工作需要，实现了一个可以滑动删除的拖拽列表。
主要是参考的这个网站 https://blog.csdn.net/sinat_17775997/article/details/74668541?locationNum=10&fps=1 不过因为他没有实现滑动删除的功能，所以我在这里狗尾续貂一下。
先看一下功能
拖拽
拖拽
添加
添加
删除
删除
实现方法。
- 拖拽是在ScrollVIew 中对data进行map，返回View 让其每个的position的值都是absolute。然后计算每个View 的位置。通过PanResponder 对小图片添加拖动的方法，在点击，移动，和释放，是对最外层的View进行操作，修改其style中的top，从而让其移动。
核心代码
componentWillMount(){
this._panResponder = PanResponder.create({
onStartShouldSetPanResponder: (evt, gestureState) => true,
onMoveShouldSetPanResponder: (evt, gestureState) => true,
onPanResponderGrant: (evt, gestureState) => {
this.setState(()=>{
return {
scrollflag:false,
}
});
const {pageY, locationY} = evt.nativeEvent;
this.index = this._getIdByPosition(pageY);
this.preY = pageY - locationY - EXPROTHEIGHT;
let item = this.items[this.index];
if(item == undefined) {
console.log(this.index);
}
this.start = this.index;
this.end = this.index;
item.setNativeProps({
style: {
shadowColor: "#333",
shadowOpacity: 0.3,
shadowRadius: 50,
shadowOffset: {height: 0, width: 2},
elevation: 5,
zIndex: 1,
backgroundColor:'gray',
}
});
},
onPanResponderMove: (evt, gestureState) => {
let top = this.preY + gestureState.dy+this.scrollOffsetY;
let item = this.items[this.index];
item.setNativeProps({
style: {top: top}
});
let collideIndex = this._getIdByPosition(evt.nativeEvent.pageY);
if(collideIndex !== this.index && collideIndex !== -1) {
let collideItem = this.items[collideIndex];
collideItem.setNativeProps({
style: {top: this._getTopValueYById(this.index)}
});
[this.items[this.index], this.items[collideIndex]] = [this.items[collideIndex], this.items[this.index]];
[this.order[this.index], this.order[collideIndex]] = [this.order[collideIndex], this.order[this.index]];
this.index = collideIndex;
this.end = this.index;
}
},
onPanResponderTerminationRequest: (evt, gestureState) => true,
onPanResponderRelease: this._releaseAndTerminate.bind(this),
onPanResponderTerminate: this._releaseAndTerminate.bind(this)
});
}
_releaseAndTerminate(evt, gestureState){
const shadowStyle = {
shadowColor: "#000",
shadowOpacity: 0,
shadowRadius: 0,
shadowOffset: {height: 0, width: 0,},
backgroundColor:'white',
elevation:2,
zIndex: 0
};
this.items.splice(this.start,0,this.items.splice(this.end,1)[0]);
for(let i = 0;i<this.items.length;i++){
this.items[i].setNativeProps({
style: {...shadowStyle,top: this._getTopValueYById(i)}
})
}
this.items = [];
this.order = [];
this.scrollArray = [];
let temp = this.state.data;
temp.splice(this.end,0,temp.splice(this.start,1)[0]);
this.setState(()=>{
return {
data:temp,
scrollflag:true,
}
})
}
- 添加比较简单。自己修改state 数据即可
addItem(){
// 这里是将所有的内部 scrollArray 回归原位
for(let i = 0;i<this.scrollArray.length;i++){
this.scrollArray[i].scrollTo({x: 0, y: 0, animated: false})
}
let temp = this.state.data;
temp[temp.length] = {name:'五花肉'+temp.length}
this.setState({
data:temp,
});
}
- 删除,删除废了很大的功夫，原先想做成，向左拖动就直接删除。尝试之后，发现容易崩溃，所以就改成这种样子了。让其先显示删除按键，然后再删除。
//拖动，判断是否超过‘删除’View宽度的一半，超过显示，不超过隐藏
onMomentumScrollEnd(e,index){
let offsetX = e.nativeEvent.contentOffset.x;
if(offsetX > this.itemHight/2){
this.scrollArray[index].scrollTo({x: this.itemHight, y: 0, animated: false})
}else{
this.scrollArray[index].scrollTo({x: 0, y: 0, animated: false})
}
}
removeItem(index){
this.scrollArray[index].scrollTo({x: 0, y: 0, animated: false});
this.items = [];
this.order = [];
if(this.scrollOffsetY > 0){
this.scrollOffsetY -= this.itemHight;
if(this.scrollOffsetY <0){
this.scrollOffsetY = 0;
}
this.outsideScroll.scrollTo({x:0,y:this.scrollOffsetY,animated:false})
}
let temp = this.state.data;
temp.splice(index,1);
this.setState({
data:temp,
})
this.scrollArray = [];
}
// 将其他显示的删除，挪回去
onTouchStart(e,index){
for(let i = 0;i<this.scrollArray.length;i++){
if(i != index){
this.scrollArray[i].scrollTo({x: 0, y: 0, animated: false})
}
}
}
全部代码
import React, {Component} from 'react';
import {
StyleSheet,
View,
Text,
TouchableOpacity,
ScrollView,
Image,
PanResponder,
} from 'react-native';
import Utils from '../../common/Utils'
const EXPROTHEIGHT = 20;
export default class CustomScrollView extends Component {
constructor(props){
super(props);
this.state={
data:[
{name:'五花肉',},
{name:'青椒',},
{name:'红椒',},
],
}
this.itemHight = 50;
this.interval = 5;
this.countHeigth = this.itemHight+this.interval; // interval为中间的间隙。
this.scrollOffsetY = 0;
this.items = [];
this.order = [];
this.ViewHeight = (this.state.data.length)*this.countHeigth>Utils.size.height-20-Utils.statusBarHeight?
