Flash Article

Visual Programming in Macromedia Flash

As a visual programmer, you may have already tried your hand at a previous version of Flash—and been you were likely confused and overwhelmed by it. Flash has never been more inherently complex than Visual Basic 6, Visual Studio .NET, or Delphi, but it comes from a lineage of animation tools, not programming tools. This fundamental difference has made Flash an impractical tool for visual programmers. Flash MX Professional 2004 changes all that.

Before I tout the benefits of the new version, here's a quick recap of where Flash has been. Flash 1 and 2 refined and improved the animation capabilities of the product. Flash 3 added the ability to individually animate movie clips and create stand-alone EXE files—the platform's first foray out of the browser. Flash 4 and 5 contributed major improvements to its scripting capabilities (called ActionScript), including XML support. Flash MX boasted more ECMA-compliant scripting, including objects and events, pre-built UI components like buttons and sliders, and a series of impressive add-ons for multiuser applications (Macromedia Flash Communication Server) and distributed application support (Macromedia Flash Remoting MX).

Despite these improvements, Flash development still required timeline-based authoring and manual coding. Flash MX Professional adds several major changes to Flash application authoring that help visual programmers start creating their own Rich Internet Applications.

With 97 percent worldwide web browser penetration, Flash content can be viewed on almost any platform, including web, wireless, embedded devices, and—with Macromedia Central—on desktops. While platforms like Java and .NET promise code reuse for mobile development, Flash makes code truly reusable across platforms, especially on mobile devices.

Flash code is truly reusable, unlike Java code, which developers must often tweak for each platform (although the Flash Player is not available on as many mobile platforms as Java is). You can also move Flash applications among platforms without redesigning or recoding them, unlike other tools such as Visual Studio .NET mobile web forms.

Building Flash Form Screens

The biggest change in Flash MX Professional is the addition of a true visual programming environment. Prior versions of Flash provided no way to easily define application screens like a login form or a display window. Flash developers had to kludge application screens into labeled Timeline keyframes or create custom movie clips that acted like application screens. Flash form applications make it possible to create structured applications that are independent of the Timeline.

Visual programmers familiar with Visual Basic, Delphi, and other environments will immediately notice how much more approachable forms make the Flash platform. As in Visual Basic, you can create a form quickly and add UI and data components to the form by dragging them from a toolbar in the IDE. Since Flash content lives primarily within web browsers and other containers, a Flash form is really a screen within the application, not a Windows form. You can use ActionScript commands to show and hide forms in your Flash application and control objects within them.

Another major difference between Windows forms and Flash form screens is that the latter are hierarchical and inherited (see Figure 1). When you create a form within a form, the child form inherits all the elements of its parent. Hierarchical forms take a bit of getting used to for Windows forms designers but the benefit is striking.

Figure 1. Hierarchical form screens make it easy to design different screens occupying the same space on the stage.

In VB, Delphi, and other environments, creating different areas that occupy the same form can be a nuisance (see Figure 2). Typically you use a Windows frame control to house different elements, but then you may have trouble viewing them in the designer. Hierarchical forms make it easy to move between subsections of a screen without the effort.

Figure 2. In this Visual Studio .NET Windows form application, the groups of controls overlap and need to be moved around so they can be properly manipulated.

Here's how you create the framework for the Flash form application:

1. In Flash MX Professional, choose File > New and select Flash Form Application. This creates a default application with two nested form screens.
2. Change the instance name (in the Property inspector) of form1 to frmSearch. This form will contain the main search interface.
3. Right-click (Control-click) frmSearch and choose Insert Nested Screen. This creates a new form screen called form2 underneath frmSearch. Change the instance name of the new form screen to frmLoading.
4. Now you can add UI components (the equivalent of VB controls) to the forms. The application form is the parent of all the other forms in the application; anything you put on that form will also appear on any of its child forms. For this application, I placed a Google graphic in the upper left corner to show how this works.
5. Select the frmSearch form. In the Components panel, drag a Label, Button TextInput, and TextArea component onto the Stage. Arrange the components as shown in Figure 3. (Right-click and choose Free Transform to resize the components.)
6. Using the Property inspector, give the components the following instance names—Label: lblSearchTime; Button: btnSearch; TextInput: txtQuery; and TextArea: txtResults.

Figure 3. Arranging the UI components on the form