book

Essential ActionScript 3.0

Name: Essential ActionScript 3.0
Author: Colin Moock
ISBN: 9780596526948

by Colin Moock

June 2007

Intermediate to advanced

948 pages

27h 2m

English

O'Reilly Media, Inc.

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Foreword
Preface
Beginners WelcomeExpert GuidanceWhat’s In This BookWhat’s Not In This BookAuthoring Tool AgnosticismActionScript OverviewThe Core LanguageFlash Runtime ClientsRuntime APIsComponentsThe Flash File Format (SWF)ActionScript Development ToolsThis Book’s Example FilesUsing Code ExamplesTypographical ConventionsHow to Contact UsAcknowledgments
I. ActionScript from the Ground Up
1. Core Concepts
1.1. Tools for Writing ActionScript Code1.2. Flash Client Runtime Environments1.3. Compilation1.3.1. Just-In-Time Compilation1.4. Quick Review1.5. Classes and Objects1.6. Creating a Program1.7. Packages1.8. Defining a Class1.8.1. Access Control Modifiers for Classes1.9. Virtual Zoo Review1.10. Constructor Methods1.11. Creating Objects1.11.1. Literal Syntax1.11.2. Object Creation Example: Adding a Pet to the Zoo1.12. Variables and Values1.12.1. Local Variables1.12.2. Instance Variables1.12.2.1. Access-control modifiers for instance variables1.13. Constructor Parameters and Arguments1.14. Expressions1.15. Assigning One Variable’s Value to Another1.15.1. Copies and References1.16. An Instance Variable for Our Pet1.17. Instance Methods1.17.1. Access Control Modifiers for Instance Methods1.17.2. Method Parameters and Arguments1.17.3. Method Return Values1.17.4. Method Signatures1.18. Members and Properties1.19. Virtual Zoo Review1.20. Break Time!
2. Conditionals and Loops
2.1. Conditionals2.1.1. The if Statement2.1.1.1. An if statement with no else2.1.1.2. Chaining if statements2.1.2. The switch Statement2.2. Loops2.2.1. The while Statement2.2.2. Processing Lists with Loops2.2.3. Ending a Loop with the break Statement2.2.4. The do-while Statement2.2.5. The for Statement2.3. Boolean Logic2.3.1. Logical OR2.3.2. Logical AND2.3.3. Logical NOT2.4. Back to Classes and Objects
3. Instance Methods Revisited
3.1. Omitting the this Keyword3.1.1. Managing Parameter/Variable Name Conflicts3.2. Bound Methods3.3. Using Methods to Examine and Modify an Object’s State3.4. Get and Set Methods3.5. Handling an Unknown Number of Parameters3.6. Up Next: Class-Level Information and Behavior
4. Static Variables and Static Methods
4.1. Static Variables4.2. Constants4.3. Static Methods4.3.1. The Class Initializer4.4. Class Objects4.5. C++ and Java Terminology Comparison4.6. On to Functions
5. Functions
5.1. Package-Level Functions5.1.1. Global Functions5.2. Nested Functions5.3. Source-File-Level Functions5.4. Accessing Definitions from Within a Function5.5. Functions as Values5.6. Function Literal Syntax5.7. Recursive Functions5.8. Using Functions in the Virtual Zoo Program5.9. Back to Classes
6. Inheritance
6.1. A Primer on Inheritance6.1.1. Static Methods and Static Variables Not Inherited6.2. Overriding Instance Methods6.2.1. Invoking an Overridden Instance Method6.3. Constructor Methods in Subclasses6.4. Preventing Classes from Being Extended and Methods from Being Overridden6.5. Subclassing Built-in Classes6.6. The Theory of Inheritance6.6.1. Why Inheritance?6.6.2. Polymorphism and Dynamic Binding6.6.3. Inheritance Versus Composition6.6.3.1. Is-A, Has-A, and Uses-A6.6.3.2. When to use composition over inheritance6.7. Abstract Not Supported6.8. Using Inheritance in the Virtual Zoo Program6.8.1. Creating Types of Pet Food6.8.2. Preparing VirtualZoo for Onscreen Display6.9. Virtual Zoo Program Code6.10. It’s Runtime!

