Recipe 8.2. Adding a Bitmap to the Display List

Problem

You have created a BitmapData and now want to make it visible.

Solution

Create a Bitmap using the BitmapData and add that to the display list.

Discussion

To make anything visible in an application in ActionScript 3.0, you must add it to the display list. (See Chapter 6 for a full discussion of the display list.) You add objects to the display list by calling the addChild( ) method from the main application class, or any other object that has already been added to the display list. However, the addChild( ) method only accepts objects that are subclasses of flash.display.DisplayObject. The BitmapData class is descended only from Object, so you may not add it to the display list directly.

To add it to the display list, use the flash.display.Bitmap class, which is a subclass of DisplayObject. It is a sort of wrapper for BitmapData, allowing a BitmapData to be displayed.

When you create a new instance of Bitmap by calling its constructor, you pass in a reference to a BitmapData. Then you can add the Bitmap to the display list using addChild( ). The following example creates a BitmapData with a red fill, and displays it via a Bitmap:

var bitmap:BitmapData = new BitmapData(100, 100, true, 0xffff0000); var image:Bitmap = new Bitmap(bitmap); addChild(image);

Problem

Solution

Discussion

See Also