最近的專案需求有一條是要實現仿QQ的側滑刪除效果，網上搜到了很多，但是與預想的都不太一樣，於是自己研究了一下，寫了一個Demo，記錄下來。

功能：

1.實現了仿QQ的Item側滑效果

2.可根據item的長度計算側滑範圍

3.實現item條目點選監聽與刪除按鈕監聽

4.解決了刪除按鈕出現時ListView滑動錯位問題（偷懶：滑動時item復位）

主要程式碼：

SlidePauseListView：

package com.jcking.slidepauselistview.view;

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
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 SlidePauseListView extends ListView {
	/**
	 * 當前滑動的ListView　position
	 */
	private int slidePosition;
	/**
	 * 手指按下X的座標
	 */
	private int downY;
	/**
	 * 手指按下Y的座標
	 */
	private int downX;
	/**
	 * 螢幕寬度
	 */
	private int screenWidth;
	/**
	 * ListView的item
	 */
	private View itemView;
	/**
	 * 滑動類
	 */
	private Scroller scroller;
	/**
	 * 滑動速度邊界值
	 */
	private static final int SNAP_VELOCITY = 600;
	/**
	 * 速度追蹤物件
	 */
	private VelocityTracker velocityTracker;
	/**
	 * 是否響應滑動，預設為不響應
	 */
	private boolean isSlide = false;
	/**
	 * 認為是使用者滑動的最小距離
	 */
	private int mTouchSlop;
	/**
	 * 最多可滑動的範圍 
	 */
	private int mTouchLimit;
	/**
	 * 是否已經側滑
	 */
	private boolean hasSlided = false;


	public SlidePauseListView(Context context) {
		this(context, null);
	}

	public SlidePauseListView(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public SlidePauseListView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		DisplayMetrics dm = new DisplayMetrics();
		((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getMetrics(dm);
		screenWidth = dm.widthPixels;
		scroller = new Scroller(context);
		mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
		mTouchLimit = screenWidth / 4;
	}
	
	/**
	 * 設定可滑動的最大值
	 * @param limit
	 */
	public void setTouchLimit(int limit){
		this.mTouchLimit = limit;
	}
	
	/**
	 * 獲取可滑動的最大值
	 * @return
	 */
	public int getTouchLimit(){
		return this.mTouchLimit;
	}

	/**
	 * 退回原位
	 */
	public void slideBack(){
		if(hasSlided && itemView != null){
			scrollXBy(itemView, -mTouchLimit);
			hasSlided = false;
		}
	}
	
	/**
	 * 分發事件，主要做的是判斷點選的是那個item, 以及通過postDelayed來設定響應左右滑動事件
	 */
	@Override
	public boolean dispatchTouchEvent(MotionEvent event) {
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN: {
			addVelocityTracker(event);

			// 假如scroller滾動還沒有結束，我們直接返回
			if (!scroller.isFinished()) {
				return super.dispatchTouchEvent(event);
			}
			// 如果已經側滑了，我們直接返回
			if(hasSlided){
				return super.dispatchTouchEvent(event);
			}
			downX = (int) event.getX();
			downY = (int) event.getY();

			slidePosition = pointToPosition(downX, downY);

			// 無效的position, 不做任何處理
			if (slidePosition == AdapterView.INVALID_POSITION) {
				return super.dispatchTouchEvent(event);
			}

			// 獲取我們點選的item view
			itemView = getChildAt(slidePosition - getFirstVisiblePosition());
			if(itemView instanceof SlideListItem){
				SlideListItem item = (SlideListItem) itemView;
				int count = item.getChildCount();
				mTouchLimit = 0;
				for (int i = 0; i < count; i++) {
					if(i > 0){
						mTouchLimit += item.getChildAt(i).getMeasuredWidth();
					}
				}
			}
			break;
		}
		case MotionEvent.ACTION_MOVE: {
//			Log.d("test", "downX : " + downX + ", event.getX() : " + event.getX() + ", mTouchSlop : " + mTouchSlop);
			if (Math.abs(getScrollVelocity()) > SNAP_VELOCITY
					|| (downX - event.getX() > mTouchSlop && Math
							.abs(event.getY() - downY) < mTouchSlop)) {
				isSlide = true;
			}
			break;
		}
		case MotionEvent.ACTION_UP:
			recycleVelocityTracker();
			break;
		}
		return super.dispatchTouchEvent(event);
	}