7. Compiling and Running a Program
7.1. Compiling with the Flash Authoring Tool7.2. Compiling with Flex Builder 27.2.1. Moving the Main Class to the Unnamed Package7.2.2. Compiling the Program7.2.3. Running the Program7.3. Compiling with mxmlc7.4. Compiler Restrictions7.5. The Compilation Process and the Classpath7.6. Strict-Mode Versus Standard-Mode Compilation7.6.1. Enabling Standard-Mode Compilation in Flex Builder 27.6.2. Enabling Standard-Mode Compilation in the Flash Authoring Tool7.7. The Fun’s Not Over
8. Datatypes and Type Checking
8.1. Datatypes and Type Annotations8.1.1. Compatible Types8.1.2. Detecting Type Mismatch Errors with Type Annotations8.2. Untyped Variables, Parameters, Return Values, and Expressions8.3. Strict Mode’s Three Special Cases8.4. Warnings for Missing Type Annotations8.5. Detecting Reference Errors at Compile Time8.6. Casting8.6.1. Avoiding Unwanted Type Mismatch Errors8.6.2. Upcasting and Downcasting8.6.3. Using the as Operator to Cast to Date and Array8.7. Conversion to Primitive Types8.8. Default Variable Values8.9. null and undefined8.10. Datatypes in the Virtual Zoo8.11. More Datatype Study Coming Up
9. Interfaces
9.1. The Case for Interfaces9.2. Interfaces and Multidatatype Classes9.3. Interface Syntax and Use9.3.1. Interface Naming Conventions9.3.2. Interface Inheritance9.3.3. Marker Interfaces9.4. Another Multiple-Type Example9.5. More Essentials Coming
10. Statements and Operators
10.1. Statements10.2. Operators10.2.1. Number of Operands10.2.2. Operator Precedence10.2.3. Operator Associativity10.2.4. Datatypes and Operators10.2.5. Operator Overview10.3. Up Next: Managing Lists of Information
11. Arrays
11.1. What Is an Array?11.2. The Anatomy of an Array11.2.1. Array Elements11.2.2. Array Element Indexing11.2.3. Array Size11.3. Creating Arrays11.3.1. Creating Arrays with Array Literals11.3.2. Creating Arrays with the new Operator11.4. Referencing Array Elements11.4.1. Retrieving an Element’s Value11.4.2. Setting an Element’s Value11.5. Determining the Size of an Array11.6. Adding Elements to an Array11.6.1. Adding New Elements Directly11.6.2. Adding New Elements with the length Variable11.6.3. Adding New Elements with Array Methods11.6.3.1. The push( ) method11.6.3.2. The unshift( ) method11.6.3.3. The splice( ) method11.6.3.4. The concat( ) method11.7. Removing Elements from an Array11.7.1. Removing Elements with the delete Operator11.7.2. Removing Elements with the length Variable11.7.3. Removing Elements with Array Methods11.7.3.1. The pop( ) method11.7.3.2. The shift( ) method11.7.3.3. The splice( ) method11.8. Checking the Contents of an Array with the toString( ) Method11.9. Multidimensional Arrays11.10. On to Events
12. Events and Event Handling
12.1. ActionScript Event Basics12.1.1. Registering an Event Listener for an Event12.1.1.1. Step 1: Determine the event type’s name12.1.1.2. Step 2: Determine the event object’s datatype12.1.1.3. Step 3: Create the event listener12.1.1.4. Step 4: Register for the event12.1.1.5. Step 5: Wait for the event to occur12.1.2. Two More Event Listener Registration Examples12.1.3. Unregistering an Event Listener for an Event12.1.4. Event Vocabulary Review12.2. Accessing the Target Object12.3. Accessing the Object That Registered the Listener12.4. Preventing Default Event Behavior12.5. Event Listener Priority12.6. Event Listeners and Memory Management12.6.1. Weak Listener References12.7. Custom Events12.7.1. A Custom “gameOver” Event12.7.2. A Custom “toggle” Event12.7.3. Preventing Default Behavior for Custom Events12.8. Type Weakness in ActionScript’s Event Architecture12.9. Handling Events Across Security Boundaries12.9.1. Module.swf Listener Registers with Main.swf Object12.9.2. Main.Swf Listener Receives Notification for an Event Targeted at a Module.swf Display Object12.9.3. An Alternative to allowDomain( ): Shared Events12.10. What’s Next?
13. Exceptions and Error Handling
13.1. The Exception-Handling Cycle13.2. Handling Multiple Types of Exceptions13.2.1. Determining Exception Type Granularity13.2.1.1. Options 1 and 2: Using a single custom-exception type13.2.1.2. Option 3: Using configurable debugging messages13.2.1.3. Option 4: Multiple custom VirtualPetNameException subclasses13.3. Exception Bubbling13.3.1. Uncaught Exceptions13.4. The finally Block13.5. Nested Exceptions13.6. Control-Flow Changes in try/catch/finally13.7. Handling a Built-in Exception13.7.1. Error Events for Problem Conditions13.8. More Gritty Work Ahead
