Adobe® Flex® 4 Language Reference
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spark.filters 
ConvolutionFilter 
Packagespark.filters
Classpublic class ConvolutionFilter
InheritanceConvolutionFilter Inheritance BaseFilter Inheritance EventDispatcher Inheritance Object
Implements IBitmapFilter

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

The ConvolutionFilter class applies a matrix convolution filter effect. A convolution combines pixels in the input image with neighboring pixels to produce an image. A wide variety of image effects can be achieved through convolutions, including blurring, edge detection, sharpening, embossing, and beveling. 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 convolution filter, use the syntax new ConvolutionFilter(). 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 value of the cacheAsBitmap property of the object is set to true. If you clear all filters, the original value of cacheAsBitmap is restored.

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.) 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 maximum dimensions.

MXML SyntaxexpandedHide MXML Syntax

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

 <s:ConvolutionFilter 
   Properties
   alpha="1"
   clamp="true"
   color="0xFF0000"
   divisor="1.0"
   matrix="[]"
   matrixX="0"
   matrixY="0"
   preserveAlpha="true"
 />
 

View the examples



Public Properties
 PropertyDefined By
  alpha : Number
The alpha transparency value for the color.
ConvolutionFilter
  bias : Number
The amount of bias to add to the result of the matrix transformation.
ConvolutionFilter
  clamp : Boolean
Indicates whether the image should be clamped.
ConvolutionFilter
  color : uint
The color of the glow.
ConvolutionFilter
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  divisor : Number
The divisor used during matrix transformation.
ConvolutionFilter
  matrix : Array
The amount of horizontal blur.
ConvolutionFilter
  matrixX : Number
The x dimension of the matrix (the number of rows in the matrix).
ConvolutionFilter
  matrixY : Number
The y dimension of the matrix (the number of columns in the matrix).
ConvolutionFilter
  preserveAlpha : Boolean
Indicates if the alpha channel is preserved without the filter effect or if the convolution filter is applied to the alpha channel as well as the color channels.
ConvolutionFilter
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
Public Methods
 MethodDefined By
  
ConvolutionFilter(matrixX:Number = 0, matrixY:Number = 0, matrix:Array = null, divisor:Number = 1.0, bias:Number = 0.0, preserveAlpha:Boolean = true, clamp:Boolean = true, color:uint = 0, alpha:Number = 0.0)
Constructor.
ConvolutionFilter
 Inherited
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
  
Returns a copy of this filter object.
ConvolutionFilter
 Inherited
Dispatches an event into the event flow.
EventDispatcher
 Inherited
Checks whether the EventDispatcher object has any listeners registered for a specific type of event.
EventDispatcher
 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
BaseFilter
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
Removes a listener from the EventDispatcher object.
EventDispatcher
 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
 Inherited
Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.
EventDispatcher
Events
 Event Summary Defined By
 Inherited[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.EventDispatcher
 Inherited[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.EventDispatcher
Public Constants
 ConstantDefined By
 InheritedCHANGE : String = "change"
[static]
BaseFilter
Property Detail

alpha

property
alpha:Number

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

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

bias

property 
bias:Number

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

The amount of bias to add to the result of the matrix transformation. The bias increases the color value of each channel, so that dark colors appear brighter.

The default value is 0.



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

clamp

property 
clamp:Boolean

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

Indicates whether the image should be clamped. For pixels off the source image, a value of true indicates that the input image is extended along each of its borders as necessary by duplicating the color values at each respective edge of the input image. A value of false indicates that another color should be used, as specified in the color and alpha properties.

The default value is true.



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

color

property 
color:uint

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

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

divisor

property 
divisor:Number

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

The divisor used during matrix transformation. The default value is 1. A divisor that is the sum of all the matrix values smooths out the overall color intensity of the result. A value of 0 is ignored and the default is used instead.

The default value is 1.0.



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

matrix

property 
matrix:Array

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 [].



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

matrixX

property 
matrixX:Number

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

The x dimension of the matrix (the number of rows in the matrix).

The default value is 0.



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

matrixY

property 
matrixY:Number

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

The y dimension of the matrix (the number of columns in the matrix).

The default value is 0.



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

preserveAlpha

property 
preserveAlpha:Boolean

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

Indicates if the alpha channel is preserved without the filter effect or if the convolution filter is applied to the alpha channel as well as the color channels. A value of false indicates that the convolution applies to all channels, including the alpha channel. A value of true indicates that the convolution applies only to the color channels.

The default value is true.



