在原生APP開發中，相信很多開發者都會見到這種場景：點擊右上角更多的選項，彈出一個更多界面供用戶選擇。這種控件在原生開發中Android可以用PopupWindow實現，在iOS中可以用CMPopTipView,也可以自己寫一個View實現。其類似的效果如下圖所示：
實現思路分析：
要實現上面的視圖，有很多種實現方式。前面的文章說過，要實現彈框相關的可以用React Native 提供的 Modal組件(Modal組件)，使用Modal組件可以實現我們原生開發中的大多數效果。
要實現下拉三角，可以讓美工切一個帶下拉三角的背景，當然也可以自己通過ART實現（ART繪制）。對于選項卡的內容，在原生開發中為了適應更多的場景，我們一般會選擇使用ListView組件，然后當點擊某個Item的時候獲得相應的屬性即可。為了控制Modal的顯示與消失，我們可以給Modal內置一個isVisible: this.props.show狀態。
源碼
要實現上面的效果，會這涉及到三個js文件：MorePopWidows.js、Utils.js、HomeActionBar.js，按照先后順序，代碼如下：
Utils.js
import {Dimensions} from 'react-native'const deviceH = Dimensions.get('window').heightconst deviceW = Dimensions.get('window').widthconst basePx = 375export 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}>掃一掃</Text> </TouchableOpacity> <SpacingView/> <TouchableOpacity activeOpacity={1} onPress={() => Alert.alert('點擊了付款碼')} style={styles.itemView}> <Image style={styles.imgStyle} source={require('../images/ic_code_white.png')} /> <Text style={styles.textStyle}>付款碼</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, }});最后是在代碼中使用MorePopWidows的代碼：
HomeActionBar.js
/** * https://github.com/facebook/react-native * @flow 首頁的標題欄 */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}}>輸入商家、商品名稱</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}>掃碼</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', },});以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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