ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Display programming
trace(container.getChildByName("banana loader") is Loader); // true
Using the getChildByName() method can result in slower performance than using the getChildAt() method.
Since a display object container can contain other display object containers as child objects in its display list, you can
traverse the full display list of the application as a tree. For example, in the code excerpt shown earlier, once the load
operation for the pict Loader object is complete, the pict object will have one child display object, which is the
bitmap, loaded. To access this bitmap display object, you can write pict.getChildAt(0). You can also write
container.getChildAt(0).getChildAt(0) (since container.getChildAt(0) == pict).
The following function provides an indented trace() output of the display list from a display object container:
function traceDisplayList(container:DisplayObjectContainer,indentString:String = ""):void
{
var child:DisplayObject;
for (var i:uint=0; i < container.numChildren; i++)
{
child = container.getChildAt(i);
trace(indentString, child, child.name);
if (container.getChildAt(i) is DisplayObjectContainer)
{
traceDisplayList(DisplayObjectContainer(child), indentString + "")
}
}
}
Adobe Flex
If you use Flex, you should know that Flex defines many component display object classes, and these classes override
the display list access methods of the DisplayObjectContainer class. For example, the Container class of the mx.core
package overrides the addChild() method and other methods of the DisplayObjectContainer class (which the
Container class extends). In the case of the addChild() method, the class overrides the method in such a way that you
cannot add all types of display objects to a Container instance in Flex. The overridden method, in this case, requires
that the child object that you are adding be a type of mx.core.UIComponent object.
Setting Stage properties
Flash Player 9 and later, Adobe AIR 1.0 and later
The Stage class overrides most properties and methods of the DisplayObject class. If you call one of these overridden
properties or methods, Flash Player and AIR throw an exception. For example, the Stage object does not have x or y
properties, since its position is fixed as the main container for the application. The x and y properties refer to the
position of a display object relative to its container, and since the Stage is not contained in another display object
container, these properties do not apply.
Note: Some properties and methods of the Stage class are only available to display objects that are in the same security
sandbox as the first SWF file loaded. For details, see “Stage security” on page 1052.
Controlling the playback frame rate
Flash Player 9 and later, Adobe AIR 1.0 and later
The frameRate property of the Stage class is used to set the frame rate for all SWF files loaded into the application.
For more information, see the ActionScript 3.0 Reference for the Adobe Flash Platform.
Last updated 6/6/2012
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