Implementation
    public function get preserveAlpha():Boolean
    public function set preserveAlpha(value:Boolean):void
Constructor Detail

ConvolutionFilter

()Constructor
public function ConvolutionFilter(matrixX:Number = 0, matrixY:Number = 0, matrix:Array = null, divisor:Number = 1.0, bias:Number = 0.0, preserveAlpha:Boolean = true, clamp:Boolean = true, color:uint = 0, alpha:Number = 0.0)

Language Version: ActionScript 3.0
Product Version: Flex 4
Runtime Versions: Flash Player 10, AIR 1.5

Constructor.

Parameters
matrixX:Number (default = 0) — The x dimension of the matrix (the number of columns in the matrix). The default value is 0.
 
matrixY:Number (default = 0) — The y dimension of the matrix (the number of rows in the matrix). The default value is 0.
 
matrix:Array (default = null) — The array of values used for matrix transformation. The number of items in the array must equal matrixX * matrixY.
 
divisor:Number (default = 1.0) — The divisor used during matrix transformation. The default value is 1. A divisor that is the sum of all the matrix values evens out the overall color intensity of the result. A value of 0 is ignored and the default is used instead.
 
bias:Number (default = 0.0) — The bias to add to the result of the matrix transformation. The default value is 0.
 
preserveAlpha:Boolean (default = true) — A value of false indicates that the alpha value is not preserved and that the convolution applies to all channels, including the alpha channel. A value of true indicates that the convolution applies only to the color channels. The default value is true.
 
clamp:Boolean (default = true) — For pixels that are off the source image, a value of true indicates that the input image is extended along each of its borders as necessary by duplicating the color values at the given edge of the input image. A value of false indicates that another color should be used, as specified in the color and alpha properties. The default is true.
 
color:uint (default = 0) — The hexadecimal color to substitute for pixels that are off the source image.
 
alpha:Number (default = 0.0) — The alpha of the substitute color.
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 — BitmapFilter A new ConvolutionFilter instance with all the same properties as the original ConvolutionMatrixFilter instance.
ConvolutionFilterExample.mxml
<?xml version="1.0"?>
<!-- filters/examples/ConvolutionGlowFilterExample .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 myOutlineConvolutionFilter:ConvolutionFilter;  
     private var mySharpnessConvolutionFilter:ConvolutionFilter;  
     private var myBrightnessConvolutionFilter:ConvolutionFilter;  

     private var outlineMatrix:Array = [    -30, 30, 0,
                                                          -30, 30, 0,
                                                          -30, 30, 0 ];

     private var sharpnessMatrix:Array = [0, -1, 0,
                                                          -1, 20, -1,
                                                          0, -1, 0];

     private var brightnessMatrix:Array = [2, 2, 2,
                                                          2, 0, 2, 
                                                          2, 2, 2];
             
     public function createFilters():void {        
        myOutlineConvolutionFilter = new ConvolutionFilter(3, 3, outlineMatrix, 9, 0, true, true, 0x00CC99, 0);
        mySharpnessConvolutionFilter = new ConvolutionFilter(3, 3, sharpnessMatrix, 9, 0, true, true, 0x00CC99, 0);
        myBrightnessConvolutionFilter = new ConvolutionFilter(3, 3, brightnessMatrix, 3, 0, true, true, 0x00CC99, 0);

        outlineImage.filters = [myOutlineConvolutionFilter];
        sharpnessImage.filters = [mySharpnessConvolutionFilter];
        brightnessImage.filters = [myBrightnessConvolutionFilter];
     }
  
  ]]></fx:Script>

    <s:VGroup>
        <s:VGroup>
            <s:Label text="Original Image"/>
            <mx:Image id="originalImage" source="@Embed(source='assets/Nokia_6630.png')"/>
        </s:VGroup>        

        <s:VGroup>
            <s:Label text="Outline Matrix Image"/>
            <mx:Image id="outlineImage" source="@Embed(source='assets/Nokia_6630.png')"/>
        </s:VGroup>        

        <s:VGroup>
            <s:Label text="Sharpness Matrix Image"/>
            <mx:Image id="sharpnessImage" source="@Embed(source='assets/Nokia_6630.png')"/>
        </s:VGroup>        

        <s:VGroup>
            <s:Label text="Brightness Matrix Image"/>
            <mx:Image id="brightnessImage" source="@Embed(source='assets/Nokia_6630.png')"/>
        </s:VGroup>        
    </s:VGroup>        
</s:Application>