MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH User manual

Learning ActionScript 2.0 in Flash

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Acknowledgments

Project Management: Sheila McGinn

Writing: Jen deHaan; Peter deHaan, Joey Lott

Managing Editor: Rosana Francescato

Lead Editor: Lisa Stanziano

Editing: Linda Adler, Geta Carlson, Evelyn Eldridge, John Hammett, Mary Kraemer, Noreen Maher, Jessie Wood, Anne Szabla

Production Management: Patrice O’Neill, Kristin Conradi, Yuko Yagi

Media Design and Production: Adam Barnett, Aaron Begley, Paul Benkman. John Francis, Geeta Karmarkar, Masayo Noda,

Paul Rangel, Arena Reed, Mario Reynoso

Special thanks to Jody Bleyle, Mary Burger, Lisa Friendly, Stephanie Gowin, Bonnie Loo, Mary Ann Walsh, Erick Vera, the beta

testers, and the entire Flash and Flash Player engineering and QA teams.

First Edition: September 2005

Macromedia, Inc.

601 Townsend St.

San Francisco, CA 94103

3

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

System requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Updating Flash XML files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

About the documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Additional resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Chapter 1: What’s New in Flash 8 ActionScript . . . . . . . . . . . . . . 19

New in ActionScript 2.0 and Flash 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Changes to security model for locally installed SWF files. . . . . . . . . . 28

Chapter 2: Writing and Editing ActionScript 2.0 . . . . . . . . . . . . . 31

About ActionScript and events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Organizing ActionScript code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Using the Actions panel and Script window. . . . . . . . . . . . . . . . . . . . . . 35

About the Actions panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

About the Script window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

About coding in the Actions panel and Script window. . . . . . . . . . . . . 38

About Actions panel features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

About behaviors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

About ActionScript publish settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Chapter 3: About ActionScript . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

What is ActionScript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

About choosing between ActionScript 1.0 and ActionScript 2.0 . . . 69

Understanding ActionScript and Flash Player . . . . . . . . . . . . . . . . . . . .70

Chapter 4: Data and Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . 71

About data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

About data types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

About variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Organizing data in objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108

About casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

4Contents

Chapter 5: Syntax and Language Fundamentals . . . . . . . . . . . . 113

About syntax, statements, and expressions . . . . . . . . . . . . . . . . . . . . . .114

About dot syntax and target paths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118

About language punctuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

About constants and keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

About statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141

About arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

About operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

Chapter 6: Functions and Methods . . . . . . . . . . . . . . . . . . . . . . . 201

About functions and methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Understanding methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222

Chapter 7: Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

About object-oriented programming and Flash . . . . . . . . . . . . . . . . . .226

Writing custom class files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235

About working with custom classes in an application . . . . . . . . . . . . .238

Example: Writing custom classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263

Example: Using custom class files in Flash . . . . . . . . . . . . . . . . . . . . . .276

Assigning a class to symbols in Flash . . . . . . . . . . . . . . . . . . . . . . . . . . .279

Compiling and exporting classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280

Understanding classes and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .283

About top-level and built-in classes . . . . . . . . . . . . . . . . . . . . . . . . . . . .286

About working with built-in classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .296

Chapter 8: Inheritance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

About inheritance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

About writing subclasses in Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

Using polymorphism in an application . . . . . . . . . . . . . . . . . . . . . . . . . 308

Chapter 9: Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313

About interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313

Creating interfaces as data types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318

Understanding inheritance and interfaces . . . . . . . . . . . . . . . . . . . . . . 320

Example: Using interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

Example: Creating a complex interface . . . . . . . . . . . . . . . . . . . . . . . . .323

Contents 5

Chapter 10: Handling Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

Using event handler methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330

Using event listeners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

Using event listeners with components. . . . . . . . . . . . . . . . . . . . . . . . . 335

Using button and movie clip event handlers. . . . . . . . . . . . . . . . . . . . . 337

Broadcasting events from component instances . . . . . . . . . . . . . . . . 342

Creating movie clips with button states. . . . . . . . . . . . . . . . . . . . . . . . . 342

