reactnative实现qq聊天消息气泡拖拽消失效果
作者:互联网
前言(可跳过)
我在开发自己的APP时遇到了一个类似于qq聊天消息气泡拖拽消息的需求,因为在网上没有找到相关的组件,所以自己动手实现了一下
需求:对聊天消息气泡拖拽到一定长度松开时该气泡会消失(可自行增加拖拽过程,以及消失的动画)
解决方案:
0.创建一个足够大的数组(长度大于聊天框实例数量),初始化每个元素为React.createRef()
const badgeRegistryArr = new Array(99).fill(React.createRef())
1.渲染聊天列表时,对每个聊天框实例创建一个ref,并映射到数组中(ref={MappingArr[index]})
2.使用PanResponder创建一个触摸手势实例以此来实现拖拽效果(即当onPanResponderMove发生时更改一次Animated的值,已将样式部署到所有实例)
pan: new Animated.ValueXY(),
};```
——————
const { pan,currentTargetId } = this.state
const [translateX, translateY] = [pan.x, pan.y];
const imageStyle = {transform: [{translateX}, {translateY}]}
——————
```style={[imageStyle,{position:'relative',zIndex:999}]}```
——————
```onPanResponderGrant: (evt, gestureState) => {
// 设置初始位置
pan.setValue({x: 0, y: 0});
},```
——————
```// 使用拖拽的偏移量来定位
onPanResponderMove: Animated.event([
null, {dx: this.state.pan.x, dy: this.state.pan.y},
]),```
3.第2步操作会改变所有聊天气泡的值,所以我们要甄别一下,在开始手势操作事件中我们进行一次setState(得到当前的_nativeTag),然后刷新聊天框实例列表,并将列表中每个元素的_nativeTag和当前_nativeTag进行比对,为true时,将样式部署到且只部署到该实例。这样单独拖拽的效果就实现了
```this.state = {
pan: new Animated.ValueXY(),
currentTargetId:0,
};```
——————
```onPanResponderGrant: (evt, gestureState) => {
// 开始手势操作。给用户一些视觉反馈,让他们知道发生了什么事情!
const { pan } = this.state
const { _nativeTag } = evt.currentTarget
this.setState({currentTargetId:_nativeTag})
pan.setValue({x: 0, y: 0});
},
——————
const { pan,currentTargetId } = this.state
const [translateX, translateY] = [pan.x, pan.y];
let _nativeTag = null
_nativeTag = badgeRegistryArr[item.id-1].current ? badgeRegistryArr[item.id-1].current._nativeTag:null
if(_nativeTag === currentTargetId){
return {transform: [{translateX}, {translateY}]}
}
}
——————
const imageStyle = this.judgeBadgeMove(item);
4.在state中创建一个数组(用来实现拖拽后消失的效果,暂且称为A数组)所有元素初始化为true,数组长度与0步中数组相同,在用户放开触摸点(视为手势操作完成)事件中,当横向或纵向移动长度超出指定值时,对数组A中的匹配元素(目标元素下标即为在第3步中比对操作中的命中元素下标)的值setState为false这样就实现了拖拽一定长度后消失的效果
pan: new Animated.ValueXY(),
currentTargetId:0,
badgeVisualArr:new Array(6).fill(true)
};```
——————
```onPanResponderRelease: (evt, gestureState) => {
const { _nativeTag } = evt.currentTarget
const { dx,dy } = gestureState
badgeRegistryArr.forEach((value,index) => {
if(_nativeTag === value.current._nativeTag){
let tempArr = this.state.badgeVisualArr
tempArr[index] = false
this.setState({badgeVisualArr:tempArr})
}
})
if(Math.abs(dx) > 80 || Math.abs(dy)){
this.setState({badgeVisualValue:false})
}
// 用户放开了所有的触摸点,且此时视图已经成为了响应者。
// 一般来说这意味着一个手势操作已经成功完成。
},```
——————
```{
item.messageValue > 0 && badgeVisualArr[item.id-1] ? <Badge
value={item.messageValue}
status='error'
badgeStyle={{borderColor:'red'}}
></Badge>:null
}```
——————
![](https://www.icode9.com/i/l/?n=20&i=blog/2158262/202110/2158262-20211029202356675-1941541600.gif)
全部代码(以上代码块来自这里,删除了无关代码)
<details>
<summary>点击查看代码</summary>
import React, { Component } from 'react';
import { View, PanResponder,Animated } from 'react-native';
import { Badge} from 'react-native-elements';
import { FlatList } from 'react-native-gesture-handler';
const badgeRegistryArr = new Array(99).fill(React.createRef())
const data = [
{
id:1,
