expo-image-manipulator/src/validators.ts

Provides functions that let you manipulation images on the local file system, eg: resize, crop.

import {
  Action,
  ActionCrop,
  ActionExtent,
  ActionFlip,
  ActionResize,
  ActionRotate,
  FlipType,
  SaveFormat,
  SaveOptions,
} from './ImageManipulator.types';

export function validateArguments(uri: string, actions: Action[], saveOptions: SaveOptions) {
  validateUri(uri);
  validateActions(actions);
  validateSaveOptions(saveOptions);
}

export function validateUri(uri: string): void {
  if (!(typeof uri === 'string')) {
    throw new TypeError('The "uri" argument must be a string');
  }
}

export function validateActions(actions: Action[]): void {
  if (!Array.isArray(actions)) {
    throw new TypeError('The "actions" argument must be an array');
  }
  for (const action of actions) {
    if (typeof action !== 'object' || action === null) {
      throw new TypeError('Action must be an object');
    }
    const supportedActionTypes = ['crop', 'extent', 'flip', 'rotate', 'resize'];
    const actionKeys = Object.keys(action);
    if (actionKeys.length !== 1) {
      throw new TypeError(
        `Single action must contain exactly one transformation: ${supportedActionTypes.join(', ')}`
      );
    }
    const actionType = actionKeys[0];
    if (!supportedActionTypes.includes(actionType)) {
      throw new TypeError(`Unsupported action type: ${actionType}`);
    }

    if (actionType === 'crop') {
      validateCropAction(action as ActionCrop);
    } else if (actionType === 'extent') {
      validateExtentAction(action as ActionExtent);
    } else if (actionType === 'flip') {
      validateFlipAction(action as ActionFlip);
    } else if (actionType === 'rotate') {
      validateRotateAction(action as ActionRotate);
    } else if (actionType === 'resize') {
      validateResizeAction(action as ActionResize);
    }
  }
}

function validateCropAction(action: ActionCrop): void {
  const isValid =
    typeof action.crop === 'object' &&
    action.crop !== null &&
    typeof action.crop.originX === 'number' &&
    typeof action.crop.originY === 'number' &&
    typeof action.crop.width === 'number' &&
    typeof action.crop.height === 'number';
  if (!isValid) {
    throw new TypeError(
      'Crop action must be an object of shape { originX: number; originY: number; width: number; height: number }'
    );
  }
}

function validateExtentAction(action: ActionExtent): void {
  const isValid =
    typeof action.extent === 'object' &&
    action.extent !== null &&
    (action.extent.backgroundColor == null || typeof action.extent.backgroundColor === 'string') &&
    (action.extent.originX == null || typeof action.extent.originX === 'number') &&
    (action.extent.originY == null || typeof action.extent.originY === 'number') &&
    typeof action.extent.width === 'number' &&
    typeof action.extent.height === 'number';
  if (!isValid) {
    throw new TypeError(
      'Extent action must be an object of shape { backgroundColor?: string; originX?: number; originY?: number; width: number; height: number }'
    );
  }
}

function validateFlipAction(action: ActionFlip): void {
  if (
    typeof action.flip !== 'string' ||
    ![FlipType.Horizontal, FlipType.Vertical].includes(action.flip)
  ) {
    throw new TypeError(`Unsupported flip type: ${action.flip}`);
  }
}

function validateRotateAction(action: ActionRotate): void {
  if (typeof action.rotate !== 'number') {
    throw new TypeError('Rotation must be a number');
  }
}

function validateResizeAction(action: ActionResize): void {
  const isValid =
    typeof action.resize === 'object' &&
    action.resize !== null &&
    (typeof action.resize.width === 'number' || typeof action.resize.width === 'undefined') &&
    (typeof action.resize.height === 'number' || typeof action.resize.height === 'undefined');
  if (!isValid) {
    throw new TypeError(
      'Resize action must be an object of shape { width?: number; height?: number }'
    );
  }
}

export function validateSaveOptions({ base64, compress, format }: SaveOptions): void {
  if (base64 !== undefined && typeof base64 !== 'boolean') {
    throw new TypeError('The "base64" argument must be a boolean');
  }
  if (compress !== undefined) {
    if (typeof compress !== 'number') {
      throw new TypeError('The "compress" argument must be a number');
    }
    if (compress < 0 || compress > 1) {
      throw new TypeError('The "compress" argument must be a number between 0 and 1');
    }
  }
  const allowedFormats = [SaveFormat.JPEG, SaveFormat.PNG, SaveFormat.WEBP];
  if (format !== undefined && !allowedFormats.includes(format)) {
    throw new TypeError(`The "format" argument must be one of: ${allowedFormats.join(', ')}`);
  }
}