Flash Goodies

Before you dive into the details of ActionScript, let’s first briefly discuss what you can do with it. Presumably, you already have at least some minimal experience with Flash, and you are familiar with the playback of the timeline. The default behavior in Flash is such that when an SWF (the compiled Flash movie format) is opened in a player, the timeline begins to play automatically. In many cases, this is not, in and of itself, problematic. However, when the playhead reaches the end of the timeline, it then loops back to the beginning of the timeline and starts playing it again. Often you want an animation to play only one time and then stop at the end. To prevent the Flash movie from looping the playback, you actually have to give it the instruction to stop. You can do this by placing one line of code on the last frame. That one line of code looks like this:

stop();

With this first command, you can see that ActionScript really can read very much like English. The command (or statement) stop() instructs the Flash movie to stop playback. Of course, you can do many more complex things with ActionScript besides a simple stopping of the playback. Using ActionScript, you can load external data into your movie for the purposes of creating dynamic, user-specific customizations or even e-commerce applications. Using
ActionScript, you can create nonlinear, interactive presentations and animations. The possibilities with ActionScript are practically limitless, and they allow you to create Flash applications with tremendous potential. In fact, there is very little that you can think up that cannot be accomplished with ActionScript.

ActionScript is the programming language used to send instructions
to your Flash movie. It is how you “talk” to your Flash movie, telling it
exactly what you want it to do. The more effectively and fluently you
are able to communicate in ActionScript, the more effective you will
be in creating Flash movies that do what you want.

To help you understand what ActionScript is, it is helpful to understand
the similarities between ActionScript and something you
already know — human languages. Any human language is merely a
collection of symbols and sounds used to represent ideas. The same
is true of any programming or scripting language. ActionScript, for
example, is merely a collection of words and symbols with the purpose
of communicating instructions to the Flash movie. Additionally,
human languages have syntax and vocabulary that are specific to
that language, but not wholly dissimilar to those of other languages.

The same is true of scripting languages. Not only is ActionScript similar to other scripting languages in many ways, but you may also find that with the right perspective it is quite similar to the English language. Programming languages are in many ways remarkably similar to the languages humans use to communicate. Therefore, although hearing a foreign language might seem like gibberish at first, with a little training, you can begin to share your ideas with people in a language they understand. It is much the same with ActionScript. Think of this book as your language teacher. You’ll start in this chapter by developing an understanding of the ActionScript culture, the environment, and the tools you can use to begin your ActionScript journey. Then, in Chapter 3 you look at and investigate the parts of speech and the syntax and structure. With these fundamentals under your belt, you’ll be well on your way to communicating with Flash. ActionScript is based on the ECMA-262 specification, although it does not adhere to it fully. If you want to learn more, you can read about it at the ECMA web site

Adobeflash

Flash has begun to mature as a product, and ActionScript has begun to mature as a language. That represents both opportunity and challenge to you. As a mature language, ActionScript provides a broad spectrum of features and functionality. The possibilities are limitless: There is great opportunity to build new, innovative, useful, and interesting applications using Flash and ActionScript. However, with that opportunity comes the challenge of learning how to use ActionScript effectively. If you want to express your thoughts and feelings well, you need the right language for communicating them. Likewise, with ActionScript the challenge is to learn the language so that there is a natural flow of expression that is seamless from its conception to its manifestation in code.

The Macromedia Flash authoring tool was originally an animation tool, but it is so much more than that today. From the early days when it was known as FutureSplash to the Flash 8 version today, Flash has always excelled as a vector-drawing and animation tool. Even though animation is still a large part of what Flash does, now it is only a fraction of the Flash toolset. Here are the broad categories available in Flash 8:

 Vector graphics—Vector drawings are made up of many lines
and curves and fills, each defined by a set of coordinates and
the paths along them. These paths—vectors—are described
via mathematical functions. Because mathematical formulas
are used to store and create the image, they are resolutionindependent
and can be resized arbitrarily smaller or larger
with no loss of quality. Also, images based on calculations are
generally smaller in file size than bitmap images, which is an
advantage for bandwidth-limited Web delivery.

 Bitmap graphics—Bitmap (a.k.a. raster) images are made up
of a grid of pixels. Every pixel’s color and location in the grid
must be stored individually, which usually (but not always)
means larger file sizes than images made of vector calculations.
Although Flash handles bitmap graphics, the program is not
built for direct image manipulation on a pixel level; rather, Flash
is primarily an image handler. Flash can retain JPEG compression
of imported JPEG files, as well as apply lossless or custom
lossy compression to imported bitmap images.