(this.state.data.length)*this.countHeigth:Utils.size.height-20-Utils.statusBarHeight,
this.scrollArray = [];
}
static navigationOptions = {
header:null,
};
render(){
return(
<View style={styles.container}>
<ScrollView
showsVerticalScrollIndicator={false}
onScrollEndDrag={(e)=>this.exportOnScrollEndDrag(e)}
onMomentumScrollEnd={(e)=>this.exportonMomentumScrollEnd(e)}
ref = {(ref)=>{this.outsideScroll = ref}}
>
<View style={{height:this.ViewHeight,width:Utils.size.width}}>
{this.state.data.map((item,index)=>{
return(
<View
ref={
(ref)=>{
if(index == this.items.length&&ref != null){
this.items[this.items.length] = ref;
this.order.push(index);
}
}
}
key={index+''}
style={{
top:this._getTopValueYById(index),
position: 'absolute',
width:Utils.size.width-40,
height:this.itemHight,
backgroundColor:'white',
marginBottom:this.interval,
elevation:2,
justifyContent:'center'
}}
>
<ScrollView
ref={(ref)=>{
if(index == this.items.length&&ref != null){
this.scrollArray[index] = ref;
}
}}
horizontal={true}
style={{
// backgroundColor:'red'
}}
showsHorizontalScrollIndicator={false}
onTouchStart = {(e)=>{this.onTouchStart(e,index)}}
onMomentumScrollEnd = {(e)=>{this.onMomentumScrollEnd(e,index)}}
>
<View style={{width:Utils.size.width-40,height:this.itemHight,justifyContent:'center'}}>
<TouchableOpacity style={{marginLeft:10,marginRight:10}} onPress={()=>{console.log(index)}}>
<View style={{flexDirection:'row',}}>
<Image
source={require('../../resources/image/moveImage.png')}
style={{width:30,height:30}}
{...this._panResponder.panHandlers}
/>
<Text style={{marginLeft:10,fontSize:18}}>
{item.name}
</Text>
</View>
</TouchableOpacity>
</View>
<TouchableOpacity
onPress={this.removeItem.bind(this,index)}
style={{
width:this.itemHight,
height:this.itemHight,
justifyContent:'center',
alignItems:'center',
backgroundColor:'red'
}}>
<Text style={{fontSize:15}}>{"删除"}</Text>
</TouchableOpacity>
</ScrollView>
</View>
)
})}
</View>
</ScrollView>
<TouchableOpacity
onPress={
this.addItem.bind(this)
}
style={{
top:0.8*Utils.size.height,
left:0.7*Utils.size.width,
position: 'absolute',
}}>
<Image style={{zIndex:2}} source={require('../../resources/image/add.png')}></Image>
</TouchableOpacity>
</View>
)
}
addItem(){
// 这里是将所有的内部 scrollArray 回归原位
for(let i = 0;i<this.scrollArray.length;i++){
this.scrollArray[i].scrollTo({x: 0, y: 0, animated: false})
}
let temp = this.state.data;
temp[temp.length] = {name:'五花肉'+temp.length}
this.setState({
data:temp,
});
}
exportOnScrollEndDrag(e){
this.scrollOffsetY = e.nativeEvent.contentOffset.y;
}
exportonMomentumScrollEnd(e){
this.scrollOffsetY = e.nativeEvent.contentOffset.y;
}
componentWillMount(){
this._panResponder = PanResponder.create({
onStartShouldSetPanResponder: (evt, gestureState) => true,
onMoveShouldSetPanResponder: (evt, gestureState) => true,
onPanResponderGrant: (evt, gestureState) => {
this.setState(()=>{
return {
scrollflag:false,
}
});
const {pageY, locationY} = evt.nativeEvent;
this.index = this._getIdByPosition(pageY);
this.preY = pageY - locationY - EXPROTHEIGHT;
let item = this.items[this.index];
if(item == undefined) {
console.log(this.index);
}
this.start = this.index;
this.end = this.index;
item.setNativeProps({
style: {
shadowColor: "#333",
