Beginning ActionScript 2.0 2006

Acknowledgments

There are too many people to count who have given me support and well wishes as I have worked away on this book. I would first like to acknowledge my parents for their constant love and support. They have helped to make me who I am. They also inspired me to pursue computing science as a career, for which I am eternally grateful. I would also like to acknowledge my fiancée, Renée. She has been supremely caring, supportive, and patient, has given me encouragement when I needed it. Through her actions she has been brought even closer to me than I could have imagined.

I would also like to acknowledge Jen DeHaan (www.deseloper.com), who gave me the generous gift of the opportunity to write this book, as well as providing me with a forum to help the Flash developer community. I am very grateful for her generosity. I am also grateful for the whole support team at Wiley, including my editor, Maryann Steinhart, for her tireless efforts to make this book happen, and my technical editor, Sean Christmann, who helped me with many valuable suggestions for improvements throughout the book.

There is no way I could undertake the effort of writing this book on my own. A big thank-you goes to Jeff Berg, who took on the daunting task of writing half of this book. He has been a great person to work with, both with the book and at IBM: Jeff has always been available to bounce ideas off of, is very creative with his solutions, and loves playing with the technology. He has also been a support on a personal level and a friend.

Thank you to Greg Charbonneau for making the time to take my photo for the cover. It was through the camera I initially bought from him that I earnestly started photography as a hobby. Thank you to all my friends and co-workers who regularly asked me about my book, and to my manager Elvyna who supported my writing efforts. Finally, thank you also for all those in the Flash Lounge who have been my champions, and who have been chomping at the bit to get an autographed copy of the book. At last it is ready!

—Nathan Derksen

I want to thank my co-author, Nathan Derksen, for his support and guidance. Nathan, your attitude, knowledge, and dedication are an inspiration. Also wish to thank Jack Blanchard. Jack, you taught me what an if statement was so many years ago, and you continue to guide me to new discoveries.

I could not have completed this project without the patient support of my wife Kara, the inspiration from my son Cary, and joy from my daughter Evie.

—Jeff Berg

Contents

Acknowledgments	viii
Introduction	xxv

Chapter 1: Getting Started with Macromedia Flash	1
Introducing the Development Environment	1
Tools Panel	2
Properties Panel	2
Timeline	3
Keyframes and Animation	3
About the Library and Symbols	4
Working with Buttons	5
Working with Movie Clips	7
About Layers, Depth, and Levels	8
Setting Up Your Scripting Environment	8
Introducing the Actions Panel	8
Exploring ActionScript Preferences	9
Automatic Indentation	9
Tab Size	10
Code Hints	10
Font	10
Color	11
ActionScript 2.0 Settings	11
Exploring Auto Format Preferences	12
Publishing a Project	13
The Flash Tab	14
The HTML Tab	15
The Image Tabs	15
Options for Detecting the Flash Player	16
Summary	18
Exercises	18

Chapter 2: Getting Started with ActionScript 2.0	19
Understanding Statements	19
Using Simple Statements	19
Using Compound Statements	20

Contents

Understanding Operators	20
Using Operator Precedence	22
Exploring Operator Associativity	22
Understanding the Common Operators	23
Using White Space	25
Using Comments	26
Introducing Variables	27
Assigning Data to a Variable	28
Viewing the Contents of a Variable	28
Passing Data from Variable to Variable	29
Naming Variables	29
Introducing Constants	30
Using Strong Variable Typing	30
Exploring Data Types	33
Distinguishing Primitive and Composite Data Types	34
Passing by Value Versus Pass by Reference	35
Duplicating Data for Composite Types	36
Using Dot Syntax	37
Discerning Special Variables and Keywords	38
_root	38
_level0	39
_global	39
this	39
Working with Collections of Data	40
Understanding Arrays	40
concat()	42
join()	43
push()	43
sort()	43
splice()	45
Exploring Associative Arrays and Objects	45
Viewing the Object Class as a Container	46
Revisiting the Associative Array	47
Summary	50
Exercises	51

