image-js/src/operations/crop.ts

Image processing and manipulation in JavaScript

import { Image } from '../Image.js';
import type { Point } from '../utils/geometry/points.js';
import { checkPointIsInteger } from '../utils/validators/checkPointIsInteger.js';
import checkProcessable from '../utils/validators/checkProcessable.js';

export interface CropOptions {
  /**
   * Origin of the crop relative to a parent image (top-left corner).
   * @default `{row: 0, column: 0}`
   */
  origin?: Point;
  /**
   * Specify the width of the cropped image.
   * @default `image.width`
   */
  width?: number;
  /**
   * Specify the width of the cropped image.
   * @default `image.height`
   */
  height?: number;
}

/**
 * Crop the input image to a desired size.
 * @param image - Image to crop.
 * @param [options] - Crop options.
 * @returns The new cropped image.
 * @example
 * var cropped = image.crop({
 *   row:20,
 *   column:100
 * });
 */
export function crop(image: Image, options: CropOptions = {}) {
  const {
    origin = { row: 0, column: 0 },
    width = image.width - origin.column,
    height = image.height - origin.row,
  } = options;
  const { column, row } = origin;

  checkProcessable(image, {
    bitDepth: [8, 16],
  });

  checkPointIsInteger(origin, 'Origin');

  if (!Number.isInteger(width) || !Number.isInteger(height)) {
    throw new RangeError(
      `Width and height (width:${width}; height:${height}) must be integers`,
    );
  }

  if (row > image.height - 1 || column > image.width - 1) {
    throw new RangeError(
      `Origin (row:${row}, column:${column}) out of range (${
        image.width - 1
      }; ${image.height - 1})`,
    );
  }
  if (width <= 0 || height <= 0) {
    throw new RangeError(
      `Width and height (width:${width}; height:${height}) must be positive numbers`,
    );
  }
  if (row < 0 || column < 0) {
    throw new RangeError(
      `Row and column (row:${row}, column:${column}) must be positive numbers`,
    );
  }
  if (width > image.width - column || height > image.height - row) {
    throw new RangeError(
      `Size is out of range (row:${row}, column:${column}, width:${width}, height:${height})`,
    );
  }

  const newImage = Image.createFrom(image, {
    width,
    height,
  });

  for (let currentRow = 0; currentRow < height; currentRow++) {
    for (let currentColumn = 0; currentColumn < width; currentColumn++) {
      newImage.setPixel(
        currentColumn,
        currentRow,
        image.getPixel(column + currentColumn, row + currentRow),
      );
    }
  }

  return newImage;
}