14. Garbage Collection
14.1. Eligibility for Garbage Collection14.2. Incremental Mark and Sweep14.3. Disposing of Objects Intentionally14.4. Deactivating Objects14.5. Garbage Collection Demonstration14.6. On to ActionScript Backcountry
15. Dynamic ActionScript
15.1. Dynamic Instance Variables15.1.1. Processing Dynamic Instance Variables with for-each-in and for-in Loops15.2. Dynamically Adding New Behavior to an Instance15.3. Dynamic References to Variables and Methods15.4. Using Dynamic Instance Variables to Create Lookup Tables15.4.1. Making Lookup Tables with Object Literals15.5. Using Functions to Create Objects15.6. Using Prototype Objects to Augment Classes15.7. The Prototype Chain15.8. Onward!
16. Scope
16.1. Global Scope16.2. Class Scope16.3. Static Method Scope16.4. Instance Method Scope16.5. Function Scope16.6. Scope Summary16.7. The Internal Details16.8. Expanding the Scope Chain via the with Statement16.9. On to Namespaces
17. Namespaces
17.1. Namespace Vocabulary17.2. ActionScript Namespaces17.3. Creating Namespaces17.3.1. Choosing the Namespace URI17.3.2. Defining the Namespace17.3.3. Explicit Versus Implicit URIs17.3.4. Namespace Terminology Review17.4. Using a Namespace to Qualify Variable and Method Definitions17.4.1. User-Defined Namespace Attributes in the Top-Level of a Class Only17.5. Qualified Identifiers17.5.1. Expanded Names17.6. A Functional Namespace Example17.7. Namespace Accessibility17.7.1. Accessibility of Package-Level Namespace Definitions17.7.2. Accessibility of Class-Level Namespace Definitions17.7.3. Accessibility of Function-Level Namespace Definitions17.8. Qualified-Identifier Visibility17.9. Comparing Qualified Identifiers17.10. Assigning and Passing Namespace Values17.10.1. Assigning a Namespace Value to a Variable17.10.2. Namespaces as Method Arguments and Return Values17.10.3. A Namespace Value Example17.11. Open Namespaces and the use namespace Directive17.11.1. Open Namespaces and Scope17.11.2. Opening Multiple Namespaces17.12. Namespaces for Access-Control Modifiers17.12.1. Import Opens Public Namespaces17.13. Applied Namespace Examples17.13.1. Example: Framework-Internal Visibility17.13.2. Example: Permission-Based Access Control17.13.3. Example: Program Modes17.14. Final Core Topics
18. XML and E4X
18.1. Understanding XML Data as a Hierarchy18.2. Representing XML Data in E4X18.3. Creating XML Data with E4X18.4. Accessing XML Data18.4.1. Accessing the Root XML Node18.4.2. Accessing Child Nodes18.4.3. Accessing Text Nodes18.4.4. Accessing Parent Nodes18.4.5. Accessing Sibling Nodes18.4.6. Accessing Attributes18.4.7. Accessing Comments and Processing Instructions18.4.8. Accessing Attributes and Elements Whose Names Contain Reserved Characters18.4.9. Treating XMLList as XML, Revisited18.5. Processing XML with for-each-in and for-in18.6. Accessing Descendants18.7. Filtering XML Data18.8. Traversing XML Trees18.9. Changing or Creating New XML Content18.9.1. Changing the Contents of an Element18.9.2. Changing an Attribute Value18.9.3. Replacing an Entire Element18.9.4. Adding New Attributes and Elements18.9.4.1. Adding a new child after all existing children18.9.4.2. Adding a new child after a specific existing child18.9.4.3. Adding a new child before a specific existing child18.9.4.4. Adding a new child before all existing children18.9.5. Deleting Elements and Attributes18.9.6. References to Parts of a Document Are Not Live18.9.7. Using XML Entities for Special Characters18.9.8. Assigning Values to an XMLList18.10. Loading XML Data18.11. Working with XML Namespaces18.11.1. Accessing Namespace-Qualified Elements and Attributes18.11.2. Creating Namespace-Qualified Elements and Attributes18.12. Converting XML and XMLList to a String18.12.1. Converting XMLList to a String18.12.2. Converting an XML Element to a String18.12.3. Converting an Attribute to a String18.12.4. Converting Comments and Processing-Instructions to Strings18.13. Determining Equality in E4X18.13.1. XML Equality18.13.2. XMLList Equality18.13.3. QName Equality18.13.4. Namespace Equality18.14. More to Learn
