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

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

The GradientGlowFilter class lets you apply a gradient glow effect to display objects. A gradient glow is a realistic-looking glow with a color gradient that you can control. You can apply a gradient glow around the inner or outer edge of an object or on top of an object. You can apply the filter to any display object (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. 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 effect 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
  alphas : Array
An array of alpha transparency values for the corresponding colors in the colors array.
GradientGlowFilter
  angle : Number
The angle, in degrees.
GradientGlowFilter
  blurX : Number
The amount of horizontal blur.
GradientGlowFilter
  blurY : Number
The amount of vertical blur.
GradientGlowFilter
  colors : Array
An array of colors that defines a gradient.
GradientGlowFilter
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  distance : Number
The offset distance of the glow.
GradientGlowFilter
  knockout : Boolean
Specifies whether the object has a knockout effect.
GradientGlowFilter
 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.
GradientGlowFilter
  ratios : Array
An array of color distribution ratios for the corresponding colors in the colors array.
GradientGlowFilter
  strength : Number
The strength of the imprint or spread.
GradientGlowFilter
  type : String
The placement of the filter effect.
GradientGlowFilter
Public Methods
 MethodDefined By
  
GradientGlowFilter(distance:Number = 4.0, angle:Number = 45, colors:Array = null, alphas:Array = null, ratios:Array = null, blurX:Number = 4.0, blurY:Number = 4.0, strength:Number = 1, quality:int = 1, type:String = "inner", knockout:Boolean = false)
Initializes the filter with the specified parameters.
GradientGlowFilter
  
[override] Returns a copy of this filter object.
GradientGlowFilter
 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

alphas

property
alphas:Array

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

An array of alpha transparency values for the corresponding colors in the colors array. Valid values for each element in the array are 0 to 1. For example, .25 sets the alpha transparency value to 25%.

The alphas property cannot be changed by directly modifying its values. Instead, you must get a reference to alphas, make the change to the reference, and then set alphas to the reference.

The colors, alphas, and ratios properties are related. The first element in the colors array corresponds to the first element in the alphas array and in the ratios array, and so on.



Implementation
    public function get alphas():Array
    public function set alphas(value:Array):void

Throws
TypeError — The Array is null when being set

See also

angle

property 
angle:Number

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

The angle, in degrees. Valid values are 0 to 360. The default is 45.

The angle value represents the angle of the theoretical light source falling on the object and determines the placement of the effect relative to the object. If distance is set to 0, the effect is not offset from the object, and therefore the angle property has no effect.



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. A blur of 1 or less means that the original image is copied as is. The default value is 4. 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. A blur of 1 or less means that the original image is copied as is. The default value is 4. 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

colors

property 
colors:Array

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

An array of colors that defines a gradient. For example, red is 0xFF0000, blue is 0x0000FF, and so on.

The colors property cannot be changed by directly modifying its values. Instead, you must get a reference to colors, make the change to the reference, and then set colors to the reference.

The colors, alphas, and ratios properties are related. The first element in the colors array corresponds to the first element in the alphas array and in the ratios array, and so on.



Implementation
    public function get colors():Array
    public function set colors(value:Array):void

Throws
TypeError — The Array is null when being set

See also

distance

property 
distance:Number

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

The offset distance of the glow. The default value is 4.



Implementation
    public function get distance():Number
    public function set distance(value:Number):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 knockout effect makes the object's fill transparent and reveals the background color of the document. The value true specifies a knockout effect; 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

ratios

property 
ratios:Array

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

An array of color distribution ratios for the corresponding colors in the colors array. Valid values are 0 to 255.

The ratios property cannot be changed by directly modifying its values. Instead, you must get a reference to ratios, make the change to the reference, and then set ratios to the reference.

The colors, alphas, and ratios properties are related. The first element in the colors array corresponds to the first element in the alphas array and in the ratios array, and so on.

Think of the gradient glow filter as a glow that emanates from the center of the object (if the distance value is set to 0), with gradients that are stripes of color blending into each other. The first color in the colors array is the outermost color of the glow. The last color is the innermost color of the glow.

Each value in the ratios array sets the position of the color on the radius of the gradient, where 0 represents the outermost point of the gradient and 255 represents the innermost point of the gradient. The ratio values can range from 0 to 255 pixels, in increasing value; for example [0, 64, 128, 200, 255]. Values from 0 to 128 appear on the outer edges of the glow. Values from 129 to 255 appear in the inner area of the glow. Depending on the ratio values of the colors and the type value of the filter, the filter colors might be obscured by the object to which the filter is applied.

In the following code and image, a filter is applied to a black circle movie clip, with the type set to "full". For instructional purposes, the first color in the colors array, pink, has an alpha value of 1, so it shows against the white document background. (In practice, you probably would not want the first color showing in this way.) The last color in the array, yellow, obscures the black circle to which the filter is applied:

	var colors:Array = [0xFFCCFF, 0x0000FF, 0x9900FF, 0xFF0000, 0xFFFF00];
	var alphas:Array = [1, 1, 1, 1, 1];
	var ratios:Array = [0, 32, 64, 128, 225];
	var myGGF:GradientGlowFilter = new GradientGlowFilter(0, 0, colors, alphas, ratios, 50, 50, 1, 2, "full", false);
	

A gradient glow filter with a ratios array of 0, 32, 64, 128, 225.

