Beginning ActionScript 2.0 2006

Contents

Chapter 17: Automated Transitions	403
The Tween Class	403
Absolute Versus Relative Tweens	404
Built-In Easing Classes and Methods	404
Tween Class Methods	405
continueTo()	406
fforward()	407
nextFrame()	407
prevFrame()	408
resume()	408
rewind()	409
start()	409
stop()	409
yoyo()	410
Tween Class Properties and Events	410
Playing Tweens in Parallel	414
Playing Tweens in a Sequence	417
Animating with the Drawing API	425
Summary	432
Exercises	432

Chapter 18: Handling Text	433
Creating Text Fields with ActionScript	434
Field Instance Names Versus Field Variable Names	434
System Fonts and Embedded Fonts	434
Creating a Text Field On-the-Fly	434
Working with Text Display Properties	436
antiAliasType	436
sharpness	437
thickness	437
Rich Text Formatting Options	439
Using TextFormat	439
New Text Format Options for Flash 8	440
Justification	440
letterSpacing	440
Kerning	441
A Note about setNewTextFormat()	445
Displaying HTML	446
Image and SWF Support in HTML Text Fields	448
Font Support	450
Hyperlinks and the ASFunction Method	452

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	Contents
Using Cascading Style Sheets	453
Creating a Cascading Style Sheet Object	454
Associating a StyleSheet with a Text Field	454
Define Styles Directly on a StyleSheet Object	456
How to Define Tags, Class, and Properties	458
Using CSS with XML	459
Scroll Text Options	461
Scrolling Text Using the TextArea Component	462
Scrolling Text Using the ScrollBar Component	463
Summary	469
Exercises	470
Chapter 19: Using ActionScript for Media	471
Managing Images	471
Smart Preloading	473
Using the MovieClipLoader to Preload an Image	473
Managing Sound	474
Sound Class Methods	474
Sound Class Events and Properties	476
Creating a Sound Object	477
Loading Library Sounds	477
Loading External MP3 Files	478
Using ID3 Tags	478
Available Properties in the V2 Tags	478
Streaming MP3 Audio	480
Starting, Stopping, and Tracking Sound	480
Event Sounds	483
Controlling Volume, setPan, and setTransform	483
Volume	483
Pan	483
Transform	483
Working with the Microphone	489
Microphone Class Methods	489
Microphone Class Properties and Events	490
Microphone Activity	492
netStream	494
Summary	494
Exercises	495
Chapter 20: Managing Video	497
Terms, Technology, and Quality	497
Data Rate	497
Progressive — HTTP	498

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Contents

Streaming — Flash Communication Server	498
Video Keyframes	498
Variable Bit Rate	499
Interlacing	499
Frame Rate	499
Creating Flash Video	500
Converting a Video	500
Loading an External Video	503
Exporting to Video	503
Loading an External FLV File	504
The netStream Class	504
The Video Class	506
clear()	506
attachVideo()	506
Video Class Properties	506
Controlling Video Position	508
Using Transparency within Video	510
Working with Video Quality	513
Deblocking and Deringing	513
Scaling and Transparency	514
Working with a Camera	515
The Camera Class Methods, Properties, and Events	515
Creating a Camera Object	516
Displaying a Camera Feed as Video on the Stage	517
Security Pop-Up Considerations	522
Summary	522
Exercises	522

Chapter 21: Using ActionScript to Communicate with a Server	523
External Data and Usability Concerns	523
Data Latency: Asynchronous Communication	524
Using LoadVars	524
Ampersand-Delimited Data	525
LoadVars Class Methods	525
Creating a LoadVars Object	527
LoadVars Event Handlers	529
onData()	529
onLoad()	529
Loading and Parsing Raw Text	531
Summary	534
Exercises	534

