image-js/lib/image/filter/subtract.js

Image processing and manipulation in JavaScript

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = subtract;
var _channel = require("../../util/channel");
var _value = require("../../util/value");
/**
 * @memberof Image
 * @instance
 * @param {*} value
 * @param {object} [options]
 * @return {this}
 */
function subtract(value, options = {}) {
  let {
    channels
  } = options;
  this.checkProcessable('subtract', {
    bitDepth: [8, 16]
  });
  channels = (0, _channel.validateArrayOfChannels)(this, {
    channels: channels
  });
  value = (0, _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.max(0, this.data[i + c] - value >> 0);
      }
    }
  } else {
    if (this.data.length !== value.length) {
      throw new Error('subtract: 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;
}