pixelgrabber.java

《移动Agent技术》一书的所有章节源代码。

/*
 * @(#)PixelGrabber.java	1.7 96/11/23
 * 
 * Copyright (c) 1995, 1996 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the confidential and proprietary information of Sun
 * Microsystems, Inc. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Sun.
 * 
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 * 
 * CopyrightVersion 1.1_beta
 * 
 */

package java.awt.image;

import java.util.Hashtable;
import java.awt.image.ImageProducer;
import java.awt.image.ImageConsumer;
import java.awt.image.ColorModel;
import java.awt.Image;

/**
 * The PixelGrabber class implements an ImageConsumer which can be attached
 * to an Image or ImageProducer object to retrieve a subset of the pixels
 * in that image.  Here is an example:
 * <pre>
 *
 * public void handlesinglepixel(int x, int y, int pixel) {
 *	int alpha = (pixel >> 24) & 0xff;
 *	int red   = (pixel >> 16) & 0xff;
 *	int green = (pixel >>  8) & 0xff;
 *	int blue  = (pixel      ) & 0xff;
 *	// Deal with the pixel as necessary...
 * }
 *
 * public void handlepixels(Image img, int x, int y, int w, int h) {
 *	int[] pixels = new int[w * h];
 *	PixelGrabber pg = new PixelGrabber(img, x, y, w, h, pixels, 0, w);
 *	try {
 *	    pg.grabPixels();
 *	} catch (InterruptedException e) {
 *	    System.err.println("interrupted waiting for pixels!");
 *	    return;
 *	}
 *	if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
 *	    System.err.println("image fetch aborted or errored");
 *	    return;
 *	}
 *	for (int j = 0; j < h; j++) {
 *	    for (int i = 0; i < w; i++) {
 *		handlesinglepixel(x+i, y+j, pixels[j * w + i]);
 *	    }
 *	}
 * }
 *
 * </pre>
 *
 * @see ColorModel#getRGBdefault
 *
 * @version 	1.7, 11/23/96
 * @author 	Jim Graham
 */
public class PixelGrabber implements ImageConsumer {
    ImageProducer producer;

    int dstX;
    int dstY;
    int dstW;
    int dstH;

    ColorModel imageModel;
    byte[] bytePixels;
    int[] intPixels;
    int dstOff;
    int dstScan;

    private boolean grabbing;
    private int flags;

    private final int GRABBEDBITS = (ImageObserver.FRAMEBITS
				     | ImageObserver.ALLBITS);
    private final int DONEBITS = (GRABBEDBITS
				  | ImageObserver.ERROR);

    /**
     * Create a PixelGrabber object to grab the (x, y, w, h) rectangular
     * section of pixels from the specified image into the given array.
     * The pixels are stored into the array in the default RGB ColorModel.
     * The RGB data for pixel (i, j) where (i, j) is inside the rectangle
     * (x, y, w, h) is stored in the array at
     * <tt>pix[(j - y) * scansize + (i - x) + off]</tt>.
     * @see ColorModel#getRGBdefault
     * @param img the image to retrieve pixels from
     * @param x the x coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image, relative to the default
     * (unscaled) size of the image
     * @param y the y coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image
     * @param w the width of the rectangle of pixels to retrieve
     * @param h the height of the rectangle of pixels to retrieve
     * @param pix the array of integers which are to be used to hold the
     * RGB pixels retrieved from the image
     * @param off the offset into the array of where to store the first pixel
     * @param scansize the distance from one row of pixels to the next in
     * the array
     */
    public PixelGrabber(Image img, int x, int y, int w, int h,
			int[] pix, int off, int scansize) {
	this(img.getSource(), x, y, w, h, pix, off, scansize);
    }

    /**
     * Create a PixelGrabber object to grab the (x, y, w, h) rectangular
     * section of pixels from the image produced by the specified
     * ImageProducer into the given array.
     * The pixels are stored into the array in the default RGB ColorModel.
     * The RGB data for pixel (i, j) where (i, j) is inside the rectangle
     * (x, y, w, h) is stored in the array at
     * <tt>pix[(j - y) * scansize + (i - x) + off]</tt>.
     * @see ColorModel#getRGBdefault
     * @param img the image to retrieve pixels from
     * @param x the x coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image, relative to the default
     * (unscaled) size of the image
     * @param y the y coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image
     * @param w the width of the rectangle of pixels to retrieve
     * @param h the height of the rectangle of pixels to retrieve
     * @param pix the array of integers which are to be used to hold the
     * RGB pixels retrieved from the image
     * @param off the offset into the array of where to store the first pixel
     * @param scansize the distance from one row of pixels to the next in
     * the array
     */
    public PixelGrabber(ImageProducer ip, int x, int y, int w, int h,
			int[] pix, int off, int scansize) {
	producer = ip;
	dstX = x;
	dstY = y;
	dstW = w;
	dstH = h;
	dstOff = off;
	dstScan = scansize;
	intPixels = pix;
	imageModel = ColorModel.getRGBdefault();
    }

