MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manuel d'utilisateur télécharger pdf (Page 12)

12 Getting Started

Application and container initialization

The initialize event is now dispatched later in the startup and component creation life

cycle. In particular, it is now dispatched after the object’s children have been created. If your

event handler assumes that the object’s children have already been created, you can use the

initialize event. If your event handler requires that the object’s children have been

processed by the LayoutManager class, use the

creationComplete event; for example:

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"

creationComplete="initApp()">

Alpha and scale properties

The scaleX, scaleY, and alpha properties now range from 0.0 to 1.0, rather than 1 to 100.

This is also true for the

Fade.alphaFrom, Fade.alphaTo, Zoom.zoomFrom, and

Zoom.zoomTo properties.

Event.currentTarget

Use the currentTarget property rather than the target property of the Event object. The

Event object now has two properties:

target and currentTarget. The former is the object

that originally dispatched the event, and the latter is the object to which your event handler is

attached. The two are often the same, but they may differ if the event has bubbled up from a

child object.

In most cases, you will want to change the

target property to the currentTarget property,

because the object that was previously the target is now most likely the current target; for

example:

switch (event.currentTarget.className) { ... }

For more information, see “Using the target property” on page 113.

Uninitialized values

Remove checks against the undefined value. In Flex 2, undefined is only for use with the *

(no-type) “type”. Other types can no longer store the

undefined value. If you assign

undefined to other types, it will be coerced into null, NaN, 0, or false. You can use the

isNaN() method to check if a variable is NaN.

If you do not initialize a variable at all, the initial value is different than in Flex 1.x. For more

information, see “Initializing variables” on page 29.

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MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manuel d'utilisateur Page 12