我尝试使用两个PanResponder来处理多点触控事件.一个PanResponder负责上半部屏幕,一个下部.只要只有一根手指触摸屏幕,两个PanResponder就能正常工作.但是当我在屏幕上放两根手指时,只有一个PanResponder工作.所以我只知道一根手指的坐标(运动)并且不知道另一根手指的状态.
如何使用成员变量将React组件重构为es6类它没有状态变量.为什么在运行下面的代码时,我会得到一个大的红色屏幕"无法添加属性计数器,对象不可扩展"？
'use strict';
let Dimensions = require('Dimensions');
let totalWidth = Dimensions.get('window').width;
let leftStartPoint = totalWidth * 0.1;
let componentWidth = totalWidth * 0.8;
import React, {
AppRegistry,
Component,
StyleSheet,
Text,
TextInput,
View
} from 'react-native';
class Login extends Component {
constructor(props) {
super(props);
this.counter =23;
this.state = {
inputedNum: ''
};
}
updateNum(aEvent) {
this.setState((state) => {
return {
inputedNum: aEvent.nativeEvent.text,
};
});
}
buttonPressed() {
this.counter++;
console.log(':::'+this.counter);
}
render() {
return (
<View style={styles.container}>
<TextInput style={styles.numberInputStyle}
placeholder={'input phone number'} …我在Windows 7上有一个RN开发环境。它运行良好，直到昨天它在我运行“ react-native”启动后突然报告错误。错误信息：
[2016-12-26 09:58:17] HMR Server listening on /hot
React packager ready.
fs.js:557
return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
^
Error: UNKNOWN: unknown error, open 'C:\Users\xitao\.babel.json'
at Object.fs.openSync (fs.js:557:18)
at Object.fs.writeFileSync (fs.js:1222:33)
at save (C:\RN\LearnRN\node_modules\babel-register\lib\cache.js:45:16)
at _combinedTickCallback (internal/process/next_tick.js:67:7)
at process._tickCallback (internal/process/next_tick.js:98:9)
fs.js:557
return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
^
Error: UNKNOWN: unknown error, open 'C:\Users\xitao\.babel.json'
at Object.fs.openSync (fs.js:557:18)
at Object.fs.writeFileSync (fs.js:1222:33)
at save (C:\RN\LearnRN\node_modules\babel-register\lib\cache.js:45:16)
at _combinedTickCallback (internal/process/next_tick.js:67:7)
at process._tickCallback (internal/process/next_tick.js:98:9)
fs.js:557
return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
^
Error: UNKNOWN: unknown error, open 'C:\Users\xitao\.babel.json'
at …