    /**
     * Create a PixelGrabber object to grab the (x, y, w, h) rectangular
     * section of pixels from the specified image.  The pixels are
     * accumulated in the original ColorModel if the same ColorModel
     * is used for every call to setPixels, otherwise the pixels are
     * accumulated in the default RGB ColorModel.  If the forceRGB
     * parameter is true, then the pixels will be accumulated in the
     * default RGB ColorModel anywya.  A buffer is allocated by the
     * PixelGrabber to hold the pixels in either case.  If (w < 0) or
     * (h < 0), then they will default to the remaining width and
     * height of the source data when that information is delivered.
     * @param img the image to retrieve the image data from
     * @param x the x coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image, relative to the default
     * (unscaled) size of the image
     * @param y the y coordinate of the upper left corner of the rectangle
     * of pixels to retrieve from the image
     * @param w the width of the rectangle of pixels to retrieve
     * @param h the height of the rectangle of pixels to retrieve
     * @param forceRGB true if the pixels should always be converted to
     * the default RGB ColorModel
     */
    public PixelGrabber(Image img, int x, int y, int w, int h,
			boolean forceRGB)
    {
	producer = img.getSource();
	dstX = x;
	dstY = y;
	dstW = w;
	dstH = h;
	if (forceRGB) {
	    imageModel = ColorModel.getRGBdefault();
	}
    }

    /**
     * Request the PixelGrabber to start fetching the pixels.
     */
    public synchronized void startGrabbing() {
	if ((flags & DONEBITS) != 0) {
	    return;
	}
	if (!grabbing) {
	    grabbing = true;
	    flags &= ~(ImageObserver.ABORT);
	    producer.startProduction(this);
	}
    }

    /**
     * Request the PixelGrabber to abort the image fetch.
     */
    public synchronized void abortGrabbing() {
	imageComplete(IMAGEABORTED);
    }

    /**
     * Request the Image or ImageProducer to start delivering pixels and
     * wait for all of the pixels in the rectangle of interest to be
     * delivered.
     * @return true if the pixels were successfully grabbed, false on
     * abort, error or timeout
     * @exception InterruptedException 
     *            Another thread has interrupted this thread.
     */
    public boolean grabPixels() throws InterruptedException {
	return grabPixels(0);
    }

    /**
     * Request the Image or ImageProducer to start delivering pixels and
     * wait for all of the pixels in the rectangle of interest to be
     * delivered or until the specified timeout has elapsed.
     * @param ms the number of milliseconds to wait for the image pixels
     * to arrive before timing out
     * @return true if the pixels were successfully grabbed, false on
     * abort, error or timeout
     * @exception InterruptedException 
     *            Another thread has interrupted this thread. 
     */
    public synchronized boolean grabPixels(long ms)
	throws InterruptedException
    {
	if ((flags & DONEBITS) != 0) {
	    return (flags & GRABBEDBITS) != 0;
	}
	long end = ms + System.currentTimeMillis();
	if (!grabbing) {
	    grabbing = true;
	    flags &= ~(ImageObserver.ABORT);
	    producer.startProduction(this);
	}
	while (grabbing) {
	    long timeout;
	    if (ms == 0) {
		timeout = 0;
	    } else {
		timeout = end - System.currentTimeMillis();
		if (timeout <= 0) {
		    break;
		}
	    }
	    wait(timeout);
	}
	return (flags & GRABBEDBITS) != 0;
    }

    /**
     * Return the status of the pixels.  The ImageObserver flags
     * representing the available pixel information are returned.
     * @see ImageObserver
     * @return the bitwise OR of all relevant ImageObserver flags
     */
    public synchronized int getStatus() {
	return flags;
    }

    /**
     * Get the width of the pixel buffer (after adjusting for image width).
     * If no width was specified for the rectangle of pixels to grab then
     * then this information will only be available after the image has
     * delivered the dimensions.
     * @return the final width used for the pixel buffer or -1 if the width
     * is not yet known
     * @see #getStatus
     */
    public synchronized int getWidth() {
	return (dstW < 0) ? -1 : dstW;
    }

    /**
     * Get the height of the pixel buffer (after adjusting for image height).