Event handler scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343

Scope of the this keyword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347

Using the Delegate class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347

Chapter 11: Working with Movie Clips. . . . . . . . . . . . . . . . . . . . . . 351

About controlling movie clips with ActionScript . . . . . . . . . . . . . . . . . 352

Calling multiple methods on a single movie clip . . . . . . . . . . . . . . . . . 354

Loading and unloading SWF files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

Changing movie clip position and appearance . . . . . . . . . . . . . . . . . . 357

Dragging movie clips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

Creating movie clips at runtime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

Adding parameters to dynamically created movie clips. . . . . . . . . . . 364

Managing movie clip depths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366

About caching and scrolling movie clips with ActionScript . . . . . . . 369

Using movie clips as masks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376

Handling movie clip events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

Assigning a class to a movie clip symbol. . . . . . . . . . . . . . . . . . . . . . . . 378

Initializing class properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379

Chapter 12: Working with Text and Strings . . . . . . . . . . . . . . . . . 381

About text fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383

About loading text and variables into text fields . . . . . . . . . . . . . . . . . 392

Using fonts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398

About font rendering and anti-alias text . . . . . . . . . . . . . . . . . . . . . . . . 406

About text layout and formatting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414

Formatting text with Cascading Style Sheet styles . . . . . . . . . . . . . . .421

Using HTML-formatted text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436

Example: Creating scrolling text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449

About strings and the String class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450

6Contents

Chapter 13: Animation, Filters, and Drawings . . . . . . . . . . . . . . 469

Scripting animation with ActionScript 2.0 . . . . . . . . . . . . . . . . . . . . . .470

About bitmap caching, scrolling, and performance . . . . . . . . . . . . . 480

About the Tween and TransitionManager classes . . . . . . . . . . . . . . . 481

Using filter effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498

Working with filters using ActionScript . . . . . . . . . . . . . . . . . . . . . . . . 505

Manipulating filter effects with code . . . . . . . . . . . . . . . . . . . . . . . . . . . 530

Creating bitmaps with the BitmapData class . . . . . . . . . . . . . . . . . . . .534

About blending modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .537

About operation order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540

Drawing with ActionScript. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540

Understanding scaling and slice guides . . . . . . . . . . . . . . . . . . . . . . . . .556

Chapter 14: Creating Interaction with ActionScript . . . . . . . . . . 561

About events and interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .562

Controlling SWF file playback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .562

Creating interactivity and visual effects . . . . . . . . . . . . . . . . . . . . . . . . .566

Creating runtime data bindings using ActionScript . . . . . . . . . . . . . . .579

Deconstructing a sample script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .588

Chapter 15: Working with Images, Sound, and Video . . . . . . . . 591

About loading and working with external media . . . . . . . . . . . . . . . . 592

Loading external SWF and image files. . . . . . . . . . . . . . . . . . . . . . . . . 593

About loading and using external MP3 files . . . . . . . . . . . . . . . . . . . . .598

Assigning linkage to assets in the library . . . . . . . . . . . . . . . . . . . . . . . 602

About using FLV video. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603

About creating progress animations for media files. . . . . . . . . . . . . . .624

Chapter 16: Working with External Data . . . . . . . . . . . . . . . . . . 633

Sending and loading variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .634

Using HTTP to connect to server-side scripts . . . . . . . . . . . . . . . . . . .638

About file uploading and downloading . . . . . . . . . . . . . . . . . . . . . . . . . 644

About XML . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .652

Sending messages to and from Flash Player . . . . . . . . . . . . . . . . . . . .663

About the External API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .667

Chapter 17: Understanding Security. . . . . . . . . . . . . . . . . . . . . . .677

About compatibility with previous Flash Player security models . . . 677

About local file security and Flash Player. . . . . . . . . . . . . . . . . . . . . . . .679

About domains, cross-domain security, and SWF files . . . . . . . . . . 694

Server-side policy files for permitting access to data . . . . . . . . . . . . .702