	/**
	 * 處理我們拖動ListView item的邏輯
	 */
	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		Log.d("test", "hasSlided : " + hasSlided + ", isSlide : " + isSlide);
		// 如果已經側滑了，迴歸原位
		if(hasSlided){
			scrollXBy(itemView, -mTouchLimit);
			hasSlided = false;
			// 攔截事件，不繼續處理
			return false;
		}

		if (isSlide && slidePosition != 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;

				// 手指拖動itemView滾動, deltaX大於0向左滾動，小於0向右滾
				scrollXBy(itemView, deltaX);
				
				return true;  //拖動的時候ListView不滾動
			case MotionEvent.ACTION_UP:
				int velocityX = getScrollVelocity();
				if (velocityX < -SNAP_VELOCITY) {
					scrollLeft();
				} else {
					scrollByDistanceX();
				}
				recycleVelocityTracker();
				// 手指離開的時候就不響應左右滾動
				isSlide = false;
				break;
			}
		}

//		boolean result = super.onTouchEvent(ev);
//		Log.d("test", "result : " + result);
		//否則直接交給ListView來處理onTouchEvent事件
		
		return super.onTouchEvent(ev);
	}
	
	/**
	 * 讓指定的view滾動x位置，設定左右邊界，view最多滾動到邊界位置
	 * @param view
	 * @param x
	 */
	private void scrollXBy(View view, int x){
		// 如果已經滑動了最大值，並希望繼續向左滑，忽略
		if(view.getScrollX() >= mTouchLimit && x >= 0) return;
		// 如果已經回到原位，並希望繼續想右劃，忽略
		if(view.getScrollX() <= 0 && x <= 0) return;
		
		if(view.getScrollX() + x > mTouchLimit){
			x = mTouchLimit - view.getScrollX();
		}else if(view.getScrollX() + x < 0){
			x = -view.getScrollX();
		}
		view.scrollBy(x, 0);
	}
	
	@Override
	public void computeScroll() {
		// 呼叫startScroll的時候scroller.computeScrollOffset()返回true，
		if (scroller.computeScrollOffset()) {
			// 讓ListView item根據當前的滾動偏移量進行滾動
			itemView.scrollTo(scroller.getCurrX(), scroller.getCurrY());
			
			postInvalidate();
		}
	}
	
	/**
	 * 向左滑動，根據上面我們知道向左滑動為正值
	 */
	private void scrollLeft() {
		final int delta = (mTouchLimit - itemView.getScrollX());
		// 呼叫startScroll方法來設定一些滾動的引數，我們在computeScroll()方法中呼叫scrollTo來滾動item
		scroller.startScroll(itemView.getScrollX(), 0, delta, 0,
				Math.abs(delta));
		postInvalidate(); // 重新整理itemView
		hasSlided = true;
	}

	/**
	 * 根據手指滾動itemView的距離來判斷是滾動到開始位置還是向左或者向右滾動
	 */
	private void scrollByDistanceX() {
		// 如果向左滾動的距離大於螢幕的二分之一，就讓其刪除
		if (itemView.getScrollX() >= mTouchLimit / 2) {
			scrollLeft();
		} else {
			// 滾回到原始位置,為了偷下懶這裡是直接呼叫scrollTo滾動
			itemView.scrollTo(0, 0);
		}
	}

