Animate the dynamic height of a view on scroll - javascript

I have a UI similar to the image below:
The Title section (the section in dark blue) is supposed to be fixed and the Body section is scrollable.
The height of the Title section would be dynamic as there can be 4 - 5 bullet points retrieved from the server.
My task is to start reducing the height of the Title section when the user starts scrolling upwards to read the content that's present beneath until the point where the user can only read the title in the header. Also, when the user starts scrolling downwards to the point where he/she can see the heading Body, I am supposed to start increasing the height so that he can again start seeing all the bullet points.
This feature is more of like hiding/showing the header on the scroll. But, the title will always be visible.
I have written the below-written code to achieve the same:
import React from 'react';
import {
View,
Text,
ScrollView,
TouchableOpacity,
Linking,
Image,
Animated,
} from 'react-native';
class App extends React.PureComponent<Props, States> {
constructor() {
super();
this.state = {
headerHeight: 0,
headerTitleHeight: 0,
};
this.scrollY = new Animated.Value(0);
}
render() {
const { navigation, pending, macroFeed } = this.props;
const { headerHeight, headerTitleHeight } = this.state;
const { themeDetails } = navigation.state.params;
const {
title, bullet1, bullet2, bullet3,
} = themeDetails;
let headerStyle = {};
if (headerHeight) {
headerStyle = {
height: this.scrollY.interpolate({
inputRange: [0, headerHeight - headerTitleHeight],
outputRange: [headerHeight, headerTitleHeight],
extrapolate: 'clamp',
}),
};
}
const sortedMacroFeed = _.sortBy(macroFeed, (o) => moment(o.date).format('YYYYMMDD')).reverse().slice(0, 5);
if (pending) {
return (
<View style={styles.maxFlex}>
<LoadingSpinner
size="large"
containerStyle={styles.loadingSpinner}
/>
</View>
);
}
return (
<View
style={styles.maxFlex}
>
<Animated.View
style={[styles.headerWrapper, headerStyle]}
onLayout={(event) => {
this.setState({
headerHeight: event.nativeEvent.layout.height,
});
}}
>
<View style={styles.macroBgWrapper}>
<Image source={themeDetails.imgUrl} style={styles.macroBg} />
<View style={styles.macroBgOverlay} />
</View>
<View
style={styles.header}
onLayout={(event) => {
this.setState({
headerTitleHeight: event.nativeEvent.layout.height,
});
}}
>
<TouchableOpacity onPress={() => navigation.goBack()}>
<View>
<Icon name="ios-arrow-back" size={32} style={styles.backIcon} />
</View>
</TouchableOpacity>
<View style={styles.titleWrap}>
<Text style={styles.headerTitle}>
{title}
</Text>
</View>
</View>
<View style={styles.bulletWrapper}>
{
!!bullet1 && (
<View style={styles.column}>
<View style={styles.row}>
<View style={styles.bullet}>
<Text style={styles.buttetListText}>
{'\u2022'}
{' '}
</Text>
</View>
<View style={styles.bulletText}>
<Text style={styles.buttetListText}>
{bullet1}
</Text>
</View>
</View>
</View>
)
}
{
!!bullet2 && (
<View style={styles.column}>
<View style={styles.row}>
<View style={styles.bullet}>
<Text style={styles.buttetListText}>
{'\u2022'}
{' '}
</Text>
</View>
<View style={styles.bulletText}>
<Text style={styles.buttetListText}>
{bullet2}
</Text>
</View>
</View>
</View>
)
}
{
!!bullet3 && (
<View style={styles.column}>
<View style={styles.row}>
<View style={styles.bullet}>
<Text style={styles.buttetListText}>
{'\u2022'}
{' '}
</Text>
</View>
<View style={styles.bulletText}>
<Text style={styles.buttetListText}>
{bullet3}
</Text>
</View>
</View>
</View>
)
}
{
!bullet1 && !bullet2 && !bullet3 && (
<View style={styles.noBulletWrapper}>
<Text style={styles.noBulletPoints}>
No description found.
</Text>
</View>
)
}
</View>
</Animated.View>
<ScrollView
style={styles.maxFlex}
showsVerticalScrollIndicator={false}
onScroll={Animated.event([
{ nativeEvent: { contentOffset: { y: this.scrollY } } },
])}
scrollEventThrottle={16}
>
<View style={[styles.section, styles.wrapGutter]}>
<Text style={styles.sectionTitle}>
Recent Headlines
</Text>
{
sortedMacroFeed.map((feed) => (
<View key={feed.id} style={styles.newsSection}>
<Text style={styles.newsHours}>
{moment(feed.date).fromNow()} | {feed.author}
</Text>
<Text style={styles.newsTitle}>
{feed.title}
<Text onPress={() => this.openWebView(feed.url)}>
<EvilIcons name="external-link" size={16} style={styles.externalLinkIcon} />
</Text>
</Text>
</View>
))
}
</View>
<View style={styles.section}>
<View style={[styles.wrapGutter, styles.sectionTitleWrap]}>
<Text style={styles.sectionTitle}>
Exposure
</Text>
<View style={styles.totalNavWrap}>
<Text style={styles.totalNav}>
$467M
</Text>
<Text style={styles.totalNavLabel}>
Total NaV (all portfolios)
</Text>
</View>
</View>
<Tabs
tabsData={TABS_DATA}
renderTabContent={this.renderTabContent}
tabName="title"
hideIfOneTab
/>
</View>
</ScrollView>
</View>
);
}
}
If you have observed I am trying to retrieve the dynamic height of the title section using onLayout.
This code only works one way i.e when I scroll up. The height of the title section reduces to the point where only the title can be seen and the bullet points get hidden. But after that, I cannot scroll down. The height gets permanently reduced.
Now, if I change the below-given code:
let headerStyle = {};
if (headerHeight) {
headerStyle = {
height: this.scrollY.interpolate({
inputRange: [0, headerHeight - headerTitleHeight],
outputRange: [headerHeight, headerTitleHeight],
extrapolate: 'clamp',
}),
};
}
to
const headerStyle = {
height: this.scrollY.interpolate({
inputRange: [0, 240],
outputRange: [300, 60],
extrapolate: 'clamp',
}),
};
everything seems to work fine. Basically, if I stop retrieving the value of the height dynamically and provide a static value like 240 or something, everything seems to work fine.
But, animation on scroll stops if I accept dynamic height. Any help to solve this would be much appreciated. Thanks in anticipation.