Chapter 3: Understanding ActionScript Expressions and Loops	53
Making Decisions	53
Expressions	54
Building Expressions	55
Using if..then..else	59
Using switch..case	60

x

	Contents
Understanding Loops	66
The for Loop	66
The for..in Loop	69
The while Loop	70
The do..while Loop	72
Dealing with Loop Errors	76
Off-by-One Errors	76
Infinite Loops	77
Summary	80
Exercises	80
Chapter 4: Exploring ActionScript Functions and Scope	83
Functions	83
Functions in Action	86
An Alternate Syntax	87
Passing Functions as Arguments	88
Variable Scope	92
Managing Variable Scope	95
Side Effects	96
Summary	98
Exercises	99
Chapter 5: Getting Started with Coding	101
Introduction to Object-Oriented Programming	101
Defining Object-Oriented Programming	101
Classes Versus Objects	103
Class Inheritance	106
Goals of Object-Oriented Programming	106
Coding Best Practices	107
Understanding Variable Naming	107
Making Variable Names Readable	107
Making Boolean Variables into Questions	108
Avoiding Reserved Words	108
Distinguishing Variable Names from Class Names	110
Variable Typing	110
Type Casting	112
Commenting	116
Formatting Code	118
Understanding Variable Scope	119
Declaring All Global and Timeline Variables in One Place	119
Creating an Object Just for Data	120

xi

Contents

Creating Access Functions	120
Managing Data with Custom Classes	121
Accessing Variables in Another Timeline	122
Creating Your Own Functions	129
Strongly Typing Function Arguments	129
Avoiding Hard-Coded Movie Clip References	130
Declaring Return Values	130
Avoiding Oversized Functions	131
Avoiding Entanglement	131
Avoiding Duplication	133
Summary	140
Exercises	141

Chapter 6: Setting Up Flash Projects	143
Setting Up the Library	143
Working with Bitmap Images	144
Keep Images Organized on the Desktop	145
Keep Images Organized in the Library	145
Embed Images into Movie Clips	145
Nesting Sections within a Movie Clip	148
Using Keyframes to Manage Application State	149
Keeping Code in External Files	151
Using Script to Manage Application State	153
Summary	157
Exercise	157

Chapter 7: Controlling Movie Clips	159
The Movie Clip Revealed	159
MovieClip Class Methods	160
attachBitmap()	161
attachMovie()	162
beginFill()	162
clear()	163
createEmptyMovieClip()	163
createTextField()	163
duplicateMovieClip()	163
endFill()	164
getBytesLoaded()	164
getBytesTotal()	165
getURL()	166
gotoAndPlay()	167
hitTest()	167

xii

	Contents
lineStyle()	168
lineTo()	169
loadMovie()	169
moveTo()	170
play()	170
removeMovieClip()	170
setMask()	171
startDrag()	171
stop()	172
stopDrag()	172
swapDepths()	173
unloadMovie()	173
MovieClip Class Properties	174
MovieClip Class Events	176
Creating Movie Clips On-the-Fly	178
Attaching Movie Clips from the Library	181
Loading External Movies	184
Loading Movies into Levels	184
Loading Media into Existing Movie Clips	185
Fully Qualified, Absolute, and Relative URLs	186
Using Movie Clips as Masks	190
Improving Movie Clip Performance	196
Bitmap Caching	196
Transparency	196
Filters and Blending Modes	197
Full Screen	197
Summary	197
Exercises	198
Chapter 8: Pre-Loading Movies	199
Using a Custom Pre-Loader	199
Polling with onEnterFrame() Versus setInterval()	204
Understanding the MovieClipLoader Class	205
MovieClipLoader Class Events	205
MovieClipLoader Class Methods	206
addListener()	206
getProgress()	207
loadClip()	207
removeListener()	208
unloadClip()	208
Implementing the MovieClipLoader Class	209

xiii

Contents

Examining the Loader and ProgressBar Components	212
Loader Component Method, Properties, and Events	212
ProgressBar Component Method, Properties, and Events	213
Implementing the Loader and ProgressBar Components	215
Strategies for Using Pre-Loaders	217
The Monolithic Movie Approach	217
The Split-Up Movie Approach	221
Summary	225
Exercises	226

