ActionScript® 3.0 Reference for the Adobe® Flash® Platform
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flash.filters 

DropShadowFilter  - AS3

Packageflash.filters
Classpublic final class DropShadowFilter
InheritanceDropShadowFilter Inheritance BitmapFilter Inheritance Object

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The DropShadowFilter class lets you add a drop shadow to display objects. The shadow algorithm is based on the same box filter that the blur filter uses. You have several options for the style of the drop shadow, including inner or outer shadow and knockout mode. You can apply the filter to any display object (that is, objects that inherit from the DisplayObject class), such as MovieClip, SimpleButton, TextField, and Video objects, as well as to BitmapData objects.

The use of filters depends on the object to which you apply the filter:

  • To apply filters to display objects use the filters property (inherited from DisplayObject). Setting the filters property of an object does not modify the object, and you can remove the filter by clearing the filters property.
  • To apply filters to BitmapData objects, use the BitmapData.applyFilter() method. Calling applyFilter() on a BitmapData object takes the source BitmapData object and the filter object and generates a filtered image as a result.

If you apply a filter to a display object, the value of the cacheAsBitmap property of the display object is set to true. If you clear all filters, the original value of cacheAsBitmap is restored.

This filter supports Stage scaling. However, it does not support general scaling, rotation, and skewing. If the object itself is scaled (if scaleX and scaleY are set to a value other than 1.0), the filter is not scaled. It is scaled only when the user zooms in on the Stage.

A filter is not applied if the resulting image exceeds the maximum dimensions. In AIR 1.5 and Flash Player 10, the maximum is 8,191 pixels in width or height, and the total number of pixels cannot exceed 16,777,215 pixels. (So, if an image is 8,191 pixels wide, it can only be 2,048 pixels high.) In Flash Player 9 and earlier and AIR 1.1 and earlier, the limitation is 2,880 pixels in height and 2,880 pixels in width. If, for example, you zoom in on a large movie clip with a filter applied, the filter is turned off if the resulting image exceeds the maximum dimensions.

View the examples

Related API Elements



Public Properties
 PropertyDefined By
  alpha : Number
The alpha transparency value for the shadow color.
DropShadowFilter
  angle : Number
The angle of the shadow.
DropShadowFilter
  blurX : Number
The amount of horizontal blur.
DropShadowFilter
  blurY : Number
The amount of vertical blur.
DropShadowFilter
  color : uint
The color of the shadow.
DropShadowFilter
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  distance : Number
The offset distance for the shadow, in pixels.
DropShadowFilter
  hideObject : Boolean
Indicates whether or not the object is hidden.
DropShadowFilter
  inner : Boolean
Indicates whether or not the shadow is an inner shadow.
DropShadowFilter
  knockout : Boolean
Applies a knockout effect (true), which effectively makes the object's fill transparent and reveals the background color of the document.
DropShadowFilter
  quality : int
The number of times to apply the filter.
DropShadowFilter
  strength : Number
The strength of the imprint or spread.
DropShadowFilter
Public Methods
 MethodDefined By
  
DropShadowFilter(distance:Number = 4.0, angle:Number = 45, color:uint = 0, alpha:Number = 1.0, blurX:Number = 4.0, blurY:Number = 4.0, strength:Number = 1.0, quality:int = 1, inner:Boolean = false, knockout:Boolean = false, hideObject:Boolean = false)
Creates a new DropShadowFilter instance with the specified parameters.
DropShadowFilter
  
[override] Returns a copy of this filter object.
DropShadowFilter
 Inherited
Indicates whether an object has a specified property defined.
Object
 Inherited
Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.
Object
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
Returns the string representation of this object, formatted according to locale-specific conventions.
Object
 Inherited
Returns the string representation of the specified object.
Object
 Inherited
Returns the primitive value of the specified object.
Object
Property Detail

alpha

property
alpha:Number

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The alpha transparency value for the shadow color. Valid values are 0.0 to 1.0. For example, .25 sets a transparency value of 25%. The default value is 1.0.



Implementation
    public function get alpha():Number
    public function set alpha(value:Number):void

angle

property 
angle:Number

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The angle of the shadow. Valid values are 0 to 360 degrees (floating point). The default value is 45.



Implementation
    public function get angle():Number
    public function set angle(value:Number):void

blurX

property 
blurX:Number

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The amount of horizontal blur. Valid values are 0 to 255.0 (floating point). The default value is 4.0.



Implementation
    public function get blurX():Number
    public function set blurX(value:Number):void

blurY

property 
blurY:Number

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The amount of vertical blur. Valid values are 0 to 255.0 (floating point). The default value is 4.0.



Implementation
    public function get blurY():Number
    public function set blurY(value:Number):void

color

property 
color:uint

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The color of the shadow. Valid values are in hexadecimal format 0xRRGGBB. The default value is 0x000000.



Implementation
    public function get color():uint
    public function set color(value:uint):void

distance

property 
distance:Number

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The offset distance for the shadow, in pixels. The default value is 4.0 (floating point).



Implementation
    public function get distance():Number
    public function set distance(value:Number):void

hideObject

property 
hideObject:Boolean

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

Indicates whether or not the object is hidden. The value true indicates that the object itself is not drawn; only the shadow is visible. The default is false (the object is shown).



Implementation
    public function get hideObject():Boolean
    public function set hideObject(value:Boolean):void

inner

property 
inner:Boolean

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

Indicates whether or not the shadow is an inner shadow. The value true indicates an inner shadow. The default is false, an outer shadow (a shadow around the outer edges of the object).



