Wednesday, January 28, 2009

Accessing proxied object

When receiving objects back from a server, they are usually wrapped up as a ObjectProxy. I wanted to know how I could access the protected object property on the ObjectProxy, so here's how you do it:
import mx.utils.ObjectProxy;
import mx.utils.object_proxy;

private function resultHandler(event:ResultEvent):void {
    var proxy:ObjecyProxy = ObjectProxy(event.result);
    var obj:Object = proxy.object_proxy::object;

I found the solution from this useful website:

Monday, January 19, 2009

FormItem label verticalAlign

As far as I've seen the label on FormItem's are always vertically aligned at the top. I have no idea why the Adobe guys didn't add the expected "verticalAlign" style to let the programmer choose where the label is positioned.

Anyways, I've extended the default mx.containers.FormItem control to add support for this style:
public class FormItemVerticalAlign extends FormItem 
    override protected function updateDisplayList(w:Number, h:Number):void {
        super.updateDisplayList(w, h);   
        // vertically align (top by default)
        var verticalAlign:String = getStyle("verticalAlign");
        if (verticalAlign == "middle") {   
            itemLabel.y = Math.max(0(h - itemLabel.height2);
        else if (verticalAlign == "bottom") {
            var padBottom:Number = getStyle("paddingBottom");
            itemLabel.y = Math.max(0, h - itemLabel.height - padBottom);


Wednesday, January 7, 2009

HTTPService performance of the various result formats

Today I was reading about the various result formats options available for using with HTTPService requests. These formats are:
  • object (default) - the resulting xml is returned as an ObjectProxy, or an ArrayCollection of ObjectProxy objects
  • array - the root object is returned as the first item in an Array
  • xml - returns the well formed xml (as an XMLNode object)
  • e4x - returns the response as an XML object
  • flashvars - result is formatted into name=value pairs like "name=value&on=true"
  • text - returns the response as a String object
Have you ever wondered which one is the fastest?

I ran some tests on an XML file that had 22,000 lines, and here are the results:
  • object: 610ms
  • array: 600ms
  • xml: 244ms
  • flashvars: 121ms
  • text: 51ms
  • e4x: 113ms
And here is the code I used to calculate the times:
private var startTime:int;

private function loadXMLFile(format:String):void {
    var service:HTTPService = new HTTPService();
    service.url = "huge.xml";  // located in the project src directory
    service.resultFormat = format;
    service.headers["Pragma""no-cache";  // no caching of the file
    service.addEventListener(ResultEvent.RESULT, resultHandler);
    startTime = getTimer();
    var token:AsyncToken = service.send();
    token.resultFormat = format;
private function resultHandler(event:ResultEvent):void {
    var time:int = getTimer() - startTime;
    trace(event.token.resultFormat + ": " + time + "ms");

Notes: there are static constants for the 6 result formats in HTTPService.
I haven't done any calculations on how long it would take to parse the XML vs. working with the ObjectProxy objects. And obviously if you are working with other files types besides XML then the results will be different.

Out of curiosity I also tested how long it would take to load the same file using a different method using the URLLoader and URLRequest classes. The result was usually around 80ms, but that was just to return the contents of the file. When converted into an XML object it was closer to 120ms.