Package	mx.core
Class	public class BitmapAsset
Inheritance	BitmapAsset FlexBitmap Bitmap DisplayObject EventDispatcher Object
Implements	IFlexAsset, IFlexDisplayObject

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

BitmapAsset is a subclass of the flash.display.Bitmap class which represents bitmap images that you embed in a Flex application. It implements the IFlexDisplayObject interface, which makes it possible for an embedded bitmap image to be displayed in an Image control, or to be used as a container background or a component skin.

The bitmap image that you're embedding can be in a JPEG, GIF, or PNG file. You can also embed a bitmap symbol that is in a SWF file produced by Flash. In each of these cases, the MXML compiler autogenerates a class that extends BitmapAsset to represent the embedded bitmap image.

You don't generally have to use the BitmapAsset class directly when you write a Flex application. For example, you can embed a GIF file and display the image in an Image control by writing the gollowing:

  <mx:Image id="logo" source="@Embed(source='Logo.gif')"/>

or use it as the application's background image in CSS syntax by writing

  <fx:Style>
      @namespace mx "library://ns.adobe.com/flex/mx"
      mx|Application {
          backgroundImage: Embed(source="Logo.gif")
      }
  <fx:Style/>

without having to understand that the MXML compiler has created a subclass of BitmapAsset for you.

However, it may be useful to understand what is happening at the ActionScript level. To embed a bitmap image in ActionScript, you declare a variable of type Class, and put [Embed] metadata on it. For example, you embed a GIF file like this:

  [Bindable]
  [Embed(source="Logo.gif")]
  private var logoClass:Class;

The MXML compiler sees the .gif extension, transcodes the GIF data into the bitmap format that the player uses, autogenerates a subclass of the BitmapAsset class, and sets your variable to be a reference to this autogenerated class. You can then use this class reference to create instances of the BitmapAsset using the new operator, and you can use APIs of the BitmapAsset class on them:

  var logo:BitmapAsset = BitmapAsset(new logoClass());
  logo.bitmapData.noise(4);

However, you rarely need to create BitmapAsset instances yourself because image-related properties and styles can simply be set to an image-producing class, and components will create image instances as necessary. For example, to display this image in an Image control, you can set the Image's source property to logoClass. In MXML you could do this as follows:

  <mx:Image id="logo" source="{logoClass}"/>

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