Class AreaAveragingScaleFilter

java.lang.Object

java.awt.image.ImageFilter

java.awt.image.ReplicateScaleFilter

java.awt.image.AreaAveragingScaleFilter

All Implemented Interfaces:

ImageConsumer, Cloneable

public class AreaAveragingScaleFilter
extends ReplicateScaleFilter

An ImageFilter class for scaling images using a simple area averaging algorithm that produces smoother results than the nearest neighbor algorithm.

This class extends the basic ImageFilter Class to scale an existing image and provide a source for a new image containing the resampled image. The pixels in the source image are blended to produce pixels for an image of the specified size. The blending process is analogous to scaling up the source image to a multiple of the destination size using pixel replication and then scaling it back down to the destination size by simply averaging all the pixels in the supersized image that fall within a given pixel of the destination image. If the data from the source is not delivered in TopDownLeftRight order then the filter will back off to a simple pixel replication behavior and utilize the requestTopDownLeftRightResend() method to refilter the pixels in a better way at the end.

It is meant to be used in conjunction with a FilteredImageSource object to produce scaled versions of existing images. Due to implementation dependencies, there may be differences in pixel values of an image filtered on different platforms.

See Also:

• FilteredImageSource
• ReplicateScaleFilter
• ImageFilter

Field Summary

Fields declared in class java.awt.image.ReplicateScaleFilter

destHeight, destWidth, outpixbuf, srccols, srcHeight, srcrows, srcWidth

Fields declared in class java.awt.image.ImageFilter

consumer

Fields declared in interface java.awt.image.ImageConsumer

COMPLETESCANLINES, IMAGEABORTED, IMAGEERROR, RANDOMPIXELORDER, SINGLEFRAME, SINGLEFRAMEDONE, SINGLEPASS, STATICIMAGEDONE, TOPDOWNLEFTRIGHT

Constructor Summary

Constructors

Constructor	Description
AreaAveragingScaleFilter(int width, int height)	Constructs an AreaAveragingScaleFilter that scales the pixels from its source Image as specified by the width and height parameters.

Method Summary

Modifier and Type	Method	Description
void	setHints(int hints)	Detect if the data is being delivered with the necessary hints to allow the averaging algorithm to do its work.
void	setPixels(int x, int y, int w, int h, ColorModel model, byte[] pixels, int off, int scansize)	Combine the components for the delivered byte pixels into the accumulation arrays and send on any averaged data for rows of pixels that are complete.
void	setPixels(int x, int y, int w, int h, ColorModel model, int[] pixels, int off, int scansize)	Combine the components for the delivered int pixels into the accumulation arrays and send on any averaged data for rows of pixels that are complete.

Methods declared in class java.awt.image.ReplicateScaleFilter

setDimensions, setProperties

Methods declared in class java.awt.image.ImageFilter

clone, getFilterInstance, imageComplete, resendTopDownLeftRight, setColorModel

Methods declared in class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AreaAveragingScaleFilter

public AreaAveragingScaleFilter(int width,
 int height)

Constructs an AreaAveragingScaleFilter that scales the pixels from its source Image as specified by the width and height parameters.

Parameters:

width - the target width to scale the image

height - the target height to scale the image

Throws:

IllegalArgumentException - if width equals zero or height equals zero

Method Details

setHints

public void setHints(int hints)

Detect if the data is being delivered with the necessary hints to allow the averaging algorithm to do its work.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

Specified by:

setHints in interface ImageConsumer

Overrides:

setHints in class ImageFilter

Parameters:

hints - a set of hints that the ImageConsumer uses to process the pixels

See Also:

• ImageConsumer.setHints(int)

setPixels

public void setPixels(int x,
 int y,
 int w,
 int h,
 ColorModel model,
 byte[] pixels,
 int off,
 int scansize)

Combine the components for the delivered byte pixels into the accumulation arrays and send on any averaged data for rows of pixels that are complete. If the correct hints were not specified in the setHints call then relay the work to our superclass which is capable of scaling pixels regardless of the delivery hints.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

Specified by:

setPixels in interface ImageConsumer

Overrides:

setPixels in class ReplicateScaleFilter

Parameters:

x - the X coordinate of the upper-left corner of the area of pixels to be set

y - the Y coordinate of the upper-left corner of the area of pixels to be set

w - the width of the area of pixels

h - the height of the area of pixels

model - the specified ColorModel

pixels - the array of pixels

off - the offset into the pixels array

scansize - the distance from one row of pixels to the next in the pixels array

See Also:

• ReplicateScaleFilter

setPixels

public void setPixels(int x,
 int y,
 int w,
 int h,
 ColorModel model,
 int[] pixels,
 int off,
 int scansize)

Combine the components for the delivered int pixels into the accumulation arrays and send on any averaged data for rows of pixels that are complete. If the correct hints were not specified in the setHints call then relay the work to our superclass which is capable of scaling pixels regardless of the delivery hints.

Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

Specified by:

setPixels in interface ImageConsumer

Overrides:

setPixels in class ReplicateScaleFilter

Parameters:

x - the X coordinate of the upper-left corner of the area of pixels to be set

y - the Y coordinate of the upper-left corner of the area of pixels to be set

w - the width of the area of pixels

h - the height of the area of pixels

model - the specified ColorModel

pixels - the array of pixels

off - the offset into the pixels array

scansize - the distance from one row of pixels to the next in the pixels array

See Also:

• ReplicateScaleFilter