	/**
	 * 新增使用者的速度跟蹤器
	 * 
	 * @param event
	 */
	private void addVelocityTracker(MotionEvent event) {
		if (velocityTracker == null) {
			velocityTracker = VelocityTracker.obtain();
		}

		velocityTracker.addMovement(event);
	}

	/**
	 * 移除使用者速度跟蹤器
	 */
	private void recycleVelocityTracker() {
		if (velocityTracker != null) {
			velocityTracker.recycle();
			velocityTracker = null;
		}
	}

	/**
	 * 獲取X方向的滑動速度,大於0向右滑動，反之向左
	 * 
	 * @return
	 */
	private int getScrollVelocity() {
		velocityTracker.computeCurrentVelocity(1000);
		int velocity = (int) velocityTracker.getXVelocity();
		return velocity;
	}

}
 

if(itemView instanceof SlideListItem){
				SlideListItem item = (SlideListItem) itemView;
				int count = item.getChildCount();
				mTouchLimit = 0;
				for (int i = 0; i < count; i++) {
					if(i > 0){
						mTouchLimit += item.getChildAt(i).getMeasuredWidth();
					}
				}
			}
 

/**
	 * 讓指定的view滾動x位置，設定左右邊界，view最多滾動到邊界位置
	 * @param view
	 * @param x
	 */
	private void scrollXBy(View view, int x){
		// 如果已經滑動了最大值，並希望繼續向左滑，忽略
		if(view.getScrollX() >= mTouchLimit && x >= 0) return;
		// 如果已經回到原位，並希望繼續想右劃，忽略
		if(view.getScrollX() <= 0 && x <= 0) return;
		
		if(view.getScrollX() + x > mTouchLimit){
			x = mTouchLimit - view.getScrollX();
		}else if(view.getScrollX() + x < 0){
			x = -view.getScrollX();
		}
		view.scrollBy(x, 0);
	}
 

SlideListItem：繼承LinearLayout，主要通過重寫onLayout方法使其中的子View不壓縮變形。

package com.jcking.slidepauselistview.view;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.LinearLayout;

public class SlideListItem extends LinearLayout {

	public SlideListItem(Context context) {
		this(context, null);
	}

	public SlideListItem(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		int count = getChildCount();
		for (int i = 0; i < count; i++) {
			measureChild(getChildAt(i), widthMeasureSpec, heightMeasureSpec);
		}
	}
	
	@Override
	public boolean dispatchTouchEvent(MotionEvent event) {
		Log.d("test", "event : " + event);
		return super.dispatchTouchEvent(event);
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		int margeLeft = 0;
		int size = getChildCount();
		for (int i = 0; i < size; i++) {
			View view = getChildAt(i);
			if (view.getVisibility() != View.GONE) {
				int childWidth = view.getMeasuredWidth();
				// 將內部子孩子橫排排列
				view.layout(margeLeft, 0, margeLeft + childWidth,
						view.getMeasuredHeight());
				margeLeft += childWidth;
			}
		}
	}
}

SlideAdapter：在Adapter中繫結Click事件，分別監聽。

package com.jcking.slidepauselistview;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.TextView;

public class SlideAdapter extends BaseAdapter {
	
	private List<String> mData;
	private LayoutInflater mInflater;
	private ViewHolder mHolder;
	private OnSlideClickListener mListener;
	
	class ViewHolder{
		TextView tv;
		View front;
		Button btnClock;
		Button btnDelete;
	}
	
	public SlideAdapter(Context context, List<String> data, OnSlideClickListener listener){
		this.mData = data;
		this.mInflater = LayoutInflater.from(context);
		this.mListener = listener;
	}

	@Override
	public int getCount() {
		return mData == null ? 0 : mData.size();
	}

	@Override
	public String getItem(int position) {
		return mData == null ? null : mData.get(position);
	}