HTTP to HTTPS protocol access between SWF files . . . . . . . . . . . . 707

Contents 7

Chapter 18: Debugging Applications . . . . . . . . . . . . . . . . . . . . . . 711

Debugging your scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 711

Using the Output panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 724

Chapter 19: Best Practices and Coding Conventions for

ActionScript 2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731

Naming conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 732

Using comments in your code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 742

ActionScript coding conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745

ActionScript and Flash Player optimization . . . . . . . . . . . . . . . . . . . . . 762

Formatting ActionScript syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 764

Appendix A: Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . .773

Appendix B: Deprecated Flash 4 operators . . . . . . . . . . . . . . . 779

Appendix C: Keyboard Keys and Key Code Values . . . . . . . . . . 781

Appendix D: Writing Scripts for

Earlier Versions of Flash Player . . . . . . . . . . . . . . . . . . . . . . . . . . .787

About targeting earlier versions of Flash Player . . . . . . . . . . . . . . . . . 787

Using Flash 8 to create content for Flash Player 4 . . . . . . . . . . . . . . 788

Appendix E: Object-Oriented Programming with

ActionScript 1.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791

About ActionScript 1.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 792

Creating a custom object in ActionScript 1.0 . . . . . . . . . . . . . . . . . . . . 794

Assigning methods to a custom object in ActionScript 1.0. . . . . . . . 795

Defining event handler methods in ActionScript 1.0 . . . . . . . . . . . . . 796

Creating inheritance in ActionScript 1.0 . . . . . . . . . . . . . . . . . . . . . . . . 798

Adding getter/setter properties to objects in ActionScript 1.0. . . . . 800

Using Function object properties in ActionScript 1.0. . . . . . . . . . . . . .801

Appendix F: Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 803

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811

8Contents

9

Introduction

Macromedia Flash Basic 8 and Macromedia Flash Professional 8 are the professional standard

authoring tools for producing high-impact web experiences. ActionScript is the language you

use to add interactivity to Flash applications, whether your applications are simple animated

SWF files or more complex rich Internet applications. You don’t have to use ActionScript to

use Flash, but if you want to provide basic or complex user interactivity, work with objects

other than those built into Flash (such as buttons and movie clips), or otherwise turn a SWF

file into a more robust user experience, you’ll probably want to use ActionScript.

For more information, see the following topics:

Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Updating Flash XML files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

System requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

About the documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Additional resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Intended audience

This manual assumes that you have already installed Flash Basic 8 or Flash Professional 8 and

know how to use the user interface.You should know how to place objects on the Stage and

manipulate them in the Flash authoring environment. If you have used a scripting language

before, ActionScript will seem familiar. But if you’re new to programming, ActionScript basics

are easy to learn. You can start with simple commands and build more complexity as you

progress. You can add a lot of interactivity to your files without having to learn (or write) a lot

of code.

10 Introduction

System requirements

ActionScript 2.0 does not have any system requirements in addition to Flash 8.

This manual assumes that you are using the default publishing settings for your Flash files:

Flash Player 8 and ActionScript 2.0. If you change either of these settings, explanations and

code samples in the documentation might not work correctly. If you develop applications for

earlier versions of Flash Player, see Appendix D, “Writing Scripts for Earlier Versions of Flash

Player,” on page 787.

Updating Flash XML files

It is important that you always have the latest Flash XML files installed. Macromedia

sometimes introduces features in dot releases (minor releases) of Flash Player. When such a

release is available, you should update your version of Flash to get the latest XML files.

Otherwise, the Flash 8 compiler might generate errors if you use new properties or methods

that were unavailable in the version of Flash Player that came with your Flash installation.

For example, Flash Player 7 (7.0.19.0) contained a new method for the System object,

System.security.loadPolicyFile. To access this method, you must use the Player

Updater installer to update all the Flash players that are installed with Flash. Otherwise, the

Flash compiler displays errors.

Remember that you can install a Player Updater that is one or more major versions ahead of

your version of Flash. By doing this, you will get the XML files that you need but shouldn’t

have any compiler errors when you publish to older versions of Flash Player. Sometimes new

methods or properties are available to older versions, and having the latest XML files

minimizes the compiler errors you get when you try to access older methods or properties.

