android自定义View之滑动删除

效果图

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

<com.example.movedelete.SlideDelete
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="80dp">

<TextView

android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:background="#33000000"
android:text="第0个条目"
android:textColor="#fff"
android:textSize="20sp" />
<TextView

android:id="@+id/delete"
android:layout_width="80dp"
android:layout_height="match_parent"
android:background="#f00"
android:gravity="center"
android:text="删除"
android:textColor="#fff"
android:textSize="20sp" />

</com.example.movedelete.SlideDelete>

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(
4000
) {
//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<String> 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<String> list;

public SlideDeleteAdapter(ArrayList<String> 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"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent">

<ListView
android:id="@+id/lv"
android:layout_width="match_parent"
android:layout_height="match_parent">

</ListView>

</RelativeLayout>

item_slide.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<com.example.movedelete.SlideDelete
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="80dp">

<TextView

android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:background="#33000000"
android:text="第0个条目"
android:textColor="#fff"
android:textSize="20sp" />
<TextView

android:id="@+id/delete"
android:layout_width="80dp"
android:layout_height="match_parent"
android:background="#f00"
android:gravity="center"
android:text="删除"
android:textColor="#fff"
android:textSize="20sp" />

</com.example.movedelete.SlideDelete>

</LinearLayout>