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MultiColumnExample.js
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MultiColumnExample.js
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/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @format
* @flow
*/
'use strict';
const React = require('react');
const ReactNative = require('react-native');
const {FlatList, StyleSheet, Text, View, Alert} = ReactNative;
const RNTesterPage = require('./RNTesterPage');
const infoLog = require('infoLog');
const {
FooterComponent,
HeaderComponent,
ItemComponent,
PlainInput,
SeparatorComponent,
genItemData,
getItemLayout,
pressItem,
renderSmallSwitchOption,
} = require('./ListExampleShared');
class MultiColumnExample extends React.PureComponent<
$FlowFixMeProps,
$FlowFixMeState,
> {
state = {
data: genItemData(1000),
filterText: '',
fixedHeight: true,
logViewable: false,
numColumns: 2,
virtualized: true,
};
_onChangeFilterText = filterText => {
this.setState(() => ({filterText}));
};
_onChangeNumColumns = numColumns => {
this.setState(() => ({numColumns: Number(numColumns)}));
};
render() {
const filterRegex = new RegExp(String(this.state.filterText), 'i');
const filter = item =>
filterRegex.test(item.text) || filterRegex.test(item.title);
const filteredData = this.state.data.filter(filter);
return (
<RNTesterPage
title={this.props.navigator ? null : '<FlatList> - MultiColumn'}
noSpacer={true}
noScroll={true}>
<View style={styles.searchRow}>
<View style={styles.row}>
<PlainInput
onChangeText={this._onChangeFilterText}
placeholder="Search..."
value={this.state.filterText}
/>
<Text> numColumns: </Text>
<PlainInput
clearButtonMode="never"
onChangeText={this._onChangeNumColumns}
value={this.state.numColumns ? String(this.state.numColumns) : ''}
/>
</View>
<View style={styles.row}>
{renderSmallSwitchOption(this, 'virtualized')}
{renderSmallSwitchOption(this, 'fixedHeight')}
{renderSmallSwitchOption(this, 'logViewable')}
</View>
</View>
<SeparatorComponent />
<FlatList
ListFooterComponent={FooterComponent}
ListHeaderComponent={HeaderComponent}
getItemLayout={
this.state.fixedHeight ? this._getItemLayout : undefined
}
data={filteredData}
key={this.state.numColumns + (this.state.fixedHeight ? 'f' : 'v')}
numColumns={this.state.numColumns || 1}
onRefresh={() =>
Alert.alert('Alert', 'onRefresh: nothing to refresh :P')
}
refreshing={false}
renderItem={this._renderItemComponent}
disableVirtualization={!this.state.virtualized}
onViewableItemsChanged={this._onViewableItemsChanged}
/>
</RNTesterPage>
);
}
_getItemLayout(
data: any,
index: number,
): {length: number, offset: number, index: number} {
const length =
getItemLayout(data, index).length + 2 * (CARD_MARGIN + BORDER_WIDTH);
return {length, offset: length * index, index};
}
_renderItemComponent = ({item}) => {
return (
<View style={styles.card}>
<ItemComponent
item={item}
fixedHeight={this.state.fixedHeight}
onPress={this._pressItem}
/>
</View>
);
};
// This is called when items change viewability by scrolling into or out of the viewable area.
_onViewableItemsChanged = (info: {
changed: Array<{
key: string,
isViewable: boolean,
item: {columns: Array<*>},
index: ?number,
section?: any,
}>,
}) => {
// Impressions can be logged here
if (this.state.logViewable) {
infoLog(
'onViewableItemsChanged: ',
info.changed.map(v => ({...v, item: '...'})),
);
}
};
_pressItem = (key: string) => {
pressItem(this, key);
};
}
const CARD_MARGIN = 4;
const BORDER_WIDTH = 1;
const styles = StyleSheet.create({
card: {
margin: CARD_MARGIN,
borderRadius: 10,
flex: 1,
overflow: 'hidden',
borderColor: 'lightgray',
borderWidth: BORDER_WIDTH,
},
row: {
flexDirection: 'row',
alignItems: 'center',
},
searchRow: {
padding: 10,
},
});
exports.title = '<FlatList> - MultiColumn';
exports.description = 'Performant, scrollable grid of data.';
exports.examples = [
{
title: 'Simple flat list multi column',
render: function(): React.Element<typeof MultiColumnExample> {
return <MultiColumnExample />;
},
},
];