	@Override
	public long getItemId(int position) {
		return position;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		if(convertView == null){
			convertView = mInflater.inflate(R.layout.item_listview, null);
			mHolder = new ViewHolder();
			mHolder.tv = (TextView) convertView.findViewById(R.id.tv);
			mHolder.front = convertView.findViewById(R.id.front);
			mHolder.btnClock = (Button) convertView.findViewById(R.id.btnClock);
			mHolder.btnDelete = (Button) convertView.findViewById(R.id.btnDelete);
			convertView.setTag(mHolder);
		}else{
			mHolder = (ViewHolder) convertView.getTag();
		}
		mHolder.tv.setText(getItem(position));
		// 使隱藏的按鈕數量不一樣，測試可滑動範圍
		mHolder.btnClock.setVisibility(position%2==0 ? View.GONE : View.VISIBLE);
		
		if(mListener != null){
			final int pos = position;
			final View item = convertView;
			mHolder.btnClock.setOnClickListener(new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					mListener.onClockClick(pos, item);
				}
			});
			mHolder.btnDelete.setOnClickListener(new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					mListener.onDeleteClick(pos, item);
				}
			});
			mHolder.front.setOnClickListener(new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					mListener.onItemClick(pos, item);
				}
			});
		}
		return convertView;
	}

	public interface OnSlideClickListener{
		public void onItemClick(int position, View item);
		public void onClockClick(int position, View item);
		public void onDeleteClick(int position, View item);
	}
}

package com.jcking.slidepauselistview;

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

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import com.jcking.slidepauselistview.SlideAdapter.OnSlideClickListener;
import com.jcking.slidepauselistview.view.SlidePauseListView;

public class MainActivity extends Activity implements OnSlideClickListener {
	private SlidePauseListView slideCutListView;
	private SlideAdapter adapter;
	private List<String> dataSourceList = new ArrayList<String>();

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

	private void init() {
		slideCutListView = (SlidePauseListView) findViewById(R.id.slideCutListView);

		for (int i = 0; i < 20; i++) {
			dataSourceList.add("滑動刪除" + i);
		}

		adapter = new SlideAdapter(this, dataSourceList, this);
		slideCutListView.setAdapter(adapter);
	}

	@Override
	public void onItemClick(int position, View item) {
		// TODO Auto-generated method stub
		Toast.makeText(this, "點選條目  " + position, Toast.LENGTH_SHORT).show();
	}

	@Override
	public void onClockClick(int position, View item) {
		// TODO Auto-generated method stub
		Toast.makeText(this, "點選鬧鐘  " + position, Toast.LENGTH_SHORT) .show();
	}

	@Override
	public void onDeleteClick(int position, View item) {
		// TODO Auto-generated method stub
		Toast.makeText(this, "點選刪除  " + position, Toast.LENGTH_SHORT) .show();
		slideCutListView.slideBack();
		dataSourceList.remove(position);
		adapter.notifyDataSetChanged();
	}

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <com.jcking.slidepauselistview.view.SlidePauseListView
        android:id="@+id/slideCutListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:cacheColorHint="@android:color/transparent"
        android:divider="#2b2b2b"
        android:dividerHeight="0.5dp"
        android:listSelector="@android:color/transparent" >
    </com.jcking.slidepauselistview.view.SlidePauseListView>

</LinearLayout>

<?xml version="1.0" encoding="UTF-8"?>
<com.jcking.slidepauselistview.view.SlideListItem xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="#acacac"
    android:orientation="horizontal" >

    <!-- 這裡一定要設定android:layout_width屬性為充滿螢幕  -->
    <LinearLayout
        android:id="@+id/front"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:clickable="true"
        android:gravity="center_vertical"
        android:orientation="horizontal"
        android:padding="5dp" >

        <TextView
            android:id="@+id/tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="測試資料"
            android:textSize="18sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/btnClock"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:background="#ff0000"
            android:text="鬧鈴"
            android:textColor="#ffffff" />

        <Button
            android:id="@+id/btnDelete"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:background="#00ffff"
            android:text="刪除"
            android:textColor="#ffffff" />
    </LinearLayout>

</com.jcking.slidepauselistview.view.SlideListItem>

1.item佈局中，第一個一定要充滿螢幕

問題：

1.靈敏度不高，不能像QQ一樣完全精確識別手勢