Changes in Flash MX 2004

Flash MX 2004 is a major upgrade for ActionScript users. Major additions include syntax and structural changes that aid the building of large ActionScript applications, greater support for text formatting, and greater support for the control and running of media streams.

The Flash component framework has been upgraded to take advantage of class-based optimizations and new features in ActionScript 2.0, including strict datatyping.

Flash MX Professional 2004's new Slides and Forms features (collectively called Screens) allow development using a PowerPoint-like or Visual Basic-style authoring metaphor with a minimum of scripting.

Even the Flash MX 2004 authoring tool's interface can be customized using the Flash JavaScript API (JSAPI). See the JSAPI Documentation section of the Flash MX 2004 Documentation page (http://www.macromedia.com/support/documentation/en/flash) for links to documents that explain how to create commands and tools for use in the Flash authoring environment.

Furthermore, JSFL (Flash JavaScript), allows you to script authoring operations. Complete coverage of JSFL is outside the scope of this book, but here's a quick example of command-line compilation for Windows. This JSFL script from Colin Moock tells Flash to create the .swf file for each .fla file in your project:

// Code in exportPetSupplies.jsfl:

// Open the .fla file.

var doc = fl.openDocument("file:///c|/data/projects/pet/petsupplies.fla");

// Export the .swf file.

doc.exportSWF("file:///c|/data/projects/pet/petsupplies.swf", true);

// Quit the Flash MX 2004 authoring tool (optional).

fl.quit(false);



// Command issued on command line from /pet/ directory:

"c:\program files\macromedia\flash mx 2004\flash.exe" exportPetSupplies.jsfl

For this command to work, Flash MX 2004 must not be running. After the command is issued, the compiled petsupplies.swf movie appears in the directory c:\data\projects\pet.

Both Flash MX 2004 and Flash MX Professional 2004 support ActionScript 2.0 but also still support ActionScript 1.0 syntax (you can set which version of the ActionScript compiler to use under FilePublish SettingsFlashActionScript Version). So developers can stick with ActionScript 1.0 or switch to ActionScript 2.0, which is geared more toward object-oriented development, at their own pace.

New ActionScript in Flash Player 7

Numerous additions to ActionScript in Flash Player 7 are available whether you are using ActionScript 1.0 or ActionScript 2.0. Flash's online Help provides a detailed list of the ActionScript changes (HelpActionScript Reference GuideWhat's New in Flash MX 2004 ActionScript).

Here is a partial list of new features:

Real-time error message feedback via the Error class, plus error handling via try/catch/finally and throw.
The ability to customize the Flash Player context menu via the ContextMenu class and the new menu property (for the Button, MovieClip, and TextField classes).
Support for the Mouse.onMouseWheel event, which detects changes in the mouse wheel position (Windows only) and an undocumented way to detect mouse wheel clicks [Hack #62] .
The MovieClipLoader class for creating preloaders (i.e., for displaying load status while the SWF file downloads).
The TextField.StyleSheet class, which offers CSS support.
SOAP support, which allows Flash Player 7 to access SOAP-based web services without requiring Flash Remoting to be installed on the server. (Prebuilt remote data connectivity components that implement SOAP communication are provided with Flash MX Professional 2004 only.)
Some methods of the MovieClip class, most notably getNextHighestDepth( ) and getInstanceAtDepth( ) for depth management.
The PrintJob class, which greatly simplifies Flash printing and gives much more control over printed output than the ActionScript 1.0 print functions.

Most Flash Player 6-format SWFs will play unmodified in Flash Player 7. However, Flash Player 7 also introduced a more stringent interdomain security policy, as described in Chapter 12, which may break certain Flash Player 6 content when viewed in Flash Player 7. The System.exactSettings property and the System.allowInsecureDomain( ) method allow you to change some of the domain security measures back to the less stringent Flash 6 style, thus allowing more Flash Player 6-format SWFs to run in Flash Player 7.

Although many of Flash Player 7's features are also supported by Flash Player 6.0.65 (a.k.a. Flash Player 6r65), many others are not. For maximum compatibility (until more end users install Flash Player 7), you should export your Flash MX 2004 files in Flash Player 6 format (choose FilePublish SettingsFlash and select Flash Player 6 as the Version, then check Optimize for Flash Player 6r65), unless you are using Flash Player 7-specific features.

Case Sensitivity and Strict Typing

ActionScript 2.0 allows you to specify the datatype for any property, variable, parameter, or function return value. The datatype is used by the compiler to perform type checking. That is, the compiler validates that only data of the correct datatype is assigned to each item for which a datatype is specified. ActionScript 2.0 is also case-sensitive (as discussed at http://swfoo.com/archives/000034.html) to bring it in conformance with the ECMA-262 Edition 4 (ECMA 4) proposed standard as discussed in detail at http://livedocs.macromedia.com/flash/mx2004/main/wwhelp/wwhimpl/common/html/wwhelp.htm?context=Flash_MX_2004_Documentation&file=01_what5.htm.

Although many nonprogrammers will see ActionScript 2.0's strict typing and case sensitivity as something they can live without, it isn't hard to use, and it can help you avoid errors. For example, in ActionScript 1.0, we could quite happily assign any data to a variable, like this:

answer = "Einstein";

However, further along in your timeline, you might mistakenly write this:

answer = 6;

The preceding statement assigns a numeric value to what was supposed to be a string variable, which is probably a mistake. ActionScript 1.0 could not detect such potential errors nor warn you about them. However, using ActionScript 2.0's strict datatyping, your code would become:

var answer:String = "Einstein";

Note the datatype, String, following the colon (known as post-colon syntax). It specifies that the answer variable should contain a string and not a value belonging to another datatype. Whenever you define a datatype for a variable, the variable must be preceded by the var keyword.

Suppose that later in the timeline you use:

answer = 6;

When you try to compile the FLA, Flash warns you of the mistake by displaying a type mismatch error in the Output panel. Using strict typing thus tends to detect errors and help you create more robust code.

ActionScript datatyping occurs at compile time in the authoring environment only. ActionScript supports type checking only when you choose ActionScript 2.0 as the ActionScript Version under FlashPublish SettingsFlash. Even when using the ActionScript 2.0 compiler, Flash does not perform type checking on any item for which you omit the post-colon datatype. This allows you to update legacy ActionScript 1.0 to ActionScript 2.0, even if you don't specify datatypes for every item.

LiveDocs

Keeping up with all the features in Flash and ActionScript isn't easy, especially since new bugs and updates mean the in-product documentation is not necessarily current. (Although if an Internet connection is available, Flash MX 2004 will periodically ask you whether it should download updated documentation.)

Although still in its early days, LiveDocs for Flash MX 2004 (http://livedocs.macromedia.com/flash/mx2004/index.html) offers users online access to the full Flash documentation. LiveDocs pages display other users' comments and include an Add Comments button that allows you to comment on a page's contents and usefulness.

Of particular interest is the online ActionScript dictionary?just the place to go if you are having trouble with getting a particular bit of code working and the in-product online Help isn't sufficient to address your question.