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

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

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.) 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

See also



Public Properties
 PropertyDefined By
  blurX : Number
The amount of horizontal blur.
BlurFilter
  blurY : Number
The amount of vertical blur.
BlurFilter
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
  quality : int
The number of times to perform the blur.
BlurFilter
Public Methods
 MethodDefined By
  
BlurFilter(blurX:Number = 4.0, blurY:Number = 4.0, quality:int = 1)
Initializes the filter with the specified parameters.
BlurFilter
  
[override] Returns a copy of this filter object.
BlurFilter
 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

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 from 0 to 255 (floating point). 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 from 0 to 255 (floating point). 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

quality

property 
quality:int

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

The number of times to perform the blur. 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 and approximates a Gaussian blur. 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 increase the number of times the blur is applied, 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.

You can use the following BitmapFilterQuality constants to specify values of the quality property:

  • BitmapFilterQuality.LOW
  • BitmapFilterQuality.MEDIUM
  • BitmapFilterQuality.HIGH



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
Runtime Versions: AIR 1.0 Flash Player 9

Initializes the filter with the specified parameters. 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 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
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 BlurFilter instance with all the same properties as the original BlurFilter instance.
BlurFilterExample.as

The following example creates a dark yellow square and applies a Gaussian-style blur filter to it. The general workflow for this example is as follows:
  1. Import the required classes.
  2. Declare three properties used in the draw() function, which draws the object to which the blur filter is applied.
  3. Create the BlurFilterExample() constructor function, which does the following:
    • Calls the draw() function, which is declared later.
    • Declares a filter variable as a BitmapFilter object and assigns it to the return of a call to getBitmapFilter().
    • Creates a new Array object myFilters and adds filter to the array, and assigns myFilters to the filters property of the BlurFilterExample object. This applies all filters found in myFilters, which in this case is only filter.
  4. Create the getBitmapFilter() function to create and set properties for the filter.
  5. Create the draw() function. This function uses methods of the Graphics class, accessed through the graphics property of the Sprite class, to draw the square.

package {
    import flash.display.Sprite;
    import flash.filters.BitmapFilter;
    import flash.filters.BitmapFilterQuality;
    import flash.filters.BlurFilter;

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

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

        private function getBitmapFilter():BitmapFilter {
            var blurX:Number = 30;
            var blurY:Number = 30;
            return new BlurFilter(blurX, blurY, BitmapFilterQuality.HIGH);
        }

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