Programming Flex 3

Creating Custom Effects

Although you can use standard effects and composite effects to solve most of an application’s effects requirements, sometimes these off-the-shelf solutions won’t achieve the intended result. For those cases, the Flex framework allows you to create your own custom effects that you can use exactly as you would use other standard effects.

Creating custom effects requires a more thorough understanding of the effect framework structure. Because working with effects is so simple, it’s not necessary to look at the inner workings of the effect framework until you want to write a custom effect.

The effect framework consists of two basic types of classes: effect factories and effect instances. When you create a new effect object using MXML or ActionScript, you are working with an effect factory class. However, when the effect is applied to a component, the actual object utilized is an effect instance (one that is created automatically behind the scenes). The effect objects that you create using MXML and/or ActionScript using classes such as Move or Resize utilize a design pattern called the Factory Method. The Factory Method pattern means that the factory class is responsible for creating the effect instances, which are what are applied to the components.

Next we’ll look at how to define factory and instance classes.

Defining an Effect Instance Class

The effect instance class is the one used as the blueprint for the actual objects that apply the effect to the components. ...