joplin/packages/app-mobile/components/getResponsiveValue.ts

// getResponsiveValue() returns the corresponding value for
// a particular device screen width based on a valueMap argument
// and breakpoints.
//
// Breakpoints:
// sm: < 481px
// md: >= 481px
// lg: >= 769px
// xl: >= 1025px
// xxl: >= 1201px
//
// Eg. [ 10, 15, 20, 25, 30 ] means { sm: 10, md: 15, lg: 20, xl: 25, xxl: 30 }
// [10] and [10, 15] are equivalent to { sm: 10 } and { sm: 10, md: 15 } respectively
//
// More Info: https://discourse.joplinapp.org/t/week-4-report/26117
import { Dimensions } from 'react-native';

export interface ValueMap {
	// Value to use on small-width displays
	sm?: number;
	// Value to use on medium-width displays
	md?: number;
	// Value to use on large-width displays
	lg?: number;
	// Value to use on extra-large width displays
	xl?: number;
	// Value to use on extra-extra-large width displays
	xxl?: number;
}

export default function getResponsiveValue(valueMap: ValueMap): number {
	if (Object.keys(valueMap).length === 0) {
		throw new Error('valueMap cannot be an empty object!');
	}

	const width = Dimensions.get('window').width;
	let value: number;
	const { sm, md, lg, xl, xxl } = valueMap;

	// This handles cases where certain values are omitted
	value = sm ?? md ?? lg ?? xl ?? xxl;

	if (width >= 481) {
		value = md ?? value;
	}

	if (width >= 769) {
		value = lg ?? value;
	}

	if (width >= 1025) {
		value = xl ?? value;
	}

	if (width >= 1201) {
		value = xxl ?? value;
	}

	return value;
}