useWindowDimensions is the preferred API for React components. Unlike Dimensions, it updates as the window’s dimensions update. This works nicely with the React paradigm. Deprecated: useKeplerWindowDimensions is the preferred API for React Native for Vega applications. Unlike useWindowDimensions, it updates when any application component’s window dimension update. useKeplerWindowDimensionsV2 use this hook instead which updates the dimensions based on root tag to handle multiple interactive component and multiple instances .

import {Dimensions} from 'react-native';

You can get the application window’s width and height using the following code:

const windowWidth = Dimensions.get('window').width;
const windowHeight = Dimensions.get('window').height;

React Native for Vega applications can get the dimensions for all application component windows using the following code:

import { DisplayMetrics, Dimensions } from 'react-native';

export const useKeplerWindowDimensionsV2 = ():DisplayMetrics => {
const rootTag = useContext(RootTagContext);
const [dimensions,
    setDimensions] = useState(NativeDeviceInfo.getDimensionsV2(rootTag));
useEffect(() => {
    const handleChange = (newDimensions) => {
        if (dimensions !== newDimensions) {
            setDimensions(newDimensions);
        }
    }
};

DisplayMetricsKepler Type:

/**
 * Vega window Dimensions
 * @platform vega
 */
export interface DisplayMetricsKepler {
  width: number;
  height: number;
  scale: number;
  fontScale: number;
  moduleName: string;
}

If your React Native for Vega application only has a single application component, you can just rely on Dimensions.get('window'). If you have more than one application component you will need to use Dimensions.get('windows') and identify the dimensions for the particular component you are interested in. When there is more than one Vega app component, Dimensions.get(‘window’) returns dimensions for the first component created in the app process. Although dimensions are available immediately, they may change (e.g due to device rotation, foldable devices etc) so any rendering logic or styles that depend on these constants should try to call this function on every render, rather than caching the value (for example, using inline styles rather than setting a value in a StyleSheet). If you are targeting foldable devices or devices which can change the screen size or app window size, you can use the event listener available in the Dimensions module as shown in the below example.

Example Vega

import React, {useState, useEffect} from 'react';
import {View, StyleSheet, Text, Dimensions} from 'react-native';

const windowDimensions = Dimensions.get('window');
const screenDimensions = Dimensions.get('screen');

const App = () => {
  const [dimensions, setDimensions] = useState({
    window: windowDimensions,
    screen: screenDimensions,
  });

  useEffect(() => {
    const handleChange = (newDimensions) => {
        if (dimensions !== newDimensions) {
            setDimensions(newDimensions);
        }
}

    const subscription = NativeDeviceInfo.addListenerV2(rootTag, 'didUpdateDimensions', handleChange);
    return () => subscription?.remove();
  });

  return (
    <View style={styles.container}>
      <Text style={styles.header}>Window Dimensions</Text>
      {Object.entries(dimensions.window).map(([key, value]) => (
        <Text>
          {key} - {value}
        </Text>
      ))}
      <Text style={styles.header}>Screen Dimensions</Text>
      {Object.entries(dimensions.screen).map(([key, value]) => (
        <Text>
          {key} - {value}
        </Text>
      ))}
    </View>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
  header: {
    fontSize: 16,
    marginVertical: 10,
  },
});

export default App;

Reference

Methods

addEventListener

Deprecated: Use addEventListenerV2() instead.

static addEventListener(
  type: 'change',
  handler: ({
    window,
    screen,
  }: DimensionsValue) => void,
): EmitterSubscription;

Add an event handler. Supported events:

change: Fires when a property within the Dimensions object changes. The argument to the event handler is a DimensionsValue type object.

addEventListenerV2

addEventListenerV2(
    type: 'didUpdateDimensions',
    handler: ({
                  dimensions
              }: {
    dimensions: DisplayMetrics;
}) => void,
): EmitterSubscription;
}

Add an event handler. addEventListenerV2 is based on root tag which supports multiple instances and multiple interactive components. Supported events:

didUpdateDimensions: Fires when a property within the Dimensions object changes. The argument to the event handler is a DimensionsValue type object.

get

static get(dim: 'window' | 'screen'): ScaledSize;

Initial dimensions are set before runApplication is called so they should be available before any other require’s are run, but may be updated later. Example: const {height, width} = Dimensions.get('window'); Vega example:

const windows = Dimensions.get('windows'); // get array of DisplayMetricsKepler objects
const rootTag = useContext(RootTagContext);
let height = 0;
let width = 0;

windows.map((element) => <DisplayMetricsKepler>{
    if (element.rootTag === rootTag) {
        height = element.width;
        width = element.height;
    }
});

Parameters:

Name	Type	Description
dim Required	string	Name of dimension as defined when calling `set`. Returns the value for the dimension.

Type definitions

DimensionsValue

Properties:

Name	Type	Description
window	ScaledSize	Size of the visible Application window.
screen	ScaledSize	Size of the device’s screen.
windows - (Vega only)	DisplayMetrics	Array of DisplayMetrics objects with sizes for each app component’s screen based on rootTag.

ScaledSize

Type
object

Properties:

Name	Type
width	number
height	number
scale	number
fontScale	number

​Example Vega

​Reference

​Methods

​addEventListener

​addEventListenerV2

​get

​Type definitions

​DimensionsValue

​ScaledSize