I found the issue. So, if you observe the line:
<Animated.View
style={[styles.headerWrapper, headerStyle]}
onLayout={(event) => {
this.setState({
headerHeight: event.nativeEvent.layout.height,
});
}}
>
onLayout used to setState as soon as the headerHeight value changed on the scroll. Due to which the height of the header used to reduce and scrolling the content down was not possible.
I changed the code to:
<Animated.View
style={[styles.headerWrapper, headerStyle]}
onLayout={(event) => {
if (!this.state.headerHeight) {
this.setState({
headerHeight: event.nativeEvent.layout.height,
});
}
}}
>
Now, everything works fine.

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I have narrowed down the problem to the width and the 'event.nativeEvent.contentOffset', the returning number is close to 1 but it is (0.9), therefor math.floor was giving 0 as the index number,
I have changed Math.floor to Math.round and it is working perfectly fine,
If anyone wants a Introduction Slider for their app they can use this

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new Set(nameInput).size === nameInput.length
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this.setState({ nameInput, loading: false });
} else {
alert(
"Please make sure there are at least two people and no duplicate names!"
);
}
}}
>
<Text style={styles.continueButtonText} allowFontScaling={false}>
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</TouchableOpacity>
</View>
</KeyboardAvoidingView>
And here is my code for the addName() function:
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let nameInput = this.state.nameInput.concat("");
this.setState({
nameInput,
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};
This page has the solution I was looking for: Is it possible to keep a ScrollView scrolled to the bottom?

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Just to be clear I will have premium and non premium content
class Browser extends Component {
scrollX = new Animated.Value(0);
renderRecommended = () => {
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<View style={[styles.flex, styles.column, styles.recommended]}>
<View style={[styles.row, styles.recommendedHeader]}>
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<View style={[styles.column, styles.recommendedList]}>
<FlatList
horizontal
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renderRecommendation = (item, index) => {
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<TouchableOpacity
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fontSize: theme.sizes.font * 1.25,
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color: 'white',
marginLeft: 10,
//paddingBottom: 20,
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{item.title}
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marginLeft: 10,
fontFamily: 'Nunito-SemiBold',
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{item.location}
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render() {
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<ScrollView style={styles.container}>
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contentContainerStyle={{paddingBottom: theme.sizes.paddin}}>
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My code is the one on the top. Just to simplify I am accesing some elements from JSON and I am creating Flatlist based on this. What I want is is to give some of the JSON files a bolean with premium or not and in this way to make some elements available for user or not.
As part of your destinations array, for each object, you can specify a boolean field called isPremiumItem. Your users should have a boolean field like isPremiumUser to show the type of their subscription.
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Trying to create two columns in react-native

I am trying to create a two column grid using flex. One column will be used to display a word or phrase and the second column will be used to translate the first column. Here is a link: http://imgur.com/nZGo8pb to give you a visual idea on what I am trying to achieve.
I am unable to get two columns side by side. I am only able to have my words appear on top of each other. This is best attempt. A huge failure.http://imgur.com/a/ICApr
My code is:
nent} from 'react';
import { Text, View,StyleSheet,Image,TextInput,ListView} from 'react-native';
class AddWords extends Component{
state = {words:['iku','konkai','kaikan'],
word:'',
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renderEnglishWords(english){
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{english}
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<Text>
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addWord(){
let words = this.state.words.concat([this.state.word]);
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render(){
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Any help will be greatly appreciated.
Thanks.
You need to wrap both inner containers in another <View> with the following style:
<View style={styles.container}>
<TextInput
style={styles.input}
onChangeText={(word) => {
this.setState({ word })
}}
onEndEditing={this.addWord}
/>
<View style={{ flexDirection: 'row', flex: 1 }}>
<View style={styles.wordContainer}>
...
</View>
<View style={styles.item2}>
...
</View>
</View>
</View>
It's because the flexDirection in styles.wordContainer is set to 'column', it should be set to 'row'.
Check out this link on flex-direction examples.

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