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	Contents
Chapter 22: Reading XML	535
Using the Built-in XML Class	535
All Wrapped Up in Tags	535
CDATA and Character Formats	537
The Flash XML Class	537
XML Class Methods	538
XML Event Handlers	541
onData()	541
onLoad()	542
ignoreWhite: A Special Property	542
Loading External XML Files	542
Measuring Bytes	545
A Note about Security and Locality	545
getBytesTotal Isn’t Working!	548
Understanding the Parent-Child Node Relationship	549
Navigating an Example Node Tree	549
Using Attributes	552
Using the XML Socket Connection	552
The XML in the XMLSocket Class	553
Null Bytes	553
XMLSocket Class Methods and Events	553
sendAndLoad	556
Using HTTP GET and POST	557
Apples and Oranges	558
How Will You Know?	558
Using the XML Component	559
Explaining Cross-Domain Security	562
Understanding Why Flash Uses Domain Policies	563
Knowing When Policy Files Are Required	564
Setting Up Policy Files	564
I’m Offering Web Services; I Want to Allow Any Domain!	567
Considering HTTPS	567
Load a Policy File from a Subfolder	568
Using a Policy File with an XML Socket, without HTTP	569
Using Shims and Proxies	570
Proxies: Forcing Data Access	570
Shims: Allowing Script Access	571
Summary	573
Exercises	574

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Contents

Chapter 23: Communicating Between the Macromedia Flash
Plug-in and the Browser	577
LocalConnection	577
Creating a localConnection Object	579
Security	581
Storing Data Locally with Shared Objects	582
Acceptable Data Types	584
Using Shared Objects as Cookies	585
Working with the User	587
Managing Disk Space	587
Sharing SharedObects	588
Giving a Flash Movie Data on Startup with FlashVars	588
Introduction to Flash Object and Embed Tag Parameters	589
Adding FlashVars	590
Creating FlashVars with JavaScript	591
Passing FlashVars via a Servlet Page	593
Summary	594
Exercises	594

Chapter 24: Putting JavaScript to Work	595
Changing Security Settings	595
Calling JavaScript from within Flash	597
Introduction to getUrl()	598
Creating a JavaScript Command with Nested Variables	598
Considering Limitations	602
Calling JavaScript Functions Using fscommand	602
Calling Flash from JavaScript	604
Basic JavaScript Methods and Events	606
Using the Flash JavaScript Integration Kit	607
Setting Up the Integration Kit	608
Calling JavaScript Functions from ActionScript	608
Calling ActionScript Functions from JavaScript	609
Using the External API	612
ExternalInterface Class Methods	612
addCallback()	612
call()	614
Calling ActionScript Functions and Methods	615
Calling an ActionScript Function from JavaScript	615
Calling an ActionScript Method from JavaScript	616
Calling JavaScript Functions from ActionScript	617
Opening a Browser Window	618
Setting and Getting Data Using ActionScript	619

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	Contents
Opening Browser Windows	629
Using getURL() to Create Pop-Up Windows	629
Use ExternalInterface to Create Pop-Up Windows	630
Calling a JavaScript Wrapper Function	630
Defining Browser Window Parameters	631
Summary	635
Exercise	635
Chapter 25: Uploading and Downloading Files	637
FileReference Class Methods	637
Using browse()	638
Using cancel()	638
Using download()	639
Using upload()	639
FileReference Class Properties	640
Downloading Files	641
Uploading Files	645
Summary	651
Exercise	651
Chapter 26: Communicating between the Flash Plug-in and
the Operating System	653
Using the System Object to Retrieve System Information	653
System Object Limitations among Player Versions	655
The setClipBoard Method	655
Projectors, Flash Executables, and Other Executables	656
Limitations	656
Using fscommand to Call Projector Functions	656
SDK	658
Third Parties	658
Summary	659
Exercises	659
Chapter 27: Creating Custom Classes	661
Working with Classes	661
Defining the Class	661
Public Versus Private	663
Defining the Constructor	665
Passing Startup Data	666
Defining Methods	669

