標

// 默認是操作ViewHolder的itemView，這里調用ItemTouchUIUtil的clearView方法傳入指定的view

getDefaultUIUtil().clearView(((SampleAdapter.ItemViewHolder) viewHolder).vItem);

((SampleAdapter.ItemViewHolder) viewHolder).vBackground.setBackgroundColor(Color.TRANSPARENT);

((SampleAdapter.ItemViewHolder) viewHolder).ivSchedule.setVisibility(View.GONE);

((SampleAdapter.ItemViewHolder) viewHolder).ivDone.setVisibility(View.GONE);

}

@Override

public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {

// 當viewHolder的滑動或拖拽狀態改變時回調

if (viewHolder != null) {

// 默認是操作ViewHolder的itemView，這里調用ItemTouchUIUtil的clearView方法傳入指定的view

getDefaultUIUtil().onSelected(((SampleAdapter.ItemViewHolder) viewHolder).vItem);

}

}

@Override

public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {

// ItemTouchHelper的onDraw方法會調用該方法，可以使用Canvas對象進行繪制，繪制的圖案會在RecyclerView的下方

// 默認是操作ViewHolder的itemView，這里調用ItemTouchUIUtil的clearView方法傳入指定的view

getDefaultUIUtil().onDraw(c, recyclerView, ((SampleAdapter.ItemViewHolder) viewHolder).vItem, dX, dY, actionState, isCurrentlyActive);

if (dX > 0) { // 向左滑動是的提示

((SampleAdapter.ItemViewHolder) viewHolder).vBackground.setBackgroundResource(R.color.colorDone);

((SampleAdapter.ItemViewHolder) viewHolder).ivDone.setVisibility(View.VISIBLE);

((SampleAdapter.ItemViewHolder) viewHolder).ivSchedule.setVisibility(View.GONE);

}

if (dX < 0) { // 向右滑動時的提示

((SampleAdapter.ItemViewHolder) viewHolder).vBackground.setBackgroundResource(R.color.colorSchedule);

((SampleAdapter.ItemViewHolder) viewHolder).ivSchedule.setVisibility(View.VISIBLE);

((SampleAdapter.ItemViewHolder) viewHolder).ivDone.setVisibility(View.GONE);

}

}

@Override

public void onChildDrawOver(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {

// ItemTouchHelper的onDrawOver方法會調用該方法，可以使用Canvas對象進行繪制，繪制的圖案會在RecyclerView的上方

// 默認是操作ViewHolder的itemView，這里調用ItemTouchUIUtil的clearView方法傳入指定的view

getDefaultUIUtil().onDrawOver(c, recyclerView, ((SampleAdapter.ItemViewHolder) viewHolder).vItem, dX, dY, actionState, isCurrentlyActive);

}

});

itemTouchHelper.attachToRecyclerView(rvList);

}

}

默認情況下，Callback操作的是ViewHolder的itemVIew；getDefaultUIUtil()方法返回ItemTouchUIUtil對象，通過ItemTouchUIUtil的方法可以指定操作的view。

源碼地址：https://github.com/zly394/RecycleViewSwipeDismiss

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