ActionScript 3 Tip of the Day

**senocular** · June 19th, 2006, 08:02 PM

ActionScript 3 is the next step forward in Flash scripting and to help with the transition (for those of you deciding to make it), I thought I'd make a new Tip of the Day thread for ActionScript 3.0 to help people prepare (after 100 tips, they will no longer be provided daily).

Note: Many of these tips were created prior to the release of Flash and pertain to AS-only projects. Others were for use with the Alpha version of Flash (released prior to the full release of Flash). Most of these are noted as being for "Flash 9". Though much has changed in Flash CS3, most of those tips should still apply to it as well.

To code AS3, you'll need one of the following:

Flash Professional CS3
Free Flex SDK (with AS3 compiler)
Flex Builder 2
http://try.flex.org/ (online Flex MXML - with AS3 - compiler)

ActionScript 3 Tips and Tricks:

Latest Additions
(All categories are ordered from oldest (top) to newest (bottom))

General

Language Elements/Behavior and Syntax

New Classes

Regular Expressions

Proxy Class

XML

Events

Errors and Error Handling

Display Objects (MovieClips)

Flash Authoring

Additional Resources:

Samples:

**senocular** · June 19th, 2006, 08:03 PM

Using ActionScript 3, you can dynamically change the frame rate of your movie using the Stage class.

The Stage class (flash.display.Stage) is the class assigned to the stage object which is accessible from your main movie sprite/movie clip (or others within the same security sandbox) using the stage property. The stage object has a frameRate property which can contain any value between 0.01 and 1000 and determines the frame rate at which the Flash player plays back your movie. Changing this value lets you change the frame rate at runtime.

Code:

// change frame rate to 12 fps:
stage.frameRate = 12;

**mathew.er** · June 19th, 2006, 09:08 PM

Nice to have an AS 3 thread. Maybe whole Flex/AS3 forum would be usefull as it seem to spred a lot.

To the stage thing... is "stage" and not "Stage" a typo or do you need to import and instance the Stage to change the framerate? Shouldnt flash.display.Stage.frameRate = 12 do the job then?

**REEF·** · June 19th, 2006, 09:18 PM

Changing FPS with AS? Isnt this a dream come true?

**TheCanadian** · June 19th, 2006, 09:26 PM

Originally Posted by mathew.er

Nice to have an AS 3 thread. Maybe whole Flex/AS3 forum would be usefull as it seem to spred a lot.

To the stage thing... is "stage" and not "Stage" a typo or do you need to import and instance the Stage to change the framerate? Shouldnt flash.display.Stage.frameRate = 12 do the job then?

No, in AS3 it has changed - the Stage class is accessed through the stage property of a DisplayObject instance. However, they all reference the same thing I think.

**ieatcotten** · June 20th, 2006, 01:33 AM

However, they all reference the same thing I think.

Thats how I understand it.

Inheritance:Stage->DisplayObjectContainer-> InteractiveObject->DisplayObject ->EventDispatcher->Object

The Stage class represents the main drawing area. The Stage represents the entire area where Flash content is shown.

The Stage object is not globally accessible. You need to access it through the stage property of a DisplayObject instance.

http://livedocs.macromedia.com/labs/...lay/Stage.html

**mathew.er** · June 20th, 2006, 02:27 AM

So that example at livedocs makes it pretty clear... "stage" is a global object allowing you to view and change its properties or to register events with it.

Code:

package {
    import flash.display.Sprite;
    import flash.display.StageAlign;
    import flash.display.StageScaleMode;
    import flash.events.Event;

    public class StageExample extends Sprite {

        public function StageExample() {
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.align = StageAlign.TOP_LEFT;
            stage.addEventListener(Event.ACTIVATE, activateHandler);
            stage.addEventListener(Event.RESIZE, resizeHandler);
        }

        private function activateHandler(event:Event):void {
            trace("activateHandler: " + event);
        }

        private function resizeHandler(event:Event):void {
            trace("resizeHandler: " + event);
            trace("stageWidth: " + stage.stageWidth + " stageHeight: " + stage.stageHeight);
        }
    }
}

@fabiopb: Why? Isnt this just a sign, that flash goes on pretty well? If your worried anout the Adobe Flash application itself, then you dont need to be... Flex is just for something else than Flash. It wont also disappear from the Internet as everybody has the plugin, people are used to use it and it still has great potential.

**sandeep_cdac200** · June 20th, 2006, 02:34 AM

one more step towards making AS to Java!! Great!!

**senocular** · June 20th, 2006, 09:55 AM

Originally Posted by sandeep_cdac200

one more step towards making AS to Java!! Great!!

There are more steps to come that reinforce this idea

**senocular** · June 20th, 2006, 10:12 AM

ActionScript 3 is entirely class-based. When you create classes, you create variables and functions (methods) which relate to and work with that class and instances of that class. Unlike ActionScript 2, methods in ActionScript 3 now retain their class scope when called, even if assigned to another object and called from that object, or if used with Function.call and Function.apply. Example:

Code:

package {
	import flash.display.Sprite;
	
	public class ClassScope extends Sprite {
		
		public function ClassScope() {			
			traceThis(); // "Class Instance"
			
			var obj:Object = new Object();
			obj.traceThis = traceThis;
			obj.traceThis(); // "Class Instance"
			
			traceThis.call(new Sprite()); // "Class Instance"
		}

		public override function toString():String {
			return "Class Instance";
		}
		
		public function traceThis():void {
			trace(this);
		}
	}
}

**sepu** · June 20th, 2006, 12:09 PM

this topic at least should be a sticky !
thx Senocular.

**senocular** · June 20th, 2006, 12:28 PM

Originally Posted by sepu

this topic at least should be a sticky !
thx Senocular.

Since it's every day it won't have problems staying near the top

**icio** · June 20th, 2006, 12:42 PM

Nice one, sen

**REEF·** · June 20th, 2006, 01:51 PM

A few questions...Whats AS 3.0 for? Is there a new flash coming out?

And PK...why do you believe flash will decline?

**senocular** · June 20th, 2006, 01:59 PM

Originally Posted by ~REEF~

A few questions...Whats AS 3.0 for? Is there a new flash coming out?

ActionScript 3 is the next release of ActionScript that will be supported in Flash Player 9. Flex 2 applications are built using ActionScript 3 and the next version of Flash (code named BLAZE) will support it when it's released some time after Flex. Unlike ActionScript 2, ActionScript 3 uses an entirely new virtual machine providing it with new robust features and increased performance.

More details on available and upcoming products can be found on http://www.adobe.com/ and http://labs.adobe.com/ (where both the Flex 2 beta and Flash Player 9 beta are currently available for download)