bmpimagereader.java

java1.6众多例子参考

        // If the destination band is set used it
        sourceBands = param.getSourceBands();
        destBands = param.getDestinationBands();

        seleBand = (sourceBands != null) && (destBands != null);
        noTransform =
            destinationRegion.equals(new Rectangle(0, 0, width, height)) ||
            seleBand;

        if (!seleBand) {
            sourceBands = new int[numBands];
            destBands = new int[numBands];
            for (int i = 0; i < numBands; i++)
                destBands[i] = sourceBands[i] = i;
        }

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

        // Get the image data.
        WritableRaster raster = null;

        if (bi == null) {
            if (sampleModel != null && colorModel != null) {
                sampleModel =
                    sampleModel.createCompatibleSampleModel(destinationRegion.x +
                                                            destinationRegion.width,
                                                            destinationRegion.y +
                                                            destinationRegion.height);
                if (seleBand)
                    sampleModel = sampleModel.createSubsetSampleModel(sourceBands);
                raster = Raster.createWritableRaster(sampleModel, new Point());
                bi = new BufferedImage(colorModel, raster, false, null);
            }
        } else {
            raster = bi.getWritableTile(0, 0);
            sampleModel = bi.getSampleModel();
            colorModel = bi.getColorModel();

            noTransform &=  destinationRegion.equals(raster.getBounds());
        }

        byte bdata[] = null; // buffer for byte data
        short sdata[] = null; // buffer for short data
        int idata[] = null; // buffer for int data

        // the sampleModel can be null in case of embedded image
        if (sampleModel != null) {
            if (sampleModel.getDataType() == DataBuffer.TYPE_BYTE)
                bdata = (byte[])
                    ((DataBufferByte)raster.getDataBuffer()).getData();
            else if (sampleModel.getDataType() == DataBuffer.TYPE_USHORT)
                sdata = (short[])
                    ((DataBufferUShort)raster.getDataBuffer()).getData();
            else if (sampleModel.getDataType() == DataBuffer.TYPE_INT)
                idata = (int[])
                    ((DataBufferInt)raster.getDataBuffer()).getData();
        }

        // There should only be one tile.
        switch(imageType) {

        case VERSION_2_1_BIT:
            // no compression
            read1Bit(bdata);
            break;

        case VERSION_2_4_BIT:
            // no compression
            read4Bit(bdata);
            break;

        case VERSION_2_8_BIT:
            // no compression
            read8Bit(bdata);
            break;

        case VERSION_2_24_BIT:
            // no compression
            read24Bit(bdata);
            break;

        case VERSION_3_1_BIT:
            // 1-bit images cannot be compressed.
            read1Bit(bdata);
            break;

        case VERSION_3_4_BIT:
            switch((int)compression) {
            case BI_RGB:
                read4Bit(bdata);
                break;

            case BI_RLE4:
                readRLE4(bdata);
                break;

            default:
                throw new
                    RuntimeException(I18N.getString("BMPImageReader1"));
            }
            break;

        case VERSION_3_8_BIT:
            switch((int)compression) {
            case BI_RGB:
                read8Bit(bdata);
                break;

            case BI_RLE8:
                readRLE8(bdata);
                break;

            default:
                throw new
                    RuntimeException(I18N.getString("BMPImageReader1"));
            }

            break;

        case VERSION_3_24_BIT:
            // 24-bit images are not compressed
            read24Bit(bdata);
            break;

        case VERSION_3_NT_16_BIT:
            read16Bit(sdata);
            break;

        case VERSION_3_NT_32_BIT:
            read32Bit(idata);
            break;

        case VERSION_3_XP_EMBEDDED:
        case VERSION_4_XP_EMBEDDED:
        case VERSION_5_XP_EMBEDDED:
            bi = readEmbedded((int)compression, bi, param);
            break;

        case VERSION_4_1_BIT:
            read1Bit(bdata);
            break;

        case VERSION_4_4_BIT:
            switch((int)compression) {

            case BI_RGB:
                read4Bit(bdata);
                break;

