wbmpimagereader.java

java1.6众多例子参考

/*
 * @(#)WBMPImageReader.java	1.11 05/11/17 14:15:06
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.imageio.plugins.wbmp;

import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.awt.image.MultiPixelPackedSampleModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;

import javax.imageio.IIOException;
import javax.imageio.ImageReader;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.spi.ImageReaderSpi;
import javax.imageio.stream.ImageInputStream;

import java.io.*;
import java.util.ArrayList;
import java.util.Iterator;

import com.sun.imageio.plugins.common.I18N;

/** This class is the Java Image IO plugin reader for WBMP images.
 *  It may subsample the image, clip the image,
 *  and shift the decoded image origin if the proper decoding parameter
 *  are set in the provided <code>WBMPImageReadParam</code>.
 */
public class WBMPImageReader extends ImageReader {
    /** The input stream where reads from */
    private ImageInputStream iis = null;

    /** Indicates whether the header is read. */
    private boolean gotHeader = false;

    /** The original image width. */
    private int width;

    /** The original image height. */
    private int height;

    private int wbmpType;
    
    private WBMPMetadata metadata;

    /** Constructs <code>WBMPImageReader</code> from the provided
     *  <code>ImageReaderSpi</code>.
     */
    public WBMPImageReader(ImageReaderSpi originator) {
        super(originator);
    }

    /** Overrides the method defined in the superclass. */
    public void setInput(Object input,
                         boolean seekForwardOnly,
                         boolean ignoreMetadata) {
        super.setInput(input, seekForwardOnly, ignoreMetadata);
        iis = (ImageInputStream) input; // Always works
        gotHeader = false;
    }

    /** Overrides the method defined in the superclass. */
    public int getNumImages(boolean allowSearch) throws IOException {
        if (iis == null) {
            throw new IllegalStateException(I18N.getString("GetNumImages0"));
        }
        if (seekForwardOnly && allowSearch) {
            throw new IllegalStateException(I18N.getString("GetNumImages1"));
        }
        return 1;
    }

    public int getWidth(int imageIndex) throws IOException {
        checkIndex(imageIndex);
        readHeader();
        return width;
    }

    public int getHeight(int imageIndex) throws IOException {
        checkIndex(imageIndex);
        readHeader();
        return height;
    }

    public boolean isRandomAccessEasy(int imageIndex) throws IOException {
        checkIndex(imageIndex);
        return true;
    }

    private void checkIndex(int imageIndex) {
        if (imageIndex != 0) {
            throw new IndexOutOfBoundsException(I18N.getString("WBMPImageReader0"));
        }
    }

    public void readHeader() throws IOException {
        if (gotHeader)
            return;

        if (iis == null) {
            throw new IllegalStateException("Input source not set!");
        }

        metadata = new WBMPMetadata();
        
        wbmpType = iis.readByte();   // TypeField
        byte fixHeaderField = iis.readByte();

        // check for valid wbmp image
        if (fixHeaderField != 0
            || !isValidWbmpType(wbmpType)) 
        {
            throw new IIOException(I18N.getString("WBMPImageReader2"));
        }

        metadata.wbmpType = wbmpType;
        
        // Read image width
        width = readMultiByteInteger();
        metadata.width = width;
        
        // Read image height
        height = readMultiByteInteger();
        metadata.height = height;
        
        gotHeader = true;
    }

    public Iterator getImageTypes(int imageIndex)
        throws IOException {
        checkIndex(imageIndex);
        readHeader();

        BufferedImage bi =
            new BufferedImage(1, 1, BufferedImage.TYPE_BYTE_BINARY);
        ArrayList list = new ArrayList(1);
        list.add(new ImageTypeSpecifier(bi));
        return list.iterator();
    }

    public ImageReadParam getDefaultReadParam() {
        return new ImageReadParam();
    }

    public IIOMetadata getImageMetadata(int imageIndex)
        throws IOException {
        checkIndex(imageIndex);
        if (metadata == null) {
            readHeader();
        }
        return metadata;
    }

    public IIOMetadata getStreamMetadata() throws IOException {
        return null;
    }

    public BufferedImage read(int imageIndex, ImageReadParam param)
        throws IOException {

        if (iis == null) {
            throw new IllegalStateException(I18N.getString("WBMPImageReader1"));
        }

        checkIndex(imageIndex);
        clearAbortRequest();
        processImageStarted(imageIndex);
        if (param == null)
            param = getDefaultReadParam();

