Photoshop javascript to overlay a progressive counter on a group of pictures

photoshop-counter.js

/* 
 * Counter Overlay Generatore
 * 
 * Call the script once to prepare the template,
 * adjust font, color and size, and write in
 * the text layer a starting number,
 * then call the script again to start the process.
 * For transparent PNG select Cancel in the file select dialog.
 * 
 */

if (documents.length && activeDocument.name = "__CNTGEN__"){
	counter(activeDocument);
}
else {
	createDoc(prompt("Image size (ex. 1920x1080)","1920x1080").split('x'))
}

/* 
 * Creates a new document of the given size
 * with a text layer and a black background
 * only used to make the text visible
 */
function createDoc(size, fontSize, fontFamily, fontColor){
	var doc = documents.add(
		new UnitValue(size[0], "px"), new UnitValue(size[1], "px"), 72,
		"__CNTGEN__",
		NewDocumentMode.RGB, DocumentFill.TRANSPARENT
	);
	
	doc.selection.selectAll();
	var black;
	(black = new SolidColor()).rgb.hexValue = "000000";
	doc.selection.fill(black);
	doc.selection.deselect();

	doc.activeLayer.name = "__BG__";

	doc.artLayers.add()
	doc.activeLayer.kind = LayerKind.TEXT;
	doc.activeLayer.name = "__CNT__";
	var txt = doc.activeLayer.textItem

	txt.size = fontSize || "100pt";
	txt.font = fontFamily || "ArialMT";
	txt.color.rgb.hexValue = fontColor || "ffffff";
	txt.position = [doc.width * .85, doc.height * .95];
	txt.justification = Justification.RIGHT;

	txt.contents = 0;
	return doc;
}

/* 
 * Loops over selected pictures increasing
 * counter from the current value of text layer
 * and overlayng it over each picture
 * If no pictures are selected the script will
 * ask for qty and generate transparent PNGs
 */
function counter(doc){
	var dest = Folder.selectDialog("Destination folder");
	if (!dest) return;
	var pics = File.openDialog("Select images, cancel for transparent PNG", true, true);
	
	var qty = pics ? pics.length : Number(prompt("How many?", "10"));
	var padding = qty.toString().length;
	
	var txt = doc.artLayers.getByName("__CNT__").textItem;
	var i0 = Number(txt.contents) || 0;
	
	doc.artLayers.getByName("__BG__").visible = false;
	
	for(var i = 0; i < qty; txt.contents = i0 + ++i){
		if (pics)
			var pic = overlayPic(txt.parent, pics[i]);
		saveCur(doc, dest.fullName, zeroPad(i0 + i, padding));
		if (pics)
			pic.remove();
	}
	
	activeDocument.artLayers.getByName("__BG__").visible = true;
	alert("Done!");
}

function overlayPic(layer, picture){
	var  pic = open(picture)
	var newl = pic.activeLayer.duplicate(layer, ElementPlacement.PLACEAFTER);
	pic.close();
	return newl;
}

function saveCur(document, path, name){
	document.saveAs(new File(path + "\\" + name + ".png"), new PNGSaveOptions(), true);
}

function zeroPad(n, length){
	n += "";
	while (n.length < length)
		n = "0" + n;
	return n;
}