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Contents

Defining Properties	675
Working with Getters and Setters	676
Implications of Getters and Setters	676
Adding Functionality to Existing Classes	681
Subclassing	681
Static Library	682
Composition	686
Summary	695
Exercises	695
Appendix A: Exercise Answers	699
Appendix B: Flash Keyboard Shortcuts	759
Tools Panel	759
Integrated Script Editor Shortcuts	760
File Menu	760
Edit Menu	761
View Menu	761
Tools Menu	761
Control Menu	762
Actions Panel Shortcuts	762
Drawing IDE Shortcuts	763
File Menu	763
Edit Menu	763
View Menu	764
Insert Menu	765
Modify Menu	765
Text Menu	767
Control Menu	767
Window Menu	768
Help Menu	769
Index	771

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Introduction

Macromedia Flash began as a vector animation tool, designed to help put a bit more punch into otherwise motionless web pages. At the time, web pages were simple and data-driven sites were few, so animation was one way to differentiate your pages from the rest of the crowd. Many people still hold the perception that Flash is only a tool for animation, in part due to the preponderance of Flash-based site intros and a very visible presence in banner and pop-up ads. While it remains a very good tool for animation, it has grown into a powerful means to do much more.

Macromedia Flash is a full-fledged application development environment. The real focus on using Flash for coding came with version 6, which introduced a new coding and event model leading to a cleaner, more flexible coding style. That version was the first major step in giving the developer power to create many interesting and useful applications. Flash 7 added a major scripting update, resulting in ActionScript 2.0. It provides a more structured, flexible, and maintainable programming style. Finally, Macromedia Flash 8 has expanded the offering, adding bitmap support, filters, and blending modes, file upload and download capabilities, an interface for communicating with the browser, and much more. All of the add-ons can be manipulated with script, not just with visual tools within the development environment.

The mature capabilities of Macromedia Flash 8 have the potential to redefine user interactions and usability on the Web. Flash enables you to develop full-fledged applications that either run in a web browser or run standalone as an executable.

Regardless of whether you are just interested in dabbling with scripting, or you want to develop applications with thousands of lines of code, ActionScript is for you. Want to build a major e-business application, to create a personal portfolio, to create a game, or to work with media? This book will help you out. If you’ve done any work with any other scripting language such as JavaScript or programming language such as Java or Perl, you are already halfway there. Even if you’ve never touched a line of code, you still can learn to apply ActionScript to Macromedia Flash projects through the many examples shown in the successful Wrox “Try It Out” format.

Who This Book Is For

The Macromedia Flash development environment is useful for a wide range of tasks, from creating marketing pieces, to creating a personal portfolio, to creating enterprise-level e-commerce applications, to creating games. As such, the diverse group of people who use it have different backgrounds, different mixes of technical and artistic skills, and different goals. This book assumes no prior programming or Macromedia Flash development experience. If you do have basic knowledge of ActionScript, there is plenty of content about how to work with different aspects of Macromedia Flash with script. This book includes techniques for animating using only code, working with audio, video, and graphics, interacting with the user, communicating with a server, and much more. This book also includes a primer on objectoriented programming, and the last chapter shows you how to create your own custom classes, a very valuable skill to acquire.

Introduction

Regardless of what you want to get out of Macromedia Flash, this book is a good starting point to get you to where you want to go.

How This Book Is Structured

Beginning ActionScript 2.0 teaches by example, using small, well-chosen programming examples, presented in the Wrox trademark “Try It Out” format. By typing each example, running it, and examining the results, you gain experience with the entire process of coding, running, and debugging Macromedia Flash projects. Experience has shown that a hands-on approach is one of the most effective ways to learn. In addition to the code samples, each example provides you with detailed descriptions of exactly what the code does, and why it was done that particular way. Where appropriate, the example overview also talks about some of the implications of developing code in that particular way, and with a mind toward other ways of performing the same task.

Here’s a breakdown of what this book provides:

In Chapter 1, you learn the aspects of the development environment, including how to create, work with, and publish a Macromedia Flash project. You create your first scripted project, put it in an HTML wrapper, and make your project viewable on the Web.

Chapters 2–4 take you right into the guts of the language. You learn all the aspects of ActionScript, including variables, data types, conditionals, loops, events, and errors. By the time you get through these chapters, you will have a good understanding of how to use the core aspects of the language.

