bmpimagereader.java

java1.6众多例子参考

            for (int i = destinationRegion.x, x = sourceRegion.x, j = 0;
                 i < destinationRegion.x + destinationRegion.width;
                 i++, j++, x += scaleX) {
                srcPos[j] = x >> 1;
                srcOff[j] = (1 - (x & 1)) << 2;
                destPos[j] = i >> 1;
                destOff[j] = (1 - (i & 1)) << 2;
            }

            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]) & 0x0F;
                    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 8 bit BMP image data
    private void read8Bit(byte[] bdata) throws IOException {

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

        int lineLength = width + padding;

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

            for (int i=0; i<height; i++) {
                if (abortRequested()) {
                    break;
                }
                iis.readFully(bdata, j, width);
                iis.skipBytes(padding);
                j += isBottomUp ? -width : width;
                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 =
                ((ComponentSampleModel)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);

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

            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, m = sourceRegion.x;
                     i < destinationRegion.width; i++, m += scaleX) {
                    //get the bit and assign to the data buffer of the raster
                    bdata[k + i] = buf[m];
                }

                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 24 bit BMP image data
    private void read24Bit(byte[] bdata) throws IOException {
        // Padding bytes at the end of each scanline
        // width * bitsPerPixel should be divisible by 32
        int padding = width * 3 % 4;
        if ( padding != 0)
            padding = 4 - padding;

        int lineStride = width * 3;
        int lineLength = lineStride + padding;

        if (noTransform) {
            int j = isBottomUp ? (height -1) * width * 3 : 0;

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

            int k = destinationRegion.y * lineStride;
            if (isBottomUp)
                k += (destinationRegion.height - 1) * lineStride;
            k += destinationRegion.x * 3;

            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, m = 3 * sourceRegion.x;
                     i < destinationRegion.width; i++, m += 3 * scaleX) {
                    //get the bit and assign to the data buffer of the raster
                    int n = 3 * i + k;
                    for (int b = 0; b < destBands.length; b++)
                        bdata[n + destBands[b]] = buf[m + sourceBands[b]];
                }

                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);
            }
        }
    }

    private void read16Bit(short sdata[]) throws IOException {
        // Padding bytes at the end of each scanline
        // width * bitsPerPixel should be divisible by 32
        int padding = width * 2 % 4;
        
        if ( padding != 0)
            padding = 4 - padding;
        
        int lineLength = width + padding / 2;
        
        if (noTransform) {
            int j = isBottomUp ? (height -1) * width : 0;
            for (int i=0; i<height; i++) {
                if (abortRequested()) {
                    break;
                }

                iis.readFully(sdata, j, width);
                iis.skipBytes(padding);
                
                j += isBottomUp ? -width : width;
                processImageUpdate(bi, 0, i,
                                   destinationRegion.width, 1, 1, 1,
                                   new int[]{0});
                processImageProgress(100.0F * i/destinationRegion.height);
            }
        } else {
            short[] buf = new short[lineLength];
            int lineStride =
                ((SinglePixelPackedSampleModel)sampleModel).getScanlineStride();
            
            if (isBottomUp) {
                int lastLine =
                    sourceRegion.y + (destinationRegion.height - 1) * scaleY;
                iis.skipBytes(lineLength * (height - 1 - lastLine) << 1);
            } else
                iis.skipBytes(lineLength * sourceRegion.y << 1);
            
            int skipLength = lineLength * (scaleY - 1) << 1;
            
            int k = destinationRegion.y * lineStride;
            if (isBottomUp)
                k += (destinationRegion.height - 1) * lineStride;
            k += destinationRegion.x;
            
            for (int j = 0, y = sourceRegion.y;
                 j < destinationRegion.height; j++, y+=scaleY) {
                
                if (abortRequested())
                    break;
                iis.readFully(buf, 0, lineLength);
                for (int i = 0, m = sourceRegion.x;
                     i < destinationRegion.width; i++, m += scaleX) {
                    //get the bit and assign to the data buffer of the raster
                    sdata[k + i] = buf[m];
                }

                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);
            }
        }
    }

    private void read32Bit(int idata[]) throws IOException {
        if (noTransform) {
            int j = isBottomUp ? (height -1) * width : 0;

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

            if (isBottomUp) {
                int lastLine =
                    sourceRegion.y + (destinationRegion.height - 1) * scaleY;
                iis.skipBytes(width * (height - 1 - lastLine) << 2);
            } else
                iis.skipBytes(width * sourceRegion.y << 2);

            int skipLength = width * (scaleY - 1) << 2;

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

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

                if (abortRequested())
                    break;
                iis.readFully(buf, 0, width);
                for (int i = 0, m = sourceRegion.x;
                     i < destinationRegion.width; i++, m += scaleX) {
                    //get the bit and assign to the data buffer of the raster
                    idata[k + i] = buf[m];
                }

                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);
            }
        }
    }

    private void readRLE8(byte bdata[]) throws IOException {
        // If imageSize field is not provided, calculate it.
        int imSize = (int)imageSize;
        if (imSize == 0) {
            imSize = (int)(bitmapFileSize - bitmapOffset);
        }

        int padding = 0;
        // If width is not 32 bit aligned, then while uncompressing each
        // scanline will have padding bytes, calculate the amount of padding
        int remainder = width % 4;
        if (remainder != 0) {
            padding = 4 - remainder;
        }

        // Read till we have the whole image
        byte values[] = new byte[imSize];
        int bytesRead = 0;
        iis.readFully(values, 0, imSize);

        // Since data is compressed, decompress it
        decodeRLE8(imSize, padding, values, bdata);
    }

    private void decodeRLE8(int imSize,
                            int padding,
                            byte[] values,
                            byte[] bdata) throws IOException {

        byte val[] = new byte[width * height];
        int count = 0, l = 0;
        int value;
        boolean flag = false;
        int lineNo = isBottomUp ? height - 1 : 0;
        int lineStride =
            ((ComponentSampleModel)sampleModel).getScanlineStride();
        int finished = 0;

        while (count != imSize) {
            value = values[count++] & 0xff;
            if (value == 0) {
                switch(values[count++] & 0xff) {

                case 0:
                    // End-of-scanline marker
                    if (lineNo >= sourceRegion.y &&
                        lineNo < sourceRegion.y + sourceRegion.height) {
                        if (noTransform) {
                            int pos = lineNo * width;
                            for(int i = 0; i < width; i++)
                                bdata[pos++] = val[i];
                            processImageUpdate(bi, 0, lineNo,
                                               destinationRegion.width, 1, 1, 1,