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	/*
	* Copyright (c) 1996, 2002, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.awt.image;

	import java.awt.image.ImageConsumer;
	import java.awt.image.ColorModel;
	import java.util.Hashtable;
	import java.awt.Rectangle;

	/**
	* An ImageFilter class for scaling images using a simple area averaging
	* algorithm that produces smoother results than the nearest neighbor
	* algorithm.
	* <p>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.
	* <p>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 FilteredImageSource
	* @see ReplicateScaleFilter
	* @see ImageFilter
	*
	* @author Jim Graham
	*/
	public class AreaAveragingScaleFilter extends ReplicateScaleFilter {
	private static final ColorModel rgbmodel = ColorModel.getRGBdefault();
	private static final int neededHints = (TOPDOWNLEFTRIGHT
	\| COMPLETESCANLINES);

	private boolean passthrough;
	private float reds[], greens[], blues[], alphas[];
	private int savedy;
	private int savedyrem;

	/**
	* Constructs an AreaAveragingScaleFilter that scales the pixels from
	* its source Image as specified by the width and height parameters.
	* @param width the target width to scale the image
	* @param height the target height to scale the image
	*/
	public AreaAveragingScaleFilter(int width, int height) {
	super(width, height);
	}

	/**
	* Detect if the data is being delivered with the necessary hints
	* to allow the averaging algorithm to do its work.
	* <p>
	* Note: This method is intended to be called by the
	* <code>ImageProducer</code> of the <code>Image</code> 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 ImageConsumer#setHints
	*/
	public void setHints(int hints) {
	passthrough = ((hints & neededHints) != neededHints);
	super.setHints(hints);
	}

	private void makeAccumBuffers() {
	reds = new float[destWidth];
	greens = new float[destWidth];
	blues = new float[destWidth];
	alphas = new float[destWidth];
	}

	private int[] calcRow() {
	float origmult = ((float) srcWidth) * srcHeight;
	if (outpixbuf == null \|\| !(outpixbuf instanceof int[])) {
	outpixbuf = new int[destWidth];
	}
	int[] outpix = (int[]) outpixbuf;
	for (int x = 0; x < destWidth; x++) {
	float mult = origmult;
	int a = Math.round(alphas[x] / mult);
	if (a <= 0) {
	a = 0;
	} else if (a >= 255) {
	a = 255;
	} else {
	// un-premultiply the components (by modifying mult here, we
	// are effectively doing the divide by mult and divide by
	// alpha in the same step)
	mult = alphas[x] / 255;
	}
	int r = Math.round(reds[x] / mult);
	int g = Math.round(greens[x] / mult);
	int b = Math.round(blues[x] / mult);
	if (r < 0) {r = 0;} else if (r > 255) {r = 255;}
	if (g < 0) {g = 0;} else if (g > 255) {g = 255;}
	if (b < 0) {b = 0;} else if (b > 255) {b = 255;}
	outpix[x] = (a << 24 \| r << 16 \| g << 8 \| b);
	}
	return outpix;
	}

	private void accumPixels(int x, int y, int w, int h,
	ColorModel model, Object pixels, int off,
	int scansize) {
	if (reds == null) {
	makeAccumBuffers();
	}
	int sy = y;
	int syrem = destHeight;
	int dy, dyrem;
	if (sy == 0) {
	dy = 0;
	dyrem = 0;
	} else {
	dy = savedy;
	dyrem = savedyrem;
	}
	while (sy < y + h) {
	int amty;
	if (dyrem == 0) {
	for (int i = 0; i < destWidth; i++) {
	alphas[i] = reds[i] = greens[i] = blues[i] = 0f;
	}
	dyrem = srcHeight;
	}
	if (syrem < dyrem) {
	amty = syrem;
	} else {
	amty = dyrem;
	}
	int sx = 0;
	int dx = 0;
	int sxrem = 0;
	int dxrem = srcWidth;
	float a = 0f, r = 0f, g = 0f, b = 0f;
	while (sx < w) {
	if (sxrem == 0) {
	sxrem = destWidth;
	int rgb;
	if (pixels instanceof byte[]) {
	rgb = ((byte[]) pixels)[off + sx] & 0xff;
	} else {
	rgb = ((int[]) pixels)[off + sx];
	}
	// getRGB() always returns non-premultiplied components
	rgb = model.getRGB(rgb);
	a = rgb >>> 24;
	r = (rgb >> 16) & 0xff;
	g = (rgb >> 8) & 0xff;
	b = rgb & 0xff;
	// premultiply the components if necessary
	if (a != 255.0f) {
	float ascale = a / 255.0f;
	r *= ascale;
	g *= ascale;
	b *= ascale;
	}
	}
	int amtx;
	if (sxrem < dxrem) {
	amtx = sxrem;
	} else {
	amtx = dxrem;
	}
	float mult = ((float) amtx) * amty;
	alphas[dx] += mult * a;
	reds[dx] += mult * r;
	greens[dx] += mult * g;
	blues[dx] += mult * b;
	if ((sxrem -= amtx) == 0) {
	sx++;
	}
	if ((dxrem -= amtx) == 0) {
	dx++;
	dxrem = srcWidth;
	}
	}
	if ((dyrem -= amty) == 0) {
	int outpix[] = calcRow();
	do {
	consumer.setPixels(0, dy, destWidth, 1,
	rgbmodel, outpix, 0, destWidth);
	dy++;
	} while ((syrem -= amty) >= amty && amty == srcHeight);
	} else {
	syrem -= amty;
	}
	if (syrem == 0) {
	syrem = destHeight;
	sy++;
	off += scansize;
	}
	}
	savedyrem = dyrem;
	savedy = dy;
	}

	/**
	* 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.
	* <p>
	* Note: This method is intended to be called by the
	* <code>ImageProducer</code> of the <code>Image</code>
	* 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 ReplicateScaleFilter
	*/
	public void setPixels(int x, int y, int w, int h,
	ColorModel model, byte pixels[], int off,
	int scansize) {
	if (passthrough) {
	super.setPixels(x, y, w, h, model, pixels, off, scansize);
	} else {
	accumPixels(x, y, w, h, model, pixels, off, 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.
	* <p>
	* Note: This method is intended to be called by the
	* <code>ImageProducer</code> of the <code>Image</code>
	* 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 ReplicateScaleFilter
	*/
	public void setPixels(int x, int y, int w, int h,
	ColorModel model, int pixels[], int off,
	int scansize) {
	if (passthrough) {
	super.setPixels(x, y, w, h, model, pixels, off, scansize);
	} else {
	accumPixels(x, y, w, h, model, pixels, off, scansize);
	}
	}
	}

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