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怎么在android中使用View实现一个滑动删除效果

这篇文章给大家介绍怎么在android中使用View实现一个滑动删除效果，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。

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实现功能

1、可以向左滑动,右侧出现删除
2、向左滑动如果删除出现一大半,松手打开删除,反之关闭删除
3、应用场景
          微信消息的删除功能

实现原理

1、外面是一个ListView
2、条目是一个自定义控件继承ViewGroup
    1）、左边一个TextView,右侧屏幕外也有一个TextView
    2）、所以继承ViewGroup

实现步骤

1、创建一个SlideDeleteView类

    1）.构造方法要关联

public class SlideDelete extends ViewGroup {

 private View leftView;
 private View rightView;
 private ViewDragHelper helper;

 //第一步关联构造方法
 //第二步重写onMeasure和onLViewayout测量子View和布局子View
 public SlideDelete(Context context) {
  this(context,null);
 }

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

 public SlideDelete(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);

  helper = ViewDragHelper.create(this, callback);

 }
}

2、在布局文件中设置SlideDeleteView里面的子View

    SlideDeleteView height=80

        TextView
            width:matchParent
            height:matchparent
        TextView

3、重写onMeasure,给子View进行测量

 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  //对当前组合View的测量,不使用的话,也可以自己设置
  measureChildren(widthMeasureSpec,heightMeasureSpec);
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);

 }

4、重写onLayout,给子View进行布局

注意事项:要设置leftView,也要设置rightView,不要都写成leftView了

 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  //第一步获取里面子View
  leftView = getChildAt(0);
  rightView = getChildAt(1);
  //第二步给子View提供相应的布局
  int leftL = 0;
  int leftT = 0;
  int leftR = leftView.getMeasuredWidth();
  int leftB = leftView.getMeasuredHeight();
  leftView.layout(leftL,leftT,leftR,leftB);

  //给rightView提供相应的布局
  int rightL = leftView.getMeasuredWidth();
  int rightT = 0;
  int rightR = leftView.getMeasuredWidth()+ rightView.getMeasuredWidth();
  int rightB = rightView.getMeasuredHeight();
  rightView.layout(rightL,rightT,rightR,rightB);

 }

5、设置View的滑动事件onTouchEvent,实现滑动
    1）.因为要滑动,所以消费该事件返回true
    2）.使用ViewDragHelper来实现滑动效果

注意事项:

只能实现leftView的滑动,右侧RightView看不到所以滑动不了

只能给滑动的View设置监听,当滑动的时候,重新设置另一个View的布局跟着滑动

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  //1,要消费该事件,所以直接返回true
  //2,使用ViewDragHelper来实现滑动效果
  helper.processTouchEvent(event);
  return true;
 }

6、重写滑动事件的监听onViewPositionChanged解决只有lefView滑动的问题

    1）.重写的方法是在ViewDragHelper.Callback的子实现类中

    2）.要实现滑动事件,必须在tryCaptureView方法中返回true

 private ViewDragHelper.Callback callback = new ViewDragHelper.Callback() {
  //手势滑动时
  @Override
  public boolean tryCaptureView(View child, int pointerId) {
   return true;
  }
  //监听控件移动状态
  @Override
  public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {

   //如果左边控件拖动,我们要让右边控件也重新布局
   if(changedView == leftView){
    rightView.layout(rightView.getLeft()+dx,0,rightView.getRight()+dx,rightView.getBottom()+dy);
   }else if(changedView == rightView){
    leftView.layout(leftView.getLeft()+dx,0,leftView.getRight()+dx,leftView.getBottom()+dy);
   }


  }

7、重写clampViewPositionHorizontal水平位置移动,解决左右越界问题

    1.返回值为移动时左侧滑动的距离
    2.如果滑动的控件是leftView时,解决越界
    3.如果滑动的控件是rightView时,解决越界

 public int clampViewPositionHorizontal(View child, int left, int dx) {
   //对左右越界问题的处理
   if(child == leftView){
    //处理两边的越界问题
    if(left >= 0){
     left = 0;
    }else if(left <= -rightView.getMeasuredWidth()){
     left = -rightView.getMeasuredWidth();
    }
   }else if(child == rightView){
    //只处理右边的越界问题,因为左侧越界的时看不到该View
    if(left <= leftView.getMeasuredWidth()- rightView.getMeasuredWidth()){
     left = leftView.getMeasuredWidth()- rightView.getMeasuredWidth();
    }else if(left >= leftView.getMeasuredWidth()){
     left = leftView.getMeasuredWidth();
    }


