imageencoder.java

openmap java写的开源数字地图程序. 用applet实现,可以像google map 那样放大缩小地图.

/**
 * ImageEncoder - abstract class for writing out an image
 *
 * Copyright (C) 1996 by Jef Poskanzer <[e-mail]>.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Visit the ACME Labs Java page for up-to-date versions of this and other
 * fine Java utilities: http://www.acme.com/java/
 */

package Acme.JPM.Encoders;

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

/**
 * Abstract class for writing out an image.
 * <P>
 * A framework for classes that encode and write out an image in a
 * particular file format.
 * <P>
 * This provides a simplified rendition of the ImageConsumer
 * interface. It always delivers the pixels as ints in the RGBdefault
 * color model. It always provides them in top-down left-right order.
 * If you want more flexibility you can always implement ImageConsumer
 * directly.
 * <P>
 * <A
 * HREF="/resources/classes/Acme/JPM/Encoders/ImageEncoder.java">Fetch
 * the software. </A> <BR>
 * <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme
 * package. </A>
 * <P>
 * 
 * @see GifEncoder
 * @see PpmEncoder
 */
public abstract class ImageEncoder implements ImageConsumer {

    protected OutputStream out;

    private ImageProducer producer;
    private int width = -1;
    private int height = -1;
    private int hintflags = 0;
    private boolean started = false;
    private boolean encoding;
    private IOException iox;
    private static final ColorModel rgbModel = ColorModel.getRGBdefault();
    private Hashtable props = null;

    /// Constructor.
    // @param img The image to encode.
    // @param out The stream to write the bytes to.
    public ImageEncoder(Image img, OutputStream out) throws IOException {
        this(img.getSource(), out);
    }

    /// Constructor.
    // @param producer The ImageProducer to encode.
    // @param out The stream to write the bytes to.
    public ImageEncoder(ImageProducer producer, OutputStream out)
            throws IOException {
        this.producer = producer;
        this.out = out;
    }

    // Methods that subclasses implement.

    /// Subclasses implement this to initialize an encoding.
    abstract void encodeStart(int w, int h) throws IOException;

    /// Subclasses implement this to actually write out some bits.
    // They
    // are guaranteed to be delivered in top-down-left-right order.
    // One int per pixel, index is row * scansize + off + col,
    // RGBdefault (AARRGGBB) color model.
    abstract void encodePixels(int x, int y, int w, int h, int[] rgbPixels,
                               int off, int scansize) throws IOException;

    /// Subclasses implement this to finish an encoding.
    abstract void encodeDone() throws IOException;

    // Our own methods.

    /// Call this after initialization to get things going.
    public synchronized void encode() throws IOException {
        encoding = true;
        iox = null;
        producer.startProduction(this);
        while (encoding)
            try {
                wait();
            } catch (InterruptedException e) {
            }
        if (iox != null)
            throw iox;
    }

    private boolean accumulate = false;
    private int[] accumulator;

    private void encodePixelsWrapper(int x, int y, int w, int h,
                                     int[] rgbPixels, int off, int scansize)
            throws IOException {
        if (!started) {
            started = true;
            encodeStart(width, height);
            if ((hintflags & TOPDOWNLEFTRIGHT) == 0) {
                accumulate = true;
                accumulator = new int[width * height];
            }
        }
        if (accumulate)
            for (int row = 0; row < h; ++row)
                System.arraycopy(rgbPixels,
                        row * scansize + off,
                        accumulator,
                        (y + row) * width + x,
                        w);
        else
            encodePixels(x, y, w, h, rgbPixels, off, scansize);
    }

    private void encodeFinish() throws IOException {
        if (accumulate) {
            encodePixels(0, 0, width, height, accumulator, 0, width);
            accumulator = null;
            accumulate = false;
        }
    }

    private synchronized void stop() {
        encoding = false;
        notifyAll();
    }

    // Methods from ImageConsumer.

    public void setDimensions(int width, int height) {
        this.width = width;
        this.height = height;
    }

    public void setProperties(Hashtable props) {
        this.props = props;
    }

    public Hashtable getProperties() {
        return this.props;
    }
    
    public void setColorModel(ColorModel model) {
    // Ignore.
    }

    public void setHints(int hintflags) {
        this.hintflags = hintflags;
    }

    public void setPixels(int x, int y, int w, int h, ColorModel model,
                          byte[] pixels, int off, int scansize) {
        int[] rgbPixels = new int[w];
        for (int row = 0; row < h; ++row) {
            int rowOff = off + row * scansize;
            for (int col = 0; col < w; ++col)
                rgbPixels[col] = model.getRGB(pixels[rowOff + col] & 0xff);
            try {
                encodePixelsWrapper(x, y + row, w, 1, rgbPixels, 0, w);
            } catch (IOException e) {
                iox = e;
                stop();
                return;
            }
        }
    }

    public void setPixels(int x, int y, int w, int h, ColorModel model,
                          int[] pixels, int off, int scansize) {
        if (model == rgbModel) {
            try {
                encodePixelsWrapper(x, y, w, h, pixels, off, scansize);
            } catch (IOException e) {
                iox = e;
                stop();
                return;
            }
        } else {
            int[] rgbPixels = new int[w];
            for (int row = 0; row < h; ++row) {
                int rowOff = off + row * scansize;
                for (int col = 0; col < w; ++col)
                    rgbPixels[col] = model.getRGB(pixels[rowOff + col]);
                try {
                    encodePixelsWrapper(x, y + row, w, 1, rgbPixels, 0, w);
                } catch (IOException e) {
                    iox = e;
                    stop();
                    return;
                }
            }
        }
    }

    public void imageComplete(int status) {
        producer.removeConsumer(this);
        if (status == ImageConsumer.IMAGEABORTED)
            iox = new IOException("image aborted");
        else {
            try {
                encodeFinish();
                encodeDone();
            } catch (IOException e) {
                iox = e;
            }
        }
        stop();
    }

}