Macromedia flex 2 Manual

228

Creating Effects

About creating a custom effect

Flex implements effects by using an architecture in which each effect is represented by two 
classes: a factory class and an instance class. Therefore, to implement a custom effect, you 
create two classes: the factory class and the instance class. 

You create a factory class by creating a subclass of the 

mx.effects.Effect

 class, or by creating a 

subclass of one of the subclasses of the mx.effects.Effect class. You create an instance class by 
creating a subclass of the 

mx.effects.EffectInstance

 class, or a subclass of one of the subclasses 

of the mx.effects.EffectInstance class.

The following image shows the class hierarchy for effects:

Defining factory and instance classes

To define a custom effect, you create two classes: the factory class and the instance class:

Factory class

The factory class creates an object of the instance class to perform the effect 

on the target. You create a factory class instance in your application, and configure it with the 
necessary properties to control the effect, such as the zoom size or effect duration. You then 
assign the factory class instance to an effect trigger of the target component, as the following 
example shows:

Factory classes

Instance classes