19. Flash Player Security Restrictions
19.1. What’s Not in This Chapter19.2. The Local Realm, the Remote Realm, and Remote Regions19.3. Security-Sandbox-Types19.3.1. How Security-Sandbox-Types Are Assigned19.4. Security Generalizations Considered Harmful19.5. Restrictions on Loading Content, Accessing Content as Data, Cross-Scripting, and Loading Data19.5.1. Loading Content19.5.2. Accessing Content as Data19.5.3. Cross-Scripting19.5.4. Loading Data19.5.5. Restrictions on Loading Content, Accessing Content as Data, Loading Data, and Cross-Scripting19.6. Socket Security19.7. Example Security Scenarios19.7.1. Snoopy Email Attachment—Without Flash Player Security19.7.2. Snoopy Email Attachment—With Flash Player Security19.7.3. Internal Corporate Information—Without Flash Player Security19.7.4. Internal Corporate Information—With Flash Player Security19.7.5. Cross-Web Site Information—Without Flash Player Security19.7.6. Cross-Web Site Information—With Flash Player Security19.8. Choosing a Local Security-Sandbox-Type19.8.1. Compiling a Local-with-Filesystem .swf File19.8.2. Compiling a Local-with-Networking .swf File19.8.3. Granting Local Trust19.8.4. Developers Automatically Trusted19.8.5. Default Local Security-Sandbox-Type19.9. Distributor Permissions (Policy Files)19.9.1. Authorizing Loading-Data and Accessing-Content-as-Data Operations19.9.1.1. Creating the policy file19.9.1.2. Posting the policy file19.9.1.3. Obtaining a policy file’s permission to load data19.9.1.4. Obtaining a policy file’s permission to access content as data19.9.2. Using a Policy File to Authorize Socket Connections19.9.2.1. Create the policy file19.9.2.2. Socket-based policy-file retrieval19.9.2.3. HTTP-based policy-file retrieval19.10. Creator Permissions (allowDomain( ))19.10.1. Allowing .swf Files Served Over HTTP to Cross-Script .swf Files Served Over HTTPS19.11. Import Loading19.12. Handling Security Violations19.13. Security Domains19.13.1. Ambiguous Use of the Term “Sandbox”19.14. Two Common Security-Related Development Issues19.14.1. Accessing Internet Subdomains19.14.2. Accessing the Loader Class’s Instance Variable Content19.15. On to Part II!
II. Display and Interactivity
20. The Display API and the Display List
20.1. Display API Overview20.1.1. Extending the Core-Display Class Hierarchy20.2. The Display List20.2.1. Containers and Depths20.2.2. Removing Assets from Containers20.2.3. Removing Assets from Memory20.2.4. Removing All Children20.2.5. Reparenting Assets20.2.6. Traversing Objects in a Display Hierarchy20.2.7. Manipulating Objects in Containers Collectively20.2.8. Descendant Access to a .swf File’s Main Class Instance20.2.8.1. The rebirth of _root20.2.8.2. Whither _level0?20.3. Containment Events20.3.1. The Event.ADDED and Event.REMOVED Events20.3.2. A Real-World Containment-Event Example20.3.3. The ADDED_TO_STAGE and REMOVED_FROM_STAGE Events20.3.3.1. Custom Event.ADDED_TO_STAGE and Event.REMOVED_FROM_STAGE events20.4. Custom Graphical Classes20.5. Go with the Event Flow
21. Events and Display Hierarchies
21.1. Hierarchical Event Dispatch21.2. Event Dispatch Phases21.3. Event Listeners and the Event Flow21.3.1. Registering an Ancestor Listener for the Capture Phase21.3.2. Registering an Ancestor Listener for the Bubbling Phase21.3.3. Registering an Ancestor Listener for Both the Capture Phase and the Bubbling Phase21.3.4. Registering a Listener with the Event Target21.3.5. The Dual Purpose of the useCapture Parameter21.3.6. Removing Event Listeners21.4. Using the Event Flow to Centralize Code21.5. Determining the Current Event Phase21.6. Distinguishing Events Targeted at an Object from Events Targeted at That Object’s Descendants21.7. Stopping an Event Dispatch21.8. Event Priority and the Event Flow21.9. Display-Hierarchy Mutation and the Event Flow21.9.1. Event Listener List Mutation21.10. Custom Events and the Event Flow21.11. On to Input Events
22. Interactivity
