Minimize memory usage with a multi-frame MovieClip - actionscript-3

Question

I have a MovieClip in Flash with 100 frames. Each frame contains a certain icon I need to use in a project. I create instances of this icon MovieClip wherever I need an icon to appear, and gotoAndStop to a certain frame to display that icon.
Will storing a 100 icons in a single movieclip cause every single icon to be created in memory whenever I create an instance of the MovieClip? If I stored each icon in the library and attached only the icon that is needed, would that consume less memory than creating this MovieClip that has all the icons in it?

Answer 1

To answer your question: When you go to a frame with an icon on it, Flash will create a new instance of that icon. When you leave that frame, Flash will make that icon eligible for garbage collection, unless you force it to hold the instance in memory somehow, such as using addEvenListener where the method that is the listener is the icon or somewhere inside it.
I think the memory usage is likely to be higher for the goToAndStop vs. the new instance. If you are not experiencing problems with goToAndStop(), you are unlikely to experience additional issues by instantiating a new icon each time you switch from one icon to another. The other people who have answered are quite right that you will use fewer CPU cycles by instantiating all the icons only once (by whatever method), and then simply using the same one every time you use that icon. However, your overall memory footprint will be higher, because you will have all of the icons (even ones you are not currently using) in memory all the time.
If you want to go the route of only instantiating each on once, I'd suggest you go with Lazy Loading, where you only instantiate each icon when it is first used. One way to do this is to use what you already have and visit the frame the first time you want to use a specific icon, then store the BitmapData or a reference to the icon itself after that and reuse it. Another way is to build a swc and use a similar pattern.
None of this requires a static variable BTW, since it sounds like you're not using tons of different copies of your icon MC. Even if you are, it's probably better to handle referencing the icons you have through dependency injection.
I think you are probably asking about file size, however, vs. actual memory usage. The answer to that questions is that all assets that are used by your fla get compiled into the swf, regardless of whether they are in a MovieClip, a SWC, or in the library with Export for Actionscript in Frame N checked.
I get it, I've got boobs, I'm guessing
Try this, to verify my "guess."
Create a swf that has a keyframe on frame 1.
Draw a circle there.
Put another keyframe on frame 10. Draw a square.
In Publish Settings, check "Generate size report."
Now, you know (or you should know) that this swf can display the circle on frame 1, even if the assets compiled on frame 10 have not yet been downloaded. So, is there any possible way that the square could be loaded into memory before Frame 10 has been downloaded? Hint: the answer is no.
Now ask yourself this: Do you think Macromedia wrote a special version of MC that is incapable of lazy loading that the MC that is the main Document Class that Flash generated for the movie you made above so obviously handles so well?
The Macromedia engineers did a lot of things that in hindsight look pretty stupid, but they're not that incompetent.

Answer 2

If each icon that goes into the 100 frames MovieClip is an image you can easily enough export that image for actionscript and access only the image you need.
Another idea is to create a static class that stores each icon frame as a symbol in a static array(if you want to access the icon by index) or Dictionary(if you want to retrieve it by name).
e.g.
package{
import flash.display.Bitmap;
public class Icons{
public static const assets:Vector.<Bitmap> = Vector.<Bitmap>([new Icon01ASExportName(),//instance bitmaps once
new Icon02ASExportName(),//reuse them later multiple times
...
new Icon99ASExportName()]);
}
}
Yet another is to generate a SpriteSheet, either once and save it as a file, either at runtime, then copyPixels() to paste the icon from the right rectangle of the main spritesheet. You've got multiple tools available for generating the spritesheet:
Zoë
SWFSheet
Flash CS6
TexturePacker (if you have movieclips, you can export them as an image sequence to drop into the software)
There are also ways to generate a spritesheet at runtime.
For some nicely explained video tutorials on spritesheets and BitmapData by Lee Brimelow: Sprite Sheets and Blitting - Part 1,2 and 3.

Answer 3

If your icons are Bitmaps then each movieclip will share the same data - the only memory increase will be due to more movieclips, rather than their contents (which shouldnt be a problem).
If your icons are not Bitmaps (other movieclips, shapes, buttons etc), then everything gets duplicated, so memory usage will increase a lot faster as more movieclips are added.
Another consideration is that lots of movieclips on screen will have more of an effect on FPS than simpler objects so you may want to consider adding the icon itself rather than the movieclip even if you are using Bitmaps.