Programming Flex 3

Using Flex Elements

The Flex framework includes a core set of languages and libraries that are the basis of any Flex application. Using MXML, ActionScript, and the Flex class library you can construct and compile .swf content that you can then deploy to Flash Player.

MXML

MXML is an XML-based markup language primarily for describing screen layout. In that respect, it is much like HTML. Using MXML tags you can add components such as form controls and media playback components to layout containers such as grids.

In addition to screen layout, you can use MXML to describe effects, transitions, data models, and data binding. MXML is robust enough that it is possible to build many applications entirely with MXML. Flex Builder enables you to construct MXML with a WYSIWYG approach, enabling you to build basic Flex applications without writing any code.

Although the WYSIWYG approach is helpful for basic prototypes and simple applications, writing MXML code is still necessary for more complex tasks. Additionally, sophisticated Flex applications generally require both MXML and ActionScript.

MXML is a declarative way to create Flex content, but the simplicity should not fool you into thinking that MXML is not powerful. MXML provides a fast and powerful way to create layout and UI content. However, MXML documents get compiled in several steps, the first of which converts the MXML to an ActionScript class. This means MXML documents provide you with all the power of object-oriented design, but with ...