How to define percentage canvas increase in photoshop javascript

I'm a javascript novice, I have this bit of code in a jsx script that I would like to resize the canvas +20 percent on both horizontal and vertical sides.

resizeCanvas = docRef.resizeCanvas(curWidth + 20, curHeight + 20, AnchorPosition.MIDDLECENTER);

20 refers to whatever unit the ruler is set to. (inches, pixels, centimeters, etc).

What is the proper method of resizing the canvas by 20 PERCENT?

I suspect that I may have to change the units before the resizeCanvas to Units.PERCENT and then back to the default after resizing. To me, that seems to be a lot of typing, is there a better metho开发者_如何学Pythond?

I would do it like this:

resizeCanvas = docRef.resizeCanvas(curWidth * 1.2, curHeight * 1.2, AnchorPosition.MIDDLECENTER);

You may need to use Math.round or Math.floor to force the width and height to be integers if the resizeCanvas function doesn't handle that automatically.

This is what I've come up with, is it the proper method?

var strtRulerUnits = app.preferences.rulerUnits; // store default ruler units

function resizecanvas(){
   app.preferences.rulerUnits = Units.PERCENT; // change units to percent
   docRef.resizeCanvas(curWidth + 20, curHeight + 20, AnchorPosition.MIDDLECENTER, ); // add 20 % to the canvas
   app.preferences.rulerUnits = strtRulerUnits; // restore to default ruler units
   }

resizecanvas ();