22.1. Mouse-Input Events22.1.1. Flash Player’s Built-in Mouse Events22.1.2. Registering for Mouse Events22.1.3. Mouse Events and Overlapping Display Objects22.1.4. Finding the Mouse Pointer’s Position22.1.5. Handling Mouse Events “Globally”22.2. Focus Events22.2.1. Focusing Objects Programmatically22.2.2. Focusing Objects with the Keyboard22.2.3. Focusing Objects with the Mouse22.2.3.1. Handling descendant focus through a single ancestor22.2.4. Flash Player’s Focus Events22.3. Keyboard-Input Events22.3.1. Global Keyboard-Event Handling22.3.2. Object-Specific Keyboard-Event Handling22.3.3. Determining the Most Recently Pressed or Released Key22.3.3.1. Multilocation keys22.3.4. Detecting Multiple Simultaneous Key Presses22.3.5. Mouse Events and Modifier Keys22.3.6. Determining the Character Associated with a Key22.4. Text-Input Events22.4.1. The TextEvent.TEXT_INPUT and Event.CHANGE Events22.4.2. The Event.SCROLL Event22.4.3. The TextEvent.LINK Event22.5. Flash Player-Level Input Events22.5.1. The Event.ACTIVATE and Event.DEACTIVATE Events22.5.2. The Event.RESIZE Event22.5.3. The Event.MOUSE_LEAVE Event22.6. From the Program to the Screen
23. Screen Updates
23.1. Scheduled Screen Updates23.1.1. No Screen Updates Within Code Blocks23.1.2. Setting the Frame Rate23.1.3. Designated Frame Rate Versus Actual Frame Rate23.2. Post-Event Screen Updates23.2.1. Post-Event Updates for Timer Events23.2.2. Automatic Post-Event Screen Updates23.3. Redraw Region23.4. Optimization with the Event.RENDER Event23.5. Let’s Make It Move!
24. Programmatic Animation
24.1. No Loops24.2. Animating with the ENTER_FRAME Event24.2.1. Frame Rate’s Effect on Event.ENTER_FRAME Animations24.3. Animating with the TimerEvent.TIMER Event24.3.1. Frame Rate’s Effect on Timer24.4. Choosing Between Timer and Event.ENTER_FRAME24.5. A Generalized Animator24.6. Velocity-Based Animation24.7. Moving On to Strokes ‘n’ Fills
25. Drawing with Vectors
25.1. Graphics Class Overview25.2. Drawing Lines25.3. Drawing Curves25.4. Drawing Shapes25.5. Removing Vector Content25.6. Example: An Object-Oriented Shape Library25.7. From Lines to Pixels
26. Bitmap Programming
26.1. The BitmapData and Bitmap Classes26.2. Pixel Color Values26.3. Creating a New Bitmap Image26.4. Loading an External Bitmap Image26.5. Examining a Bitmap26.5.1. getPixel32() Versus getPixel( )26.5.2. Transparency’s Effect on Color-Value Retrieval26.5.3. ColorPicker: A getPixel32( ) Example26.5.4. Retrieving the Color of a Region of Pixels26.5.5. Other Examination Tools26.6. Modifying a Bitmap26.6.1. Improve Performance with BitmapData.lock( )26.6.2. ScribbleAS3: A setPixel32( ) Example26.6.3. Assigning the Color of a Region of Pixels26.6.4. Other Manipulation Tools26.6.5. Resizing a Bitmap26.7. Copying Graphics to a BitmapData Object26.7.1. The BitmapData Class’s Instance Method draw( )26.7.1.1. How draw( ) handles Alpha channel values26.7.1.2. No arbitrary screen captures26.7.2. The BitmapData Class’s Instance Method copyPixels( )26.8. Applying Filters and Effects26.8.1. Applying Filters26.9. Freeing Memory Used by Bitmaps26.10. Words, Words, Words
27. Text Display and Input
27.1. Creating and Displaying Text27.1.1. Word Wrapping27.1.2. Automatic Resizing27.1.3. Rotated, Skewed, and Transparent Text Requires Embedded Fonts27.2. Modifying a Text Field’s Content27.3. Formatting Text Fields27.3.1. Formatting Text with the TextFormat Class27.3.1.1. Available TextFormat variables27.3.1.2. Embedded font warning: Bold and italic require separate fonts27.3.1.3. setTextFormat( ) does not apply to future text assignments27.3.1.4. Applying paragraph-level formatting27.3.1.5. Retrieving formatting information for a span of characters27.3.1.6. Default formatting for text fields27.3.2. Formatting Text with HTML27.3.2.1. Entity support27.3.2.2. Quoting attribute values27.3.2.3. Interactions between the text and htmlText variables27.3.2.4. Unrecognized tags and attributes27.3.3. Formatting Text with the StyleSheet Class27.3.3.1. Notable style sheet limitations in ActionScript27.3.3.2. Formatting text with a programmatically created style sheet27.3.3.3. Class selectors27.3.3.4. Formatting XML tags with CSS27.3.3.5. Formatting text with an externally loaded style sheet27.4. Fonts and Text Rendering27.4.1. Embedding Font Outlines in the Flash Authoring Tool27.4.2. Embedding Font Outlines in Flex Builder 2 and mxmlc27.4.3. Formatting Text with an Embedded Font27.4.3.1. Using bold and italic with embedded fonts27.4.4. Loading Fonts at Runtime27.5. Missing Fonts and Glyphs27.6. Determining Font Availability27.7. Determining Glyph Availability27.8. Embedded-Text Rendering27.8.1. Tweaking the FlashType Renderer27.9. Text Field Input27.9.1. Text Entry27.9.1.1. Formatting user input27.9.2. Text Selection27.9.3. Hypertext Links27.10. Text Fields and the Flash Authoring Tool27.11. Loading . . . Please Wait . . .