About the documentation

This manual provides an overview of ActionScript syntax and information on how to use

ActionScript when working with different types of objects. For details on the syntax and usage

of every language element, see the ActionScript 2.0 Language Reference.

For more information, see the following topics:

■ “Learning ActionScript 2.0 book overview” on page 11

■ “About the sample files” on page 14

■ “Terms used in this document” on page 13

■ “Copy and paste code” on page 13

About the documentation 11

Learning ActionScript 2.0 book overview

The following list summarizes the contents of this manual:

■ Chapter 1, “What’s New in Flash 8 ActionScript,” describes features that are new in

ActionScript, changes to the compiler and debugger, and the new programming model for

the ActionScript 2.0 language.

■ Chapter 2, “Writing and Editing ActionScript 2.0,” describes features of the ActionScript

editor within Flash that make it easier to write code.

■ Chapter 3, “About ActionScript,” outlines what the ActionScript language is and details

how to choose between which version of ActionScript to use.

■ Chapter 4, “Data and Data Types,” describes the terminology and basic concepts about

data, data types, and variables. You use these concepts throughout the manual.

■ Chapter 5, “Syntax and Language Fundamentals,” describes the terminology and basic

concepts of the ActionScript language. You use these concepts throughout the manual.

■ Chapter 6, “Functions and Methods,” describes how to write different kinds of functions

and methods and how to use them in your application.

■ Chapter 7, “Classes,” describes how to create custom classes and objects in ActionScript.

This chapter also lists the built-in classes in ActionScript and provides a brief overview of

how you use them to access powerful features in ActionScript.

■ Chapter 8, “Inheritance,” describes inheritance in the ActionScript language and describes

how to extend built-in or custom classes.

■ Chapter 9, “Interfaces,” describes how to create and work with interfaces in ActionScript.

■ Chapter 10, “Handling Events,” describes a few different ways to handle events: event

handler methods, event listeners, and button and movie clip event handlers.

■ Chapter 11, “Working with Movie Clips,” describes movie clips and the ActionScript you

can use to control them.

■ Chapter 12, “Working with Text and Strings,” describes the different ways you can control

text and strings in Flash and includes information on text formatting and FlashType

(advanced text rendering, such as anti-alias text).

■ Chapter 13, “Animation, Filters, and Drawings,” describes how to create code-based

animation and images, add filters to objects, and draw using ActionScript.

■ Chapter 14, “Creating Interaction with ActionScript,” describes some simple ways in

which you can create more interactive applications, including controlling when SWF files

play, creating custom pointers, and creating sound controls.

12 Introduction

■ Chapter 15, “Working with Images, Sound, and Video,” describes how to import external

media files, such as bitmap images, MP3 files, Flash Video (FLV) files, and other SWF

files, in your Flash applications. This chapter also provides an overview of how to work

with video in your applications, and how to create progress bar loading animations.

■ Chapter 16, “Working with External Data,” describes how to process data from external

sources using server- or client-side scripts in your applications. This chapter describes how

to integrate data with your applications.

■ Chapter 17, “Understanding Security,” explains security in Flash Player, as it pertains to

working with SWF files locally on your hard disk. This chapter also explains cross-domain

security issues, and how to load data from servers, or across domains.

■ Chapter 18, “Debugging Applications,” describes the ActionScript debugger within Flash

that makes it easier to write applications.

■ Chapter 19, “Best Practices and Coding Conventions for ActionScript 2.0,” explains the

best practices for using Flash and writing ActionScript. This chapter also lists standardized

coding conventions, such as naming variables, and other conventions.

■ Appendix A, “Error Messages,” lists the error messages that the Flash compiler can

generate.

■ Appendix B, “Deprecated Flash 4 operators,” lists all the deprecated Flash 4 operators and

their associativity.

■ Appendix C, “Keyboard Keys and Key Code Values,” lists all the keys on a standard

keyboard and the corresponding ASCII key code values that are used to identify the keys

in ActionScript.

