react native仿微信PopupWindow效果

在原生APP开发中，相信很多开发者都会见到这种场景：点击右上角更多的选项，弹出一个更多界面供用户选择。这种控件在原生开发中Android可以用PopupWindow实现，在ios中可以用CMPopTipView,也可以自己写一个View实现。其类似的效果如下图所示： 

实现思路分析： 
要实现上面的视图，有很多种实现方式。前面的文章说过，要实现弹框相关的可以用React Native 提供的 Modal组件(Modal组件)，使用Modal组件可以实现我们原生开发中的大多数效果。 
要实现下拉三角，可以让美工切一个带下拉三角的背景，当然也可以自己通过ART实现（ART绘制）。对于选项卡的内容，在原生开发中为了适应更多的场景，我们一般会选择使用ListView组件，然后当点击某个Item的时候获得相应的属性即可。为了控制Modal的显示与消失，我们可以给Modal内置一个isVisible: this.props.show状态。

源码

要实现上面的效果，会这涉及到三个js文件：MorePopWidows.js、Utils.js、HomeActionBar.js，按照先后顺序，代码如下： 
Utils.js

import {Dimensions} from 'react-native'

const deviceH = Dimensions.get('window').height
const deviceW = Dimensions.get('window').width

const basePx = 375

export default function px2dp(px) {
    return px *  deviceW / basePx
}

MorePopWidows.js

import React from 'react'
import {
    StyleSheet,
    Platform,
    View,
    Text,
    Image,
    TouchableOpacity,
    Alert,
    Modal,
    Dimensions,
} from 'react-native'
import SpacingView from "./SpacingView";
import QRScanPage from "../home/QRScanPage";

const { width, height } = Dimensions.get('window');
import px2dp from '../util/Utils'

const mTop = px2dp(Platform.OS == "ios" ? 64 : 44)

let mwidth = 95;
let mheight = 100;
const marginTop = mTop;

export default class MorePopWidows extends React.Component {

    constructor(props) {
        super(props);
        this.state = {
            isVisible: this.props.show,
        }
        mwidth = this.props.width ;
        mheight = this.props.height ;
    }

    componentWillReceiveProps(nextProps) {
        this.setState({ isVisible: nextProps.show });
    }

    closeModal() {
        this.setState({
            isVisible: false
        });
        this.props.closeModal(false);
    }

    scan() {
        this.props.navigator.push({
            component: QRScanPage,
        })
    }

    render() {
        return (
            <View style={styles.container}>
              <Modal
                  transparent={true}
                  visible={this.state.isVisible}
                  animationType={'fade'}
                  onRequestClose={() => this.closeModal()}>
                <TouchableOpacity style={styles.container} activeOpacity={1} onPress={() => this.closeModal()}>

                  <View style={styles.modal}>
                    <TouchableOpacity activeOpacity={1} onPress={this.scan.bind(this)} style={styles.itemView}>
                      <Image style={styles.imgStyle} source={require('../images/ic_scan_code_white.png')} />
                      <Text style={styles.textStyle}>扫一扫</Text>
                    </TouchableOpacity>
                     <SpacingView/>
                    <TouchableOpacity activeOpacity={1} onPress={() => Alert.alert('点击了付款码')} style={styles.itemView}>
                      <Image style={styles.imgStyle} source={require('../images/ic_code_white.png')} />
                      <Text style={styles.textStyle}>付款码</Text>
                    </TouchableOpacity>
                  </View>
                </TouchableOpacity>
              </Modal>
            </View>
        )
    }
}
const styles = StyleSheet.create({
    container: {
        width: width,
        height: height,
    },
    modal: {
        backgroundColor: '#696969',
        width: mwidth,
        height: mheight,
        position: 'absolute',
        left: width - mwidth - 10,
        top: marginTop,
        padding: 5,
        justifyContent: 'center',
        alignItems: 'center',
        borderRadius: 3,
    },
    itemView: {
        flexDirection: 'row',
        justifyContent: 'center',
        alignItems: 'center',
        flex: 1,
    },
    textStyle: {
        color: '#fff',
        fontSize: 14,
        marginLeft: 2,
    },
    imgStyle: {
        width: 20,
        height: 20,
    }
});

最后是在代码中使用MorePopWidows的代码： 
HomeActionBar.js

/**
 * https://github.com/facebook/react-native
 * @flow 首页的标题栏
 */

import React, {Component} from 'react';
import {Platform, View, Dimensions, Text, StyleSheet, TouchableOpacity, Image} from 'react-native';
import SelectCityPage from '../home/SelectCityPage'
import MorePopWidows from '../component/MorePopWidows'
import px2dp from '../util/Utils'

const isIOS = Platform.OS == "ios"
const {width, height} = Dimensions.get('window')
const headH = px2dp(isIOS ? 64 : 44)

export default  class HomeActionBar extends Component {

    constructor(props) {
        super(props);
        this.state = {
            showPop: false,
        }
    }

    city() {
        this.props.navigator.push({
            component: SelectCityPage,
        })
    }

    renderHeader() {
        return (
            <View >
            <View style={styles.headerStyle}>
                <TouchableOpacity style={styles.action} onPress={this.city.bind(this)}>
                    <Text style={styles.text}>上海</Text>
                    <Image
                        source={require('../images/ic_arrow_down.png')}/>
                </TouchableOpacity>
                <TouchableOpacity style={styles.searchBar}>
                    <Image source={require('../images/ic_search.png')} style={styles.iconStyle}/>
                    <Text style={{fontSize: 13, color: "#666", marginLeft: 5}}>输入商家、商品名称</Text>
                </TouchableOpacity>
                <TouchableOpacity style={styles.action} onPress={() => { this.setState({ showPop: !this.state.showPop }) }}>
                    <Image style={styles.scanIcon}
                           source={require('../images/ic_scan_code_white.png')}/>
                    <Text style={styles.scanText}>扫码</Text>
                </TouchableOpacity>
            </View>
                <View style={{ position: 'absolute', top: headH, left: 0, width: width, height: height }}>
                    <MorePopWidows width={90} height={100} show={this.state.showPop} closeModal={(show) => {
                        this.setState({showPop: show})
                    }} {...this.props}/>
                </View>

            </View>
        )
    }

    render() {
        return (
            <View>
                {this.renderHeader()}
            </View>
        );
    }
}

const styles = StyleSheet.create({
    headerStyle: {
        backgroundColor: "#06C1AE",
        height: headH,
        paddingTop: px2dp(isIOS ? 20 : 0),
        paddingHorizontal: 16,
        flexDirection: 'row',
        alignItems: 'center',
    },
    searchBar: {
        width: width * 0.65,
        height: 30,
        borderRadius: 19,
        marginLeft: 10,
        flexDirection: 'row',
        justifyContent: 'flex-start',
        alignItems: 'center',
        backgroundColor: 'white',
        alignSelf: 'center',
        paddingLeft: 10,
    },
    text: {
        fontSize: 16,
        color: '#ffffff',
        justifyContent: 'center',
    },
    iconStyle: {
        width: 22,
        height: 22,
    },
    action: {
        flexDirection: 'row',
        justifyContent: 'center',
        alignItems: 'center',
    },
    scanIcon: {
        width: 28,
        height: 28,
        alignItems: 'center',
        marginLeft: 10,
    },
    scanText: {
        fontSize: 14,
        color: '#ffffff',
        justifyContent: 'center',
        alignItems: 'center',
    },
});