Long Text doesn't render correctly when in ScrollView

[zuccha]

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Environment

React Native Environment Info:
System:
OS: macOS High Sierra 10.13.6
CPU: (8) x64 Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
Memory: 1.82 GB / 16.00 GB
Shell: 5.3 - /bin/zsh
Binaries:
Node: 10.11.0 - ~/.nvm/versions/node/v10.11.0/bin/node
Yarn: 1.12.3 - /usr/local/bin/yarn
npm: 6.4.1 - ~/.nvm/versions/node/v10.11.0/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
Android SDK:
API Levels: 25, 26, 27, 28
Build Tools: 26.0.3, 27.0.3, 28.0.2
System Images: android-26 | Google APIs Intel x86 Atom, android-27 | Google Play Intel x86 Atom
IDEs:
Android Studio: 3.1 AI-173.4907809
Xcode: 10.1/10B61 - /usr/bin/xcodebuild
npmPackages:
react: 16.6.3 => 16.6.3
react-native: 0.57.8 => 0.57.8
npmGlobalPackages:
react-native-cli: 2.0.1

Description

When placing a Text component into a ScrollView on iOS, if Text contains too many characters, then no text is rendered, however the Text component occupies the correct amount of space (i.e., the view scrolls). The number of characters for breaking the Text component varies depending on the device, but it is usually around 25,000.

N.B.: The bug is not present if we replace ScrollView with View.

This bug is not present on Android.

Wrong behaviour (no text, but the view scrolls):

Correct behaviour (text and the view scrolls):

Reproducible Demo

To reproduce the bug, run the following code on iOS

import React from 'react';
import { Text, ScrollView } from 'react-native';

export default () => (
  <ScrollView>
    <Text>{'a'.repeat(25000)}</Text>
  </ScrollView>
);

[triplea24]

Hi @zuccha, You should add some style to the ScrollView's container so it can stretch and completely fit in the screen.

Just replace it with this snippet:

export default () => (
  <ScrollView contentContainerStyle={{ flex: 1}}>
    <Text style={{ flex: 1}}>{'a'.repeat(25000)}</Text>
  </ScrollView>
);

[zuccha]

Hi @triplea24 thank for your help. I tried with flex: 1, but that way the ScrollView is not scrollable anymore. It is easy to see by putting two long texts one after the other

import React from 'react';
import { Text, ScrollView } from 'react-native';

export default () => (
  <ScrollView contentContainerStyle={{flex:1}}>
    <Text>{'a'.repeat(25000)}</Text>
    <Text>{'b'.repeat(25000)}</Text>
  </ScrollView>
);

The texts should have the same length, but I can't scroll through the 'b's. However, if I remove the flex: 1, the text disappears (but the view has the correct size). I don't think it's a problem of size (again, the view has the correct size).

[LucasMonteiro1]

Same problem

[grigorii-lapshin]

Have same problem but with even with text half of the specified length

[danilobuerger]

The bug seems to be related to the height of the content. So with a smaller font size, more text can be displayed.

[danilobuerger]

Seems to be a long standing issue: #9077

[alangumer]

Same problem here, agreed with @zuccha seems like the issue is with the Text component, the View size is correct.
@zuccha did you find a workaround this?

The workaround I found is to use a WebView

<WebView style={styles.transcript} source={{html: `<p style="font-size:48px;text-align:center">${slide.description}</p>`}} />

[ericlewis]

I did some investigation in to this bug, and it appears to be related to Yoga, or the way we calculate heights using NSTextStorage. I wasn’t able to dig in much further.

[CatapultJesse]

Snack reproducing: https://snack.expo.io/@jkcooper/rn22713-long-text-in-scrollview

[CatapultJesse]

Related Issue: https://github.com/faceabook/react-native/issues/19453

[rickhanlonii]

Dupe of #19453 👌

[KaviduAloka]

Add flexShrink: 1

<Text style={{ flexShrink: 1 }}>