XLEFF - an XML Layout Engine For Flash

XLEFF is the acronym of XML Layout Engine For Flash, which is reminiscent of what XLEFF is: an XML layout engine, designed to be included in an SWF file.

The XML Layout Engine concept

An XML Layout Engine is a software functionality that allows you to generate a component-based user interface starting from an XML description.

A concrete example will clarify what XML Layout Engines do: let's consider the case of creating a Flash user interface made of one instance of the Button component only, as shown in the following figure:

In our example the stage size is 300x200 pixels and the Button instance is placed at (X: 100, Y: 89) as highlighted by the next figure:

Flash developers currently have two options to create a component-based user interface like that:

• They can create the Button instance in the authoring environment, or
• They can use ActionScript to generate the Button instance at runtime

Creating the Button instance in the authoring environment is a manual process that requires dragging the component on the stage and then adjusting its position and size, if needed.

The following example shows how the ActionScript code generating the same Button instance may look like:

var myButton:Button =
createClassObject(Button, "myButton", getNextHighestDepth(),
{_x:100, _y:89});

An XML Layout Engine, quite simply, provides a third option by allowing the creation of the same user interface via an XML description similar to the following snippet:

<button name="myButton" x="100" y="89" />

First conclusion

The three options considered in this article are very different from each other. The second part will explain what are the exclusive benefits deriving from the approach supported by XLEFF.