Chapter 9: Working with Components	229
New to Version 2.0	229
Exploring Components	230
Data Components	230
FLV Playback and FLV Playback Custom UI Components	231
Media Components for Flash Players 6 and 7	233
User Interface Components	233
Placing Components Manually	234
Placing Components on the Stage with Script	237
Scripting Components	242
Summary	245
Exercises	245

Chapter 10: Interacting with the User	247
Handling Events	247
Creating a Listener Object	247
Variation of Creating a Listener Object	254
Creating a Listener Function	255
Which Listener Technique Should You Use?	257
Attaching Multiple Listeners to Multiple Components	262
Organizing the Listeners	263
Handling Events from Multiple Sources	264
Manually Invoking Events in a Component	270
Summary	271
Exercise	272

Chapter 11: Controlling Components	273
Introducing the Component Inspector Panel	273
Creating Data Bindings between Components Using the Bindings Tab	275
Using an XML File as a Data Source	277

xiv

	Contents
Controlling Component Appearance	281
Using setStyle() to Change Component Styles	282
Setting Styles Globally	282
Setting Styles for a Component Type	283
Setting Styles Using Custom Classes	283
Style Search Order	283
Available Styles	284
Alert Style Names	286
Custom Date Classes	287
Skinning Components	290
Summary	294
Exercises	295
Chapter 12: Debugging Debugged	297
Types of Bugs	297
Compile-Time Bugs	297
Logic Bugs	298
If Statement Logic Errors	298
Uninitialized Variables	299
Off-by-One Errors	301
Fence Post Errors	301
Infinite Loops	302
Numerical Precision Errors	302
Develop to Debug	303
Make Your Code Readable	303
Develop in Small Chunks	304
Use Small Functions	304
The Science of Debugging	305
Develop a Theory	305
Run an Experiment	306
Using the Built-In Debugger	306
Using the Trace Statement	311
Commenting Out Code	312
Analyze the Results	313
Summary	314
Exercises	314
Chapter 13: Working with Vector Graphics	319
Using the Drawing API	320
Tools for Drawing Vectors with ActionScript	320
lineStyle()	320
beginFill()	322

xv

Contents

beginBitmapFill()	322
beginGradientFill()	323
endFill()	324
moveTo()	324
lineTo()	325
curveTo()	325
clear()	325
Drawing Vectors with ActionScript	325
The Matrix Object	334
Summary	334
Exercises	334

Chapter 14: Applying Filter Effects	335
DropShadowFilter	336
BlurFilter	337
GlowFilter	337
BevelFilter	338
GradientGlowFilter	339
GradientBevelFilter	339
ConvolutionFilter	340
ColorMatrixFilter	343
DisplacementMapFilter	345
Cloning Filters	346
Applying Multiple Filters	346
Applying Blending Modes	352
Summary	353
Exercises	353

Chapter 15: Working Directly with Bitmap Data	355
The Bitmap Object’s Methods	356
applyFilter()	356
clone()	356
colorTransform()	356
copyChannel()	357
copyPixels()	357
dispose()	357
draw()	358
fillRect()	358
floodFill()	358
generateFilterRect()	359

xvi

	Contents
getColorBoundsRect()	359
getPixel()	359
getPixel32()	360
hitTest()	360
loadBitmap()	360
merge()	361
noise()	361
paletteMap()	362
perlinNoise()	362
pixelDissolve()	363
scroll()	364
setPixel()	364
setPixel32()	364
threshold()	365
The bitmapData Object’s Properties	365
Converting a Movie Clip into a Bitmap Image	366
Manipulating Bitmap Data	366
Summary	368
Exercises	368
Chapter 16: Using ActionScript for Animation	369
Scripted Versus Non-Scripted Animation	369
Creating Animations Using Keyframes	370
Creating Animations Using ActionScript	372
Moving a Movie Clip Using onEnterFrame()	372
Moving a Movie Clip Using setInterval()	374
Frame-Based Versus Time-Based Animation	376
The Effect of Movie Frame Rate on Animation	376
Which Technique Should You Use?	379
Choosing a Frame Rate or Update Interval	379
Creating Animation with Movie Clips	380
Animating Multiple Movie Clips	381
Adding Random Behavior	382
Introducing Easing and Acceleration	387
Easing Out	387
Easing In	391
Summary	402
Exercises	402

xvii