■ Appendix D, “Writing Scripts for Earlier Versions of Flash Player,” provides guidelines to

help you write scripts that are syntactically correct for the player version you are targeting.

■ Appendix E, “Object-Oriented Programming with ActionScript 1.0,” provides

information on using the ActionScript 1.0 object model to write scripts.

■ Appendix F, “Terminology,” lists commonly used terminology when working with the

ActionScript language and provides descriptions for the terms.

This manual explains how to use the ActionScript language. For information on the language

elements themselves, see the ActionScript 2.0 Language Reference.

Typographical conventions

This manual uses the following typographical conventions:

■ Code font indicates ActionScript code.

About the documentation 13

■ Bold code font, typically within a procedure, indicates code that you need to modify or

add to code you have already added to your FLA file. In some case, it might be used to

highlight code to look at.

■ Boldface text indicates data you need to type into the user interface, such as a filename or

instance name.

■ Italic text indicates a new term defined in the text that follows. In a file path, it might

indicate a value that should be replaced (for example, with a directory name on your own

hard disk).

Terms used in this document

The following terms are used in this manual:

■ You refers to the developer who is writing a script or application.

■ The user refers to the person who is running your scripts and applications.

■ Compile time is the time at which you publish, export, test, or debug your document.

■ Runtime is the time at which your script is running in Flash Player.

ActionScript terms such as method and object are defined in Appendix F, “Terminology,” on

page 803.

Copy and paste code

When you paste ActionScript from the Help panel into your FLA or ActionScript file, you

have to be careful about special characters. Special characters include special quotation marks

(also called curly quotation marks or smart quotation marks). These characters are not

interpreted by the ActionScript editor, so your code throws an error if you try to compile it

in Flash.

You can determine that your quotation mark characters are special characters if they do not

color-code correctly. That is, if all your strings do not change in color in the code editor, you

need to replace the special characters with regular straight quotation mark characters. If you

type a single or double quotation mark character directly into the ActionScript editor, you

always type a straight quotation mark character. The compiler (when you test or publish a

SWF file) throws an error and lets you know if there are the wrong kind (special quotation

marks or curly quotation marks) of characters in your code.

NOTE

You might also encounter special quotation marks if you paste ActionScript from other

locations, such as a web page or a Microsoft Word document.

14 Introduction

Be cautious of proper line breaks when you copy and paste code. If you paste your code from

some locations, the line of code might break in an improper location. Make sure that the color

coding of your syntax is correct in the ActionScript editor if you think line breaks might be a

problem. You might want to compare your code in the Actions panel to that in the Help panel

to see if it matches. Try turning on Word Wrap in the ActionScript editor to help solve

surplus line breaks in your code (select View > Word Wrap in the Script window, or Word

Wrap from the Actions panel pop-up menu.)

Additional resources

In addition to this manual about ActionScript, there are manuals on other Flash topics, such

as components and Macromedia Flash Lite. You can access each manual in the Help panel

(Help > Flash Help), by viewing the default Table of Contents. Click the Clear button to see

each manual that’s available; for more information, see “Where to find documentation on

other subjects” on page 17.

For more information about other available resources, see the following topics:

■ “About the sample files” on page 14

■ “Where to find PDF files or printed documentation” on page 15

■ “About LiveDocs” on page 15

■ “Additional online resources” on page 16

■ “Where to find documentation on other subjects” on page 17

About the sample files

There are numerous ActionScript-based sample files available that install with Flash. These

sample files show you how code works in a FLA file; this is often a useful learning tool. The

chapters in this manual often reference these files, but we recommend that you also check out

the sample files folder on your hard disk.

The sample files include application FLA files that use common Flash functionality installed

with Flash. These applications were designed to introduce new Flash developers to the

capabilities of Flash applications, as well as show advanced developers how Flash features work

in context.

Additional resources 15

You can find the ActionScript-focused sample source files in the Samples folder on your

hard disk.

■ In Windows, browse to boot drive\Program Files\Macromedia\Flash 8\

Samples and Tutorials\Samples\ActionScript\.

■ On the Macintosh, browse to Macintosh HD/Applications/Macromedia Flash 8/

Samples and Tutorials/Samples/ActionScript/.

