pngimagewriter.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

/*
 * @(#)PNGImageWriter.java	1.37 07/09/12
 *
 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.imageio.plugins.png;

import java.awt.Rectangle;
import java.awt.image.ColorModel;
import java.awt.image.IndexColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.awt.image.RenderedImage;
import java.awt.image.SampleModel;
import java.io.ByteArrayOutputStream;
import java.io.DataOutput;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Iterator;
import java.util.Locale;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import javax.imageio.IIOException;
import javax.imageio.IIOImage;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.spi.ImageWriterSpi;
import javax.imageio.stream.ImageOutputStream;
import javax.imageio.stream.ImageOutputStreamImpl;

class CRC {

    private static int[] crcTable = new int[256];
    private int crc = 0xffffffff;

    static {
        // Initialize CRC table
        for (int n = 0; n < 256; n++) {
            int c = n;
            for (int k = 0; k < 8; k++) {
                if ((c & 1) == 1) {
                    c = 0xedb88320 ^ (c >>> 1);
                } else {
                    c >>>= 1;
                }

                crcTable[n] = c;
            }
        }
    }

    public CRC() {}

    public void reset() {
        crc = 0xffffffff;
    }

    public void update(byte[] data, int off, int len) {
        for (int n = 0; n < len; n++) {
            crc = crcTable[(crc ^ data[off + n]) & 0xff] ^ (crc >>> 8);
        }
    }

    public void update(int data) {
        crc = crcTable[(crc ^ data) & 0xff] ^ (crc >>> 8);
    }

    public int getValue() {
        return crc ^ 0xffffffff;
    }
}


final class ChunkStream extends ImageOutputStreamImpl {
    
    private ImageOutputStream stream;
    private long startPos;
    private CRC crc = new CRC();

    public ChunkStream(int type, ImageOutputStream stream) throws IOException {
        this.stream = stream;
        this.startPos = stream.getStreamPosition();
        
        stream.writeInt(-1); // length, will backpatch
        writeInt(type);
    }

    public int read() throws IOException {
        throw new RuntimeException("Method not available");
    }

    public int read(byte[] b, int off, int len) throws IOException {
        throw new RuntimeException("Method not available");
    }

    public void write(byte[] b, int off, int len) throws IOException {
        crc.update(b, off, len);
        stream.write(b, off, len);
    }

    public void write(int b) throws IOException {
        crc.update(b);
        stream.write(b);
    }

    public void finish() throws IOException {
        // Write CRC
        stream.writeInt(crc.getValue());

        // Write length
        long pos = stream.getStreamPosition();
        stream.seek(startPos);
        stream.writeInt((int)(pos - startPos) - 12);

        // Return to end of chunk and flush to minimize buffering
        stream.seek(pos);
        stream.flushBefore(pos);
    }

    protected void finalize() throws Throwable {
        // Empty finalizer (for improved performance; no need to call
        // super.finalize() in this case)
    }
}

// Compress output and write as a series of 'IDAT' chunks of
// fixed length.
final class IDATOutputStream extends ImageOutputStreamImpl {
    
    private static byte[] chunkType = {
        (byte)'I', (byte)'D', (byte)'A', (byte)'T'
    };

    private ImageOutputStream stream;
    private int chunkLength;
    private long startPos;
    private CRC crc = new CRC();

    Deflater def = new Deflater(Deflater.BEST_COMPRESSION);
    byte[] buf = new byte[512];

    private int bytesRemaining;

    public IDATOutputStream(ImageOutputStream stream, int chunkLength) 
        throws IOException {
        this.stream = stream;
        this.chunkLength = chunkLength;
        startChunk();
    }

    private void startChunk() throws IOException {
        crc.reset();
        this.startPos = stream.getStreamPosition();
        stream.writeInt(-1); // length, will backpatch

        crc.update(chunkType, 0, 4);
        stream.write(chunkType, 0, 4);

        this.bytesRemaining = chunkLength;
    }

    private void finishChunk() throws IOException {
        // Write CRC
        stream.writeInt(crc.getValue());

        // Write length
        long pos = stream.getStreamPosition();
        stream.seek(startPos);
        stream.writeInt((int)(pos - startPos) - 12);

        // Return to end of chunk and flush to minimize buffering
        stream.seek(pos);
        stream.flushBefore(pos);
    }

    public int read() throws IOException {
        throw new RuntimeException("Method not available");
    }

    public int read(byte[] b, int off, int len) throws IOException {
        throw new RuntimeException("Method not available");
    }

    public void write(byte[] b, int off, int len) throws IOException {
        if (len == 0) {
            return;
        }

	if (!def.finished()) {
	    def.setInput(b, off, len);
	    while (!def.needsInput()) {
		deflate();
	    }
	}
    }

    public void deflate() throws IOException {
	int len = def.deflate(buf, 0, buf.length);
        int off = 0;

        while (len > 0) {
            if (bytesRemaining == 0) {
                finishChunk();
                startChunk();
            }

            int nbytes = Math.min(len, bytesRemaining);
            crc.update(buf, off, nbytes);
            stream.write(buf, off, nbytes);

            off += nbytes;
            len -= nbytes;
            bytesRemaining -= nbytes;
        }
    }

    public void write(int b) throws IOException {
        byte[] wbuf = new byte[1];
        wbuf[0] = (byte)b;
        write(wbuf, 0, 1);
    }

    public void finish() throws IOException {
	if (!def.finished()) {
	    def.finish();
	    while (!def.finished()) {
		deflate();
	    }
	}
        finishChunk();
    }

    protected void finalize() throws Throwable {
        // Empty finalizer (for improved performance; no need to call
        // super.finalize() in this case)
    }
}


class PNGImageWriteParam extends ImageWriteParam {
    
    public PNGImageWriteParam(Locale locale) {
        super();
        this.canWriteProgressive = true;
        this.locale = locale;
    }
}

