I am developing a component that can list files that users select from their filesystem. I'm using a (extended) FileReferenceList and (my own) FileReferenceDisplayList. The latter listens for events from the former.
If the FileReferenceDisplayList receives a FileReferenceListEvent.ADDED event, it should display the new item in the displaylist. However, when multiple files are added at once I want to animate them sequentially in stead of at the same time. What would be the best strategy for making sure the items are animated with small pauses between them?
I thought about putting newly added items in a queue and then polling the queue for existing items with an Event.ENTER_FRAME. But maybe you can suggest another method that doesn't need to make use of Event.ENTER_FRAME?
Edit
I guess I forgot to mention that the part that puzzles me the most how I can set some timeout if multiple files are added. Maybe I should use the queue's length to multiply the timeouts for the items? So, if a file is added, I set the animation timeout for that item to be multiplied by the current length of the queue? (Just thinking out loud here).
take a look at TimeLineLite from Greensock - http://blog.greensock.com/timelinelite/
insertMultiple() and appendMultiple()
provide some very powerful sequencing
tools, allowing you to add an Array of
tweens or timelines and optionally
align them with SEQUENCE or START
modes, and even stagger them if you
want.
You can use a Timer but why not stick with the ENTER_FRAME.
Related
I'm unclear on how memory works in Actionscript 3. I create a series of buttons and store the address to each of them in an array. Those buttons are used to play various music files, and I want the one that is playing to have a particular color (red) and the rest to be white. I call the following code when the currently selected button is to be replaced by a different button:
removeChild(songSelectButton[currSong]);
var songSelWhite:Button = new Button(null, "images/TrackButtonNo.jpg", TRACK_SELECT_WIDTH, TRACK_SELECT_HEIGHT);
songSelectButton[currSong] = songSelWhite;
That allows the array to have the right buttons. However, I am concerned about whether I am wasting memory. Does garbage collection take care of this, or do I need a better approach?
In most cases, garbage collection is pretty smart and can clean up whatever mess you make. But it can take its time getting around to it, and it can really tie up the CPU when it decides to do it's thing. So careful management of memory is valuable.
In your case, why create a new Button? You've got a Button already, and it looks like its already in the right spot and everything. Just change the image, any listeners, and any other properties that you really need to change. Then you won't have to worry about new buttons getting allocated and deallocated, and you won't even have to worry about a new layout being calculated.
There was many discussions about this problem, but I want to pay attention on the situations that IMHO seems not so clear:
Yes the general rules are:
Remove chachedAsBitmap
Stop movieClip if playing
Remove events
Delete references
etc.
But let's look:
First Example:
I have nested sprite (ex: mainSprite), it contains other sprites with dynamic textFields in it (and are chached as bitmaps), just textFileds and MovieClips with event listeners on it (with weak reference).
When I need to remove this sprite I need first to remove all it's nested content via loops or just
removeChild(mainSprite);
mainSprite=null;
is just enough?
Second Example:
I have some sprite in which I'm loading bitmap and manipulating with bitmapData, later I'm just replacing content of this sprite with another bitmap, is allocated memory for older bitmap automatically erases and is overwritten or it still exists?
Third example:
I have some "graphics template" MovieClip (in library with Export for Actionscript property set on it) which I'm adding on the stage and filling with dynamic data (and adding event listeners), let's say that it's one scene of the app, on another scene I need same MovieClip with other dynamic data, but inbetween need to clear my stage (need something like transition animation which is also library MovieClip), what's the best way: to set this MovieClip visible property to false (while transition animation is plays) and then reuse it, or just remove it with removeChild and then add when add with addChild once more?
All I wrote is more about Air Mobile, cause in most cases for the desktop these situations aren't so problematic, but in case of mobile development they are.
You can visually monitor memory usage along with fps etc using this lib: http://code.google.com/p/flash-console/
hope that helps.
P.S. gc in flash is always a weird thing :)
First example: removing mainSprite from display list is enough if there are only weak listeners on its children.
Second example: I'd advice reusing the same object with visible = false. Recreating the same object is more resource expensive plus you get another instance of the same thing being in memory before it gets gc'ed.
Before I go making major change in my ongoing game project, I just want to hear from others if anyone has found any issues with getObjectsUnderPoint() function of the DisplayObject?
Update:
Not just the performance issue but any other limitations of using it (like it doesn't detect certain type of UIelements (just as example))
I will have three layers in my application (which an Isometric game)
Background -- This is just a background which stays in the bottom, has nothing to do with game
Middle Layer -- This is the playable area, Here all my game elements will be placed on this layer
Top Layer -- This is one dummy transparent layer covers entire playable area which interrupts all the mouse events. This is where I want to use the getObjectsUnderPoint()
So, player wants to click on the element, the top layer will interrupt the mouseevent and then check if there is something placed or just a plain background and take appropriate action like, notify the underneath object.
This really doesn't require to be done this way because I could simply add moues events for all those items placed on the map directly but because I would be using getObjectsUnderPoint() anyway to check if there is anything beneath the item.
If anyone can explain how this function works then it would be little easy for me to make a decision.
There was one annoying problem though. I don't know if they fixed it or not. At least it was there in 10.1 times.
If you have a container and you scaled it container.getObjectsUnderPoint will return wrong result. All the time. So everywhere where I needed getObjectsUnderPoint I had to call it from stage to get proper result.
It's an incomplete function. It returns graphical objects under the mouse, NOT all potential mouse targets for event or interaction purposes. It actually requires complex logic to examine the array returned by getObjectsUnderPoint to determine the mouse target, because the appropriate target (the one Flash would choose if you actually clicked that point) may not be in the list.
