InDesign Javascript - Document Dimensions Width and Height In Pixels or Any Unit

Question

Looking up how to get document dimensions in pixels but coming up empty. Just sharing this function I created as InDesign can be a bit verbose. Compared to photoshop converting dimensions is not as straightforward since InDesign doesn't include the unit of measurement.Edit, updated function based on @rob day's solution function idDocDims(doc){
        app.scriptPreferences.measurementUnit = MeasurementUnits.PIXELS;
        var w = doc.documentPreferences.pageWidth;
        var h = doc.documentPreferences.pageHeight;
        app.scriptPreferences.measurementUnit = AutoEnum.AUTO_VALUE;
        return {w:w,h:h}
    }
    alert(idDocDims(app.activeDocument).w+" - "+idDocDims(app.activeDocument).h); Olde Solution:function idDocDims(doc,unit){var w = doc.documentPreferences.pageWidth;var h = doc.documentPreferences.pageHeight;var wU = doc.viewPreferences.horizontalMeasurementUnits;var hU = doc.viewPreferences.verticalMeasurementUnitsvar wPX = UnitValue(w,wU).as(unit);var hPX = UnitValue(h,hU).as(unit);return [wPX,hPX]}alert(idDocDims(app.activeDocument,"px"));

rob day · Accepted Answer

Hi @wckdtall , there‘s also the scriptPreferences measurementUnit, which is useful when you don’t want to get and set ruler units

app.scriptPreferences.measurementUnit = MeasurementUnits.PIXELS;
alert(app.activeDocument.documentPreferences.pageWidth + " x " +app.activeDocument.documentPreferences.pageHeight)
app.scriptPreferences.measurementUnit = AutoEnum.AUTO_VALUE;

Marc Autret · Answer

Hi @wckdtall

Be careful, your method will fail (runtime error) if one of the MeasurementUnits enum is set to:

MeasurementUnits.AGATES
MeasurementUnits.INCHES_DECIMAL
MeasurementUnits.CUSTOM

(and in CJK editions other units won't work either: AMERICAN_POINTS, BAI, HA, MILS, Q, U).

Note. — Disparities between MeasurementUnits (DOM) and UnitValue (ExtendScript tool) are more widely documented in the $$.Unit module of IdExtenso, which tries to fill the gap. See in particular:
→ https://github.com/indiscripts/IdExtenso/blob/2a2020f0d235d91d1f28cde8400d2476342be2f4/etc/%24%24.Unit.jsxlib#L213

Now an interesting question is, why should the syntax UnitValue(<number>, <MeasurementUnitsEnum>) work at all? The UnitValue constructor is known to support the following schemes:

UnitValue( valUnit ); // valUnit:string -- e.g. ("5 mm")
UnitValue( value, unit ); // value:number, unit:string -- e.g. (8, "px")

Hence, what happens invisibly when the interpreter meets a code like

var wPX = UnitValue( 10, MeasurementUnits.INCHES ).as("px");

is type coercion. Namely, MeasurementUnits.INCHES.toString() is passed as 2nd argument to the UnitValue constructor. By good fortune this yields the string "INCHES" and since the unit parameter in the constructor is case-insensitive, this happens to work.

Note 1. — Units can be specified in abbreviated, singular, or plural form, and are parsed disregarding the case ('cm' = 'CM' = 'centimeter' = 'CENTimeterS').

Note 2. — Enumerators won't coerce to a string in oldest InDesign versions, since they were then encoded as simple numbers.

But, as I hope I have shown above, this is not a safe pattern. I recommend everyone to turn to the solution proposed by Rob instead.

Best,

Marc

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