/**
 * @version 0.5
 */
public class PNGImageWriter extends ImageWriter {

    ImageOutputStream stream = null;

    PNGMetadata metadata = null;

    // Factors from the ImageWriteParam
    int sourceXOffset = 0;
    int sourceYOffset = 0;
    int sourceWidth = 0;
    int sourceHeight = 0;
    int[] sourceBands = null;
    int periodX = 1;
    int periodY = 1;

    int numBands;
    int bpp;

    RowFilter rowFilter = new RowFilter();
    byte[] prevRow = null;
    byte[] currRow = null;
    byte[][] filteredRows = null;

    // Per-band scaling tables
    //
    // After the first call to initializeScaleTables, either scale and scale0
    // will be valid, or scaleh and scalel will be valid, but not both.
    //
    // The tables will be designed for use with a set of input but depths
    // given by sampleSize, and an output bit depth given by scalingBitDepth.
    //
    int[] sampleSize = null; // Sample size per band, in bits
    int scalingBitDepth = -1; // Output bit depth of the scaling tables

    // Tables for 1, 2, 4, or 8 bit output
    byte[][] scale = null; // 8 bit table
    byte[] scale0 = null; // equivalent to scale[0]

    // Tables for 16 bit output
    byte[][] scaleh = null; // High bytes of output
    byte[][] scalel = null; // Low bytes of output

    int totalPixels; // Total number of pixels to be written by write_IDAT
    int pixelsDone; // Running count of pixels written by write_IDAT

    public PNGImageWriter(ImageWriterSpi originatingProvider) {
        super(originatingProvider);
    }
 
    public void setOutput(Object output) {
        super.setOutput(output);
        if (output != null) {
            if (!(output instanceof ImageOutputStream)) {
                throw new IllegalArgumentException("output not an ImageOutputStream!");
            }
            this.stream = (ImageOutputStream)output;
        } else {
            this.stream = null;
        }
    }

    private static int[] allowedProgressivePasses = { 1, 7 };

    public ImageWriteParam getDefaultWriteParam() {
        return new PNGImageWriteParam(getLocale());
    }

    public IIOMetadata getDefaultStreamMetadata(ImageWriteParam param) {
        return null;
    }

    public IIOMetadata getDefaultImageMetadata(ImageTypeSpecifier imageType,
                                               ImageWriteParam param) {
        PNGMetadata m = new PNGMetadata();
        m.initialize(imageType, imageType.getSampleModel().getNumBands());
        return m;
    }

    public IIOMetadata convertStreamMetadata(IIOMetadata inData,
                                             ImageWriteParam param) {
        return null;
    }

    public IIOMetadata convertImageMetadata(IIOMetadata inData,
                                            ImageTypeSpecifier imageType,
                                            ImageWriteParam param) {
        // TODO - deal with imageType
        if (inData instanceof PNGMetadata) {
            return (PNGMetadata)((PNGMetadata)inData).clone();
        } else {
            return new PNGMetadata(inData);
        }
    }

    private void write_magic() throws IOException {
        // Write signature
        byte[] magic = { (byte)137, 80, 78, 71, 13, 10, 26, 10 };
        stream.write(magic);
    }

    private void write_IHDR() throws IOException {
        // Write IHDR chunk
        ChunkStream cs = new ChunkStream(PNGImageReader.IHDR_TYPE, stream);
        cs.writeInt(metadata.IHDR_width);
        cs.writeInt(metadata.IHDR_height);
        cs.writeByte(metadata.IHDR_bitDepth);
        cs.writeByte(metadata.IHDR_colorType);
        if (metadata.IHDR_compressionMethod != 0) {
            throw new IIOException(
"Only compression method 0 is defined in PNG 1.1");
        }
        cs.writeByte(metadata.IHDR_compressionMethod);
        if (metadata.IHDR_filterMethod != 0) {
            throw new IIOException(
"Only filter method 0 is defined in PNG 1.1");
        }
        cs.writeByte(metadata.IHDR_filterMethod);
        if (metadata.IHDR_interlaceMethod < 0 ||
            metadata.IHDR_interlaceMethod > 1) {
            throw new IIOException(
"Only interlace methods 0 (node) and 1 (adam7) are defined in PNG 1.1");
        }
        cs.writeByte(metadata.IHDR_interlaceMethod);
        cs.finish();
    }

    private void write_cHRM() throws IOException {
        if (metadata.cHRM_present) {
            ChunkStream cs = new ChunkStream(PNGImageReader.cHRM_TYPE, stream);
            cs.writeInt(metadata.cHRM_whitePointX);