voluptasquisquam/src/image/filter/multiply.js

Image processing and manipulation in JavaScript

import {validateArrayOfChannels} from '../../util/channel';
import {checkNumberArray} from '../../util/value';

/**
 * @memberof Image
 * @instance
 * @param {*} value
 * @param {object} [options]
 * @return {this}
 */
export default function multiply(value, options = {}) {
    let {channels} = options;
    this.checkProcessable('multiply', {
        bitDepth: [8, 16]
    });
    if (value <= 0) {
        throw new Error('multiply: the value must be greater than 0');
    }

    channels = validateArrayOfChannels(this, {channels: channels});
    value = checkNumberArray(value);

    if (!isNaN(value)) {
        for (let j = 0; j < channels.length; j++) {
            let c = channels[j];
            for (let i = 0; i < this.data.length; i += this.channels) {
                this.data[i + c] = Math.min(this.maxValue, (this.data[i + c] * value) >> 0);
            }
        }
    } else {
        if (this.data.length !== value.length) {
            throw new Error('multiply: the data size is different');
        }
        for (let j = 0; j < channels.length; j++) {
            let c = channels[j];
            for (let i = 0; i < this.data.length; i += this.channels) {
                this.data[i + c] = Math.max(0, Math.min(this.maxValue, (this.data[i + c] * value[i + c]) >> 0));
            }
        }
    }

    return this;
}