You might find the following components-focused sample files useful, because they contain a

lot of ActionScript code. They’re also in the Samples folder on your hard disk:

■ In Windows, browse to boot drive\Program Files\Macromedia\Flash 8\

Samples and Tutorials\Samples\Components\.

■ On the Macintosh, browse to Macintosh HD/Applications/Macromedia Flash 8/

Samples and Tutorials/Samples/Components/.

You can also find additional sample files for download on the Internet. The following web

page contains links and descriptions of additional sample files: www.macromedia.com/go/

flash_samples/.

Where to find PDF files or printed documentation

If you prefer to read documentation in printed format, the PDF versions of each Help manual

are available for downloading. Go to www.macromedia.com/support/documentation/ and

select the product you’re interested in. You can view or download the PDF or link to the

LiveDocs version of the manual.

Often, you can also purchase printed documentation. For updated information, go to the

Documentation support site and select Flash Basic 8 or Flash Professional 8.

About LiveDocs

You can access documentation at the LiveDocs website, in addition to accessing it from the

Help panel. The LiveDocs website contains all of the Flash Help pages and might contain

comments that clarify, update, or correct parts of the documentation. Click View Comments

on LiveDocs at the bottom of a page in the Help panel to display the equivalent page on the

LiveDocs website. Go to http://livedocs.macromedia.com to see a list of all of the available

documentation in the LiveDocs format.

16 Introduction

Technical writers monitor the LiveDocs website. One of the advantages of LiveDocs is seeing

comments that clarify the documentation or correct any errata or issues that arise after a

software release. LiveDocs is not the place to make help requests, such as asking questions

about your code that doesn’t work, comment on problems with software or installation, or ask

how to create something with Flash. It is the correct place to provide feedback about the

documentation (for example, you notice a sentence or paragraph that could be clarified).

When you click the button to add a comment on LiveDocs, there are several points about the

kinds of comments that are acceptable on the system. Please read these guidelines closely, or

your comment might be removed from the website.

If you have a question about Flash, please ask it on the Macromedia web forums:

www.macromedia.com/support/forums/. The web forums are the best place to ask questions,

because there are many Macromedia employees, Team Macromedia volunteers, Macromedia

user group managers and members, and even technical writers who monitor these forums.

Engineers do not monitor the LiveDocs system but do monitor the Flash wish list. If you

think you have found a bug in the software, or you would like to request an enhancement to

Flash, please fill out the wishform at www.macromedia.com/go/wish. If you report your bug

or enhancement request on LiveDocs, it will not be officially added to the bug database. You

must use the wishform instead, if you want an engineer to see your bug or request.

Remember to be careful about special characters and line breaks when you paste from the

web, including LiveDocs. Macromedia has made every effort to remove all special characters

from code samples, but if you have problems pasting code, see “Copy and paste code”

on page 13.

Additional online resources

There are several resources online that offer a wealth of instruction, help, and guidance to help

you learn Macromedia Flash 8. Check the following websites often for updates:

The Macromedia Developer Center website (www.macromedia.com/devnet) is updated

regularly with the latest information on Flash, plus advice from expert users, advanced topics,

examples, tips, tutorials (including multipart tutorials), and other updates. Check the website

often for the latest news on Flash and how to get the most out of the program.

The Macromedia Flash Support Center (www.macromedia.com/support/flash) provides

TechNotes, documentation updates, and links to additional resources in the Flash

community.

The Macromedia Weblogs website (http://weblogs.macromedia.com) provides a list of both

Macromedia employee and community weblogs (also known as blogs).

Additional resources 17

The Macromedia web forums (http://webforums.macromedia.com) provides numerous

forums for asking specific questions about Flash, your applications, or the ActionScript

language. The forums are monitored by Team Macromedia volunteers and often visited by

Macromedia employees as well. If you’re not sure where to go, or how to solve a problem, a

Flash forum is a good place to start.

The Macromedia Community website (www.macromedia.com/community) regularly hosts

Macrochats, a series of live presentations on a variety of topics by Macromedia employees or

community members. Check the website often for updates and to register for Macrochats.