   }

   return left;
  }

8、手松开时重写onViewReleased方法,实现滑动手松开时,rightView是打开还是关闭

    1.使用ViewDragHelper滑动时,要调用invalidate方法,回调computeScroll方法
    2.重写computeScroll方法

        1）.先判断是否要继承滑动

        2）.使用兼容的invalidate方法来实现匀速滑动

  @Override
  public void onViewReleased(View releasedChild, float xvel, float yvel) {

   //松开后,什么时候打开rightView,什么时候关闭leftView
   //临界值,rightView.getLeft() 和 屏幕的宽度-rightView.getWidth()/2
   if(releasedChild == leftView){
    if(rightView.getLeft() < getMeasuredWidth() - rightView.getMeasuredWidth()/2){
     //使用ViewDragHelper来滑动
     helper.smoothSlideViewTo(rightView,getMeasuredWidth()-rightView.getMeasuredWidth(),0);

     invalidate();
    }else{
     helper.smoothSlideViewTo(rightView,getMeasuredWidth(),0);
     invalidate();
    }
   }

  }



 //需要重写computeScroll

 @Override
 public void computeScroll() {
  //判断是否要继承滑动
  if(helper.continueSettling(true)){
   //invalidate();
   //兼容使用
   ViewCompat.postInvalidateOnAnimation(this);
  }
 }

9、实现删除rightView的点击删除事件

    1.在listView的adapter中找到右侧的rightView
    2.调用rightView的点击事件
    3.删除该条目

        1）删除集合中的数据
            list.remove(position);
        2）更新adapter
            notifyDataSetChanged();
        3）重新绘制整个条目
            requestLayout();

  //设置删除的点击事件
  vh.delete.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    //删除当前的数据
    list.remove(position);
    notifyDataSetChanged();

    //让父容器更新下

   }
  });

  vh.container.requestLayout();

注意事项

1、在重写onLayout方法的时候,给rightView设置布局的时候,写成leftView一直出错
2、在onTouchEvent中要返回true,因为要消费该事件
3、在使用ViewDragHelper.Callback时,重写tryCaptureView时要返回true
4、在onTouchEvent中,不使用scrollby或者scrollTo,而是使用ViewDragHelper工具类,不需要判断滑动的距离

总结

1、首先该控件是自定义View,不是组合控件,因为组合的话rightView在屏幕右侧不能实现
2、是自定义View中的继承ViewGroup,因为左侧leftView和右侧rightView都是TextView不需要自己画

源码

SlideDelete的源码

package com.example.movedelete;

import android.content.Context;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ViewDragHelper;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by guixin on 2017/1/5.
 */

public class SlideDelete extends ViewGroup {

 private View leftView;
 private View rightView;
 private ViewDragHelper helper;



 //第一步关联构造方法
 //第二步重写onMeasure和onLViewayout测量子View和布局子View


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

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

 public SlideDelete(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);

  helper = ViewDragHelper.create(this, callback);

 }

 private ViewDragHelper.Callback callback = new ViewDragHelper.Callback() {
  //手势滑动时
  @Override
  public boolean tryCaptureView(View child, int pointerId) {
   return true;
  }


  //拖动控件水平移动
  @Override
  public int clampViewPositionHorizontal(View child, int left, int dx) {
   //对左右越界问题的处理
   if(child == leftView){
    //处理两边的越界问题
    if(left >= 0){
     left = 0;
    }else if(left <= -rightView.getMeasuredWidth()){
     left = -rightView.getMeasuredWidth();
    }
   }else if(child == rightView){
    //只处理右边的越界问题,因为左侧越界的时看不到该View
    if(left <= leftView.getMeasuredWidth()- rightView.getMeasuredWidth()){
     left = leftView.getMeasuredWidth()- rightView.getMeasuredWidth();
    }else if(left >= leftView.getMeasuredWidth()){
     left = leftView.getMeasuredWidth();
    }


   }

   return left;
  }


  //监听控件移动状态
  @Override
  public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {

   //如果左边控件拖动,我们要让右边控件也重新布局
   if(changedView == leftView){
    rightView.layout(rightView.getLeft()+dx,0,rightView.getRight()+dx,rightView.getBottom()+dy);
   }else if(changedView == rightView){
    leftView.layout(leftView.getLeft()+dx,0,leftView.getRight()+dx,leftView.getBottom()+dy);
   }


