Adobe® Flash® CS4 Professional Bible

Chapter 17. Understanding Actions and Event Handlers

IN THIS CHAPTER

• Knowing events and event handlers

• Adding interactivity with the Behaviors panel

• Understanding Flash actions

• Using the Actions panel with Script Assist

• Learning your first Flash actions

• Executing actions with event handlers

• Using getURL

Interactivity in a Flash movie can broadly be thought of as the elements that react and respond to a user's activity or input. A user has many ways to give input to a Flash movie, and Flash has even more ways to react. But how does interactivity actually work? It all starts with actions and event handlers.

Actions and Event Handlers

Even the most complex interactivity in Flash is fundamentally composed of two basic parts: the behavior (what happens), and the cause of the behavior (what makes it happen). Here's a simple example: Suppose you have a looping soundtrack in a movie and a button that, when clicked, turns the soundtrack off. The behavior is the sound turning off, and the cause of the behavior is the mouse clicking the button. Another example is stopping an animation when it reaches a certain frame on its timeline. When the last keyframe of the animation is played (the cause), an action on that keyframe stops the animation (the behavior). In Flash, the building blocks of behaviors are referred to as actions.

Note

Flash CS4 features an interactive authoring tool called the Behaviors panel. Our usage of the term behaviors in the preceding description should not be confused with this feature. ...