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m1b
m1b
Community Expert
January 13, 2021
Answered

Scripting: handling units of length

  • January 13, 2021
  • 2 replies
  • 1462 views

How do you all handle using different units in your scripts?

 

Where I'm from we mostly use millimetres for measuring, but I know a lot of you use inches, and of course most of the built-in methods use points.

 

Here's some ways I've used to deal with different units:

 

(a) make a conversion function

 

// preparation:
var inches = function (n) { return n * 72 };
var mm = function (n) { return n * 72 / 25.4 };

// usage:
needsValueInPoints(inches(2));
needsValueInPoints(mm(60));

// just for testing:
function needsValueInPoints(lengthInPts) {
    alert(lengthInPts + ' points!');
}

 


(b) overload Number.prototype with the conversion methods

 

// preparation:
Number.prototype.inches = function () { return this * 72 };
Number.prototype.mm = function () { return this * 72 / 25.4 };

// usage:
needsValueInPoints((2).inches());
needsValueInPoints((60).mm());
// note: must surround literal number with parenthesis or dot notation will look like decimal point! Awkward!

// just for testing:
function needsValueInPoints(lengthInPts) {
    alert(lengthInPts + ' points!');
}

 

 

(c) make a converting wrapper function

 

// preparation:
function needsValueInInches(lengthInInches) {
    needsValueInPoints(lengthInInches * 72);
}
function needsValueInMM(lengthInMM) {
    needsValueInPoints(lengthInMM * 72 / 25.4);
}

// usage:
needsValueInInches(2);
needsValueInMM(60);

// just for testing:
function needsValueInPoints(lengthInPts) {
    alert(lengthInPts + ' points!');
}

 

 

Any better ways?

    This topic has been closed for replies.
    Correct answer CarlosCanto

    depends on what I'm doing, I usually go the lazy way

    var inch = 72;
var pt = 2*inch;

$.writeln(pt)

     

    but there's a whole chapter in the Tools Guide that deals with Units, so more properly this is what I use

    // Unit Value Usage
// Carlos Canto)

var pt1 = convertToPoints (5, 'in');
var pt2 = convertToPoints (2, 'millimeters');

$.writeln(pt1); 
$.writeln(pt2);


function convertToPoints (value, units) {
    if (units) {
        var UV = new UnitValue(Number(value), units);
    }
    else {
        var UV = new UnitValue(value);
    }

    if (UV.type=='?') {
        alert('Units were not provided, try again...'); return 0;
    }
    else {
        var pts = UV.as('pt'); //$.writeln(pts);
        return pts; 
    }
}

     

     

    2 replies

    femkeblanco
    femkeblanco
    Brainiac
    January 13, 2021

    https://extendscript.docsforadobe.dev/extendscript-tools-features/specifying-measurement-values.html 

      m1b
      m1bAuthor
      Community Expert
      January 13, 2021

      Thanks femkeblanco, that's helpful.

      CarlosCanto
      CarlosCantoCorrect answer
      Community Expert
      January 13, 2021

      depends on what I'm doing, I usually go the lazy way

      var inch = 72;
var pt = 2*inch;

$.writeln(pt)

       

      but there's a whole chapter in the Tools Guide that deals with Units, so more properly this is what I use

      // Unit Value Usage
// Carlos Canto)

var pt1 = convertToPoints (5, 'in');
var pt2 = convertToPoints (2, 'millimeters');

$.writeln(pt1); 
$.writeln(pt2);


function convertToPoints (value, units) {
    if (units) {
        var UV = new UnitValue(Number(value), units);
    }
    else {
        var UV = new UnitValue(value);
    }

    if (UV.type=='?') {
        alert('Units were not provided, try again...'); return 0;
    }
    else {
        var pts = UV.as('pt'); //$.writeln(pts);
        return pts; 
    }
}

       

       

        m1b
        m1bAuthor
        Community Expert
        January 13, 2021

        Oh yes! I remember doing the 2*inch way! I can't believe I didn't remember it here. It's not bad for quick things.

         

        I'll look into the UnitValue class. It seems like the 'correct' way to go for a proper effort, but it's going to be a bit verbose.

         

        // (d) using UnitValue object
needsValueInPoints(UnitValue ('2 inches').as('pt'));
needsValueInPoints(UnitValue ('60 mm').as('pt'));

// just for testing:
function needsValueInPoints(lengthInPts) {
    alert(lengthInPts + ' points!');
}

         

        Or I could modify the functions (I'm thinking about those Live Effect functions) to expect UnitValues, but that seems excessive. But I notice that Adobe's own objects don't accept UnitValues—I just tried item.width = UnitValue ('60 mm') and it registered as 60pt.

         

        I think it's better to just expect points, and leave it to the user to do the conversion. Personally I'd probably end up using either Carlos' quick way, or option (a).

         

        Thanks for the quick response!

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