Java Windows Bitmap decoder and encoder

/** * Decodes and shows true color,2 color,16 color or 256 color windows 3.x * BMP images,this class currently support true color,2 color uncompressed; * 256 color and 16 color uncompressed as well as RLE compressed format. */ /** * This software is provided "AS IS," without a warranty of any kind. * anyone can use it for free,emails are welcomed concerning bugs or * suggestions. */ /** * BMPReader.java. * * @version 1.05 03/28/2008 * @author Wen Yu, yuwen_66@yahoo.com * * Changes: * 1. colorPalette to use bitmapHeader.colorsUsed if it's nonzero * instead of always relying on 1<<bitsPerPixel. * 2. check the bitmapHeader.dataOffSet for possible bytes to skip */ package cafe.image.codecs.reader; import java.io.*; import java.awt.*; import java.awt.image.*; import java.awt.event.*; import javax.swing.*; public class BMPReader extends ImageReader { //biCompression types private static final int BI_RGB = 0;//No compression private static final int BI_RLE8 = 1;//8 bit RLE Compression (8 bit only) private static final int BI_RLE4 = 2;//4 bit RLE Compression (4 bit only) private static final int BI_BITFIELDS = 3;//No compression (16 & 32 bit only) int bytePerScanLine = 0; BitmapHeader bitmapHeader; /** * This method could have returned an Image object directly using * Toolkit.getDefaultToolkit().createImage(ImageProducer) method, * but it is somewhat slow when called in a non-gui class to create * an image, a subclass of JFrame would do much faster! */ public void unpackImage(InputStream is) throws Exception { bitmapHeader = new BitmapHeader(); bitmapHeader.readHeader(is); width = bitmapHeader.imageWidth; height = bitmapHeader.imageHeight; pix = new int[width*height]; bitsPerPixel = bitmapHeader.bitCount; int bitPerWidth = width*bitsPerPixel; if(bitPerWidth%32 == 0)//to make sure scan lines are padded out to even 4-byte boundaries. { bytePerScanLine = (bitPerWidth>>>3); } else { bytePerScanLine = (bitPerWidth>>>3)+(4-(bitPerWidth>>>3)%4); //a different method to do the same thing as above! //bytePerScanLine = (((bitPerWidth+31) & ~31 ) >> 3); } switch (bitmapHeader.bitCount) { case 1: { unpack2ColorBitmapFile(is); break; } case 4: { if(bitmapHeader.compression == BI_RLE4) unpack16ColorCompressedBitmapFile(is); else unpack16ColorBitmapFile(is); break; } case 8: { if(bitmapHeader.compression == BI_RLE8) unpack256ColorCompressedBitmapFile(is); else unpack256ColorBitmapFile(is); break; } case 16: { System.out.println("16 bit BMP, decoding not implemented!"); System.exit(1); //unpack16bitTrueColorBitmapFile(is); //break; } case 24: { unpackTrueColorBitmapFile(is); break; } case 32: { unpack32bitTrueColorBitmapFile(is); break; } default: { System.out.println("Unsupported bitmap format!"); System.exit(1); } } } private void readPalette(InputStream is) throws Exception { int index = 0,nindex = 0; int numOfColors = (bitmapHeader.colorsUsed == 0)?(1<<bitsPerPixel):bitmapHeader.colorsUsed; byte brgb[] = new byte[numOfColors*4]; colorPalette = new int[numOfColors]; indexedColor = true; is.read(brgb,0,numOfColors*4); for(int i = 0; i < numOfColors; i++) { colorPalette[index++] = ((0xff<<24)|(brgb[nindex]&0xff)|((brgb[nindex+1]&0xff)<<8)|((brgb[nindex+2]&0xff)<<16)); nindex += 4; } //There may be some extra bits between color platte and actual image data is.skip(bitmapHeader.dataOffSet - numOfColors*4 - 54); } private void unpackTrueColorBitmapFile(InputStream is) throws Exception { System.out.println("24 bits bitmap color image!"); int index = 0,nindex = 0; int npad = bytePerScanLine-3*width; byte brgb[] = new byte[bytePerScanLine]; is.skip(bitmapHeader.dataOffSet - 54); for(int i = 1; i <= height; i++) { is.read(brgb,0,bytePerScanLine); index = width*(height-i); nindex = 0; for(int j = 0; j < width; j++) { pix[index++] = ((0xff<<24)|(brgb[nindex++]&0xff)|((brgb[nindex++]&0xff)<<8)|((brgb[nindex++]&0xff)<<16)); } nindex += npad; } is.close(); } private void unpack32bitTrueColorBitmapFile(InputStream is) throws Exception { System.out.println("32 bits bitmap color image!"); int index = 0,nindex = 0; byte brgb[] = new byte[bytePerScanLine]; is.skip(bitmapHeader.dataOffSet - 54); for(int i = 1; i <= height; i++) { is.read(brgb,0,bytePerScanLine); index = width*(height-i); nindex = 0; for(int j = 0; j < width; j++) { pix[index++] = ((brgb[nindex++]&0xff)|((brgb[nindex++]&0xff)<<8)|((brgb[nindex++]&0xff)<<16)|(0xff<<24)); nindex++; } } is.close(); } private void unpack256ColorBitmapFile(InputStream is) throws Exception { System.out.println("256 color bitmap color image!"); readPalette(is); int index = 0, nindex = 0; int npad = bytePerScanLine-width; byte brgb[] = new byte[bytePerScanLine]; for(int i = 1; i <= height; i++) { is.read(brgb,0,bytePerScanLine); index = width*(height-i); nindex = 0; for(int j = 0; j < width; j++) { pix[index++] = colorPalette[brgb[nindex++]&0xff]; } nindex += npad; } is.close(); } private void unpack16ColorBitmapFile(InputStream is) throws Exception { System.out.println("16 color bitmap color image!"); readPalette(is); int bit = 0, index = 0, nindex = 0; byte brgb[]; int npad = (32-((width*4)%32))/8; if (npad == 4) npad = 0; brgb = new byte[bytePerScanLine]; for(int i = 1; i <= height; i++) { is.read(brgb,0,bytePerScanLine); index = width*(height-i); nindex = 0; for(int j = 0; j < width/2; j++) { bit = brgb[nindex++]; pix[index++] = colorPalette[((bit>>>4)&0x0F)]; pix[index++] = colorPalette[bit&(0x0F)]; } if((width%2) != 0) { bit = brgb[nindex++]; pix[index++] = colorPalette[((bit>>>4)&0x0F)]; } nindex += npad; } is.close(); } private void unpack2ColorBitmapFile(InputStream is) throws Exception { System.out.println("2 color bitmap color image!"); readPalette(is); int bit = 0, index = 0, nindex = 0; byte brgb[]; brgb = new byte[bytePerScanLine]; int npad = (32-(width%32))/32; if (npad == 4) npad = 0; for(int i = 1; i <= height; i++) { is.read(brgb,0,bytePerScanLine); index = width*(height-i); nindex = 0; for(int j = 0; j < width/8; j++) { bit = brgb[nindex++]; for (int k = 0; k < 8; k++) { pix[index++] = colorPalette[((bit>>>(7-k))&0x01)]; } } if((width%8) != 0) { bit = brgb[nindex++]; for (int k = 0; k < width%8; k++) { pix[index++] = colorPalette[((bit>>>(7-k))&0x01)]; } } nindex += npad; } is.close(); } private void unpack256ColorCompressedBitmapFile(InputStream is) throws Exception { System.out.println("256 color bitmap color image!"); System.out.println("compressed format!"); readPalette(is); int rgb_table_index = 0, index = 0, nindex = 0;