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ScrollableTabBar.js
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ScrollableTabBar.js
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// @flow
import React, { Component } from 'react';
import PropTypes from 'prop-types';
import {
View,
Text,
ScrollView,
StyleSheet,
Dimensions,
TouchableOpacity,
ViewPropTypes,
} from 'react-native';
import _ from 'lodash';
const { width:ScreenW } = Dimensions.get('window');
export default class ScrollableTabBar extends Component {
constructor(props) {
super(props);
this.state = { scrollItemLayoutInfos:[] };
this.offsetX = 0;
}
componentWillReceiveProps(nextProps) {
const nextTab = (nextProps && nextProps.activeTab) || 0;
if (this._currentItem != nextTab) {
this._currentItem = nextTab;
const beyond = this._itemBeyondScreen(nextTab);
if (beyond > 0) {
const newOffset = this._offsetForItemToDockRight(nextTab);
this.refs.scrollView.scrollTo({ y:0, x:newOffset }, true);
} else if (beyond < 0) {
const newOffset = this._offsetForItemToDockLeft(nextTab);
this.refs.scrollView.scrollTo({ y:0, x:newOffset }, true);
}
}
}
/**
* if item beyond screen
* @param {[type]} index [description]
* @return {[type]} [description]
*/
_itemBeyondScreen(index) {
const layout = this.scrollItemLayoutInfos[index];
if (layout) {
const offsetRight = layout.x + layout.width - this.offsetX - ScreenW;
if (offsetRight > 0) {
return offsetRight;
}
const offsetLeft = layout.x - this.offsetX;
if (offsetLeft < 0) {
return offsetLeft;
}
}
return 0;
}
_offsetForItemToDockLeft(index) {
return this.scrollItemLayoutInfos[index].x;
}
_offsetForItemToDockRight(index) {
const w = this.scrollItemLayoutInfos[index].width;
let ret = this._offsetForItemToDockLeft(index);
if (w < ScreenW) {
ret -= (ScreenW - w);
}
return ret;
}
renderTabOption(name, page, pageCount, passProps) {
const isTabActive = this.props.activeTab === page;
return (<TouchableOpacity
style={{ height:50, alignItems:'center', justifyContent:'center', marginLeft: 22, marginRight: page == pageCount - 1 ? 22 : 38 }}
key={name}
accessible={true}
accessibilityLabel={name}
accessibilityTraits="button"
onPress={() => this.props.goToPage(page)}
{...passProps}
>
{this.renderTabName(name, page, isTabActive)}
</TouchableOpacity>);
}
renderTabName(name, page, isTabActive) {
const { activeTextColor, inactiveTextColor, textStyle, } = this.props;
const textColor = isTabActive ? activeTextColor : inactiveTextColor;
const fontWeight = isTabActive ? 'bold' : 'normal';
return (<View style={[styles.tab, this.props.tabStyle, { alignItems:'center', justifyContent:'center' }]}>
<Text style={[{ color: textColor, fontWeight, }, textStyle,]}>
{name}
</Text>
</View>);
}
_onLayoutTabItem(index, size) {
if (size) {
const arr = this.scrollItemLayoutInfos;
arr[index] = size;
this.scrollItemLayoutInfos = arr;
}
}
get scrollItemLayoutInfos() {
return this.state.scrollItemLayoutInfos;
}
set scrollItemLayoutInfos(arr) {
this.setState({ scrollItemLayoutInfos:arr });
}
render() {
const containerWidth = this.props.containerWidth;
const numberOfTabs = this.props.tabs.length;
let currentItemLayout = this.scrollItemLayoutInfos[this.props.activeTab];
if (!currentItemLayout) {
currentItemLayout = { x: 0, width: 0 };
}
const tabUnderlineStyle = {
position: 'absolute',
left: currentItemLayout.x,
width: currentItemLayout.width,
height: this.props.underlineHeight,
backgroundColor: this.props.underlineColor,
bottom: 0,
};
return (
<View>
<ScrollView
ref={'scrollView'}
style={[styles.tabs, { backgroundColor: this.props.backgroundColor, }, this.props.style, { height:50 }]}
showsHorizontalScrollIndicator={false}
scrollEventThrottle={16}
horizontal
contentContainerStyle={{ alignItems:'center' }}
onScroll={this._onScroll.bind(this)}
>
<View style={{ flexDirection:'row' }}>
{
this.props.tabs.map(
(tab, i) => this.renderTabOption(
tab, i, this.props.tabs.length, { onLayout:e => this._onLayoutTabItem(i, e && e.nativeEvent && e.nativeEvent.layout) }
)
)
}
<View style={tabUnderlineStyle} />
</View>
</ScrollView>
</View>
);
}
_onScroll(e) {
const offset = e.nativeEvent.contentOffset;
this.offsetX = offset.x;
}
}
ScrollableTabBar.propTypes = {
goToPage: PropTypes.func,
activeTab: PropTypes.number,
tabs: PropTypes.array,
underlineColor: PropTypes.string,
underlineHeight: PropTypes.number,
backgroundColor: PropTypes.string,
activeTextColor: PropTypes.string,
inactiveTextColor: PropTypes.string,
textStyle: Text.propTypes.style,
tabStyle: ViewPropTypes.style,
};
ScrollableTabBar.defaultProps = {
activeTextColor: 'navy',
inactiveTextColor: 'black',
underlineColor: 'navy',
backgroundColor: null,
underlineHeight: 4,
};
const styles = StyleSheet.create({
tab: {
alignItems: 'center',
justifyContent: 'center',
paddingBottom: 10,
},
tabs: {
height: 50,
borderWidth: 1,
borderTopWidth: 0,
borderLeftWidth: 0,
borderRightWidth: 0,
borderBottomColor: '#ccc',
},
});