ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Display programming
Although all visible display objects inherit from the DisplayObject class, the type of each is of a specific subclass of
DisplayObject class. For example, there is a constructor function for the Shape class or the Video class, but there is
no constructor function for the DisplayObject class.
Important concepts and terms
The following reference list contains important terms that you will encounter when programming ActionScript
graphics:
Alpha The color value representing the amount of transparency (or more correctly, the amount of opacity) in a color.
For example, a color with an alpha channel value of 60% only shows 60% of its full strength, and is 40% transparent.
Bitmap graphic A graphic that is defined in the computer as a grid (rows and columns) of colored pixels. Commonly
bitmap graphics include digital photos and similar images.
Blending mode A specification of how the contents of two overlapping images should interact. Commonly an opaque
image on top of another image simply blocks the image underneath so that it isn’t visible at all; however, different
blending modes cause the colors of the images to blend together in different ways so the resulting content is some
combination of the two images.
Display list The hierarchy of display objects that will be rendered as visible screen content by Flash Player and AIR.
The Stage is the root of the display list, and all the display objects that are attached to the Stage or one of its children
form the display list (even if the object isn’t actually rendered, for example if it’s outside the boundaries of the Stage).
Display object An object which represents some type of visual content in Flash Player or AIR. Only display objects can
be included in the display list, and all display object classes are subclasses of the DisplayObject class.
Display object container A special type of display object which can contain child display objects in addition to
(generally) having its own visual representation.
Main class of the SWF file The class that defines the behavior for the outermost display object in a SWF file, which
conceptually is the class for the SWF file itself. For instance, in a SWF created in Flash authoring, the main class is the
document class. It has a “main timeline” which contains all other timelines; the main class of the SWF file is the class
of which the main timeline is an instance.
Masking A technique of hiding from view certain parts of an image (or conversely, only allowing certain parts of an
image to display). The portions of the mask image become transparent, so content underneath shows through. The
term is related to painter’s masking tape that is used to prevent paint from being applied to certain areas.
Stage The visual container that is the base or background of all visual content in a SWF.
Transformation An adjustment to a visual characteristic of a graphic, such as rotating the object, altering its scale,
skewing or distorting its shape, or altering its color.
Vector graphic A graphic that is defined in the computer as lines and shapes drawn with particular characteristics
(such as thickness, length, size, angle, and position).
Last updated 6/6/2012
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