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About Flash Optimization

kajyr — Thu, 01 Jul 2010 13:14:30 +0000

Working with flash and actionscript I often stumble upon bad and slow code (either old code of mine or written by others – designers); In this post I’ll try to list some resources worth knowing if you want to write fast and nice code.

Best Practices

Do not use Objects, if you know which properties will be finally involved: dynamic properties are slow to read. Create custom classes instead.
Strong type everything. If you think there is a reason to avoid strong typing, at least use * as type.
Try out and test different strategies with Grant Skinner’s performance framework.

Resources

Quick as a Flash – by Grant Skinner. The bible.
Best Practices in optimizing content for Flash Player 10.1 by Thibault Imbert (The Product Manager of the Flash Player). It’s about optimizing for Flash Player 10.1 on mobile devices, worth knowing also for the desktop / browser developers.
Some ActionScript 3.0 Optimizations

Feel free to suggest more :-)

Quickreference: flipping DisplayObjects

kajyr — Wed, 19 May 2010 10:00:04 +0000

This one flips DisplayObjects on a vertical or horizontal axe.

public static function flipHorizontal(obj:DisplayObject):void {
var m:Matrix = obj.transform.matrix;
m.transformPoint(new Point(obj.width * .5, obj.height * .5));
m.tx = (m.a > 0)?obj.width + obj.x:obj.x - obj.width;
m.a = -1 * m.a;
obj.transform.matrix = m;
}

public static function flipVertical(obj:DisplayObject):void {
var m:Matrix = obj.transform.matrix;
m.transformPoint(new Point(obj.width * .5, obj.height * .5));
m.ty = (m.d > 0)?obj.y + obj.height:obj.y - obj.height;
m.d = -1 * m.d;
obj.transform.matrix = m;
}

Sealed and dynamic classes

kajyr — Thu, 10 Dec 2009 11:07:48 +0000

Back in the days of actionscript 2, you could add any property to pretty much any object, just calling it and setting a value, like this:

myMovieClip.thePropertyILikeWithAStrangeName = "some string"

Actionscript 3.0 instead, being a more serious language, defines the basic class as sealed. That means that you can’t add any property on a object. You have to extends that class, and adding public properties.

public class MyClass extends MovieClip {
public thePropertyILikeWithAStrangeName:String
public function MyClass() {
super();
}
}

That class is sealed. You can’t

var foo:MyClass = new MyClass();
foo.anotherProperty = 42;

The dynamic keyword, permits to ‘unseal’ a class, giving back the possibility to add any property on runtime.

public dynamic class MyClass extends MovieClip {
public thePropertyILikeWithAStrangeName:String
public function MyClass() {
super();
}
}

Now you can:

var foo:MyClass = new MyClass();
foo.anotherProperty = 42;

There are speed and cleaness drawbacks on using dynamic classes. The rule is that if you use it, you should be able to seriously motivate it.

Note that there are few dynamic classes in the default Actionscript framework; the most known is of course, Object .

Basic random functions

kajyr — Sat, 28 Nov 2009 13:53:26 +0000

Here are some really basic (but useful) functions that returns random stuff…

The really basic one, is built in the Flash api and it returns a Number between 0 and 1:

var n:Number = Math.random();

A number in a range

Sometime is more useful to have a random number in a different range, let’s say between 15 and 45, instead of 0 and 1.

public static function randNumber(max:Number = 1, min:Number = 0):Number {
return Math.random() * (max - min) + min;
}

Random int

and what if we don’t need decimals? Round’em!

public static function randInt(max:Number = 1, min:Number = 0):int {
return Math.round(Math.random() * (max - min) + min);
}

Random boolean

True or false? Flip a coin.

public static function bool():Boolean {
return (Math.round(Math.random()) == 0);
}

Random sign

-1 or 1; Useful when you have to random select random rotation verse, for example, -1*45 or 1*45, rotates counterclockwise or clockwise.

public static function sign():Number {
return (Math.round(Math.random()) == 0):-1:1;
}

Random color

Really useful when drawing debug shapes on screen..

