react-native-scaler

React-Native-Scaler

react-native-scaler is a library that provides a set of scaling functions to help you make your React Native app responsive. It exports an initScalers function that returns four scaling functions: scaleWidth, scaleHeight, moderateScaleWidth, and moderateScaleHeight.

Installation

npm install react-native-scaler

OR

yarn add react-native-scaler

Initialization

Import the initScalers function from the react-native-scaler library and initialize it with the base width and height of your design layout.

import { initScalers } from 'react-native-scaler';

const { scaleWidth, scaleHeight, moderateScaleWidth, moderateScaleHeight } =
  initScalers(350, 680);

The numbers 350 and 680 represent the base width and height (in dp) of your design layout. You can adjust these values according to your needs.

You can also initialize without passing any arguments, in which case the default base width and height will be used.

const { scaleWidth, scaleHeight, moderateScaleWidth, moderateScaleHeight } =
  initScalers();

Additionally, you can use the shorthand notation for the scaling functions:

const { sw, sh, mw, mh } = initScalers();

Usage

After initialization, you can use the scaling functions in your components to scale dimensions according to the device's screen size.

const styles = StyleSheet.create({
  container: {
    width: sw(50), //same as scaleWidth(50)
    height: sh(100), //same as scaleHeight(50)
  },
});

You can also use the moderateScaleWidth and moderateScaleHeight functions with an optional factor. For example:

const styles = StyleSheet.create({
  container: {
    width: mw(50, 0.3),
    height: mh(100, 0.7),
  },
});

Functions

The initScalers function returns four scaling functions:

• scaleWidth (sw): Scales a value based on the device's screen width.
• scaleHeight (sh): Scales a value based on the device's screen height.
• moderateScaleWidth (mw): Provides moderate scaling based on the device's screen width. It takes two parameters: size and an optional factor.
• moderateScaleHeight (mh): Provides moderate scaling based on the device's screen height. It takes two parameters: size and an optional factor.

Each of these functions takes a number as an argument and returns a scaled number.

ScaledSheet

The ScaledSheet is a special feature of react-native-scaler that allows you to automatically apply the scale functions in your stylesheets. It takes the same styles object as a regular StyleSheet, but with an optional annotation that applies the scale functions for you.

const { ScaledSheet, scaleWidth } = initScalers();

const styles = ScaledSheet.create({
  container: {
    width: '50@sw', //same as scaleWidth(50)
    height: '100@sh', //same as scaleHeight(100)
  },
});

In the above example, 50@sw applies the scaleWidth function to the size 50, and 100@sh applies the scaleHeight function to the size 100.

You can also use @mw and @mh to apply moderateScaleWidth and moderateScaleHeight respectively, with a resize factor of 0.5. If you want to specify a different resize factor, you can do so by appending it after @mw or @mh, like 50@mw0.3.

Here is an example of using ScaledSheet with moderateScaleWidth and moderateScaleHeight with a resize factor:

const styles = ScaledSheet.create({
  container: {
    padding: '10@mw0.3', // = moderateScaleWidth(10, 0.3)
    width: '50@mw', // = moderateScaleWidth(50)
    padding: '2@mw', // moderateScaleWidth(2)
  },
});

Best Practices

It's recommended to initialize the scaler in a specific file or hook, so it can be reused across different components, instead of initializing it in every page. Here's an example of how you can do this:

// scaler.js
import { initScalers } from 'react-native-scaler';

export const { sw, sh, mw, mh, ScaledSheet } = initScalers();

Then, in your component file, you can import the scaling functions and ScaledSheet from scaler.js:

// MyComponent.js
import { sw, sh, mw, mh, ScaledSheet } from './scaler';

const styles = ScaledSheet.create({
  container: {
    width: '50@sw',
    height: '100@sh',
  },
});

This way, you can ensure that the scaling functions are consistently applied across your app.

Conclusion

The react-native-scaler library provides a simple and effective way to make your React Native app responsive. By using the scaling functions and the ScaledSheet feature it provides, you can ensure that your app looks great on devices with different screen sizes.