Custom Event in actionscript 3

Posted by admin in Flash, as3 on 10 26th, 2008 | Comments

Adding custom event in as3 can make life easy. Sometime it needs to set root variable from different class or need to call root function for a specific application. Its better to use custom event than using "root" in class. Its easy to trigger and also can be listen from anywhere. Its make a class independent. Creating custom event handlers in ActionScript 3 is pretty much simple. Here i’m showing a simple myCustomEvent class which extends the flash Event class.

   1: //Declare a class for myCustomEvent   2: package wneeds.events{   3:        4:     import flash.events.Event;   5:     6:     public class myCustomEvent extends Event {   7:            8:         public var myMessage:String;   9:           10:         public function myCustomEvent(msg) {  11:               12:             super("myCustomEvent");  13:             myMessage = msg;  14:         }  15:     }  16: }

In the above class i also declare a variable named "myMessage" to show how to pass variable in a custom event class. For triggering the custom event, it just need to include the class and use the dispatchEvent method as like below…

   1: //How to asign a event   2: import wneeds.events.myCustomEvent;   3:     4: dispatchEvent(new myCustomEvent("Hello ..."));

Now time to add Listener to listen the event from anywhere….

   1: //How to add the listener for the myCustomEvent..   2:     3: this.addEventListener("myCustomEvent", showMessage);   4:     5: function showMessage(e:myCustomEvent):void {   6:     trace(e.myMessage);   7: }

In various purpose its better to pass object. Because in object its easy to pass multiple properties and easy to write in json format.

   1: dispatchEvent(new myCustomEvent({name:'tma',height: 100, msg : 'Hello...'}));

Then it can be easily possible to get all the properties from the listener….

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Oliver 10 months ago 1 point
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Hi,
great tutorial, i got it so far working as i can send the one var back to e.myMessage

But when i try you example line with multi values , i get stuck and only get erros.

can you make a example how the myCustomEvent class needs to look if i
dipatch this message.:
dispatchEvent(new myCustomEvent({Amode:'tma',SID:this.SID,MYID:this.MYID,PRID:this.PRID,TYP:this.TYP}));

where SID, MYID,PRID,TYP are all byte arrays.
Best regards Oliver

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apueee 10 months ago 1 point
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Dear Oliver,

Thanks for ur comment.

Have u changed at myCustomEvent ? in myCustomEvent class i have set the type of myMessage as string. But you are passing the message as object. So its need to change the myMessage as Object or u can set * for any type.

package wneeds.events{

import flash.events.Event;

public class myCustomEvent extends Event {

public var myMessage:*;

public function myCustomEvent(msg) {

super("myCustomEvent");
myMessage = msg;
}
}
}

Try it . i think it should work.

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Purwanto 11 months ago 1 point
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I'm still confused about custom event. I have search many many sample but it's still make me don't get it. I like the sample that you have above, but I don't know which code will act as document class. Thus, in the part ..."dispatchEvent("new MyCustomEvent("Hello....")); >> it's still the same class with the myCustomEvent class or other new class??
Oh yeah, this custom Event can do something like accessing other movieclip object that have linkage with a class, can it?

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apueee 11 months ago 1 point
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Dear Purwanto

Thanks for ur comment.

The following code need to write where you want to call the event. first u need to import the custom event class. then u need to call the dispatchEvent method to call ur custom event. This is not a part of myCustomEvent Class. Here you just using the myCustomEvent class. :)
**************
import wneeds.events.myCustomEvent; //import ur class here
dispatchEvent(new myCustomEvent("Hello ...")); // call your custom event.
*******************

To track the event in any where of ur code u need to put the following code:
**********
addEventListener("myCustomEvent", showMessage);
function showMessage(e:myCustomEvent):void {
trace(e.myMessage);
}
*********************
I'm not clear about your last question. Do you want to call a event from a movieclip and receive the event from main timeline?

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Purwanto 11 months ago 1 point
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Not from the timeline, but receive event from other class (that linkaged by a movieclip). Example, from first class after finished some tween, I want to control other movieclip that do something. To do that, I want to access other class from the first class. After access that class, I can control that Movieclip.

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