QueueLoader AS3 rev 7 + Garbage Collection + SoundManager
Posted: October 29, 2007 at 5:34 pmLatest Version Info:
Click here for the current rev
Click here for the usage guide
Also click here for any posts related to the latest changes:
QueueLoader Updates
First things first. I've thrown in an additional utility that may or may not turn into it's own project. Most likely it will as I hope to add gapless playback of loops, sound mixing, etc. But I'm already getting ahead of myself:) The reason I included my SoundManager utility is to illustrate how easy it is to use the new feature of accessing loaded swf library assets, as well as using it in a more advance management type setting. There's a lot to cover, but first let me go over the updates I made to this revision.
- Added a stop() method for stopping the queue. resume() is in the works.
- Added LoaderContext for accessing the classes and references in QueueLoaded external swf.
- Added an error dispatch for an undefined target/container.
- Added a dispose() method for unloading loaded items from memory for Garbage Collection. More on this later.
- More cleanup and optimization of code
The most significant changes I will go over is with the LoaderContext and dispose() method. The rest are pretty self explanatory.
dispose() + Garbage Collection
This download is a lot heavier in file size as I've included some large images to clearly indicate what's happening with the Garbage Collector. I'm not going to go into too much detail on how Garbage Collection works. Essentially it is the process the Actionscript Virtual Machine uses to free up/dump unused memory. It does this intermittently and during times of low processing load, or when the memory has reached a certain level and needs to flush. To deal with this it is important to null out your variables and use removeChild to remove instances from a Display object. AS3 will retain the object in memory if there is a reference to it anywhere in the code. This can be a pain when trying to track data flow so it's better to keep this in mind when planning your plan of attack. To learn more about Garbage Collection, check out Grant Skinner's posts here.
I've included monitoring of garbage collection in the source example. System.totalMemory is the property for getting this info. But wait! There are some important things to be aware of.
- Either there is a bug with System.totalMemory, or with the Loader.unload() method, so you will need to see changes to the GC in the browser.
- Because of the above issue I have set the publish for local access only, so just make a note
- System.totalMemory will give you what it says, total memory. So if you have other flash apps open in the browser you will see the memory used for those apps added to your QueueLoader Example. So be sure to close everything out.
When you dispose of a section that has used QueueLoader for loading of assets, you would use dispose() to remove the loaded assets and ready them for Garbage Collection. Lets assume we've set up a QueueLoader and it's already loaded it's assets, say for an image gallery. Here's the block of code we would use to set up the QueueLoaded assets and the loader for GC:
_oLoader.dispose(); // Delete the QueueLoader containers while(imageContainer.numChildren > 0){ imageContainer.removeChildAt(0); } _oLoader = null;
You can clearly see this working in the example fla, but you get the idea. On to the next exciting feature…
Accessing externally loaded classes and library assets:
First caveat to this. Sandbox security issues come into play if you are loading things across domains. For this example we are assuming you are loading within the same domain. QueueLoader will do this, but you need to add some extra code. For more on cross scripting go here.
This feature allows you to add Library assets to an external swf, export them for actionscript as classes, and access those classes in your parent swf. This is great for loaded sounds, images, interface widgets, etc. Personally I use a separate swf for each library asset type. This also helps if you want to add a Manager class to one of your external swf files. In this example I added the SoundManager class.
You would do this by adding:
//Definition vars for accessing loaded swf libary classes in this scope var addedDefinitions:LoaderContext = new LoaderContext(); addedDefinitions.applicationDomain = ApplicationDomain.currentDomain; // Scope and Instantiate variables var _oLoader:QueueLoader = new QueueLoader(false, addedDefinitions);
and then once your assets are loaded using QueueLoader you would access them using:
var Loop1Reference:Class = getDefinitionByName("Loop1") as Class; var loop1:Sound = new Loop1Reference(); soundChannel = loop1.play();
I know I'm using code snippets so if it seems unclear, open up the queueloader.fla and you can see all of this in its entirety.
SoundManager
SoundManager is a class I added that may or may not be used in conjunction with QueueLoader. It's in its infancy so this class is pretty straight forward. Basically what is happening is on the first frame of the externalsounds.swf there is code to add the library assets intro the SoundManager.
import com.hydrotik.utils.SoundManager; SoundManager.getInstance().addItem(new Glitch1()); SoundManager.getInstance().addItem(new Glitch2()); SoundManager.getInstance().addItem(new Loop1());
Now anywhere in your application you can now play these sounds. Check out the source for more info.
