react-native-zoom-toolkit/src/commons/utils/getMaxScale.ts

Most complete set of pinch to zoom utilites for React Native

import type { SizeVector } from '../types';

export const getMaxScale = (
  canvasSize: SizeVector<number>,
  resolution: SizeVector<number>
): number => {
  'worklet';

  if (resolution.width > resolution.height) {
    return Math.max(1, resolution.width / canvasSize.width);
  }

  return Math.max(1, resolution.height / canvasSize.height);
};