another-dimension.js

// UMD header
(function (root, factory) { 
/* c8 ignore start */
  // AMD
  if (typeof define === 'function' && define.amd) { 
    define([],factory);
  }
  // Node, CommonJS-like
  else if (typeof exports === 'object') {         
    module.exports = factory();
  }
  // Browser globals
  else {                                          
    let globalName = "Dimension";
    if (document && document.currentScript && document.currentScript.getAttribute) {
      globalName = document.currentScript.getAttribute("data-another-dimension-global") || globalName;
    }
    root[globalName] = factory();
  }
/* c8 ignore stop */
}(this, function () {
  
// start library code 
  

let config = {
  defaultUnit: "mm",
  defaultOutputUnit: null, // default unit when converted to number
  anchorUnit: "mm",        // unit to use when direct conversion is not available
  pixelDensity: 96,        // pixel per inch
  viewingDistance: 600,    // in mm
  aliases: {
    //'"': "in",   // not configured by default, as this can be confused with arcseconds
    "um": "µ",
    "µm": "µ",
    "°": "deg"
  },
  toJSON: d => ({value: d.value, unit: d.unit}),
  dimensionRegEx: /^\s*(?<value>-?[0-9]*\.?[0-9]+)\s*(?<unit>[^\s\d]+)\s*$/
};


let conversions = {
  "mm": {
    "km": 1000000,
    "m": 1000,
    "cm": 10,
    "hm": 0.01,
    "µ": 0.001,
    "in": 25.4,
    "thou": 0.0254,
    "pt": 25.4 / 72,
    "pc": 25.4 / 6,
    "px": (v,c) => v * 25.4 / c.pixelDensity,
    "deg": (v,c) => Math.tan(v / 2 / 180 * Math.PI ) * 2 * c.viewingDistance,
    "arcmin": (v,c) => conversions.mm.deg(v/60, c),
    "arcsec": (v,c) => conversions.mm.deg(v/3600, c)
  },
  "in": {
    "m": 1 / 0.0254,
    "cm": 1 / 2.54,
    "mm": 1 / 25.4,
    "hm": 1 / 2540,
    "µ": 1 / 25400,
    "thou": 0.001,
    "pt": 1 / 72,
    "pc": 1 / 6,
    "px": (v,c) => v / c.pixelDensity,
    "deg": (v,c) => conversions.mm.deg(v,c) / 25.4,
    "arcmin": (v,c) => conversions.mm.arcmin(v,c) / 25.4,
    "arcsec": (v,c) => conversions.mm.arcsec(v,c) / 25.4      
  },
  "px": {
    "m": (v,c) => v * c.pixelDensity / 0.0254,
    "cm": (v,c) => v * c.pixelDensity / 2.54,
    "mm": (v,c) => v * c.pixelDensity / 25.4,
    "hm": (v,c) => v * c.pixelDensity / 2540,
    "µ": (v,c) => v * c.pixelDensity / 25400,
    "in": (v,c) => v * c.pixelDensity,
    "thou": (v,c) => v * c.pixelDensity / 1000,
    "pt": (v,c) => v * c.pixelDensity / 72,
    "pc": (v,c) => v * c.pixelDensity / 6,
    "deg": (v,c) => conversions.mm.deg(v,c) * c.pixelDensity / 25.4,
    "arcmin": (v,c) => conversions.mm.arcmin(v,c) * c.pixelDensity / 25.4,
    "arcsec": (v,c) => conversions.mm.arcsec(v,c) * c.pixelDensity / 25.4
  },
  "deg": {
    "mm": (v,c) => Math.atan2(v, 2 * c.viewingDistance) / Math.PI * 360,
    "arcmin": 1/60,
    "arcsec": 1/3600
  },
  "arcmin": {
    "mm": (v,c) => Math.atan2(v, 2 * c.viewingDistance) / Math.PI * 360 * 60,
    "deg": 60,
    "arcsec": 1/60
  },
  "arcsec": {
    "mm": (v,c) => Math.atan2(v, 2 * c.viewingDistance) / Math.PI * 360 * 3600,
    "deg": 3600,
    "arcmin": 60
  }