            case BI_RLE4:
                readRLE4(bdata);
                break;

            default:
                throw new
                    RuntimeException(I18N.getString("BMPImageReader1"));
            }

        case VERSION_4_8_BIT:
            switch((int)compression) {

            case BI_RGB:
                read8Bit(bdata);
                break;

            case BI_RLE8:
                readRLE8(bdata);
                break;

            default:
                throw new
                    RuntimeException(I18N.getString("BMPImageReader1"));
            }
            break;

        case VERSION_4_16_BIT:
            read16Bit(sdata);
            break;

        case VERSION_4_24_BIT:
            read24Bit(bdata);
            break;

        case VERSION_4_32_BIT:
            read32Bit(idata);
            break;
        }

        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();
    }

    private void resetHeaderInfo() {
        gotHeader = false;
        bi = null;
        sampleModel = originalSampleModel = null;
        colorModel = originalColorModel = null;
    }

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

    // Deal with 1 Bit images using IndexColorModels
    private void read1Bit(byte[] bdata) throws IOException {
        int bytesPerScanline = (width + 7) / 8;
        int padding = bytesPerScanline % 4;
        if (padding != 0) {
            padding = 4 - padding;
        }

        int lineLength = bytesPerScanline + padding;

        if (noTransform) {
            int j = isBottomUp ? (height -1)*bytesPerScanline : 0;

            for (int i=0; i<height; i++) {
                if (abortRequested()) {
                    break;
                }
                iis.readFully(bdata, j, bytesPerScanline);
                iis.skipBytes(padding);
                j += isBottomUp ? -bytesPerScanline : bytesPerScanline;
                processImageUpdate(bi, 0, i,
                                   destinationRegion.width, 1, 1, 1,
                                   new int[]{0});
                processImageProgress(100.0F * i/destinationRegion.height);
            }
        } else {
            byte[] buf = new byte[lineLength];
            int lineStride =
                ((MultiPixelPackedSampleModel)sampleModel).getScanlineStride();

            if (isBottomUp) {
                int lastLine =
                    sourceRegion.y + (destinationRegion.height - 1) * scaleY;
                iis.skipBytes(lineLength * (height - 1 - lastLine));
            } else
                iis.skipBytes(lineLength * sourceRegion.y);

            int skipLength = lineLength * (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);
            }

            int k = destinationRegion.y * lineStride;
            if (isBottomUp)
                k += (destinationRegion.height - 1) * lineStride;

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

                if (abortRequested())
                    break;
                iis.read(buf, 0, lineLength);
                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;
                    bdata[k + destPos[i]] |= v << destOff[i];
                }

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

    // Method to read a 4 bit BMP image data
    private void read4Bit(byte[] bdata) throws IOException {

        int bytesPerScanline = (width + 1) / 2;

        // Padding bytes at the end of each scanline
        int padding = bytesPerScanline % 4;
        if (padding != 0)
            padding = 4 - padding;

        int lineLength = bytesPerScanline + padding;

        if (noTransform) {
            int j = isBottomUp ? (height -1) * bytesPerScanline : 0;

            for (int i=0; i<height; i++) {
                if (abortRequested()) {
                    break;
                }
                iis.readFully(bdata, j, bytesPerScanline);
                iis.skipBytes(padding);
                j += isBottomUp ? -bytesPerScanline : bytesPerScanline;
                processImageUpdate(bi, 0, i,
                                   destinationRegion.width, 1, 1, 1,
                                   new int[]{0});
                processImageProgress(100.0F * i/destinationRegion.height);
            }
        } else {
            byte[] buf = new byte[lineLength];
            int lineStride =
                ((MultiPixelPackedSampleModel)sampleModel).getScanlineStride();

            if (isBottomUp) {
                int lastLine =
                    sourceRegion.y + (destinationRegion.height - 1) * scaleY;
                iis.skipBytes(lineLength * (height - 1 - lastLine));
            } else
                iis.skipBytes(lineLength * sourceRegion.y);

            int skipLength = lineLength * (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];