bmpimagewriter.java

java1.6众多例子参考

            // Partially filled last byte, if any
            if (scanlineBytes%8 > 0) {
                pixel = 0;
                for (int j=0; j<scanlineBytes%8; j++) {
                    pixel |= (pixels[l++] << (7 - j));
                }
                bpixels[k++] = (byte)pixel;
            }
            stream.write(bpixels, 0, (scanlineBytes+7)/8);

            break;

        case 4:
            if (compressionType == BMPConstants.BI_RLE4){
                byte[] bipixels = new byte[scanlineBytes];
                for (int h=0; h<scanlineBytes; h++) {
                    bipixels[h] = (byte)pixels[l++];
                }
                encodeRLE4(bipixels, scanlineBytes);
            }else {
                for (int j=0; j<scanlineBytes/2; j++) {
                    pixel = (pixels[l++] << 4) | pixels[l++];
                    bpixels[k++] = (byte)pixel;
                }
                // Put the last pixel of odd-length lines in the 4 MSBs
                if ((scanlineBytes%2) == 1) {
                    pixel = pixels[l] << 4;
                    bpixels[k++] = (byte)pixel;
                }
                stream.write(bpixels, 0, (scanlineBytes+1)/2);
            }
            break;

        case 8:
            if(compressionType == BMPConstants.BI_RLE8) {
                for (int h=0; h<scanlineBytes; h++) {
                    bpixels[h] = (byte)pixels[l++];
                }
                encodeRLE8(bpixels, scanlineBytes);
            }else {
                for (int j=0; j<scanlineBytes; j++) {
                    bpixels[j] = (byte)pixels[l++];
                }
                stream.write(bpixels, 0, scanlineBytes);
            }
            break;

        case 16:
            if (spixels == null)
                spixels = new short[scanlineBytes / numBands];
            /*
             * We expect that pixel data comes in RGB order.
             * We will assemble short pixel taking into account
             * the compression type:
             *
             * BI_RGB        - the RGB order should be maintained.
             * BI_BITFIELDS  - use bitPos array that was built
             *                 according to bitfields masks.
             */
            for (int j = 0, m = 0; j < scanlineBytes; m++) {
                spixels[m] = 0;
                if (compressionType == BMPConstants.BI_RGB) {
                    /*
                     * please note that despite other cases,
                     * the 16bpp BI_RGB requires the RGB data order
                     */ 
                    spixels[m] = (short)
                        (((0x1f & pixels[j    ]) << 10) |
                         ((0x1f & pixels[j + 1]) <<  5) |
                         ((0x1f & pixels[j + 2])      ));
                     j += 3;
                } else {
                    for(int i = 0 ; i < numBands; i++, j++) {
                        spixels[m] |=
                            (((pixels[j]) << bitPos[i]) & bitMasks[i]);
                    }
                } 
            }   
            stream.writeShorts(spixels, 0, spixels.length);
            break;

        case 24:
            if (numBands == 3) {
                for (int j=0; j<scanlineBytes; j+=3) {
                    // Since BMP needs BGR format
                    bpixels[k++] = (byte)(pixels[l+2]);
                    bpixels[k++] = (byte)(pixels[l+1]);
                    bpixels[k++] = (byte)(pixels[l]);
                    l+=3;
                }
                stream.write(bpixels, 0, scanlineBytes);
            } else {
                // Case where IndexColorModel had > 256 colors.
                int entries = icm.getMapSize();

                byte r[] = new byte[entries];
                byte g[] = new byte[entries];
                byte b[] = new byte[entries];

                icm.getReds(r);
                icm.getGreens(g);
                icm.getBlues(b);
                int index;

                for (int j=0; j<scanlineBytes; j++) {
                    index = pixels[l];
                    bpixels[k++] = b[index];
                    bpixels[k++] = g[index];
                    bpixels[k++] = b[index];
                    l++;
                }
                stream.write(bpixels, 0, scanlineBytes*3);
            }
            break;

