Adobe® Flex® 4 Language Reference
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flash.filters 
GlowFilter 
Packageflash.filters
Classpublic final class GlowFilter
InheritanceGlowFilter Inheritance BitmapFilter Inheritance Object

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

The GlowFilter class lets you apply a glow effect to display objects. You have several options for the style of the glow, including inner or outer glow and knockout mode. The glow filter is similar to the drop shadow filter with the distance and angle properties of the drop shadow filter set to 0. 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 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. For example, if 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

See also



Public Properties
 PropertyDefined By
  alpha : Number
The alpha transparency value for the color.
GlowFilter
  blurX : Number
The amount of horizontal blur.
GlowFilter
  blurY : Number
The amount of vertical blur.
GlowFilter
  color : uint
The color of the glow.
GlowFilter
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  inner : Boolean
Specifies whether the glow is an inner glow.
GlowFilter
  knockout : Boolean
Specifies whether the object has a knockout effect.
GlowFilter
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
  quality : int
The number of times to apply the filter.
GlowFilter
  strength : Number
The strength of the imprint or spread.
GlowFilter
Public Methods
 MethodDefined By
  
GlowFilter(color:uint = 0xFF0000, alpha:Number = 1.0, blurX:Number = 6.0, blurY:Number = 6.0, strength:Number = 2, quality:int = 1, inner:Boolean = false, knockout:Boolean = false)
Initializes a new GlowFilter instance with the specified parameters.
GlowFilter
  
[override] Returns a copy of this filter object.
GlowFilter
 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 color. Valid values are 0 to 1. For example, .25 sets a transparency value of 25%. The default value is 1.



Implementation
    public function get alpha():Number
    public function set alpha(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 (floating point). The default value is 6. Values that are a power of 2 (such as 2, 4, 8, 16, and 32) are optimized to render more quickly than other values.



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 (floating point). The default value is 6. Values that are a power of 2 (such as 2, 4, 8, 16, and 32) are optimized to render more quickly than other values.



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 glow. Valid values are in the hexadecimal format 0xRRGGBB. The default value is 0xFF0000.



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

inner

property 
inner:Boolean

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

Specifies whether the glow is an inner glow. The value true indicates an inner glow. The default is false, an outer glow (a glow 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

Specifies whether the object has a knockout effect. A value of true makes the object's fill transparent and reveals the background color of the document. The default value is false (no knockout effect).



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

See also

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 glow and the background. Valid values are 0 to 255. The default is 2.



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

GlowFilter

()Constructor
public function GlowFilter(color:uint = 0xFF0000, alpha:Number = 1.0, blurX:Number = 6.0, blurY:Number = 6.0, strength:Number = 2, quality:int = 1, inner:Boolean = false, knockout:Boolean = false)

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

Initializes a new GlowFilter instance with the specified parameters.

Parameters
color:uint (default = 0xFF0000) — The color of the glow, in the hexadecimal format 0xRRGGBB. The default value is 0xFF0000.
 
alpha:Number (default = 1.0) — The alpha transparency value for the color. Valid values are 0 to 1. For example, .25 sets a transparency value of 25%.
 
blurX:Number (default = 6.0) — The amount of horizontal blur. Valid values are 0 to 255 (floating point). Values that are a power of 2 (such as 2, 4, 8, 16 and 32) are optimized to render more quickly than other values.
 
blurY:Number (default = 6.0) — The amount of vertical blur. Valid values are 0 to 255 (floating point). Values that are a power of 2 (such as 2, 4, 8, 16 and 32) are optimized to render more quickly than other values.
 
strength:Number (default = 2) — The strength of the imprint or spread. The higher the value, the more color is imprinted and the stronger the contrast between the glow and the background. Valid values are 0 to 255.
 
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, see the description of the quality property.

 
inner:Boolean (default = false) — Specifies whether the glow is an inner glow. The value true specifies an inner glow. The value false specifies an outer glow (a glow around the outer edges of the object).
 
knockout:Boolean (default = false) — Specifies whether the object has a knockout effect. The value true makes the object's fill transparent and reveals the background color of the document.

See also

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 GlowFilter instance with all the properties of the original GlowFilter instance.
GlowFilterExample.as

The following example draws a square and applies a blur filter to it. The general workflow of the example is as follows:
  1. Import the required classes.
  2. Declare three properties used in the draw method, which uses methods of the Graphics class accessed through the graphics property of Sprite to draw an orange square.
  3. Create the constructor function, which does the following:
    • Calls the draw method.
    • Creates a new BitmapFilter object named filter and assigns it the return value of a call to getBitmapFilter(), which defines the filter.
    • Creates a new array named myFilters and adds filter to it.
    • Assigns myFilters to the filters property of the BevelFilterExample 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.GlowFilter;

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

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

        private function getBitmapFilter():BitmapFilter {
            var color:Number = 0x33CCFF;
            var alpha:Number = 0.8;
            var blurX:Number = 35;
            var blurY:Number = 35;
            var strength:Number = 2;
            var inner:Boolean = false;
            var knockout:Boolean = false;
            var quality:Number = BitmapFilterQuality.HIGH;

            return new GlowFilter(color,
                                  alpha,
                                  blurX,
                                  blurY,
                                  strength,
                                  quality,
                                  inner,
                                  knockout);
        }

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