[FlatList] Scrolling issues with FlatList when rows are variable height

I’m using a FlatList where each row can be of different height (and may contain a mix of both text and zero or more images from a remote server).

I cannot use getItemLayout because I don’t know the height of each row (nor the previous ones) to be able to calculate.

The problem I’m facing is that I cannot scroll to the end of the list (it jumps back few rows when I try) and I’m having issues when trying to use scrollToIndex (I’m guessing due to the fact I’m missing getItemLayout).

I wrote a sample project to demonstrate the problem (simply try to scroll to the end with your finger - it won’t allow you)

import React, { Component } from 'react';
import { AppRegistry, StyleSheet, Text, View, Image, FlatList } from 'react-native';
import autobind from 'autobind-decorator';

const items = count => [...Array(count)].map((v, i) => ({
    key: i,
    index: i,
    image: 'https://dummyimage.com/600x' + (((i % 4) + 1) * 50) + '/000/fff',
}));

class RemoteImage extends Component {
    constructor(props) {
        super(props);
        this.state = {
            style: { flex: 1, height: 0 },
        };
    }

    componentDidMount() {
        Image.getSize(this.props.src, (width, height) => {
            this.image = { width, height };
            this.onLayout();
        });
    }

    @autobind
    onLayout(event) {
        if (event) {
            this.layout = {
                width: event.nativeEvent.layout.width,
                height: event.nativeEvent.layout.height,
            };
        }
        if (!this.layout || !this.image || !this.image.width)
            return;
        this.setState({
            style: {
                flex: 1,
                height: Math.min(this.image.height,
                    Math.floor(this.layout.width * this.image.height / this.image.width)),
            },
        });
    }
    render() {
        return (
            <Image
                onLayout={this.onLayout}
                source={{ uri: this.props.src }}
                style={this.state.style}
                resizeMode='contain'
            />
        );
    }
}

class Row extends Component {
    @autobind
    onLayout({ nativeEvent }) {
        let { index, item, onItemLayout } = this.props;
        let height = Math.max(nativeEvent.layout.height, item.height || 0);
        if (height != item.height)
            onItemLayout(index, { height });
    }

    render() {
        let { index, image } = this.props.item;
        return (
            <View style={[styles.row, this.props.style]}>
                <Text>Header {index}</Text>
                <RemoteImage src = { image } />
                <Text>Footer {index}</Text>
            </View>
        );
    }
}

export default class FlatListTest extends Component {
    constructor(props) {
        super(props);
        this.state = { items: items(50) };
    }

    @autobind
    renderItem({ item, index }) {
        return <Row
        item={item}
        style={index&1 && styles.row_alternate || null}
        onItemLayout={this.onItemLayout}
        />;
    }

    @autobind
    onItemLayout(index, props) {
        let items = [...this.state.items];
        let item = { ...items[index], ...props };
        items[index] = { ...item, key: [item.height, item.index].join('_') };
        this.setState({ items });
    }

    render() {
        return (
            <FlatList
                    ref={ref => this.list = ref}
                    data={this.state.items}
                    renderItem={this.renderItem}
                />
        );
    }
}

const styles = StyleSheet.create({
    row: {
        padding: 5,
    },
    row_alternate: {
        backgroundColor: '#bbbbbb',
    },
});

AppRegistry.registerComponent('FlatListTest', () => FlatListTest);

[hramos]

Hi there! This issue is being closed because it has been inactive for a while. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. Either way, we’re automatically closing issues after a period of inactivity. Please do not take it personally!

If you think this issue should definitely remain open, please let us know. The following information is helpful when it comes to determining if the issue should be re-opened:

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If you would like to work on a patch to fix the issue, contributions are very welcome! Read through the contribution guide, and feel free to hop into #react-native if you need help planning your contribution.

[AnisDerbel]

you should not close the issue unless it’s fixed , I’m having the same issue , I’m using a custom TreeView based on Flatlists , when you click on item the sub item will be visible then the height will be dynamic and the scrollToIndex doesn’t work properly!

There is no scrollToItem? that might resolve my problem