Android 自定义ListView实现Item左右滑动删除
最近工作之中，要实现ListView左右滑动删除Item功能，在此做个记录。
案例图：
1.自定义ListView
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Scroller;
public class SlideDelListView extends ListView {
private int mSlideCurPosition;
private int downY;
private int downX;
private int mScreenWidth;
private View mItemView;
private Scroller mScroller;
private static final int SNAP_VELOCITY = 200;
private VelocityTracker velocityTracker;
private boolean mIsSlide = false;
private int mTouchSlop;
private SlideDelListener mSlideDelListener;
private SlideDelDirection mSlideDelDirection;
public enum SlideDelDirection {
RIGHT, LEFT
}
public SlideDelListView(Context context) {
this(context, null);
}
public SlideDelListView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public SlideDelListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScreenWidth = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getWidth();
mScroller = new Scroller(context);
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
public void setSlideDelListener(SlideDelListener slideDelListener) {
this.mSlideDelListener = slideDelListener;
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
addVelocityTracker(event);
// 假如scroller滚动还没有结束，我们直接返回
if (!mScroller.isFinished()) {
return super.dispatchTouchEvent(event);
}
downX = (int) event.getX();
downY = (int) event.getY();
mSlideCurPosition = pointToPosition(downX, downY);
// 无效的position, 不做任何处理
if (mSlideCurPosition == AdapterView.INVALID_POSITION) {
return super.dispatchTouchEvent(event);
}
// 获取我们点击的item view
mItemView = getChildAt(mSlideCurPosition - getFirstVisiblePosition());
break;
}
case MotionEvent.ACTION_MOVE: {
if (Math.abs(getScrollVelocity()) > SNAP_VELOCITY
|| (Math.abs(event.getX() - downX) > mTouchSlop && Math
.abs(event.getY() - downY) < mTouchSlop)) {
mIsSlide = true;
}
break;
}
case MotionEvent.ACTION_UP:
recycleVelocityTracker();
break;
}
return super.dispatchTouchEvent(event);
}
/**
* 往右滑动，getScrollX()返回的是左边缘的距离，就是以View左边缘为原点到开始滑动的距离，所以向右边滑动为负值
*/
private void scrollRight() {
mSlideDelDirection = SlideDelDirection.RIGHT;
// 设置滚动的参数
mScroller.startScroll(mItemView.getScrollX(), 0, -200, 0,
200);
postInvalidate(); //刷新itemView
}
/**
* 向左滑动
*/
private void scrollLeft() {
mSlideDelDirection = SlideDelDirection.LEFT;
// 设置滚动的参数
mScroller.startScroll(mItemView.getScrollX(), 0, 200, 0,
200);
postInvalidate(); // 刷新itemView
}
/**
* 根据手指滚动的距离来判断是滚动到开始位置还是向左或者向右滚动
*/
private void scrollByDistanceX() {
if (mItemView.getScrollX() >= 200) {
scrollLeft();
} else if (mItemView.getScrollX() <= -200) {
scrollRight();
} else {
mItemView.scrollTo(0, 0);
}
}
/**
* 处理我们拖动ListView item的逻辑
*/
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (mIsSlide && mSlideCurPosition != AdapterView.INVALID_POSITION) {
requestDisallowInterceptTouchEvent(true);
addVelocityTracker(ev);
final int action = ev.getAction();
int x = (int) ev.getX();
switch (action) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
MotionEvent cancelEvent = MotionEvent.obtain(ev);
cancelEvent.setAction(MotionEvent.ACTION_CANCEL |
(ev.getActionIndex() << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
onTouchEvent(cancelEvent);
int deltaX = downX - x;
downX = x;
// 手指拖动itemView滚动, deltaX大于0向左滚动，小于0向右滚
mItemView.scrollBy(deltaX, 0);
return true; //拖动的时候ListView不滚动
case MotionEvent.ACTION_UP:
int velocityX = getScrollVelocity();
if (velocityX > SNAP_VELOCITY) {
scrollRight();
} else if (velocityX < -SNAP_VELOCITY) {
scrollLeft();
} else {
scrollByDistanceX();
}
recycleVelocityTracker();
// 手指离开的时候就不响应左右滚动
mIsSlide = false;
break;
}
}
//否则直接交给ListView来处理onTouchEvent事件
return super.onTouchEvent(ev);
}
@Override
public void computeScroll() {
// 调用startScroll的时候scroller.computeScrollOffset()返回true，
if (mScroller.computeScrollOffset()) {
// 让ListView item根据当前的滚动偏移量进行滚动
mItemView.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
// 滚动动画结束的时候调用回调接口
if (mScroller.isFinished()) {
if (mSlideDelListener == null) {
throw new NullPointerException("SlideDelListener is null, we should called setSlideDelListener()");
}
mItemView.scrollTo(0, 0);
mSlideDelListener.removeItem(mSlideDelDirection, mSlideCurPosition);
}
}
}
/**
* 添加用户的速度跟踪器
*
* @param event
*/
private void addVelocityTracker(MotionEvent event) {
if (velocityTracker == null) {
velocityTracker = VelocityTracker.obtain();
}
velocityTracker.addMovement(event);
}
/**
* 移除用户速度跟踪器
*/
private void recycleVelocityTracker() {
if (velocityTracker != null) {
velocityTracker.recycle();
velocityTracker = null;
}
}
/**
* 获取X方向的滑动速度,大于0向右滑动，反之向左
*
* @return
*/
private int getScrollVelocity() {
velocityTracker.computeCurrentVelocity(1000);
int velocity = (int) velocityTracker.getXVelocity();
return velocity;
}
/**
* 当ListView item滑出屏幕，回调这个接口
* 我们需要在回调方法removeItem()中移除该Item,然后刷新ListView
*
* @author xiaanming
*/
public interface SlideDelListener {
public void removeItem(SlideDelDirection direction, int position);
}
}
2.Activity中调用:
import android.app.Activity;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Toast;
public class SlideCutActivity extends Activity implements SlideDelListView.SlideDelListener {
private SlideDelListView slideCutListView ;
private ArrayAdapter<String> adapter;
private List<String> dataSourceList = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_slidecut);
init();
}
private void init() {
slideCutListView = (SlideDelListView) findViewById(R.id.slideCutListView);
slideCutListView.setSlideDelListener(this);
for(int i=0; i<20; i++){
dataSourceList.add("滑动删除" + i);
}
adapter = new ArrayAdapter<String>(this, R.layout.layout_slidecut_item, R.id.list_item, dataSourceList);
slideCutListView.setAdapter(adapter);
slideCutListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(SlideCutActivity.this, dataSourceList.get(position), Toast.LENGTH_SHORT).show();
}
});
}
//滑动删除之后的回调方法
@Override
public void removeItem(SlideDelListView.SlideDelDirection direction, int position) {
adapter.remove(adapter.getItem(position));
switch (direction) {
case RIGHT:
Toast.makeText(this, "向右删除 "+ position, Toast.LENGTH_SHORT).show();
break;
case LEFT:
Toast.makeText(this, "向左删除 "+ position, Toast.LENGTH_SHORT).show();
break;
default:
break;
}
}
}
- xml文件
layout_slidecut.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/darker_gray">
<com.android.peter.notificationdemo.SlideDelListView
android:id="@+id/slideCutListView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:listSelector="@android:color/transparent"
android:cacheColorHint="@android:color/transparent">
</com.android.peter.notificationdemo.SlideDelListView>
</RelativeLayout>
layout_slidecut_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/list_item"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="15dip" />
</LinearLayout>
</LinearLayout>