28. Loading External Display Assets
28.1. Using Loader to Load Display Assets at Runtime28.1.1. Creating the Loader Instance28.1.2. Specifying the Asset’s Location28.1.3. Starting the Load Operation28.1.4. Accessing the Loaded Asset28.1.5. Displaying the Loaded Asset On Screen28.1.6. Displaying Load Progress28.1.6.1. Why not use Event.OPEN?28.1.7. Handling Load Errors28.1.7.1. Environment-specific behavior for load failures28.1.7.2. Debugging with HTTPStatusEvent28.2. Compile-Time Type-Checking for Runtime-Loaded Assets28.2.1. Opting Out of Compile-Time Type-Checking28.2.2. Give the Compiler Access to the Loaded Class28.2.3. Add the Module Class File to Main.swf’s source-path28.2.4. Add the Module Class File to Main.swf’s library-path28.2.5. Add the Module Class File to Main.swf’s external-library-path28.3. Accessing Assets in Multiframe .swf Files28.4. Instantiating a Runtime-Loaded Asset28.4.1. Instantiating a Loaded .swf File28.4.2. Instantiating a Loaded Image28.5. Using Socket to Load Display Assets at Runtime28.5.1. Server-Side: Sending the Asset28.5.2. Client-Side: Receiving the Asset28.5.2.1. Creating and connecting to the socket28.5.2.2. Placing bytes in a buffer28.5.2.3. Creating a display asset from the loaded bytes28.6. Removing Runtime Loaded .swf Assets28.7. Embedding Display Assets at Compile Time28.7.1. A Note on File Size and Memory Consumption28.7.2. General [Embed] Syntax28.7.3. Supported Asset Types28.7.4. Embedding Bitmap Images28.7.5. Embedding SVG28.7.6. Embedding Entire .swf Files28.7.7. Embedding Symbols from Legacy .swf Files28.7.8. Embedding Files as Binary Data28.7.9. Using getDefinition( ) to Access a Class in an Embedded .swf File28.7.10. An [Embed] Example28.7.11. Clean the Project to See Changes28.8. On to Part III
III. Applied ActionScript Topics
29. ActionScript and the Flash Authoring Tool
29.1. The Flash Document29.2. Timelines and Frames29.2.1. Keyframes and Regular Frames29.3. Timeline Scripting29.4. The Document Class29.4.1. Variable and Function Definitions in Frame Scripts29.5. Symbols and Instances29.5.1. Types of Symbols29.5.2. Movie Clip Symbols29.6. Linked Classes for Movie Clip Symbols29.7. Accessing Manually Created Symbol Instances29.7.1. Instance Names29.7.2. Matching Variables for Instance Names29.8. Accessing Manually Created Text29.9. Programmatic Timeline Control29.10. Instantiating Flash Authoring Symbols via ActionScript29.11. Instance Names for Programmatically Created Display Objects29.12. Linking Multiple Symbols to a Single Superclass29.13. The Composition-Based Alternative to Linked Classes29.14. Preloading Classes29.15. Up Next: Using the Flex Framework
30. A Minimal MXML Application
30.1. The General Approach30.1.1. Create the Flex Project30.1.2. Create the Application Point of Entry30.1.3. Trigger the Application Point of Entry30.2. A Real UI Component Example30.3. Sharing with Your Friends
31. Distributing a Class Library
31.1. Sharing Class Source Files31.2. Distributing a Class Library as a .swc File31.2.1. Creating a .swc-Based Class Library in Flex Builder 231.2.2. Using a .swc-Based Class Library in Flex Builder 231.2.3. Creating a .swc-Based Class Library in the Flash Authoring Tool31.2.4. Using a .swc-Based Class Library in the Flash Authoring Tool31.3. Distributing a Class Library as a .swf File31.3.1. Creating a .swf-Based Class Library in Flex Builder 231.3.1.1. Compiling a .swf file using mxmlc31.3.2. Using a .swf-Based Class Library in Flex Builder 231.3.3. Creating a .swf-Based Class Library in the Flash Authoring Tool31.3.4. Using a .swf-Based Class Library in Flash CS331.4. But Is It Really Over?
A. The Final Virtual Zoo
Index
About the Author
Colophon
Special Upgrade Offer
Copyright