};


function Dimension(spec, options) {
  
  if (spec instanceof Dimension && (!options || !options.clone)) {
    // short-circuit if spec is already a Dimension
    return spec;
  }
  
  if (!(this instanceof Dimension)) {
    // 
    return new Dimension(spec, options);
  }

  if (typeof options == "string") {
    options = {defaultUnit: options};
  }
  
  options = Object.assign({
    defaultUnit: config.defaultUnit
  }, options);

  
  if (typeof spec == "string") {
    spec = Dimension.parseDimensionString(spec);
  }
  else if (typeof spec == "object" && "value" in spec) {
    spec = {
      value: spec.value,
      unit: spec.unit || options.defaultUnit
    }
  }
  else {
    // Number or Object
    spec = {
      value: +(spec||0).valueOf(),
      unit: options.defaultUnit
    }
  }
  
  this.value = spec.value || 0;
  this.unit = Dimension.unAlias(spec.unit);
  
  this.valueOf = function() {
    if (config.defaultOutputUnit) {
      return this.toNumber(config.defaultOutputUnit);
    }
    return this.value;
  }
  
  this.toFixed = function(digits, targetUnit) {
    let val = this.toNumber(targetUnit);
    val = val.toFixed(digits);
    return val;
  }
  
  this.toNumber = function(targetUnit) {
    // no unit specified -> return value
    if (!targetUnit) return this.value;
    
    let func = Dimension.getConversionFunction(this.unit, targetUnit);
    
    if (func) return func(this.value);
    
    throw new Error("No conversion path from " + this.unit + " to " + targetUnit + " found!");
  }
  
  this.toDimension = function(targetUnit, options) {
    return Dimension({value: this.toNumber(targetUnit), unit: targetUnit}, options);
  }
  
  this.toJSON = function() {
    return config.toJSON(this);
  }

  this.toString = function(targetUnit, digits) {
    
    // if only a number is specified, use it as digits parameter
    if (typeof targetUnit == "number" && digits === undefined) {
      digits = targetUnit;
      targetUnit = undefined;
    }
    
    let val;
    
    if (digits === undefined) {
      val = this.toNumber(targetUnit);
    } 
    else {
      val = this.toFixed(digits, targetUnit);
    }
    
    return val + (targetUnit || this.unit);
  }
  
  return this;
}

Dimension.configure = function(options) {
  /*
  Attention: if you configure aliases here, the internal aliases table will be replaced.
  Use Dimension.addAlias() to add alias names to the internal table.
  */
  Object.assign(config, options);
  if (!config.aliases) {
    config.aliases = {};
  }
}

Dimension.unAlias = function(unit) {
  
  return config.aliases[unit] || unit;
  
}

Dimension.addAlias = function(unit, alias) {
  
  config.aliases[alias] = unit;
  
}

Dimension.addConversion = function(fromUnit, toUnit, factorOrFunction) {
  
  if (!conversions[toUnit]) {
    conversions[toUnit] = {};
  }
  conversions[toUnit][fromUnit] = factorOrFunction;
  
}

Dimension.getConversionFunction = function(fromUnit, toUnit, options) {

  let _config = config;
  
  if (options && options.freezeConfig) {
    _config = Object.assign({}, config);
  }
  
  fromUnit = Dimension.unAlias(fromUnit);
  toUnit = Dimension.unAlias(toUnit);
  
  if (fromUnit == toUnit) {
    // no conversion - return unity function
    return x => x;
  }

  // direct conversion
  let conversionsToUnit = conversions[toUnit];
  if (conversionsToUnit) {
    let conversion = conversionsToUnit[fromUnit];
    if (conversion) {
      if (typeof conversion == "function") {
        return value => conversion(value, _config)
      }
      return value => value * conversion;
    }
  }
  
  // reverse conversion
  // can only be done for numeric factors
  let conversionsFromUnit = conversions[fromUnit];
  if (conversionsFromUnit) {
    let conversion = conversionsFromUnit[toUnit];
    if (typeof conversion == "number") {
      return value => value / conversion;
    }
  }
  
  // indirect conversion
  // check if we do not already use the anchorUnit, to avoid infinite recursion
  if (fromUnit != config.anchorUnit && toUnit != config.anchorUnit) {
    let conversion = Dimension.getConversionFunction(fromUnit, config.anchorUnit, options);
    let conversion2 = Dimension.getConversionFunction(config.anchorUnit, toUnit, options);
    if (conversion && conversion2) {
      let func = (value => conversion2(conversion(value, _config), _config));
      func.indirect = true;
      return func;
    }
  }
  
  return null;
}

Dimension.parseDimensionString = function(str) {
  
  let match = config.dimensionRegEx.exec(str);
  if (match) {
    return {
      value: +match.groups.value,
      unit: match.groups.unit
    }
  }
  else if (config.defaultUnit) {
    let numberRegEx = /^(?<value>-?[0-9]*\.?[0-9]+)$/;
    let match = numberRegEx.exec(str);
    if (match) {
      return {
        value: parseFloat(str),
        unit: config.defaultUnit
      }
    }  
  }
  return null;
}

Dimension.getUnits = function() {
  
  let units = new Set();
  
  for (let unit1 of Object.keys(conversions)) {
    units.add(unit1);
    for (let unit2 of Object.keys(conversions[unit1])) {
      units.add(unit2);
    } 
  }
  return Array.from(units);
}

return Dimension;

// UMD end

}));