// Distribute Layers Horizontally - Adobe Photoshop Script
// Description: distributes selected layers horizontally
// Requirements: Adobe Photoshop CS2, or higher
// Version: 0.1.4, 9/July/2009
// Author: Trevor Morris (trevor@morris-photographics.com)
// Website: http://morris-photographics.com/
// ============================================================================
// Installation:
// 1. Place script in 'C:\Program Files\Adobe\Adobe Photoshop CS#\Presets\Scripts\'
// 2. Restart Photoshop
// 3. Choose File > Scripts > Distribute Layers Horizontally
// ============================================================================

// enable double-clicking from Mac Finder or Windows Explorer
// this command only works in Photoshop CS2 and higher
#target photoshop

// bring application forward for double-click events
app.bringToFront();

///////////////////////////////////////////////////////////////////////////////
// main - distributes selected layers horizontally
///////////////////////////////////////////////////////////////////////////////
function main() {
	// declare local variables
	var doc = activeDocument;

	// group selected layers
	groupSelectedLayers();

	// initialize local variables	
	var selectedLayers = new Array();
	var groupLayers = doc.activeLayer.layers;
	var len = groupLayers.length;

	// get layer id of grouped layers	
	for (var i = 0; i < len; i++) {
		doc.activeLayer = groupLayers[i];
		selectedLayers.push(getActiveLayerID());
	}

	// undo layer group
	executeAction(cTID('undo'), undefined, DialogModes.NO);

	// display alert for less than two layers
	len = selectedLayers.length;
	if (len <= 2) {
		alert('This command requires three or more selected layers.', 'Too Few Layers Selected', false);
		return;
	}

	// initialize local variables
	var min = Number(doc.width);
	var max = 0, width = 0, left = 0, right = 0;
	var bounds;
	var sortArray = new Array();
	var leftArray = new Array();

	// get layer bounds and store into arrays
	for (var i = 0; i < len; i++) {
		selectLayerById(selectedLayers[i]);
		bounds = doc.activeLayer.bounds;
		left = Number(bounds[0]);
		right = Number(bounds[2]);
		min = Math.min(min, left);
		max = Math.max(max, right);
		leftArray.push(left);
		sortArray.push([selectedLayers[i], left]);
		width += right - left;
	}

	// number sort left position array
	leftArray.sort(numberorder);
	function numberorder(a, b) {return a - b;}

	// re-sort selected layers array to match left position array
	selectedLayers = new Array();
	for (var i = 0; i < len; i++) {
		for (var j = 0; j < len; j++) {
			if (leftArray[i] == sortArray[j][1]) {
				selectedLayers.push(sortArray[j][0]);
			}
		}
	}

	// distributes selected layers horizontally
	for (var i = 0; i < (len - 1); i++) {
		// determine spacing between layers
		if (!gap) {
			var gap = (max - min - width) / (len - 1);
			selectLayerById(selectedLayers[i]);
			i++;
		}
		bounds = doc.activeLayer.bounds;
		right = Number(bounds[2]) + gap;

		// select and reposition layer
		selectLayerById(selectedLayers[i]);
		layer = doc.activeLayer;
		bounds = layer.bounds;
		left = Number(bounds[0]);
		layer.translate(right - left, 0);
	}

	// reselect layers
	for (var i = 0; i < len; i++) {
		selectLayerById(selectedLayers[i], true);
	}
}

///////////////////////////////////////////////////////////////////////////////
// isCorrectVersion - check for Adobe Photoshop CS2 (v9) or higher
///////////////////////////////////////////////////////////////////////////////
function isCorrectVersion() {
	if (parseInt(version, 10) >= 9) {
		return true;
	}
	else {
		alert('This script requires Adobe Photoshop CS2 or higher.', 'Wrong Version', false);
		return false;
	}
}

///////////////////////////////////////////////////////////////////////////////
// isOpenDocs - ensure at least one document is open
///////////////////////////////////////////////////////////////////////////////
function isOpenDocs() {
	if (documents.length) {
		return true;
	}
	else {
		alert('There are no documents open.', 'No Documents Open', false);
		return false;
	}
}

///////////////////////////////////////////////////////////////////////////////
// showError - display error message if something goes wrong
///////////////////////////////////////////////////////////////////////////////
function showError(err) {
	if (confirm('An unknown error has occurred.\n' +
		'Would you like to see more information?', true, 'Unknown Error')) {
			alert(err + ': on line ' + err.line, 'Script Error', true);
	}
}

///////////////////////////////////////////////////////////////////////////////
// groupSelectedLayers - from Paul MR
// http://www.ps-scripts.com/bb/viewtopic.php?t=2339
///////////////////////////////////////////////////////////////////////////////
function groupSelectedLayers() {
	var ref = new ActionReference();
	ref.putClass(sTID('layerSection'));
	var desc = new ActionDescriptor();
	desc.putReference(cTID('null'), ref);
	var ref2 = new ActionReference();
	ref2.putEnumerated(cTID('Lyr '), cTID('Ordn'), cTID('Trgt'));
	desc.putReference(cTID('From'), ref2);
	executeAction(cTID('Mk  '), desc, DialogModes.NO);
}

///////////////////////////////////////////////////////////////////////////////
// xtools functions
// Copyright: (c)2009, xbytor
// License: http://creativecommons.org/licenses/LGPL/2.1
// Contact: xbytor@gmail.com
///////////////////////////////////////////////////////////////////////////////
function getActiveLayerID() {
	var d = getActiveLayerDescriptor();
	return d.getInteger(cTID('LyrI'));
}

function getActiveLayerDescriptor() {
	var ref = new ActionReference();
	ref.putEnumerated(cTID('Lyr '), cTID('Ordn'), cTID('Trgt'));
	return executeActionGet(ref);
}

// function modified by Trevor Morris
function selectLayerById(id, add) {
	var ref = new ActionReference();
	ref.putIdentifier(cTID('Lyr '), id);
	var desc = new ActionDescriptor();
	desc.putReference(cTID('null'), ref);
	if (add) {
		desc.putEnumerated(sTID('selectionModifier'), sTID('selectionModifierType'), sTID('addToSelection'));
	}
	//desc.putBoolean(cTID('MkVs'), false);
	executeAction(cTID('slct'), desc, DialogModes.NO);
}

function cTID(s) {return app.charIDToTypeID(s);}
function sTID(s) {return app.stringIDToTypeID(s);}


///////////////////////////////////////////////////////////////////////////////
// test initial conditions prior to running main function
///////////////////////////////////////////////////////////////////////////////
if (isCorrectVersion() && isOpenDocs()) {
	// remember unit settings; switch to pixels
	displayDialogs = DialogModes.NO;
	var originalRulerUnits = preferences.rulerUnits;
	preferences.rulerUnits = Units.PIXELS;

	try {
		// suspend history for CS3 (v10) or higher
		if (parseInt(version, 10) >= 10) {
			activeDocument.suspendHistory('Distribute Horizontally', 'main()');
		}
		// just run main for CS2 (v9)
		else {
			main();
		}
	}
	catch(e) {
		// don't report error on user cancel
		if (e.number != 8007) {
			showError(e);
		}
	}

	// restore original ruler units
	displayDialogs = DialogModes.NO;
	preferences.rulerUnits = originalRulerUnits;
}