Actionscript 3 :: Advantage / Disadvantage Of Using Weak References In EventListeners?
Aug 5, 2009
I've been teaching myself actionscript 3 over the past month or so and recently ran into an issue where an object kept doing things after I thought it had been removed. I figured out that the problem was caused by an event listener using the default of useWeakReference = false and I'm wondering why that's the default. what is the advantage to not using a weak reference? and why is that the default? it seems to me that in general you'd want to use weak references, so I must be missing something.
Is there an advantage/disadvantage to designing multimedia (for example a simple animation with music) using fully as3, or is it the same as using the the editor (timeline)? will it boost performance/speed to code the tweens, clips and textfields?
The default value for weakReference in the call to addEventListener() is false. Many memory issues can be resolved by using weakReferences; in fact, some industry experts "strongly recommend always using weak references with listeners".If this is the case, can someone provide me with a good reason why weakReference defaults to true? (Note that I'm not asking why someone would ever want a listener that is not a weakReference, but rather why weakReference=false is the default)
The default value for weakReference in the call to addEventListener() is false. Many memory issues can be resolved by using weakReferences; in fact, some industry experts "strongly recommend always using weak references with listeners".If this is the case, can someone provide me with a good reason why weakReference defaults to true? (Note that I'm not asking why someone would ever want a listener that is not a weakReference, but rather why weakReference=false is the default)
As I currently understand, if an event listener is added to an object with useWeakReference set to true, then it is eligible for garbage collection and will be removed if and when the garbage collection does a sweep.
public function myCustomSpriteClass() //constructor { this.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownListener, false, 0, true); this.addEventListener(MouseEvent.MOUSE_UP, mouseUpListener, false, 0, true); }
In this case, is it not appropriate to initialize an object with weak references event listeners, incase the garbage collector does activate a sweep removing the objects event listeners since they were added during initialization of the object? In this case, would it only be appropriate to create a type of deallocate() method which removes the event listeners before the object is nullified?
I understand how weak references work, but I am bit confused regarding it's use in actionscript event listeners. Consider the example below:
public class Rectangle extends MovieClip { public function Rectangle() { var screen:Shape=new Shape();
[code]...
If the Rectangle object has no other references, then it is a candidate for garbage collection, but since there is an event listener within the object, the event dispatcher holds a reference to the object, even though there are no other references to the object(other than the one held by the event listener). Hence it is prevented from being garbage collected. Is this the reason why weak event listeners are prescribed? Is the flash player so naive that, it cannot figure out that the event listener is defined within the same object?
i heard that weak references can be used for memory optimization, but i really don't understand what it is. does anyone around here know a good tutorial, blog or something that covers this issue?
I'm compiling with the SDK 4.5.1 (latest I think) in FlashDevelop, and I have the settings of the project to export for Flash Player 11. I also have set the wmode param to "direct", and my browser flash player is version 11 also.
Is there anything else I should do in order to use the Flash player 11 hardware acceleration features. To be honest... I can not see any difference in my game between flash player 10 or flash player 11...
Is the only advantage that you can now create the XML files using a database, or a script,Or is there something else? Because reading the XML files (through AS) isn't easy at all !
I'm pretty familiar with using Adobe Flex & AS3, and compared with writing apps in JS/HTML I think it's very cool. However, since AIR is essentially a non-browser version of Flex with benefits like local storage, it seems to be competing as a cross-platform desktop application platform... and in that space it's much less mature than more established desktop technologies.
So what's the advantage of creating a desktop application using AIR compared to something like Java (or C++ using a cross-platform GUI library like wxWidgets)? Java's equally capable of communicating with the server for instance, I'm not quite sure what AIR adds when competing head-to-head in the desktop development world?
This might be a very stupid question, but I have to ask it anyway. I am graduating in about a month and while studying, I have always been taught to use properties instead of public variables. So I started wondering what the advantage was and I must say that in some cases, I have no clue at all. Of course it is handy when some other logic needs to be executed when setting properties or getting properties, but is there any advantage to using properties when you are only getting/setting a variable? An example of what I mean is shown below (As3).
As I understand it if I set the weak reference param to true in my event listeners I don't need to worry about removing the listeners. I'm not really clear what would cause the listener to be set for garbage collection. I would hate to have a situation where the listener was removed before I wanted it to.
Is there an advantage to store loaded images into a sprite?
var container:Sprite = new Sprite();addChild(container);var pictLdr:Loader = new Loader();var pictURL:String = "banana.jpg"var pictURLReq:URLRequest = new URLRequest(pictURL);pictLdr.load(pictURLReq);pictLdr.contentLoaderInfo.addEventListener(Event.COMPLETE, imgLoaded);function imgLoaded(event:Event):void{ container.addChild(pictLdr.content);}
I just started using Swiz, and, it seems like Swiz forces you to create classes with weak encapsulation. Swiz requires all event handlers to be public in order to mediate events.
Assume that component 'A' dispatches a few events, which I want to listen to in component 'B'. Traditionally, I'll just add event listeners on 'A' in 'B' and all the event handlers in 'B' can be kept private. However, if, I am using Swiz, I need to make all the handlers, mediating events, public.
