Preface
This book teaches both ActionScript's fundamentals and its
advanced usage. Over the next 675 meaty pages, we'll be
exploring every detail of the ActionScript language -- from the
basics of variables and movie clip control to advanced topics such as
objects and classes, server communication, and XML. By the end,
we'll have covered everything there is to know about Flash
programming.
This book is not just for programmers. The text moves pretty quickly,
but a prior knowledge of programming is not required to read it. All
you need is experience with the non-ActionScript aspects of Flash and
an eagerness to learn. Of course, if you are already a programmer, so
much the better; you'll be applying your code-junkie skills to
ActionScript in no time.
This book fully documents the material that may be undocumented or
underdocumented by Macromedia or by other third-party books. Flash is
notorious for word-of-mouth techniques and esoteric features. How are
layers, movie clips, and loaded movies stacked in the Player? (See
Chapter 13, "Movie Clips".) What governs the execution order of
code on any given frame? (See Chapter 13, "Movie Clips".) Do event
handlers have a local scope? (See Chapter 10, "Events and Event Handlers".) Why
does the number 90 sometimes show up as 89.9999999997? (See Chapter 4, "Primitive Datatypes".) It has been my particular goal to chart
these unknown waters. Of course, I also cover the basic programming
techniques required in any language, such as how to make a segment of
code execute repeatedly. (See Chapter 8, "Loop Statements".)
This book is designed to be kept on your desk, not to wallow away its
life on your shelf. Part III, "Language Reference", exhaustively
covers every object, class, property, method, and event handler in
ActionScript. You'll use it regularly to learn new things and
remind yourself of the things you always forget.
Above all, this book is a Definitive Guide. It's the product of
years of research, thousands of emails to Macromedia employees, and
feedback from users of all levels. I hope that it is self-evident
that I've suffused the book with both my intense passion for
the subject and the painfully won real-world experience from which
you can benefit immediately. It covers ActionScript with exhaustive
authority and -- thanks to a technical review by Gary Grossman,
the creator of ActionScript -- with unparalleled accuracy.
0.1. What Can ActionScript Do?
Frankly, there's no practical limit to what a full-fledged
language like Flash 5 ActionScript can achieve. Let's take a
look at some of ActionScript's specific capabilities to offer a
taste of the topics we'll cover throughout the book. Begin
thinking about how you can combine these techniques to accomplish
your particular goals.
0.1.1. Timeline Control
Flash movies are composed of frames residing
in a linear sequence called the timeline. Using
ActionScript, we can control the playback of a movie's
timeline, play segments of a movie, display a particular frame, halt
a movie's playback, loop animations, and synchronize animated
content.
0.1.2. Interactivity
Flash
movies can accept and respond to user
input. Using ActionScript, we can create interactive elements such
as:
Buttons that react to mouseclicks (e.g., a classic navigation button) Content that animates based on mouse movements (e.g., a mouse trailer) Objects that can be moved via the mouse or keyboard (e.g., a car in a
driving game) Text fields that allow users to supply input to a movie (e.g., a
fill-in form)
0.1.3. Visual and Audio Content Control
ActionScript can be used to examine or
modify the properties of the audio and visual content in a movie. We
may, for example, change an object's color and location, reduce
a sound's volume, or set the font face of a text block. We may
also modify these properties repeatedly over time to produce unique
behaviors such as physics-based motion and collision detection.
0.1.4. Programmatic Content Generation
Using ActionScript, we can generate visual and audio content directly
from a movie's Library or by duplicating existing content on
the Stage. Programmatically generated content may serve as a strictly
static element, such as a random visual pattern, or as an interactive
element, such as an enemy spaceship in a video game or an option in a
pull-down menu.
0.1.5. Server Communication
ActionScript provides a wide
variety of tools for sending information to and receiving information
from a server. The following applications all involve server
communication:
These examples, of course, offer only a limited account of potential
ActionScript applications. The goal of this book is to give you the
fundamental skills to explore the myriad other possibilities on your
own. This is not a recipe book -- it's a lesson in cooking
code from scratch. What's on the menu is up to you.
 |  |  | | 0. Foreword |  | 0.2. The Code Depot |
Copyright © 2002 O'Reilly & Associates. All rights reserved.
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