voluptasquisquam/src/image/transform/crop.js

Image processing and manipulation in JavaScript

import Image from '../Image';

/**
 * Crops the image
 * @memberof Image
 * @instance
 * @param {object} [options]
 * @param {number} [options.x=0] - x coordinate to place the zero of the new image
 * @param {number} [options.y=0] - y coordinate to place the zero of the new image
 * @param {number} [options.width=this.width-x] - width of the new image
 * @param {number} [options.height=this.height-y] - height of the new image
 * @return {Image} The new cropped image
 * @example
 * var cropped = image.crop({
 *   x:0,
 *   y:0
 * });
 */
export default function crop(options = {}) {
    let {
        x = 0,
        y = 0,
        width = this.width - x,
        height = this.height - y
    } = options;

    this.checkProcessable('max', {
        bitDepth: [8, 16]
    });

    x = Math.round(x);
    y = Math.round(y);
    width = Math.round(width);
    height = Math.round(height);

    if (x > (this.width - 1) || y > (this.height - 1)) {
        throw new RangeError(`crop: origin (x:${x}, y:${y}) out of range (${this.width - 1}; ${this.height - 1})`);
    }
    if (width <= 0 || height <= 0) {
        throw new RangeError(`crop: width and height (width:${width}; height:${height}) must be positive numbers`);
    }
    if (x < 0 || y < 0) {
        throw new RangeError(`crop: x and y (x:${x}, y:${y}) must be positive numbers`);
    }
    if (width > (this.width - x) || height > (this.height - y)) {
        throw new RangeError(`crop: (x: ${x}, y:${y}, width:${width}, height:${height}) size is out of range`);
    }

    let newImage = Image.createFrom(this, {width, height, position: [x, y]});

    let xWidth = width * this.channels;
    let y1 = y + height;

    let ptr = 0; // pointer for new array

    let jLeft = x * this.channels;

    for (let i = y; i < y1; i++) {
        let j = (i * this.width * this.channels) + jLeft;
        let jL = j + xWidth;
        for (; j < jL; j++) {
            newImage.data[ptr++] = this.data[j];
        }
    }

    return newImage;
}