        case 32:
            if (ipixels == null)
                ipixels = new int[scanlineBytes / numBands];
            if (numBands == 3) {
                /*
                 * We expect that pixel data comes in RGB order.
                 * We will assemble int pixel taking into account
                 * the compression type.
                 *
                 * BI_RGB        - the BGR order should be used.
                 * BI_BITFIELDS  - use bitPos array that was built
                 *                 according to bitfields masks.
                 */
                for (int j = 0, m = 0; j < scanlineBytes; m++) {
                    ipixels[m] = 0;
                    if (compressionType == BMPConstants.BI_RGB) {
                        ipixels[m] =
                            ((0xff & pixels[j + 2]) << 16) |
                            ((0xff & pixels[j + 1]) <<  8) |
                            ((0xff & pixels[j    ])      );
                        j += 3;
                    } else {
                        for(int i = 0 ; i < numBands; i++, j++) {
                            ipixels[m] |= 
                                (((pixels[j]) << bitPos[i]) & bitMasks[i]);
                        }
                    }
                }
            } else {
                // We have two possibilities here:
                // 1. we are writing the indexed image with bitfields
                //    compression (this covers also the case of BYTE_BINARY)
                //    => use icm to get actual RGB color values.
                // 2. we are writing the gray-scaled image with BI_BITFIELDS
                //    compression
                //    => just replicate the level of gray to color components.
                for (int j = 0; j < scanlineBytes; j++) {
                    if (icm != null) {
                        ipixels[j] = icm.getRGB(pixels[j]);
                    } else {
                        ipixels[j] =
                            pixels[j] << 16 | pixels[j] << 8 | pixels[j];
                    }
                }
            }
            stream.writeInts(ipixels, 0, ipixels.length);
            break;
        }

        // Write out the padding
        if (compressionType == BMPConstants.BI_RGB){
            for(k=0; k<padding; k++) {
                stream.writeByte(0);
            }
        }
    }

    private void encodeRLE8(byte[] bpixels, int scanlineBytes)
      throws IOException{

        int runCount = 1, absVal = -1, j = -1;
        byte runVal = 0, nextVal =0 ;

        runVal = bpixels[++j];
        byte[] absBuf = new byte[256];

        while (j < scanlineBytes-1) {
            nextVal = bpixels[++j];
            if (nextVal == runVal ){
                if(absVal >= 3 ){
                    /// Check if there was an existing Absolute Run
                    stream.writeByte(0);
                    stream.writeByte(absVal);
                    incCompImageSize(2);
                    for(int a=0; a<absVal;a++){
                        stream.writeByte(absBuf[a]);
                        incCompImageSize(1);
                    }
                    if (!isEven(absVal)){
                        //Padding
                        stream.writeByte(0);
                        incCompImageSize(1);
                    }
                }
                else if(absVal > -1){
                    /// Absolute Encoding for less than 3
                    /// treated as regular encoding
                    /// Do not include the last element since it will
                    /// be inclued in the next encoding/run
                    for (int b=0;b<absVal;b++){
                        stream.writeByte(1);
                        stream.writeByte(absBuf[b]);
                        incCompImageSize(2);
                    }
                }
                absVal = -1;
                runCount++;
                if (runCount == 256){
                    /// Only 255 values permitted
                    stream.writeByte(runCount-1);
                    stream.writeByte(runVal);
                    incCompImageSize(2);
                    runCount = 1;
                }
            }
            else {
                if (runCount > 1){
                    /// If there was an existing run
                    stream.writeByte(runCount);
                    stream.writeByte(runVal);
                    incCompImageSize(2);
                } else if (absVal < 0){
                    // First time..
                    absBuf[++absVal] = runVal;
                    absBuf[++absVal] = nextVal;
                } else if (absVal < 254){
                    //  0-254 only
                    absBuf[++absVal] = nextVal;
                } else {
                    stream.writeByte(0);
                    stream.writeByte(absVal+1);
                    incCompImageSize(2);
                    for(int a=0; a<=absVal;a++){
                        stream.writeByte(absBuf[a]);
                        incCompImageSize(1);
                    }
                    // padding since 255 elts is not even
                    stream.writeByte(0);
                    incCompImageSize(1);
                    absVal = -1;
                }
                runVal = nextVal;
                runCount = 1;
            }

