react - native 文字跑马灯组件上下滚动

import React, { Component } from 'react'
import {
Text,
View,
Animated,
Easing,
StyleSheet,
} from 'react-native'
import PropTypes from 'prop-types'

export default class ScrollVertical extends Component {

static defaultProps = { enableAnimation: true }

constructor(props) {
    super(props)
    const translateValue = new Animated.ValueXY({ x: 0, y: 0 })
    this.state = {
        translateValue,
        // 滚屏高度
        scrollHeight: this.props.scrollHeight || 32,
        // 滚屏内容
        kb_content: [],
        // Animated.View 滚动到的 y轴坐标
        kb_tempValue: 0,
        // 最大偏移量
        kb_contentOffsetY: 0,
        // 每一次滚动切换之前延迟的时间
        delay: this.props.delay || 500,
        // 每一次滚动切换的持续时间
        duration: this.props.duration || 500,
        enableAnimation: true,
    }
    this.createKbItem = this.createKbItem.bind(this)
}

componentDidMount() {
    const content = this.props.data || []
    if (content.length !== 0) {
        const h = (content.length + 1) * this.state.scrollHeight
        this.setState({
            kb_content: content.concat(content[0]),
            kb_contentOffsetY: h
        })
        // 开始动画
        this.startAnimation()
    }
}
componentWillReceiveProps(nextProps) {
    const context = nextProps.data;
    if (context.length !== 0) {
        const h = (context.length + 1) * this.state.scrollHeight;
        this.setState({
            kb_content: context.concat(context[0]),
            kb_contentOffsetY: h
        });
    }
    this.setState({
        enableAnimation: !!nextProps.enableAnimation
    }, () => {
        this.startAnimation()
    });
}

componentWillUnmount() {
    if (this.animation) {
        clearTimeout(this.animation)
    }
    if (this.state.translateValue) {
        this.state.translateValue.removeAllListeners()
    }
}

overStep(name, num = 13) {
    if (name.length > num) {
        return `${name.substring(0, num)}...`
    }
    return name
}

createKbItem(kbItem, index) {
    return (
        
            
                {this.overStep(kbItem.title)}
            
        
    )
}
startAnimation = () => {
    if (this.state.enableAnimation) {
        if (!this.animation) {
            this.animation = setTimeout(() => {
                this.animation = null
                this.startAnimationSeamless()
            }, this.state.delay)
        }
    }
}

startAnimationSeamless = () => {
    this.state.kb_tempValue -= this.state.scrollHeight
    if (this.props.onChange) {
        const index = Math.abs(this.state.kb_tempValue) / (this.state.scrollHeight)
        this.props.onChange(index < this.state.kb_content.length - 1 ? index : 0)
    }
    Animated.sequence([
        Animated.timing(
            this.state.translateValue, {
                isInteraction: false,
                toValue: { x: 0, y: this.state.kb_tempValue },
                duration: this.state.duration, // 动画持续的时间（单位是毫秒），默认为500
                easing: Easing.linear
            }),
    ])
        .start(() => {
            // 无缝切换
            if (this.state.kb_tempValue - this.state.scrollHeight === -this.state.kb_contentOffsetY) {
                // 快速拉回到初始状态
                this.state.translateValue.setValue({ x: 0, y: 0 })
                this.state.kb_tempValue = 0
            }
            this.startAnimation()
        })
}

render() {
    return (
        
            {
                this.state.kb_content.length !== 0 ?
                    
                        {this.state.kb_content.map(this.createKbItem)}
                     : null
            }
            
    )
}

}

const styles = StyleSheet.create({
kbContainer: {
// 必须要有一个背景或者一个border，否则本身高度将不起作用
backgroundColor: 'transparent',
overflow: 'hidden'
},
kb_text_c: {
fontSize: 18,
color: '#181818'
}
})

// PropTypes类型
ScrollVertical.propTypes={
scrollHeight: PropTypes.number,
data: PropTypes.array,
textStyle: PropTypes.object,
scrollStyle: PropTypes.object,
kbContainer: PropTypes.object,
onChange: PropTypes.func,
enableAnimation: PropTypes.bool,
duration: PropTypes.number,
delay: PropTypes.number,
onPress: PropTypes.func
}

// 默认属性
ScrollVertical.defaultProps = {
translateValue: [],
scrollHeight: 34,
kb_content: [],
kb_tempValue: 0,
kb_contentOffsetY: 0,
delay: 500,
duration: 500,
enableAnimation: true
}

                                   跑马灯的使用

const dataArray = [{title: '保险全场五折'}, {title: '打到骨折'},{ title: '骨折甩卖,全场骨折甩卖'},{title: '保险全场五折,你买不了吃亏买不了上当嗷嗷嗷'}]
onChange={(index => {this.index = index})}
onPress={(value) => {this.setModalVisible(value)}}
enableAnimation
data={arrayContent}
delay={1000}
duration={300}
scrollHeight={20}
scrollStyle={{ alignItems: 'flex-start' }}
textStyle={{ fontSize: 12, color: 'red' }}
/>