/*
JET_ReplaceWithSymbolCenteredDK.js
(formerly JET_ReplaceWithSymbol.jsx)
(found on https://forums.adobe.com/message/4093796#4093796 and/or https://forums.adobe.com/thread/939631 )
A Javascript for Adobe Illustrator
Purpose: Replaces selected items with Instances of a Symbol from the Symbols Panel.
The desired Symbol can be defined by its index number (its number of occurrance in the Panel, with the first symbol being # 1).

The new Symbol Instances get placed in the first/top Layer, which MUST BE UNLOCKED (and visible?).

HEAVILY MODIFIED BY DK, JUNE 2015. MAIN CHANGES:
--centers the Symbol on the graphic it is replacing (as best as possible)
--does not resize the Symbol (uses the Symbol's "native" size)
NOTE:
According to my tests in Illustrator CC 2014 (see K:\trails\New 2015 Print Trail Maps\Illustrator\scripts\CoordinateTest.xlsx ):
--Coordinates are in Points (pt) and appear to have their origin (0,0) at the lower left corner of the artboard
--X coordinates increase as you go right (east); Y coordinates increase as you go up (north)
--The various PageItem methods to get coordinates are quirky; some include the extent of any stroke the graphic might have, and some don't.
	--Methods that DO include the stroke's extent: .left, .top, .visibleBounds
	--Methods that DO NOT include the stroke's extent: .width, .height, .position, .geometricBounds
*/
var docRef=app.activeDocument;
var symbolNum=prompt("Enter the number of the Symbol you want to replace each selected object",1); // first symbol = 1, etc.
if (symbolNum) {
	for (i=0;i<docRef.selection.length;i++) { // loop through selected graphics
		var currObj=docRef.selection[i]; // gets the next selected graphic
		var currLeft=currObj.left; // left X coordinate of PageItem, including stroke
		var currTop=currObj.top; // top Y coordinate of PageItem, including stroke
		//var currWidth=currObj.width; // width of PageItem, NOT including stroke
		//var currHeight=currObj.height; // height of PageItem, NOT including stroke
		var currVisBnd = currObj.visibleBounds; // boundary rectangle/array of PageItem, including stroke [left,top,right,bottom]
	//alert(currVisBnd[0] + " ~ " + currVisBnd[1] + " ~ " + currVisBnd[2] + " ~ " + currVisBnd[3]);
		var currWidth = currVisBnd[2] - currVisBnd[0]; // width including stroke (left minus right)
		var currHeight = currVisBnd[1] - currVisBnd[3]; // height including stroke (top minus bottom)
		var currCenterX = currLeft + (currWidth / 2); // added by DK
		var currCenterY = currTop - (currHeight / 2); // added by DK
		if (!isNaN(symbolNum)) { // make sure the user entered a number
			symbolNum = Math.floor(symbolNum);
			if (symbolNum > 0) {
				var chosenSymbol = docRef.symbols[symbolNum - 1]; // added by DK
				if (chosenSymbol) {
					var currInstance=docRef.symbolItems.add(chosenSymbol); // creates new Symbol Instance
					//currInstance.width*=currHeight/currInstance.height; // DK: we're not resizing the Symbol
					//currInstance.height=currHeight; // DK: we're not resizing the Symbol
					currInstance.left = currCenterX - (currInstance.width / 2); // added by DK - assumes Symbol .height is reliable/includes stroke
					currInstance.top = currCenterY + (currInstance.height / 2); // added by DK - assumes Symbol .height is reliable/includes stroke
					//alert("i = " + i + "; currLeft = " + currLeft + "; currTop = " + currTop + "; currWidth = " + currWidth + "; currHeight = " + currHeight + "; currCenterX = " + currCenterX + "; currCenterY = " + currCenterY + "; currInstance.left = " + currInstance.left + "; currInstance.top = " + currInstance.top);
					currInstance.selected=true; // select new Symbol Instance
					currObj.remove(); // delete old page item
				} else {alert("Symbol #" + symbolNum + " is not valid. Try a Symbol # between 1 and " + docRef.symbols.length);}
			} else {alert("Symbol #" + symbolNum + " is not valid. Try a Symbol # between 1 and " + docRef.symbols.length);}
		} else {alert(symbolNum + " is not a valid number. Try a Symbol # between 1 and " + docRef.symbols.length);}
	}
	redraw();
} else {alert("No symbol replacement occurred");}