image-js/lib/util/converter.js

Image processing and manipulation in JavaScript

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.factorDimensions = factorDimensions;
exports.getFactor = getFactor;
exports.getThreshold = getThreshold;
/**
 * Converts a factor value to a number between 0 and 1
 * @private
 * @param {string|number} value
 * @return {number}
 */
function getFactor(value) {
  if (typeof value === 'string') {
    const last = value[value.length - 1];
    value = parseFloat(value);
    if (last === '%') {
      value /= 100;
    }
  }
  return value;
}

/**
 * We can specify a threshold as "0.4", "40%" or 123
 * @private
 * @param {string|number} value
 * @param {number} maxValue
 * @return {number}
 */
function getThreshold(value, maxValue) {
  if (!maxValue) {
    throw Error('getThreshold : the maxValue should be specified');
  }
  if (typeof value === 'string') {
    let last = value[value.length - 1];
    if (last !== '%') {
      throw Error('getThreshold : if the value is a string it must finish by %');
    }
    return parseFloat(value) / 100 * maxValue;
  } else if (typeof value === 'number') {
    if (value < 1) {
      return value * maxValue;
    }
    return value;
  } else {
    throw Error('getThreshold : the value is not valid');
  }
}
function factorDimensions(factor, width, height) {
  factor = getFactor(factor);
  let newWidth = Math.round(factor * width);
  let newHeight = Math.round(factor * height);
  if (newWidth <= 0) {
    newWidth = 1;
  }
  if (newHeight <= 0) {
    newHeight = 1;
  }
  return {
    width: newWidth,
    height: newHeight
  };
}