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

Most complete set of pinch to zoom utilites for React Native

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

type Options = {
  crop: SizeVector<number>;
  resolution: SizeVector<number>;
  angle: number;
};

export const getRatioSize = (
  aspectRatio: number,
  container: Partial<SizeVector<number>>
): SizeVector<number> => {
  'worklet';

  if (container.width !== undefined) {
    return {
      width: container.width,
      height: container.width / aspectRatio,
    };
  }

  return {
    width: container.height! * aspectRatio,
    height: container.height!,
  };
};

export const getCropRotatedSize = (options: Options): SizeVector<number> => {
  'worklet';
  const { crop, angle, resolution } = options;
  const cropAspectRatio = crop.width / crop.height;
  let base = crop;

  const flipped = angle % Math.PI === 0;
  const aspectRatio = resolution.width / resolution.height;
  const inverseAspectRatio = resolution.height / resolution.width;

  const currentAspectRatio = flipped ? aspectRatio : inverseAspectRatio;
  base = getRatioSize(currentAspectRatio, {
    width: cropAspectRatio >= 1 ? undefined : crop.width,
    height: cropAspectRatio >= 1 ? crop.height : undefined,
  });

  let sizeModifier = 1;
  if (base.height < crop.height) sizeModifier = crop.height / base.height;
  if (base.width < crop.width) sizeModifier = crop.width / base.width;
  base.width = base.width * sizeModifier;
  base.height = base.height * sizeModifier;

  const maxWidth =
    Math.abs(base.height * Math.sin(angle)) +
    Math.abs(base.width * Math.cos(angle));

  const maxHeight =
    Math.abs(base.height * Math.cos(angle)) +
    Math.abs(base.width * Math.sin(angle));

  return getRatioSize(aspectRatio, {
    width: aspectRatio >= 1 ? undefined : maxWidth,
    height: aspectRatio >= 1 ? maxHeight : undefined,
  });
};