My thanks to those who have commented and brought issues to my attention. Helps me to enhance this class and make it more powerful for simple as well as advanced usage. I always welcome your constructive criticism and suggestions for upcoming revisions. Please keep this in mind though. QueueLoader is a utility, and most of the control and administrative functions should be handled outside of the utility in its parent class.
If you're using QueueLoader on a project or have used it, I'd love to hear about it!
Enjoy! 
Donovan
A more recent version of this code has been posted! Go HERE
The Discussion
see what everyone is saying
Hey D this is sweet stuff… you're really ripping up the AS3, nice work. I'm going to dl these and check 'em out soon, it all looks supremely useful!
- m
Thanks man! Yes let me know how you make out with it.
And I promise next on my list is a posting on GO
D
What about XML and CSS loading? How hard would that be to add?
That's a great idea Jesse, something I will definitely look into adding. However, I would say 99% of my workflow requires that I load an XML first, with the path to the CSS in the XML file., then load the CSS, then I run the QueueLoader as the items I need to load using QueueLoader are in the XML file. Because of that, I guess I never thought to include those file types:)
I can very easily add it in there, but if you wanted to store assets in an XML to be loaded with QueueLoader you would need to run a seperate QueueLoader (with the way it's set up now), which might add extra over head when you can use a simple XML loader.
I actually made a post with the source for these files here.
Thanks!
THANKS! That was a very quick reply and I'm surprised to have inspired a new post. BTW – QueueLoader rocks!
As far as loading XML and CSS first, I agree and do the same, but… I hate having to divide the steps for a total progress. That is the beauty of QueueLoader. Regardless of a site's structure, XML and CSS still feel like very good candidates for QueueLoader items.
I went ahead and tried to see how hard it might be to add XML, and it was pretty straight forward.
The only hitch I ran into was if the xml was mistyped the queue would just stop loading. That leads me into my next suggestion which would be a backup plan for failed loads.
I switch a private method to public and bypassed the issue with:
In queueloader.fla|onItemError() added:
_oLoader.loadNextItem();
Then I tried adding more images than were available. Increasing the number from 7 to 12 reported the Queue Progress as 62% when complete. I can see a scenario where if loading a gallery of images, and if one fails, I don't want the user to know.
It might be nice get an option to output % of the total loaded vs. % of successful loads.
Anyway, here is some quick code I added to include XML;
In queueloader.fla|loadImages() added:
_oLoader.addItem( prefix("") + "flashassets/xml/site.xml", new XML(), {title:"XML!!" });
In QueueLoader.as|loadNextItem() added:
case FILE_XML:
trace("External XML");
_URLLoader = new URLLoader();
_URLLoader.addEventListener(Event.COMPLETE, completeHandler);
_URLLoader.addEventListener(IOErrorEvent.IO_ERROR, ioErrorHandler);
_URLLoader.addEventListener(ProgressEvent.PROGRESS, progressHandler);
_URLLoader.load(request);
break;
In QueueLoader.as|completeHandler() added:
if ( _currType == FILE_XML )
{
currItem.targ = new XML(event.target.data);
}
else if(_currType != FILE_AUDIO)
{
}
In queueloader.fla|onItemInit() added:
if ( event.filetype == QueueLoader.FILE_XML )
{
var xml = event.targ;
trace( "xml: \n" + xml )
}
In queueloader.fla|onItemError() added:
_oLoader.loadNextItem();
This all looks good Jesse. One thing I ask is you don't make load next item public:) Reason being, there is a very easy way to bypass failed loads with setting the second argument to true;
var _oLoader:QueueLoader = new QueueLoader(true, addedDefinitions);
But feel free to use it however you want:) Might be a few days before I can add these updates
No, you're right – a private function is that way for a reason. I should have looked at the constructor.
[...] QueueLoader AS3 rev 7 + Garbage Collection + SoundManager – Donovan [...]
Nice work, with css and xml loading this would be a killer.
A few suggestions:
* Add a method to prioritize or move objects up the que, this is a good thing to have when you have a que working in the background and you suddenly need to display certain elements as soon as possible.
* Add a method to delete objects from the que.
Thanks for sharing,
Nick
A new version has been posted!