So there I was, creating a small app that allowed user to upload custom images. Everything went smooth, until......<insert horror music here> So you want to validate that its an image, and not something else. Well you restrict it with the File filter...but there are ways around that. So as a double check, you check the file type after a file is selected. <drum roll>
Awesome, the type method returns null if the image doesnt have the proper headers....what the hell....So most images are compressed for smaller file size, thus the headers are stripped out. So...Type method appears to be useless....There was a simple way around this using the name method..but what the hell...type method is weak!!
Because of the inability to create Vectors dynamically, I'm forced to create one with a very primitive type, i.e. Object: var list:Vector.<Object> = new Vector.<Object>(); I'm assuming that Vector gains its power from being typed as closely as possible, rather than the above, but I may be wrong and there are in-fact still gains when using the above in place of a normal Array or Object:
My problem is basically as follows. There is an instance of a class extending EventDispatcher. Everything goes well when I add event listener to the object like this:
[Code]...
Now someFunction is not called even though the line containing dispatchEvent('eventName') is being executed just like before (and there is an external reference to myObject as well). The application I'm developing is quite complex so, unfortunately, I can't post the exact code.
I do understand the differance between ssas and as3. Not all, but all most everything I see written in SSAS can be writen into a external AS3 file. This leads me to quite a few questions I'm hoping you kind people can shed some light on for me.
1) What is the advantage of writing a SSAS file over an external AS3 file?
2) Can I write an .asc file in AS3 or do I have to use AS1? Please understand I'm using tuts from fmsguru.com and the books "Learning Flash Media Server" (pdf) and "Programming Flash Communication Server". I'm not a javascript programmer so nothing I do in AS1 seems to make any sence while everything I do in AS3 does. It may not seem like it to you people that are programmers, but to those of us that aren't, AS1 and AS3 are miles apart.
3) kind of off topic, but a security question. I'm not a "hacker" and don't like the jerks that are. My question is on external AS / SSAS files and swf files. When my fla is compiled into a swf does my external AS files remain external? I assume they do, but then what is the threat of the swf being decompiled? In most projects I would do I could care less if somebody had access to my fla as long as they don't have my actionscript files.
I don't know. Maybe on questions one and two I'm getting confused becasue I'm using out dated material. Again I assume that even though fms was built off of the javascript engine it should be able to read and execute my AS3 file. Other wise what was the point of the evolution of actionscript into a fully functional programming language?
Let's say I have a global SoundChannel object, and inside a function I am repeatedly creating new instances of the Sound object to play songs one after the other. Each time I do this, I need to add a new eventListener to the SoundChannel to call the function 'onSoundComplete' that will load the next song on completion.Coming from a strict C++ programming background, I often wonder if it's necessary to do some kind of cleanup in Flash, or if it handles it automagically.Here's example code that specifically removes the eventListener from the previous Sound object everytime a new one is created, but I don't want to be doing this if it isn't necessary:
Code: // Setup sound object buffer var slc:SoundLoaderContext = new SoundLoaderContext(3000);
I have images loading from an array. A slideshow. This works fine, but they pile on top of each other. I cannot figure out how to remove them. what's the simplest way to remove them? How do I say - if pic1 is loaded, before loading pic2, remove pic1?
Code:
var aPics:Array=new Array("pic1.jpg","pic2.jpg","pic3.jpg","pic4.jpg","pic5.jpg"); var threeSeconds:Timer=new Timer(3000,aPics.length); threeSeconds.start();
Trying to add EventListeners to Bitmaps.Can I add an EventListener directly to a bitmap?If I load an image to a UILoader then addEventListener to the UILoader instance that works just fine, but if I use a Bitmap instead, nada...I could load the Bitmap into a Sprite and add the EventListener to that, but would prefer the direct method...
Is there a way to listen for the cursor in the input text field? I am making a form, and when the user clicks on the input box I want text to appear to the right side and than fade when they leave that text field.
the text field is called input_txt;
psuedo code
input_txt.addEventLister(event.MouseEvent, showText); function showText(evt:MouseEvent):void{ text_mc.visibile = true; }
I'm working on an image gallery which builds dynamically at runtime, simple enough.imageList is an array loaded with the images to display.
var imageList:Array = _root.images.split(",");var imageArray = new Array();var count = 0;for( var i = 0; i < imageList.length; i++ ){ _root.createEmptyMovieClip("myMC"+i, (i + 1)); _root["tmpMCL"+i] = new MovieClipLoader(); imageArray[i] = new Array(); ima
Inside a .fla file I have some buttons and each button will tween a different image to the stage. All the images are outside the stage in the same x and y position and I just need to tween the x coordinate.
Now I'm working with an external document class where I'm trying to hold all my functions and I'm stucked with the Tweens. I'm willing to stay away from the flash tween engine and I'm trying to work with tweenLite.
Is it possible to pass parameters through eventListeners so I can use something like this inside my docClass?
public function animeThis (e:MouseEvent, mc:MovieClip, ep:int):void { //ep stands for endPoint. TweenLite.to(mc, 2, {x:ep}); }
If this is possible, how am I supposed to write the listeners so it will pass the event to be listened for AND those parameters? And how to build the function so it will receive those parameters and the event?
I've got a few MouseEvent listeners outside of a function that contains nested functions that need to use the functions attached to the listeners.
button1.addEventListener(MouseEvent.ROLL_OVER, buttonOver); function navigation (): void { if statements;
[code]....
I keep getting an "1120:Access of undefined property buttonOver" error. I know it's because the EventListener is outside of the function "navigation" but I need it to be accessed by other functions later.