Chapters 5 and 6 get you up and running with ActionScript, explaining such things as where to place your code and how to structure your Macromedia Flash project. You learn simple coding conventions that will help you create projects that are easier to read and to update. You see different ways to structure your project, learn the benefits and issues with each, and find out about some techniques that will help you through the debugging process.

In Chapters 7 and 8, you start using ActionScript to work with a core Macromedia Flash technology: components. You find out all about components—how to apply them to your project, have them communicate with each other, and customize their look on-the-fly through component styles. When you’ve finished these chapters, you’ll be well on your way to building form-based applications.

Chapters 9–11 show you how to work with the core container: the movie clip. You explore how to create blank movie clips and how to draw in them on-the-fly, how to work with movie clips in the library, and how to load external movie clips. You learn how to change variables and content in one movie clip from another and how to implement a movie pre-loader. You also study different ways to structure movie clips within a project. After you have completed this chapter, you will have a good understanding of many aspects the Macromedia Flash core building block.

Chapter 12 teaches you some techniques for debugging code. You learn some of the methodology that makes debugging less of a hit-or-miss scenario, how to use the debugger, and how to use the output panel to get a better sense of what is going on with your code.

Chapters 13–15 teach you how to work with drawing and to apply effects with ActionScript. You learn how to use the drawing API, how to apply filters and blending modes, and how to work with the new Bitmap class to manipulate individual pixels.

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Introduction

You extend your knowledge of the movie clip in Chapters 16 and 17. You learn the concepts of timebased and frame-based animation, and how to animate with ActionScript. That knowledge is extended by adding basic physics to your animations, and is topped off by using the Tween class to simplify some types of animations. After finishing these chapters, you’ll know how to create scripted animations.

In Chapter 18, you learn the intricacies of working with text, including the different types of text fields, issues related to embedding fonts into your project, and how to apply visual styles to text. Because text handling is one of the largest sources of problems with new Macromedia Flash developers, this chapter is replete with annotated examples illustrating how to deal with this subject.

Chapters 19 and 20 show you how to integrate images, sound, video, and live camera feeds into your project. You learn to work with features such as loading, streaming, and embedding media. Through this chapter, you get a good grasp of the various media management issues, and learn ways to deal with issues specific to working with different media types.

Chapters 21 and 22 explain how to get your project to pass data between the web browser and a server. You learn the details of communicating with a server using a number of different communication techniques, including LoadVars and XML. Security issues are reviewed and solutions are presented for dealing with many of those issues.

Chapters 23–25 provide techniques for communication between a movie and the browser, and between separate movies. You learn to use new classes for communicating between the browser and the Macromedia Flash plug-in, for starting up movies on-the-fly with JavaScript, and for saving information long-term on the user’s computer. Cross-platform communication issues are addressed, so you can ensure that your project will work in different browsers on different platforms.

Chapter 26 examines the capabilities and limitations of working with the user’s operating system. You learn to retrieve information about the user’s operating environment through the System object. You learn to launch programs, open windows, and make your own system calls from a standalone projector. You also see examples of using third-party tools to greatly expand the capabilities of the projector. Basically, this chapter teaches you how to interact with the operating system from within the Macromedia Flash plug-in.

Chapter 27 shows you how to create custom ActionScript classes, how to think in a more object-oriented way, and some techniques for working with your own classes.

Each chapter ends with exercises for you to work on your own, and Appendix A provides solutions to those exercises.

What You Need to Use This Book

This book targets Flash 8, but because ActionScript 2.0 made its debut in Macromedia Flash MX 2004 and because the language has not substantially changed in Flash 8, much of this book is also relevant to those using Macromedia Flash MX 2004. A few features require Flash 8, and that’s noted as they’re used. You can use either Macromedia Flash MX 2004 or Flash 8 development environments, although this book assumes that you are using the professional version. You can download a fully functioning 30-day demo of Flash 8 from www.macromedia.com/downloads. Flash player version 7 does exist for Linux, although version 8 is not yet available for Linux. Macromedia does not provide a Linux development environment. As a result, you need to use either at least Mac OS X 10.3 or at least Windows 2000 to run the Flash development environment.

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