Measure text height without laying it out

React Native Measure Text

Measure text height and/or width without laying it out.

Installation

Automatic installation

$ yarn add react-native-measure-text

$ react-native link react-native-measure-text

Manual installation

iOS

1. In XCode, in the project navigator, right click Libraries ➜ Add Files to [your project's name]
2. Go to node_modules ➜ react-native-measure-text and add RNMeasureText.xcodeproj
3. In XCode, in the project navigator, select your project. Add libRNMeasureText.a to your project's Build Phases ➜ Link Binary With Libraries
4. Run your project (Cmd+R)<

Android

1. Open up android/app/src/main/java/[...]/MainActivity.java

• Add import io.github.airamrguez.RNMeasureTextPackage; to the imports at the top of the file
• Add new RNMeasureTextPackage() to the list returned by the getPackages() method

2. Append the following lines to android/settings.gradle:

   include ':react-native-measure-text'
   project(':react-native-measure-text').projectDir = new File(rootProject.projectDir, 	'../node_modules/react-native-measure-text/android')
   

3. Insert the following lines inside the dependencies block in android/app/build.gradle:

     compile project(':react-native-measure-text')
   

Usage

import MeasureText from 'react-native-measure-text';

const texts = [
  'This is an example',
  'This is the second line'
];
const width = 100;
const fontSize = 15;
const fontFamily = 'Anton';

class Test extends Component {
  state = {
    heights: [],
  }
  async componentDidMount() {
    const heights = await MeasureText.heights({(
      texts, /* texts to measure */
      width, /* container width */
      fontSize,
      fontFamily /* fontFamily is optional! */
    );
    this.setState({ heights });
  }
  render() {
    const { heights } = this.state;
    return (
      <View>
        {texts.map((text, i) => (
          <Text
            key={`text-${i}`}
            style={{
              width,
              fontSize,
              fontFamily,
              height: heights[i],
            }}
          >
            {text}
          </Text>
        ))}
    </View>
  }
}

API

MeasureText.heights(options)

Returns a promise that resolves to all the heights of the texts passed in options.

MeasureText.widths(options)

Returns a promise that resolves to all the widths of the texts passed in options.

Measure options:

• texts: An array of texts to measure.
• width: Container width when you want to measure the height.
• height: Container height when you want to measure the width.
• fontSize: The size of the font.
• fontFamily: The name of a custom font or a preinstalled font. This is optional.

How to use a custom font?

Follow these steps:

1. Create assets/fonts at the root of your React Native project.
2. Add this piece of JSON into your package.json file:

  "rnpm": {
    "assets": [
      "./assets/fonts/"
    ]
  }

3. If you want to use the same font cross-platform, in order to avoid platform incompatibility issues, be sure that your font file name matches the font name! For example if the font name is "Anton" the file should be named "Anton.ttf". You can specify different fonts for each platform if you want.
4. Run the command react-native link on the root of your project to link the added fonts.

GitHub