Export assets from a Flash fla as a spritesheet and automatically repopulate the Unity atlas metadata with the correct sprite dimensions

ExportFlashLibraryAsUnitySpritesheet.jsfl

//http://help.adobe.com/en_US/flash/cs/extend/index.html

var outputScaleFactor = 1;
var libraryFolderName = "Export";
var shouldExportSubfolderNames = true;

main();

function main()
{
	fl.outputPanel.clear();
	
	var doc = fl.getDocumentDOM();

	if(!doc.pathURI) //check if this document has never been saved
	{
		alert("Export failed! We are in an untitled document!");
		return;
	}
	
	var newDoc = fl.createDocument();
	
	var folderURI = doc.pathURI.substring(0, doc.pathURI.lastIndexOf("/"));
	
	var docName = doc.pathURI.substring(doc.pathURI.lastIndexOf("/")+1,doc.pathURI.lastIndexOf("."));
	
	folderURI = folderURI+"/";
	FLfile.createFolder(folderURI); //make the export folder if it doesn't exist
	
	var ss = new SpriteSheetExporter();
	
	ss.beginExport();
	ss.layoutFormat = "JSON";
	ss.shapePadding = 4;
	ss.borderPadding = 4;
	ss.allowTrimming = false; //could try to support this later
	
	var namesToReplace = {};

	for(i in doc.library.items)
	{
		var currentItem = doc.library.items[i];
		if(currentItem.itemType == "graphic" ||
			currentItem.itemType == "bitmap" ||
			currentItem.itemType == "movie clip")
		{
			exportItemAsPng(currentItem, outputScaleFactor);
		}
	}
	
	function exportItemAsPng(item, scaleFactor)
	{
		
		if(item.name.indexOf(libraryFolderName) == -1) return; 
		
		var itemName;

		if(shouldExportSubfolderNames)
		{
			itemName = item.name.substring(item.name.indexOf("/")+1,item.name.length);
		}
		else 
		{
			itemName = item.name.substring(item.name.lastIndexOf("/")+1,item.name.length);
		}
		
		var exportPath = folderURI + "/" + itemName;

		newDoc.addItem({x:0.0, y:0.0}, item);
		newDoc.library.selectItem(item.name, false);
		newDoc.scaleSelection(scaleFactor, scaleFactor);
		
		//use the instance instead of the library item so we can give it a unique name
		var instance = newDoc.selection[0];
		
		if(item.itemType == "movie clip")
		{
			ss.addSymbol(instance, itemName);
			
			var topLayer = item.timeline.layers[0];
			
			for(var f = 0; f<item.timeline.frameCount; f++)
			{
				var zeropad = ("0000" + f).slice(-4);
				
				if(topLayer.name == "names")
				{
					var frame = topLayer.frames[f];
					if(frame && frame.startFrame == f && frame.name && frame.name != "")
					{
						namesToReplace[itemName+zeropad] = itemName+"_"+frame.name;
					}
					else 
					{
						namesToReplace[itemName+zeropad] = itemName+"_"+f;
					}
				}
				else 
				{
					if(item.timeline.frameCount == 1) //don't add frame number unless it has multiple frames
					{
						namesToReplace[itemName+zeropad] = itemName;
					}
					else 
					{
						namesToReplace[itemName+zeropad] = itemName+"_"+f;
					}
				}
			}
				
		}

		newDoc.deleteSelection();
	}

	var docPath = folderURI+"/"+docName;
	
	var ssdata = ss.exportSpriteSheet(docPath,{format:"png", bitDepth:32, backgroundColor:"#00000000"},true);
	
	fl.closeDocument(newDoc, false);
		
	//remove the json file from the disk since we already have the data we need
	FLfile.remove(docPath+".json");
	
	eval("var ssjson = " + ssdata); //parse the json using eval
	
	if(!ssjson) //there were no items found
	{
		alert("No items found! You must put the stuff you want to export in a library folder called '"+libraryFolderName+"'");
		return; 
	}
	
	for(var frameName in ssjson.frames)
	{
		if(namesToReplace[frameName])
		{
			ssjson.frames[namesToReplace[frameName]] = ssjson.frames[frameName];
			delete(ssjson.frames[frameName]);
		}
	}
	
	var atlasHeight = ssjson.meta.size.h;
	
	var umeta = FLfile.read(docPath+".png.meta");
	
	if(!umeta || umeta == "")
	{
		fl.trace("We created the atlas but could not fine the unity .png.meta file. Set the png to be a spritesheet asset in Unity.");
		return;
	}
	
	var startIndex = umeta.indexOf("sprites:")+8;
	var endIndex = umeta.indexOf("spritePackingTag:");
	
	var content = "";
	
	for(var frameName in ssjson.frames)
	{
		var frameContent = ssjson.frames[frameName];
	
		//we have to flip the frameY because unity's tex coord Y is inverted
		var frameY = (atlasHeight-frameContent.frame.y)-frameContent.frame.h;
	
		content += "\n    - name: " + frameName;
		content += "\n      rect: ";
		content += "\n        serializedVersion: 2";
		content += "\n        x: " + frameContent.frame.x;
		content += "\n        y: " + frameY; 
		content += "\n        width: "+ frameContent.frame.w;
		content += "\n        height: "+ frameContent.frame.h;
		content += "\n      alignment: 0";
		content += "\n      pivot: {x: 0.5, y: 0.5}";
		content += "\n      border: {x: 0, y: 0, z: 0, w: 0}";
	}
	
	var result = umeta.substring(0,startIndex) + content + "\n" + umeta.substring(endIndex,umeta.length);
	
	FLfile.write(docPath+".png.meta",result);
	
	fl.trace(docName + " exported successfully!");
}