shadowOpacity: 0.3,
shadowRadius: 50,
shadowOffset: {height: 0, width: 2},
elevation: 5,
zIndex: 1,
backgroundColor:'gray',
}
});
},
onPanResponderMove: (evt, gestureState) => {
let top = this.preY + gestureState.dy+this.scrollOffsetY;
let item = this.items[this.index];
item.setNativeProps({
style: {top: top}
});
let collideIndex = this._getIdByPosition(evt.nativeEvent.pageY);
if(collideIndex !== this.index && collideIndex !== -1) {
let collideItem = this.items[collideIndex];
collideItem.setNativeProps({
style: {top: this._getTopValueYById(this.index)}
});
[this.items[this.index], this.items[collideIndex]] = [this.items[collideIndex], this.items[this.index]];
[this.order[this.index], this.order[collideIndex]] = [this.order[collideIndex], this.order[this.index]];
this.index = collideIndex;
this.end = this.index;
}
},
onPanResponderTerminationRequest: (evt, gestureState) => true,
onPanResponderRelease: this._releaseAndTerminate.bind(this),
onPanResponderTerminate: this._releaseAndTerminate.bind(this)
});
}
componentWillUpdate(){
this.ViewHeight = (this.state.data.length)*this.countHeigth>Utils.size.height-20-Utils.statusBarHeight?
(this.state.data.length)*this.countHeigth:Utils.size.height-20-Utils.statusBarHeight;
}
_releaseAndTerminate(evt, gestureState){
const shadowStyle = {
shadowColor: "#000",
shadowOpacity: 0,
shadowRadius: 0,
shadowOffset: {height: 0, width: 0,},
backgroundColor:'white',
elevation:2,
zIndex: 0
};
this.items.splice(this.start,0,this.items.splice(this.end,1)[0]);
for(let i = 0;i<this.items.length;i++){
this.items[i].setNativeProps({
style: {...shadowStyle,top: this._getTopValueYById(i)}
})
}
this.items = [];
this.order = [];
this.scrollArray = [];
let temp = this.state.data;
temp.splice(this.end,0,temp.splice(this.start,1)[0]);
this.setState(()=>{
return {
data:temp,
scrollflag:true,
}
})
}
_getIdByPosition(pageY){
pageY = pageY - EXPROTHEIGHT;
var id = -1;
id = Math.floor(parseFloat((pageY+this.scrollOffsetY)/(this.countHeigth)));
if(id<0 || id >= this.state.data.length) {
return -1;
}
return id;
}
_getTopValueYById(id){
return (id) * (this.countHeigth);
}
//拖动，判断是否超过‘删除’View宽度的一半，超过显示，不超过隐藏
onMomentumScrollEnd(e,index){
let offsetX = e.nativeEvent.contentOffset.x;
if(offsetX > this.itemHight/2){
this.scrollArray[index].scrollTo({x: this.itemHight, y: 0, animated: false})
}else{
this.scrollArray[index].scrollTo({x: 0, y: 0, animated: false})
}
}
onTouchStart(e,index){
for(let i = 0;i<this.scrollArray.length;i++){
if(i != index){
this.scrollArray[i].scrollTo({x: 0, y: 0, animated: false})
}
}
}
removeItem(index){
this.scrollArray[index].scrollTo({x: 0, y: 0, animated: false});
this.items = [];
this.order = [];
if(this.scrollOffsetY > 0){
this.scrollOffsetY -= this.itemHight;
if(this.scrollOffsetY <0){
this.scrollOffsetY = 0;
}
this.outsideScroll.scrollTo({x:0,y:this.scrollOffsetY,animated:false})
}
let temp = this.state.data;
temp.splice(index,1);
this.setState({
data:temp,
})
this.scrollArray = [];
}
}
const styles = StyleSheet.create({
container: {
flex:1,
marginRight:20,
marginLeft:20,
marginTop:20
},
});
另外 Utils 文件在
https://gitee.com/yizhi108/react-native-location/
可以下载到。
其实里面全部都是一些常量，可以直接用常量进行替换。
如果能帮助到大家深感荣幸。
另外如有其它问题，欢迎留言讨论。
