java.awt.image
Class AreaAveragingScaleFilter

java.lang.Object
  java.awt.image.ImageFilter
      java.awt.image.ReplicateScaleFilter
          java.awt.image.AreaAveragingScaleFilter

All Implemented Interfaces:

Cloneable, ImageConsumer

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.

Author:

Jim Graham

See Also:

FilteredImageSource, ReplicateScaleFilter, ImageFilter

Field Summary

private float[]	alphas
private float[]	blues
private float[]	greens
private static int	neededHints
private boolean	passthrough
private float[]	reds
private static ColorModel	rgbmodel
private int	savedy
private int	savedyrem

Fields inherited from class java.awt.image.ReplicateScaleFilter

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

Fields inherited from class java.awt.image.ImageFilter

consumer

Fields inherited from interface java.awt.image.ImageConsumer

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

Constructor Summary

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

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()
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 inherited from class java.awt.image.ReplicateScaleFilter

setDimensions, setProperties

Methods inherited from class java.awt.image.ImageFilter

clone, getFilterInstance, imageComplete, resendTopDownLeftRight, setColorModel

Methods inherited from class java.lang.Object

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

Field Detail

rgbmodel

private static final ColorModel rgbmodel

neededHints

private static final int neededHints

See Also:

Constant Field Values

passthrough

private boolean passthrough

reds

private float[] reds

greens

private float[] greens

blues

private float[] blues

alphas

private float[] alphas

savedy

private int savedy

savedyrem

private int savedyrem

Constructor Detail

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

Method Detail

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

See Also:

ImageConsumer.setHints(int)

makeAccumBuffers

private void makeAccumBuffers()

calcRow

private int[] calcRow()

accumPixels

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

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

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

See Also:

ReplicateScaleFilter