        //read header
        readHeader();

        Rectangle sourceRegion = new Rectangle(0, 0, 0, 0);
        Rectangle destinationRegion = new Rectangle(0, 0, 0, 0);

        computeRegions(param, this.width, this.height,
                       param.getDestination(),
                       sourceRegion,
                       destinationRegion);

        int scaleX = param.getSourceXSubsampling();
        int scaleY = param.getSourceYSubsampling();
        int xOffset = param.getSubsamplingXOffset();
        int yOffset = param.getSubsamplingYOffset();

        // If the destination is provided, then use it.  Otherwise, create new one
        BufferedImage bi = param.getDestination();

        if (bi == null)
            bi = new BufferedImage(destinationRegion.x + destinationRegion.width,
                              destinationRegion.y + destinationRegion.height,
                              BufferedImage.TYPE_BYTE_BINARY);

        boolean noTransform = 
            destinationRegion.equals(new Rectangle(0, 0, width, height)) &&
            destinationRegion.equals(new Rectangle(0, 0, bi.getWidth(), bi.getHeight()));
        
        // Get the image data.
        WritableRaster tile = bi.getWritableTile(0, 0);

        // Get the SampleModel.
        MultiPixelPackedSampleModel sm =
            (MultiPixelPackedSampleModel)bi.getSampleModel();

        if (noTransform) {
            if (abortRequested()) {
                processReadAborted();
                return bi;
            }

            // If noTransform is necessary, read the data.
            iis.read(((DataBufferByte)tile.getDataBuffer()).getData(),
                     0, height*sm.getScanlineStride());
            processImageUpdate(bi,
                               0, 0,
                               width, height, 1, 1,
                               new int[]{0});
            processImageProgress(100.0F);
        } else {
            int len = (this.width + 7) / 8;
            byte[] buf = new byte[len];
            byte[] data = ((DataBufferByte)tile.getDataBuffer()).getData();
            int lineStride = sm.getScanlineStride();
            iis.skipBytes(len * sourceRegion.y);
            int skipLength = len * (scaleY - 1);

            // cache the values to avoid duplicated computation
            int[] srcOff = new int[destinationRegion.width];
            int[] destOff = new int[destinationRegion.width];
            int[] srcPos = new int[destinationRegion.width];
            int[] destPos = new int[destinationRegion.width];

            for (int i = destinationRegion.x, x = sourceRegion.x, j = 0;
                i < destinationRegion.x + destinationRegion.width;
                    i++, j++, x += scaleX) {
                srcPos[j] = x >> 3;
                srcOff[j] = 7 - (x & 7);
                destPos[j] = i >> 3;
                destOff[j] = 7 - (i & 7);
            }

            for (int j = 0, y = sourceRegion.y,
                k = destinationRegion.y * lineStride;
                j < destinationRegion.height; j++, y+=scaleY) {

                if (abortRequested())
                    break;
                iis.read(buf, 0, len);
                for (int i = 0; i < destinationRegion.width; i++) {
                    //get the bit and assign to the data buffer of the raster
                    int v = (buf[srcPos[i]] >> srcOff[i]) & 1;
                    data[k + destPos[i]] |= v << destOff[i];
                }

                k += lineStride;
                iis.skipBytes(skipLength);
                        processImageUpdate(bi,
                                           0, j,
                                           destinationRegion.width, 1, 1, 1,
                                           new int[]{0});
                        processImageProgress(100.0F*j/destinationRegion.height);
            }
        }

        if (abortRequested())
            processReadAborted();
        else
            processImageComplete();
        return bi;
    }

    public boolean canReadRaster() {
        return true;
    }

    public Raster readRaster(int imageIndex,
                             ImageReadParam param) throws IOException {
        BufferedImage bi = read(imageIndex, param);
        return bi.getData();
    }

    public void reset() {
        super.reset();
        iis = null;
        gotHeader = false;
    }

    private int readMultiByteInteger() throws IOException {
        int value = iis.readByte();
        int result = value & 0x7f;
        while((value & 0x80) == 0x80) {
            result <<= 7;
            value = iis.readByte();
            result |= (value & 0x7f);
        }
        return result;
    }
    
    /*
     * This method verifies that given byte is valid wbmp type marker.
     * At the moment only 0x0 marker is described by wbmp spec.
     */      
    boolean isValidWbmpType(int type) {
        return type == 0;
    }
}