7.0. Introduction
With
ActionScript, you can
programmatically draw many display objects such as Shape, Sprite, Button, and MovieClip. Each of these classes
has a graphics property that is an instance of the flash.display.Graphics class. The
Graphics class defines
an API for drawing content programmatically. Most recipes in this
chapter discuss how to use the Graphics class API.
Since the Shape, Sprite,
Button, and MovieClip classes already define graphics
properties that are references to Graphics instances, it is
not necessary to construct new Graphics objects. The
graphics property for a display object draws within that display
object. For example, the following code sets the line style for the
Graphics object targeting a sprite called
sampleSprite:
sampleSprite.graphics.lineStyle( );
The Graphics class defines an API for
drawing basic lines and simple shapes. However, some common shapes
are difficult to draw with the Graphics API. For that
reason, the AS3CBLibrary
(available at http://www.rightactionscript.com/ascb)
includes an ascb.drawing.Pen class. The
Pen class is a proxy
(a wrapper) for the Graphics class. You can construct a new
Pen instance by passing it a
reference to the Graphics object you want to target:
var pen:Pen = new Pen(sampleSprite.graphics);
The Pen class proxies requests to all the
methods of the Graphics class. That means you can call any
of the Graphics methods from the Pen class. In
addition, the Pen class defines an API that allows you to
more simply draw arcs, ellipses, polygons, stars, and more. The
Pen class methods are discussed in the relevant recipes in
this chapter.
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