To achieve a seamless effect with your document background when you set the type value to "outer" or "full", set the first color in the array to the same color as the document background, or set the alpha value of the first color to 0; either technique makes the filter blend in with the background.

If you make two small changes in the code, the effect of the glow can be very different, even with the same ratios and colors arrays. Set the alpha value of the first color in the array to 0, to make the filter blend in with the document's white background; and set the type property to "outer" or "inner". Observe the results, as shown in the following images.

outer glow inner glow

Keep in mind that the spread of the colors in the gradient varies based on the values of the blurX, blurY, strength, and quality properties, as well as the ratios values.



Implementation
    public function get ratios():Array
    public function set ratios(value:Array):void

Throws
TypeError — The Array is null when being set

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. A value of 0 means that the filter is not applied. The default value is 1.



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

type

property 
type:String

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

The placement of the filter effect. Possible values are flash.filters.BitmapFilterType constants:

  • BitmapFilterType.OUTER — Glow on the outer edge of the object
  • BitmapFilterType.INNER — Glow on the inner edge of the object; the default.
  • BitmapFilterType.FULL — Glow on top of the object



Implementation
    public function get type():String
    public function set type(value:String):void

Throws
TypeError — The string is null when being set
Constructor Detail

GradientGlowFilter

()Constructor
public function GradientGlowFilter(distance:Number = 4.0, angle:Number = 45, colors:Array = null, alphas:Array = null, ratios:Array = null, blurX:Number = 4.0, blurY:Number = 4.0, strength:Number = 1, quality:int = 1, type:String = "inner", knockout:Boolean = false)

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

Initializes the filter with the specified parameters.

Parameters
distance:Number (default = 4.0) — The offset distance of the glow.
 
angle:Number (default = 45) — The angle, in degrees. Valid values are 0 to 360.
 
colors:Array (default = null) — An array of colors that defines a gradient. For example, red is 0xFF0000, blue is 0x0000FF, and so on.
 
alphas:Array (default = null) — An array of alpha transparency values for the corresponding colors in the colors array. Valid values for each element in the array are 0 to 1. For example, a value of .25 sets the alpha transparency value to 25%.
 
ratios:Array (default = null) — An array of color distribution ratios. Valid values are 0 to 255. This value defines the percentage of the width where the color is sampled at 100 percent.
 
blurX:Number (default = 4.0) — The amount of horizontal blur. Valid values are 0 to 255. A blur of 1 or less means that the original image is copied as is. 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 = 4.0) — The amount of vertical blur. Valid values are 0 to 255. A blur of 1 or less means that the original image is copied as is. 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 = 1) — 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 larger the value, the stronger the imprint. A value of 0 means the filter is not applied.
 
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.

 
type:String (default = "inner") — The placement of the filter effect. Possible values are the flash.filters.BitmapFilterType constants:
  • BitmapFilterType.OUTER — Glow on the outer edge of the object
  • BitmapFilterType.INNER — Glow on the inner edge of the object; the default.
  • BitmapFilterType.FULL — Glow on top of the object
 
knockout:Boolean (default = false) — Specifies whether the object has a knockout effect. A knockout effect makes the object's fill transparent and reveals the background color of the document. The value true specifies a knockout effect; the default is false (no knockout effect).
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 GradientGlowFilter instance with all the same properties as the original GradientGlowFilter instance.
GradientGlowFilterExample.as

The following example draws a square and applies a gradient glow filter to it. The general workflow of the example is as follows:
  1. Import the required classes.
  2. Declare global variables used to define the square and filter.
  3. Create the constructor function, which does the following:
    • Calls the draw() method, which uses methods of the Graphics class accessed through the graphics property of Sprite to draw a square.
    • Creates a BitmapFilter object named filter and assigns it the return value of a call to getBitmapFilter(), which creates the filter.
    • Creates a new array named myFilters and adds filter to it.
    • Assigns myFilters to the filters property of the GradientGlowFilterExample object. This applies all filters found in myFilters, which in this case is only filter.
package {
    import flash.filters.BitmapFilter;
    import flash.filters.BitmapFilterQuality;
    import flash.filters.BitmapFilterType;
    import flash.filters.GradientGlowFilter;
    import flash.display.Sprite;

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

        private var distance:Number  = 0;
        private var angleInDegrees:Number = 45;
        private var colors:Array     = [0xFFFFFF, 0xFF0000, 0xFFFF00, 0x00CCFF];
        private var alphas:Array     = [0, 1, 1, 1];
        private var ratios:Array     = [0, 63, 126, 255];
        private var blurX:Number     = 50;
        private var blurY:Number     = 50;
        private var strength:Number  = 2.5;
        private var quality:Number   = BitmapFilterQuality.HIGH;
        private var type:String      = BitmapFilterType.OUTER;
        private var knockout:Boolean = false;

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

        private function getBitmapFilter():BitmapFilter {
            return new GradientGlowFilter(distance,
                                          angleInDegrees,
                                          colors,
                                          alphas,
                                          ratios,
                                          blurX,
                                          blurY,
                                          strength,
                                          quality,
                                          type,
                                          knockout);
        }

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