Where to find documentation on other subjects

The following manuals offer additional information on subjects commonly associated with

ActionScript 2.0:

■ For information about the elements that compose the ActionScript language, see the

ActionScript 2.0 Language Reference.

■ For information about working in the Flash authoring environment, see How to Use Help.

■ For information about working with components, see Using Components.

18 Introduction

19

1

CHAPTER 1

What’s New in Flash 8

ActionScript

Macromedia Flash Basic 8 and Macromedia Flash Professional 8 provide several

enhancements that make it easy for you to write robust scripts using the ActionScript (AS)

language. The new features, which are discussed in this chapter, include new language

elements (see “Additions to the ActionScript language” on page 22), improved editing tools

(see “ActionScript editing changes” on page 27), changes to the security model, and other

ActionScript-related improvements to the authoring tool.

For more information, see the following topics:

New in ActionScript 2.0 and Flash 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Changes to security model for locally installed SWF files. . . . . . . . . . . . . . . . . . . . . . 28

New in ActionScript 2.0 and Flash 8

The ActionScript language has grown and developed since its introduction several years ago.

With each new release of Flash, additional keywords, objects, methods, and other language

elements were added to ActionScript. There are also ActionScript-related improvements to

the Flash 8 authoring environments. Flash Basic 8 and Flash Professional 8 introduce several

new language elements for expressive features, such as filters and blending modes, and

application development, such as JavaScript integration (ExternalInterface) and file input and

output (FileReference and FileReferenceList).

This section provides an overview of the ActionScript language elements and classes that are

new or changed in Flash 8 and ActionScript-related improvements to the authoring tool. For

a list of specific additions to ActionScript 2.0, see “Additions to the ActionScript language”

on page 22. To use any of the new language elements in your scripts, you must target Flash

Player 8 (the default) when you publish your documents.

20 What’s New in Flash 8 ActionScript

The following features were added to both Flash Basic 8 and Flash Professional 8 (unless

noted otherwise):

■ ActionScript editor enhancements let you show hidden characters in your scripts. For

more information, see “Showing hidden characters” on page 53.

■ Debug options are now available in the Script window, as well as the Actions panel, for

ActionScript files.

■ The Configuration directory that includes XML files and Class files is reorganized. See

“Configuration files that install with Flash 8” on page 65 for details.

■ You can set a preference to reload modified script files when working on an application,

which helps you avoid working with older versions of script files, and overwriting newer

script files. For more information, see “About ActionScript preferences” on page 42.

■ The Script window feature is available in Flash Basic 8 and Flash Professional 8. That

means you can now create an ActionScript file in either program.

■ Script Assist (similar to Normal Mode in earlier editions of Flash) helps you code without

needing to understand syntax. For more information on Script Assist, see “About Script

Assist” on page 58.

■ You can load new kinds of image files at runtime, which include progressive JPEG images,

and non-animated GIF and PNG files. If you load an animated file, the first frame of the

animation appears.

■ You can assign linkage identifiers to bitmap and sound files stored in the Library, which

means that you can attach images to the Stage or work with these assets in shared libraries.

■ Bitmap caching lets you improve the performance of your applications at runtime by

caching a bitmap representation of your instances. You can use ActionScript code to access

this property. For more information, see “About bitmap caching, scrolling, and

performance” on page 480.

■ 9-slice scaling lets you scale movie clip instances without widening the strokes that outline

the movie clip. You can use ActionScript code to access this feature in Flash Basic 8 and

Flash Professional 8, or in the Flash 8 authoring tool. For more information, see “Working

with 9-slice scaling in ActionScript” on page 558. For information about accessing 9-slice

scaling in the authoring tool, see “About 9-slice scaling and movie clip symbols”

on page 79 in Using Flash.

■ You can now add metadata information to your FLA files in the Publish Settings dialog

box. You can add a name and description to your FLA file using the dialog box to help

increase online search visibility.

■ The Strings panel is improved to include multiline support in the String field and a

language XML file. For more information, see “About the Strings panel” on page 452.

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