Content preview from Essential ActionScript 3.0

Chapter 28. Loading External Display Assets

In ActionScript, there are three ways to programmatically add an external display asset to an application:

Use the flash.display.Loader class to load the asset at runtime
Use the flash.net.Socket class in combination with the Loader class’s instance method loadBytes( ) to load the asset at runtime over a direct TCP/IP socket
Use the [Embed] metadata tag to include the asset from the local filesystem at compile-time

The Loader and Socket classes are built-in to the Flash runtime API, while the [Embed] metadata tag requires the Flex framework. All three approaches support the following display asset formats:

SWF (compiled Flash applications)
JPEG, GIF, or PNG (bitmap images)

Additionally, the [Embed] metadata tag supports SVG-formatted display assets.

Note

The Loader class replaces the following ActionScript 2.0 loading tools:

MovieClipLoader class
loadMovie( ) and loadMovieNum( )
global functionsMovieClip class’s instance methods loadMovie( ) and loadMovieNum( )

In this chapter, we’ll learn how to use Loader, Socket, and [Embed] to load external display assets. For information on loading fonts, see Chapter 27. For information on loading XML, see Chapter 18. For information on loading other nondisplay assets, such as variables, binary data, or sound, see the URLLoader, URLStream, and Sound class entries in Adobe’s ActionScript Language Reference.

Using Loader to Load Display Assets at Runtime

The Loader class loads an external display asset at runtime. ...

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