Drop shadows give the impression that there is a separate light
source situated above a target object. The position and intensity
of this light source can be modified to produce a variety of different
drop shadow effects.
The DropShadowFilter class uses an algorithm that is similar
to the blur filter’s algorithm. The main difference is that the
drop shadow filter has a few more properties that you can modify
to simulate different light-source attributes (such as alpha, color,
offset and brightness).
The drop shadow filter also allows you to apply custom transformation
options on the style of the drop shadow, including inner or outer
shadow and knockout (also known as cutout) mode.
The following code creates a square box sprite and applies a
drop shadow filter to it:
import flash.display.Sprite;
import flash.filters.DropShadowFilter;
// Draw a box.
var boxShadow:Sprite = new Sprite();
boxShadow.graphics.lineStyle(1);
boxShadow.graphics.beginFill(0xFF3300);
boxShadow.graphics.drawRect(0, 0, 100, 100);
boxShadow.graphics.endFill();
addChild(boxShadow);
// Apply the drop shadow filter to the box.
var shadow:DropShadowFilter = new DropShadowFilter();
shadow.distance = 10;
shadow.angle = 25;
// You can also set other properties, such as the shadow color,
// alpha, amount of blur, strength, quality, and options for
// inner shadows and knockout effects.
boxShadow.filters = [shadow];