nickName:'wdnmd',
messageValue:0,
face:'../../../assets/images/boy.png',
},{
id:2,
nickName:'我带你们打',
messageValue:10,
face:'../../../assets/images/boy.png',
},{
id:3,
messageValue:0,
nickName:'wdnmd',
messageValue:20,
face:'../../../assets/images/boy.png',
},{
id:4,
nickName:'wdnmd',
messageValue:1,
face:'../../../assets/images/boy.png',
},{
id:5,
nickName:'wdnmd',
messageValue:0,
face:'../../../assets/images/boy.png',
},{
id:6,
nickName:'wdnmd',
messageValue:999,
face:'../../../assets/images/boy.png',
}
]
class Direct extends Component {
constructor(props) {
super(props);
this.state = {
searchBarValue:null,
pan: new Animated.ValueXY(),
currentTargetId:0,
badgeVisualArr:new Array(99).fill(true)
};
}
componentWillMount = function (){
this._panResponder = PanResponder.create({
// 要求成为响应者:
onStartShouldSetPanResponder: (evt, gestureState) => true,
onStartShouldSetPanResponderCapture: (evt, gestureState) => true,
onMoveShouldSetPanResponder: (evt, gestureState) => true,
onMoveShouldSetPanResponderCapture: (evt, gestureState) => true,
onPanResponderGrant: (evt, gestureState) => {
// 开始手势操作。给用户一些视觉反馈,让他们知道发生了什么事情!
const { pan } = this.state
const { _nativeTag } = evt.currentTarget
this.setState({currentTargetId:_nativeTag})
pan.setValue({x: 0, y: 0});
// gestureState.{x,y} 现在会被设置为0
},
onPanResponderMove: Animated.event([
null, {dx: this.state.pan.x, dy: this.state.pan.y},
]),
onPanResponderTerminationRequest: (evt, gestureState) => true,
onPanResponderRelease: (evt, gestureState) => {
const { _nativeTag } = evt.currentTarget
const { dx,dy } = gestureState
badgeRegistryArr.forEach((value,index) => {
if(_nativeTag === value.current._nativeTag){
let tempArr = this.state.badgeVisualArr
tempArr[index] = false
this.setState({badgeVisualArr:tempArr})
console.log('binngo')
}
})
if(Math.abs(dx) > 80 || Math.abs(dy)){
this.setState({badgeVisualValue:false})
}
// 用户放开了所有的触摸点,且此时视图已经成为了响应者。
// 一般来说这意味着一个手势操作已经成功完成。
},
onPanResponderTerminate: (evt, gestureState) => {
// 另一个组件已经成为了新的响应者,所以当前手势将被取消。
},
onShouldBlockNativeResponder: (evt, gestureState) => {
// 返回一个布尔值,决定当前组件是否应该阻止原生组件成为JS响应者
// 默认返回true。目前暂时只支持android。
return true;
},
});
}
judgeBadgeMove = (item) => {
const { pan,currentTargetId } = this.state
const [translateX, translateY] = [pan.x, pan.y];
let _nativeTag = null
_nativeTag = badgeRegistryArr[item.id-1].current ? badgeRegistryArr[item.id-1].current._nativeTag:null
if(_nativeTag === currentTargetId){
return {transform: [{translateX}, {translateY}]}
}
}
renderItem = ({item}) => {
const { badgeVisualArr} = this.state
const imageStyle = this.judgeBadgeMove(item);
return (
<Animated.View
ref={badgeRegistryArr[item.id-1]}
{...this._panResponder.panHandlers}
style={[imageStyle,{position:'relative',zIndex:999}]}
>
{
item.messageValue > 0 && badgeVisualArr[item.id-1] ? <Badge
value={item.messageValue}
status='error'
badgeStyle={{borderColor:'red'}}
>:null
}
</Animated.View>
)
}
render() {
return (
);
}
}
export default Direct;
</details>
标签:qq,const,..,state,nativeTag,evt,拖拽,pan,reactnative 来源: https://www.cnblogs.com/zhaowendao233/p/15483465.html