First you'd have to examine the object array in reverse, since the items are ordered back to front. You'd have to examine each object's entire parent chain, looking for a parent with mouseChildren = false that would cause it to intercept the event and become the target. Whether or not such an object is found, this final object you arrive at must have its mouseEnabled property set to true, otherwise you must skip it and move on to the next object in the array, which would be, for example, the next sprite or shape behind the one you initially checked. While going through the list, you must notice when the parent changes, at which point you need to assume that all children of that common parent had their mouseEnabled property set to false, in which case the parent would become the next candidate. This is actually extremely complicated, because you're working backwards in a bottom-up approach with an incomplete set of objects that was generated from the top-down.
To get actual potential mouse event targets, consistent with the default dispatching logic... it is actually easier to start from the stage in a top-down manner and walk backwards through the display hierarchy in a depth-first search, checking mouseChildren to determine whether you need to step into children, and checking mouseEnabled if it's to be a target, otherwise stepping into the container's children and repeating the process from back to front again. This is much more accurate, complete, and staightforward. The only problem is you have to code it yourself.
I am using the frames in the timeline of a .swf as pages in a flash app. The user can advance to the next page by clicking a button that takes her to the next frame. Similarly, it is possible to navigate to the previous frame/page as well.
Most of the content is placed on the stage (i.e. created by dragging an instance of a library symbol to the stage) but properties of those instances, such as .visible might be changed via actionscript. Also, some objects are loaded from external flash files and displayed programmatically with addChild / addChildAt.
The problem is, if I am on Frame N+1 and there is an object displayed on the stage programmatically (i.e. with addChild, not by having it placed on the stage) and navigate to Frame N where there is an object that is placed on the stage (i.e. dragged from the library),
then the instance of that object is undefined/null and throws an error if I try to set its properties (like .visible).
The error does not occur if I am moving to the NEXT frame, only if I am moving to the PREVIOUS one. Therefore I assume that some kind of initialization is not getting called while going one frame back.
I was also thinking that the objects would just not "live" to the next timeframe, that is, their value would be lost and re-initialized because of scope, but if there is no dynamically created object on the stage, I can navigate back and forth just fine.
Is there a way to ensure that the objects created on the stage do not disappear while navigating back to the previous frame?
The first, and more useful, part of the answer is this: timeline keyframes and scripts can give conflicting information about display objects - whether they should exist, where they should be, and so on. For example, when you add an item by playing into its frame, and then delete it with script, and then play into its frame again. When this happens, there's no unambiguously correct thing for Flash to do, so it tends to be unpredictable. I believe what generally happens is that once you fiddle with a given object via script, it's considered to no longer pay attention to the timeline - but your mileage will vary.
Having said that, the reason things are different when you play backwards is the second and more arcane part of the answer. Internally Flash functions differently when seeking forward and backwards on the timeline. Flash internally treats keyframes as changes to be applied in the forward direction, so as you play forward, it applies those changes in sequence. When you move backwards, however, from frame N+X to frame N, it doesn't scan through the intervening X frames reversing those changes - it jumps back to frame 1 and fast-forwards along to frame N. Normally, it amounts to the same thing and you don't need to worry about it, but when you get into the twitchy area where scripts and the timeline have a different idea of what should be on the stage, you're liable to see things behave differently depending on which way you jump (as you are now).
The super-short version is, for things to work predictably, try to ensure that any given object gets added, updated, and removed the same way - either all via script, or all via the timeline. When that seems impossible, fiddle with your content structure - usually, the best solution is to change your object into two nested ones, so that the things you want to do with script occur one level higher or lower than the things you want to do with the timeline.
I'm not sure I got your question right, but as3 does not instantiate elements on the timeline as soon as you gotoAndSomething, but later that frame.
That is, you can't
this.gotoAndPlay(10)
this.elementOnTimelineFrame10.DoSomething()
without errors.
I remember using this chunk of code in the past to work around this problem. It uses the Stage.Invalidate() function to wait for an Event.RENDER before trying to access and children, more info (although vague as hell) is here
private function init():void
{
stage.addEventListener(Event.RENDER, stage_renderHandler);
}
private function stage_renderHandler(evt:Event):void
{
// Run your code here
updateChildren();
}
private function enterFrameHandler(evt:Event):void
{
// triggers the RENDER event
stage.invalidate();
}
This also might me very costly (performance wise). I would strongly advise against dynamically adding/removing objects to an existing timeline, is there any way in which you can place an empty Sprite above the timeline animation and use that for all your dynamic content?
Hope this helps
I'm loading some swf files at 0 on my stage. They are the pages of my site.
To change from page to page I use removeChildAt(0) and then I addChildAt("page_title", 0).
The problem is that removeChild dont delete the functions from the first swf file loaded (before unloaded).
How can I stop then?
Do I have to use other way to removeChild?
Thanx!
It sounds to me like you aren't actually removing them. First things first, removing something from the display list is only a visual/interactive change. It is still running until you remove any references to it, being event listeners or w/e, and then you must set it to null so that garbage collection will grab it on the next cycle.
If you are using Flash Player 10, spender is correct that unloadAndStop will work for you as they just recently created it to fix your very problem.
I just thought I should explain what is going on, because people should not only know about the fix, but why things happen.
One other suggestion, I wouldn't load these movies to stage, I would create a container Sprite/MovieClip to hold them, that way even if you add other things later, they are separated, clean, and easy to access through their parent (imageContainer_mc for instance).
Assuming you are loading with a Loader you can use the unloadAndStop method.
More info here:
http://www.gskinner.com/blog/archives/2008/07/additional_info.html
Alternatively, you can load the submovie into a different ApplicationDomain to insulate the loaded code from your main app. Take a look at the flash.system.ApplicationDomain class (it's a parameter to the Loader.load() method).