spark.filters.BlurFilter - Adobe® Flex® 4 Language Reference (Flex 4)

Package	spark.filters
Class	public class BlurFilter
Inheritance	BlurFilter BaseFilter EventDispatcher Object
Implements	IBitmapFilter

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

The BlurFilter class lets you apply a blur visual effect to display objects. A blur effect softens the details of an image. You can produce blurs that range from a softly unfocused look to a Gaussian blur, a hazy appearance like viewing an image through semi-opaque glass. When the quality property of this filter is set to low, the result is a softly unfocused look. When the quality property is set to high, it approximates a Gaussian blur filter. 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.

To create a new filter, use the constructor new BlurFilter(). The use of filters depends on the object to which you apply the filter:

To apply filters to movie clips, text fields, buttons, and video, 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 remove 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 (scaleX and scaleY are not set to 100%), 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.) 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.

MXML Syntax expanded

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The <s:BlurFilter> tag inherits all of the tag attributes of its superclass and adds the following tag attributes:

  <s:BlurFilter
    Properties
    blurX="4.0"
    blurY="4.0"
    quality="low"
  />

View the examples

Public Properties

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	Property		Defined By
		blurX : Number The amount of horizontal blur.	BlurFilter
		blurY : Number The amount of vertical blur.	BlurFilter
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		prototype : 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.	BlurFilter

Public Methods

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	Method		Defined By
		BlurFilter(blurX:Number = 4.0, blurY:Number = 4.0, quality:int = 1) Constructor.	BlurFilter
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	EventDispatcher
		clone():BitmapFilter Returns a copy of this filter object.	BlurFilter
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		notifyFilterChanged():void	BaseFilter
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher

Events

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	Event		Summary	Defined By
		activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
		deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher

Public Constants

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	Constant		Defined By
		CHANGE : String = "change" [static]	BaseFilter

Property Detail

blurX

property

blurX:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

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.

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

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

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.

The default value is 4.0.

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

quality

property

quality:int

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

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.

The default value is "low".

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

Constructor Detail

BlurFilter

()

Constructor

public function BlurFilter(blurX:Number = 4.0, blurY:Number = 4.0, quality:int = 1)

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

Constructor. The default values create a soft, unfocused image.

Parameters

	`blurX:Number` (default = `4.0`) — The amount to blur horizontally. Valid values are from 0 to 255.0 (floating-point value).

	`blurY:Number` (default = `4.0`) — The amount to blur vertically. Valid values are from 0 to 255.0 (floating-point value).

	`quality:int` (default = `1`) — The number of times to apply the filter. You can specify the quality using the flash.filters.BitmapFilterQuality constants: `flash.filters.BitmapFilterQuality.LOW` `flash.filters.BitmapFilterQuality.MEDIUM` `flash.filters.BitmapFilterQuality.HIGH` High quality approximates a Gaussian blur. For most applications, these three values are sufficient. Although you can use additional numeric values up to 15 to achieve different effects, be aware that higher values are rendered more slowly.

Method Detail

clone

()

method

public function clone():BitmapFilter

Language Version:

ActionScript 3.0

Product Version:

Flex 4

Runtime Versions:

Flash Player 10, AIR 1.5

Returns a copy of this filter object.

Returns

BitmapFilter — A new BlurFilter instance with all the same properties as the original BlurFilter instance.

Examples ( How to use this example )

BlurFilterExample.mxml

<?xml version="1.0"?>
<!-- filters/examples/BlurFilterExample.mxml -->
<s:Application 
    xmlns:fx="http://ns.adobe.com/mxml/2009" 
    xmlns:mx="library://ns.adobe.com/flex/mx" 
    xmlns:s="library://ns.adobe.com/flex/spark" 
    creationComplete="createFilters()">
    
  <fx:Script><![CDATA[ 
     import spark.filters.*;
     import flash.filters.BitmapFilterQuality;
     import flash.filters.BitmapFilterType;
  
     private var myBlurFilter:BlurFilter;  
     private var color:Number = 0xFF33FF;
  
     public function createFilters():void {        
        myBlurFilter = new BlurFilter(3, 3, BitmapFilterQuality.MEDIUM);
        b1.filters = [myBlurFilter];
     }
  
  ]]></fx:Script>

    <s:VGroup>
        <!-- This button has a filter applied in ActionScript. -->
        <s:Button id="b1" label="Click me"/>
        
        <!-- This button has a filter applied in MXML. -->
        <s:Button id="b2" label="Click me">
            <s:filters>
                <s:BlurFilter 
                    blurX="3" 
                    blurY="3" 
                    quality="{BitmapFilterQuality.MEDIUM}"/>
            </s:filters>
        </s:Button>
        
    </s:VGroup>        
</s:Application>