Align_2_Grid.jsx

/*

Align_2_Grid.jsx
Version 1.0
Bruno Herfst 2011

An InDesign javascript to align Rectangles and TextFrames to the Document Grid

*/

#target InDesign;

try {
	//global vars
	var myDoc = app.activeDocument;
	//save measurements units
	myOldXUnits = myDoc.viewPreferences.horizontalMeasurementUnits,
	OldYUnits = myDoc.viewPreferences.verticalMeasurementUnits;
	
	setRulerUnits(myDoc, MeasurementUnits.points, MeasurementUnits.points);
	var G = getGridDivision(myDoc);
	if(app.selection.length != 0){
		//Get the first item in the selection.
		for(var i=0;i<app.selection.length;i++){
			var mySelection = app.selection[i];
			switch(mySelection.constructor.name){
				case "Rectangle": case "TextFrame":
					var bounds = mySelection.geometricBounds; //array [y1, x1, y2, x2], [top, left, bottom, right]
					mySelection.geometricBounds = [roundTo(bounds[0],G.h), roundTo(bounds[1],G.w), roundTo(bounds[2],G.h), roundTo(bounds[3],G.w)];
					break;
				default:
					var ws = mySelection.constructor.name;
					alert("Didn’t do "+ws+" in selection");
			}
		}
	}else{
		alert("Please select something first.");
	}
} catch(err) {
	var txt=err.description;
	alert(txt);
	exit();
}

function getGridDivision(myDoc){
	var G = new Object();
	G.w = myDoc.gridPreferences.horizontalGridlineDivision / myDoc.gridPreferences.horizontalGridSubdivision;
	G.h = myDoc.gridPreferences.verticalGridlineDivision / myDoc.gridPreferences.verticalGridSubdivision;
	return G;
}

function setRulerUnits(myDoc,XUnits,YUnits){
    //myUnits choices are:
    //MeasurementUnits.picas
    //MeasurementUnits.points
    //MeasurementUnits.inches
    //MeasurementUnits.inchesDecimal
    //MeasurementUnits.millimeters
    //MeasurementUnits.centimeters
    //MeasurementUnits.ciceros
    //MeasurementUnits.gates
    myDoc.viewPreferences.horizontalMeasurementUnits = XUnits;
    myDoc.viewPreferences.verticalMeasurementUnits = YUnits;
}

function roundTo(num,grid){
	return doRound(Math.round(num/grid)*grid,3);
}

function doRound(myNum, roundDec) {
	var roundMulit = Math.pow(10,roundDec);
	return Math.round(myNum*roundMulit)/roundMulit;
}

function exit(){
	//reset rulers
	setRulerUnits(myDoc, myOldXUnits, OldYUnits);
}