            if (j == scanlineBytes-1){ // EOF scanline
                // Write the run
                if (absVal == -1){
                    stream.writeByte(runCount);
                    stream.writeByte(runVal);
                    incCompImageSize(2);
                    runCount = 1;
                }
                else {
                    // write the Absolute Run
                    if(absVal >= 2){
                        stream.writeByte(0);
                        stream.writeByte(absVal+1);
                        incCompImageSize(2);
                        for(int a=0; a<=absVal;a++){
                            stream.writeByte(absBuf[a]);
                            incCompImageSize(1);
                        }
                        if (!isEven(absVal+1)){
                            //Padding
                            stream.writeByte(0);
                            incCompImageSize(1);
                        }

                    }
                    else if(absVal > -1){
                        for (int b=0;b<=absVal;b++){
                            stream.writeByte(1);
                            stream.writeByte(absBuf[b]);
                            incCompImageSize(2);
                        }
                    }
                }
                /// EOF scanline

                stream.writeByte(0);
                stream.writeByte(0);
                incCompImageSize(2);
            }
        }
    }

    private void encodeRLE4(byte[] bipixels, int scanlineBytes)
      throws IOException {

        int runCount=2, absVal=-1, j=-1, pixel=0, q=0;
        byte runVal1=0, runVal2=0, nextVal1=0, nextVal2=0;
        byte[] absBuf = new byte[256];


        runVal1 = bipixels[++j];
        runVal2 = bipixels[++j];

        while (j < scanlineBytes-2){
            nextVal1 = bipixels[++j];
            nextVal2 = bipixels[++j];

            if (nextVal1 == runVal1 ) {

                //Check if there was an existing Absolute Run
                if(absVal >= 4){
                    stream.writeByte(0);
                    stream.writeByte(absVal - 1);
                    incCompImageSize(2);
                    // we need to exclude  last 2 elts, similarity of
                    // which caused to enter this part of the code
                    for(int a=0; a<absVal-2;a+=2){
                        pixel = (absBuf[a] << 4) | absBuf[a+1];
                        stream.writeByte((byte)pixel);
                        incCompImageSize(1);
                    }
                    // if # of elts is odd - read the last element
                    if(!(isEven(absVal-1))){
                        q = absBuf[absVal-2] << 4| 0;
                        stream.writeByte(q);
                        incCompImageSize(1);
                    }
                    // Padding to word align absolute encoding
                    if ( !isEven((int)Math.ceil((absVal-1)/2)) ) {
                        stream.writeByte(0);
                        incCompImageSize(1);
                    }
                } else if (absVal > -1){
                    stream.writeByte(2);
                    pixel = (absBuf[0] << 4) | absBuf[1];
                    stream.writeByte(pixel);
                    incCompImageSize(2);
                }
                absVal = -1;

                if (nextVal2 == runVal2){
                    // Even runlength
                    runCount+=2;
                    if(runCount == 256){
                        stream.writeByte(runCount-1);
                        pixel = ( runVal1 << 4) | runVal2;
                        stream.writeByte(pixel);
                        incCompImageSize(2);
                        runCount =2;
                        if(j< scanlineBytes - 1){
                            runVal1 = runVal2;
                            runVal2 = bipixels[++j];
                        } else {
                            stream.writeByte(01);
                            int r = runVal2 << 4 | 0;
                            stream.writeByte(r);
                            incCompImageSize(2);
                            runCount = -1;/// Only EOF required now
                        }
                    }
                } else {
                    // odd runlength and the run ends here
                    // runCount wont be > 254 since 256/255 case will
                    // be taken care of in above code.
                    runCount++;
                    pixel = ( runVal1 << 4) | runVal2;
                    stream.writeByte(runCount);
                    stream.writeByte(pixel);
                    incCompImageSize(2);
                    runCount = 2;
                    runVal1 = nextVal2;
                    // If end of scanline
                    if (j < scanlineBytes -1){
                        runVal2 = bipixels[++j];
                    }else {