public static function color():uint {
return Math.random() * 0xFFFFFF;
}

Random point

Inside an area. I like to use the flash.geom.Rectangle struct to describe an area, more than using 4 parameters (Flash api are quite inconsistent about this choice)

public static function point(area:Rectangle):Point {
return new Point(randInt(area.x, area.x + area.width), randInt(area.y, area.y + area.height));
}

Quickreference: display elements in a circle

kajyr — Thu, 30 Jul 2009 13:00:54 +0000

How to display elements in a circle? A small function to do that is:

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Parameters are:

items: the items to be displayed a a circle
center: the center of the circle
distance: the distance from the center
initialAngle: the angle of the first item. Zero means that the item wil be aligned orizontally with the center, on his right.

Here’s an example:

Graph examples

kajyr — Wed, 29 Jul 2009 16:30:45 +0000

I’ve always been fascinated by networks, and everything that can be modeled as a graph. In some spare time one I’ve tried to model a simple graph structure in actionscript 3 that can be implemented to render some nice example. I want to extend it by adding some graph algorhythm like Breadth-first search, Depth-first seach, Dijkstra and others, just to keep mind busy in the summer, since in 3 days from now i’ll be officially unemployed.

So the first example consists in a bunch of nodes connected.. uhhu! Nodes can be activated, and each time this happens to a node, there is a chance that he activates his neighbours.

If you want to see the code, there are two steps: I’ve stored the code that models the network (the Graph class and the INode interface) in a simple framework of mine that you can checkout from here; then you can download the project as a zip file from this link)

As a references, you should see Levitated examples on networks, starting by this one or by this one.

Tweening global volume in flash

kajyr — Mon, 08 Jun 2009 14:22:12 +0000

Just a quick reminder on how to shut up the master volume on a flash project. I like a smooth tween to the silence, so I’m using the TweenLite libraries.

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The trick here is to tween the volume property of a throw-away SoundTransform object, and on each step of the Tween apply that object as the SoundMixer.soundTransform Object, with an helper function. Note that I’m not going to write the function inside the TweenLite’s partameter list, as it is gross and dirty.

Tweening the volume back to 1 is so easy that I’m not writing it, to not offend anyone.

Saving preferences in Air Applications

kajyr — Wed, 15 Apr 2009 09:43:20 +0000

Every now and then, while working on a AIR application, i feel the need to save or restore some config info, like the last window position, or the last opened files.

Instead of embedding this login in every app, I thought about a PreferenceManager class that stores and restores values.

How it should behave:

It must save data on a file.
It must save data on an open and editable format, so if something goes wrong..
It should be a static class, so i can access it in every other class of my application, whitout the need to have the reference to the instantiated object.
It should be really simple to use. And should not require any setup.

So having stated this, the public interface looks like this:

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Preferences will be saved in a file in File.applicationStorageDirectory called preferences.xml, so every Application will have his own preference file.

The usage comes easy, when I want to save a preference, let’s say the last user name entered I’ll

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and next time I open the application, to retrieve the data

GeSHi Error: GeSHi could not find the language actionscript3 (using path /nfs/c03/h01/mnt/85630/domains/nightdrops.com/html/wp-content/plugins/snipplr/geshi/geshi/) (code 2)

This implies two things: when i get a preference that hasn’t been set, the method will return null and I can only save string values.

Sooner or later I’ll talk about reflection and how to serialize any kind of object.

So now go download the Preferences.as class!

Quick reference: Drawing a scaled object in Actionscript

kajyr — Mon, 23 Feb 2009 09:43:52 +0000

Just as a quick reference, since I usually forgot each time how to do it.

Assume to have a DisplayObject obj, you want to draw in a Bitmap a scaled snapshot of that object.

Just like when you are drawing thumbs.

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Flash & Math

kajyr — Thu, 19 Feb 2009 21:56:59 +0000

Since my particular relationship with math during all of my studies, one site about ActionScript programming I really do like following is FlashAndMath. There are a lot of good tutorial about non trivial problems, so fire up your (Google) Reader and start tracking this site.

I usually talk about problems and tricks i see during work hours, but I really should evolve and talk a little more about maths here. :-)

www.flashandmath.com

On a side note, if anyone has suggestions about things i may talk about, just drop a line.