APIdia Launch Partner
Top Description Fields Constructors Methods
java.awt.image

public Class AreaAveragingScaleFilter

extends ReplicateScaleFilter
Class Inheritance
Imports
java.awt.image.ImageConsumer, .ColorModel, java.util.Hashtable, java.awt.Rectangle
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.

Author
Jim Graham
See Also
FilteredImageSource, ReplicateScaleFilter, ImageFilter

Field Summary

Modifier and TypeField and Description
private float[]
alphas

private float[]
blues

private float[]
greens

private static final int
neededHints

private boolean
passthrough

private float[]
reds

private static final ColorModel
rgbmodel

private int
savedy

private int
savedyrem

Inherited from java.awt.image.ReplicateScaleFilter:
destHeightdestWidthoutpixbufsrccolssrcHeightsrcrowssrcWidth

Constructor Summary

AccessConstructor and Description
public
AreaAveragingScaleFilter(int
the target width to scale the image
width, int
the target height to scale the image
height)

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

Method Summary

Modifier and TypeMethod and Description
private void
accumPixels(int x, int y, int w, int h, ColorModel model, Object pixels, int off, int scansize)

private int[]
calcRow()

private void
makeAccumBuffers()

public void
setHints(int hints)

Overrides java.awt.image.ImageFilter.setHints.

Implements java.awt.image.ImageConsumer.setHints.

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

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

Overrides java.awt.image.ReplicateScaleFilter.setPixels.

Implements java.awt.image.ImageConsumer.setPixels.

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.

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

Overrides java.awt.image.ReplicateScaleFilter.setPixels.

Implements java.awt.image.ImageConsumer.setPixels.

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.

Inherited from java.awt.image.ReplicateScaleFilter:
setDimensionssetProperties

Field Detail

alphasback to summary
private float[] alphas
bluesback to summary
private float[] blues
greensback to summary
private float[] greens
neededHintsback to summary
private static final int neededHints
passthroughback to summary
private boolean passthrough
redsback to summary
private float[] reds
rgbmodelback to summary
private static final ColorModel rgbmodel
savedyback to summary
private int savedy
savedyremback to summary
private int savedyrem

Constructor Detail

AreaAveragingScaleFilterback to summary
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:int

the target width to scale the image

height:int

the target height to scale the image

Exceptions
IllegalArgumentException:
if width equals zero or height equals zero

Method Detail

accumPixelsback to summary
private void accumPixels(int x, int y, int w, int h, ColorModel model, Object pixels, int off, int scansize)
calcRowback to summary
private int[] calcRow()
makeAccumBuffersback to summary
private void makeAccumBuffers()
setHintsback to summary
public void setHints(int hints)

Overrides java.awt.image.ImageFilter.setHints.

Implements java.awt.image.ImageConsumer.setHints.

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.

See Also
ImageConsumer#setHints
setPixelsback to summary
public void setPixels(int x, int y, int w, int h, ColorModel model, byte[] pixels, int off, int scansize)

Overrides java.awt.image.ReplicateScaleFilter.setPixels.

Implements java.awt.image.ImageConsumer.setPixels.

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.

See Also
ReplicateScaleFilter
setPixelsback to summary
public void setPixels(int x, int y, int w, int h, ColorModel model, int[] pixels, int off, int scansize)

Overrides java.awt.image.ReplicateScaleFilter.setPixels.

Implements java.awt.image.ImageConsumer.setPixels.

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.

See Also
ReplicateScaleFilter