Flex Direction

決定布局的主軸，默認(rèn)（row）豎直軸。

import React, { Component } from 'react';
import { AppRegistry, View } from 'react-native';

class FlexDirectionBasics extends Component {
  render() {
    return (
      // 嘗試把`flexDirection`改為`column`看看
      <View style={{flex: 1, flexDirection: 'row'}}>
        <View style={{width: 50, height: 50, backgroundColor: 'powderblue'}} />
        <View style={{width: 50, height: 50, backgroundColor: 'skyblue'}} />
        <View style={{width: 50, height: 50, backgroundColor: 'steelblue'}} />
      </View>
    );
  }
};

AppRegistry.registerComponent('AwesomeProject', () => FlexDirectionBasics);

justify Content

在組件的style中指定justifyContent可以決定其子元素沿著主軸的排列方式。子元素是應(yīng)該靠近主軸的起始端還是末尾段分布呢？亦或應(yīng)該均勻分布？對(duì)應(yīng)的這些可選項(xiàng)有：flex-start、center、flex-end、space-around以及space-between。

import React, { Component } from 'react';
import { AppRegistry, View } from 'react-native';

class JustifyContentBasics extends Component {
  render() {
    return (
      // 嘗試把`justifyContent`改為`center`看看
      // 嘗試把`flexDirection`改為`row`看看
      <View style={{
        flex: 1,
        flexDirection: 'column',
        justifyContent: 'space-between',
      }}>
        <View style={{width: 50, height: 50, backgroundColor: 'powderblue'}} />
        <View style={{width: 50, height: 50, backgroundColor: 'skyblue'}} />
        <View style={{width: 50, height: 50, backgroundColor: 'steelblue'}} />
      </View>
    );
  }
};

AppRegistry.registerComponent('AwesomeProject', () => JustifyContentBasics);

Align Items

在組件的style中指定alignItems可以決定其子元素沿著次軸（與主軸垂直的軸，比如若主軸方向?yàn)閞ow，則次軸方向?yàn)閏olumn）的排列方式。子元素是應(yīng)該靠近次軸的起始端還是末尾段分布呢？亦或應(yīng)該均勻分布？對(duì)應(yīng)的這些可選項(xiàng)有：flex-start、center、flex-end以及stretch。

注意：要使stretch選項(xiàng)生效的話，子元素在次軸方向上不能有固定的尺寸。以下面的代碼為例：只有將子元素樣式中的width: 50去掉之后，alignItems: 'stretch'才能生效。

import React, { Component } from 'react';
import { AppRegistry, View } from 'react-native';

class AlignItemsBasics extends Component {
  render() {
    return (
      // 嘗試把`alignItems`改為`flex-start`看看
      // 嘗試把`justifyContent`改為`flex-end`看看
      // 嘗試把`flexDirection`改為`row`看看
      <View style={{
        flex: 1,
        flexDirection: 'column',
        justifyContent: 'center',
        alignItems: 'center',
      }}>
        <View style={{width: 50, height: 50, backgroundColor: 'powderblue'}} />
        <View style={{width: 50, height: 50, backgroundColor: 'skyblue'}} />
        <View style={{width: 50, height: 50, backgroundColor: 'steelblue'}} />
      </View>
    );
  }
};

AppRegistry.registerComponent('AwesomeProject', () => AlignItemsBasics);