image-js/lib/geometry/resize.js

Image processing and manipulation in JavaScript

import { assert } from '../utils/validators/assert.js';
import { transform } from './transform.js';
/**
 * Returns a resized copy of an image.
 * @param image - Original image.
 * @param options - Resize options.
 * @returns The new image.
 */
export function resize(image, options) {
    const { interpolationType = 'bilinear', borderType = 'replicate', borderValue = 0, } = options;
    const { width, height, xFactor, yFactor } = checkOptions(image, options);
    return transform(image, [
        [xFactor, 0, xFactor / 2],
        [0, yFactor, yFactor / 2],
    ], {
        interpolationType,
        borderType,
        borderValue,
        height,
        width,
    });
}
/**
 * Verify that the resize options are valid.
 * @param image - Image.
 * @param options - Resize options.
 * @returns Resize options.
 */
function checkOptions(image, options) {
    const { width, height, xFactor, yFactor, preserveAspectRatio = true, } = options;
    if (width === undefined &&
        height === undefined &&
        xFactor === undefined &&
        yFactor === undefined) {
        throw new TypeError('at least one of the width, height, xFactor or yFactor options must be passed');
    }
    let newWidth;
    let newHeight;
    const maybeWidth = getSize(width, xFactor, image.width, preserveAspectRatio);
    const maybeHeight = getSize(height, yFactor, image.height, preserveAspectRatio);
    if (maybeWidth === undefined) {
        assert(maybeHeight !== undefined);
        newWidth = Math.round(maybeHeight * (image.width / image.height));
    }
    else {
        newWidth = maybeWidth;
    }
    if (maybeHeight === undefined) {
        assert(maybeWidth !== undefined);
        newHeight = Math.round(maybeWidth * (image.height / image.width));
    }
    else {
        newHeight = maybeHeight;
    }
    return {
        width: newWidth,
        height: newHeight,
        xFactor: xFactor ?? newWidth / image.width,
        yFactor: yFactor ?? newHeight / image.height,
    };
}
/**
 * Compute automatic new size.
 * @param sizeOpt - Size option.
 * @param factor - Factor option.
 * @param sizeImg - Size of the image.
 * @param preserveAspectRatio - Whether to preserve the aspect ratio.
 * @returns New size.
 */
function getSize(sizeOpt, factor, sizeImg, preserveAspectRatio) {
    if (sizeOpt === undefined) {
        if (factor !== undefined) {
            return Math.round(sizeImg * factor);
        }
        else if (!preserveAspectRatio) {
            return sizeImg;
        }
    }
    else if (factor !== undefined) {
        throw new TypeError('factor and size cannot be passed together');
    }
    else {
        return sizeOpt;
    }
    return undefined;
}
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