  }

  //解决滑动一半松手时,View的复位

  /**
   *
   * @param releasedChild 松开的View
   * @param xvel
   * @param yvel
   */
  @Override
  public void onViewReleased(View releasedChild, float xvel, float yvel) {

   //松开后,什么时候打开rightView,什么时候关闭leftView
   //临界值,rightView.getLeft() 和 屏幕的宽度-rightView.getWidth()/2
   if(releasedChild == leftView){
    if(rightView.getLeft() < getMeasuredWidth() - rightView.getMeasuredWidth()/2){
     //使用ViewDragHelper来滑动
     helper.smoothSlideViewTo(rightView,getMeasuredWidth()-rightView.getMeasuredWidth(),0);

     invalidate();
    }else{
     helper.smoothSlideViewTo(rightView,getMeasuredWidth(),0);
     invalidate();
    }
   }

  }
 };

 //需要重写computeScroll

 @Override
 public void computeScroll() {
  //判断是否要继承滑动
  if(helper.continueSettling(true)){
   //invalidate();
   //兼容使用
   ViewCompat.postInvalidateOnAnimation(this);
  }
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  //对当前组合View的测量,不使用的话,也可以自己设置
  measureChildren(widthMeasureSpec,heightMeasureSpec);
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);



 }

 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  //第一步获取里面子View
  leftView = getChildAt(0);
  rightView = getChildAt(1);
  //第二步给子View提供相应的布局
  int leftL = 0;
  int leftT = 0;
  int leftR = leftView.getMeasuredWidth();
  int leftB = leftView.getMeasuredHeight();
  leftView.layout(leftL,leftT,leftR,leftB);

  //给rightView提供相应的布局
  int rightL = leftView.getMeasuredWidth();
  int rightT = 0;
  int rightR = leftView.getMeasuredWidth()+ rightView.getMeasuredWidth();
  int rightB = rightView.getMeasuredHeight();
  rightView.layout(rightL,rightT,rightR,rightB);

 }

 //View的事件传递

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  //1,要消费该事件,所以直接返回true
  //2,使用ViewDragHelper来实现滑动效果
  helper.processTouchEvent(event);
  return true;
 }
}

MainActivity.java源码

package com.example.movedelete;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;

import com.example.movedelete.adapter.SlideDeleteAdapter;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

 private ListView lv;
 private ArrayList list;

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

  //初始化视图
  initView();
  //初始化数据
  initData();
  //初始化事件
  initEvent();


 }

 //初始化视图
 private void initView() {
  lv = (ListView) findViewById(R.id.lv);
 }

 //初始化数据
 private void initData() {
  list = new ArrayList<>();
  for (int i = 0; i < 20; i++) {
   list.add("第"+i+"项条目");
  }
 }

 //初始化事件
 private void initEvent() {
  SlideDeleteAdapter adapter = new SlideDeleteAdapter(list);
  lv.setAdapter(adapter);

 }
}

SlideDeleteAdapter.java源码

package com.example.movedelete.adapter;

import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.example.movedelete.R;
import com.example.movedelete.SlideDelete;

import java.util.ArrayList;

/**
 * Created by guixin on 2017/1/5.
 */
public class SlideDeleteAdapter extends BaseAdapter{
 private ArrayList list;

 public SlideDeleteAdapter(ArrayList list) {
  this.list = list;
 }

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

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

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

 @Override
 public View getView(final int position, View convertView, ViewGroup parent) {
  ViewHolder vh;
  if(convertView == null){
   convertView = View.inflate(parent.getContext(), R.layout.item_slide,null);
   vh = new ViewHolder(convertView);

   convertView.setTag(vh);
  }else{
   vh = (ViewHolder) convertView.getTag();
  }

  vh.content.setText(list.get(position));

  //设置删除的点击事件
  vh.delete.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    //删除当前的数据
    list.remove(position);
    notifyDataSetChanged();

    //让父容器更新下

   }
  });

  vh.container.requestLayout();

  return convertView;
 }

 class ViewHolder{
  private TextView content;
  private TextView delete;
  private SlideDelete container;

  public ViewHolder(View v){
    container = (SlideDelete) v.findViewById(R.id.container);
   content = (TextView) v.findViewById(R.id.content);
    delete = (TextView) v.findViewById(R.id.delete);
  }
 }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

item_slide.xml

<?xml version="1.0" encoding="utf-8"?>

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