Implementation
    public function get inner():Boolean
    public function set inner(value:Boolean):void

knockout

property 
knockout:Boolean

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

Applies a knockout effect (true), which effectively makes the object's fill transparent and reveals the background color of the document. The default is false (no knockout).



Implementation
    public function get knockout():Boolean
    public function set knockout(value:Boolean):void

quality

property 
quality:int

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The number of times to apply the filter. The default value is BitmapFilterQuality.LOW, which is equivalent to applying the filter once. The value BitmapFilterQuality.MEDIUM applies the filter twice; the value BitmapFilterQuality.HIGH applies it three times. Filters with lower values are rendered more quickly.

For most applications, a quality value of low, medium, or high is sufficient. Although you can use additional numeric values up to 15 to achieve different effects, higher values are rendered more slowly. Instead of increasing the value of quality, you can often get a similar effect, and with faster rendering, by simply increasing the values of the blurX and blurY properties.



Implementation
    public function get quality():int
    public function set quality(value:int):void

Related API Elements

strength

property 
strength:Number

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

The strength of the imprint or spread. The higher the value, the more color is imprinted and the stronger the contrast between the shadow and the background. Valid values are from 0 to 255.0. The default is 1.0.



Implementation
    public function get strength():Number
    public function set strength(value:Number):void
Constructor Detail

DropShadowFilter

()Constructor
public function DropShadowFilter(distance:Number = 4.0, angle:Number = 45, color:uint = 0, alpha:Number = 1.0, blurX:Number = 4.0, blurY:Number = 4.0, strength:Number = 1.0, quality:int = 1, inner:Boolean = false, knockout:Boolean = false, hideObject:Boolean = false)

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

Creates a new DropShadowFilter instance with the specified parameters.

Parameters
distance:Number (default = 4.0) — Offset distance for the shadow, in pixels.
 
angle:Number (default = 45) — Angle of the shadow, 0 to 360 degrees (floating point).
 
color:uint (default = 0) — Color of the shadow, in hexadecimal format 0xRRGGBB. The default value is 0x000000.
 
alpha:Number (default = 1.0) — Alpha transparency value for the shadow color. Valid values are 0.0 to 1.0. For example, .25 sets a transparency value of 25%.
 
blurX:Number (default = 4.0) — Amount of horizontal blur. Valid values are 0 to 255.0 (floating point).
 
blurY:Number (default = 4.0) — Amount of vertical blur. Valid values are 0 to 255.0 (floating point).
 
strength:Number (default = 1.0) — The strength of the imprint or spread. The higher the value, the more color is imprinted and the stronger the contrast between the shadow and the background. Valid values are 0 to 255.0.
 
quality:int (default = 1) — The number of times to apply the filter. Use the BitmapFilterQuality constants:
  • BitmapFilterQuality.LOW
  • BitmapFilterQuality.MEDIUM
  • BitmapFilterQuality.HIGH

For more information about these values, see the quality property description.

 
inner:Boolean (default = false) — Indicates whether or not the shadow is an inner shadow. A value of true specifies an inner shadow. A value of false specifies an outer shadow (a shadow around the outer edges of the object).
 
knockout:Boolean (default = false) — Applies a knockout effect (true), which effectively makes the object's fill transparent and reveals the background color of the document.
 
hideObject:Boolean (default = false) — Indicates whether or not the object is hidden. A value of true indicates that the object itself is not drawn; only the shadow is visible.

Related API Elements

Method Detail

clone

()method
override public function clone():BitmapFilter

Language Version: ActionScript 3.0
Runtime Versions: AIR 1.0, Flash Player 9

Returns a copy of this filter object.

Returns
BitmapFilter — A new DropShadowFilter instance with all the properties of the original DropShadowFilter instance.
DropShadowFilterExample.as

The following example creates a yellow square and applies a drop shadow to it. The general workflow of this example is as follows:
  1. Declare three properties that are used to draw the square to which the filter is applied.
  2. Create the constructor function. The constructor calls the draw() method, which uses methods of the Graphics class accessed through the graphics property of Sprite to draw an orange square.
  3. In the constructor, declare a variable filter as a BitmapFilter object and assign it to the return value of a call to getBitmapFilter(). The getBitmapFilter() method defines the drop shadow filter used.
  4. Create a new Array object myFilters and add filter to the array. Assign the myFilters array to the filters property of the DropShadowFilterExample object. This applies all filters found in myFilters, which in this case is only filter.

package {
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.filters.BitmapFilter;
    import flash.filters.BitmapFilterQuality;
    import flash.filters.DropShadowFilter;

    public class DropShadowFilterExample extends Sprite {
        private var bgColor:uint = 0xFFCC00;
        private var size:uint    = 80;
        private var offset:uint  = 50;

        public function DropShadowFilterExample() {
            draw();
            var filter:BitmapFilter = getBitmapFilter();
            var myFilters:Array = new Array();
            myFilters.push(filter);
            filters = myFilters;
        }

        private function getBitmapFilter():BitmapFilter {
            var color:Number = 0x000000;
            var angle:Number = 45;
            var alpha:Number = 0.8;
            var blurX:Number = 8;
            var blurY:Number = 8;
            var distance:Number = 15;
            var strength:Number = 0.65;
            var inner:Boolean = false;
            var knockout:Boolean = false;
            var quality:Number = BitmapFilterQuality.HIGH;
            return new DropShadowFilter(distance,
                                        angle,
                                        color,
                                        alpha,
                                        blurX,
                                        blurY,
                                        strength,
                                        quality,
                                        inner,
                                        knockout);
        }

        private function draw():void {
            graphics.beginFill(bgColor);
            graphics.drawRect(offset, offset, size, size);
            graphics.endFill();
        }
    }
}