bmp.java

自己编写的一个BMP图片读取类

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import java.util.Vector.*;

public class BMP{   //读取BMP图像源代码
 public static Image loadbitmap(String sfile) throws Exception{
   Image image;
   try{
     FileInputStream fs = new FileInputStream(sfile);

     int bflen = 14; // 14 byte BITMAPFILEHEADER
     byte bf[] = new byte[bflen];
     fs.read(bf, 0, bflen);
     int bilen = 40; // 40-byte BITMAPINFOHEADER
     byte bi[] = new byte[bilen];
     fs.read(bi, 0, bilen);

     // Interperet data.
     int nsize = (((int)bf[5] & 0xff) << 24)
         | (((int)bf[4] & 0xff) << 16)
         | (((int)bf[3] & 0xff) << 8)
         | (int)bf[2] & 0xff;
     //System.out.println("File type is :"+(char)bf[0]+(char)bf[1]);
     //System.out.println("Size of file is :"+nsize);

     int nbisize = (((int)bi[3] & 0xff) << 24)
         | (((int)bi[2] & 0xff) << 16)
         | (((int)bi[1] & 0xff) << 8)
         | (int)bi[0] & 0xff;
     //System.out.println("Size of bitmapinfoheader is :"+nbisize);

     int nwidth = (((int)bi[7] & 0xff) << 24)
         | (((int)bi[6] & 0xff) << 16)
         | (((int)bi[5] & 0xff) << 8)
         | (int)bi[4] & 0xff;
     //System.out.println("Width is :"+nwidth);

     int nheight = (((int)bi[11] & 0xff) << 24)
         | (((int)bi[10] & 0xff) << 16)
         | (((int)bi[9] & 0xff) << 8)
         | (int)bi[8] & 0xff;
     //System.out.println("Height is :"+nheight);

     int nplanes = (((int)bi[13] & 0xff) << 8) | (int)bi[12] & 0xff;
     //System.out.println("Planes is :"+nplanes);

     int nbitcount = (((int)bi[15] & 0xff) << 8) | (int)bi[14] & 0xff;
     //System.out.println("BitCount is :"+nbitcount);

     // Look for non-zero values to indicate compression
     int ncompression = (((int)bi[19]) << 24)
         | (((int)bi[18]) << 16)
         | (((int)bi[17]) << 8)
         | (int)bi[16];
     //System.out.println("Compression is :"+ncompression);

     int nsizeimage = (((int)bi[23] & 0xff) << 24)
         | (((int)bi[22] & 0xff) << 16)
         | (((int)bi[21] & 0xff) << 8)
         | (int)bi[20] & 0xff;
     //System.out.println("SizeImage is :"+nsizeimage);

     int nxpm = (((int)bi[27] & 0xff) << 24)
         | (((int)bi[26] & 0xff) << 16)
         | (((int)bi[25] & 0xff) << 8)
         | (int)bi[24] & 0xff;
     //System.out.println("X-Pixels per meter is :"+nxpm);

     int nypm = (((int)bi[31] & 0xff) << 24)
         | (((int)bi[30] & 0xff) << 16)
         | (((int)bi[29] & 0xff) << 8)
         | (int)bi[28] & 0xff;
     //System.out.println("Y-Pixels per meter is :"+nypm);

     int nclrused = (((int)bi[35] & 0xff) << 24)
         | (((int)bi[34] & 0xff) << 16)
         | (((int)bi[33] & 0xff) << 8)
         | (int)bi[32] & 0xff;
     //System.out.println("Colors used are :"+nclrused);

     int nclrimp = (((int)bi[39] & 0xff) << 24)
         | (((int)bi[38] & 0xff) << 16)
         | (((int)bi[37] & 0xff) << 8)
         | (int)bi[36] & 0xff;
     //System.out.println("Colors important are :"+nclrimp);

     if(nbitcount == 24){
       // No Palatte data for 24-bit format but scan lines are
       // padded out to even 4-byte boundaries.
       int npad = (nsizeimage / nheight) - nwidth * 3;
       //added for Bug correction
       if(npad == 4){
         npad = 0;
       }
       int ndata[] = new int[nheight * nwidth];
       byte brgb[] = new byte[(nwidth + npad) * 3 * nheight];
       fs.read(brgb, 0, (nwidth + npad) * 3 * nheight);
       int nindex = 0;
       for(int j = 0; j < nheight; j++){
         for(int i = 0; i < nwidth; i++){
           ndata[nwidth * (nheight - j - 1) + i] =
               (255 & 0xff) << 24
               | (((int)brgb[nindex + 2] & 0xff) << 16)
               | (((int)brgb[nindex + 1] & 0xff) << 8)
               | (int)brgb[nindex] & 0xff;
           nindex += 3;
         }
         nindex += npad;
       }

       image = Toolkit.getDefaultToolkit().createImage(new MemoryImageSource(
           nwidth, nheight, ndata, 0, nwidth));
     } else if(nbitcount == 8){
       // Have to determine the number of colors, the clrsused
       // parameter is dominant if it is greater than zero. If
       // zero, calculate colors based on bitsperpixel.
       int nNumColors = 0;
       if(nclrused > 0){
         nNumColors = nclrused;
       } else{
         nNumColors = (1 & 0xff) << nbitcount;
       }
       //System.out.println("The number of Colors is"+nNumColors);

       // Some bitmaps do not have the sizeimage field calculated
       // Ferret out these cases and fix 'em.
       if(nsizeimage == 0){
         nsizeimage = ((((nwidth * nbitcount) + 31) & ~31) >> 3);
         nsizeimage *= nheight;
         //System.out.println("nsizeimage (backup) is"+nsizeimage);
       }

       // Read the palatte colors.
       int npalette[] = new int[nNumColors];
       byte bpalette[] = new byte[nNumColors * 4];
       fs.read(bpalette, 0, nNumColors * 4);
       int nindex8 = 0;
       for(int n = 0; n < nNumColors; n++){
         npalette[n] = (255 & 0xff) << 24
             | (((int)bpalette[nindex8 + 2] & 0xff) << 16)
             | (((int)bpalette[nindex8 + 1] & 0xff) << 8)
             | (int)bpalette[nindex8] & 0xff;
         nindex8 += 4;
       }
       // Read the image data (actually indices into the palette)
       // Scan lines are still padded out to even 4-byte
       // boundaries.
       int npad8 = (nsizeimage / nheight) - nwidth;
       //System.out.println("nPad is:"+npad8);

       int ndata8[] = new int[nwidth * nheight];
       byte bdata[] = new byte[(nwidth + npad8) * nheight];
       fs.read(bdata, 0, (nwidth + npad8) * nheight);
       nindex8 = 0;
       for(int j8 = 0; j8 < nheight; j8++){
         for(int i8 = 0; i8 < nwidth; i8++){
           ndata8[nwidth * (nheight - j8 - 1) + i8] =
               npalette[((int)bdata[nindex8] & 0xff)];
           nindex8++;
         }
         nindex8 += npad8;
       }

       image = Toolkit.getDefaultToolkit().createImage(new MemoryImageSource(
           nwidth, nheight, ndata8, 0, nwidth));
     } else{
       System.out.println("Not a 24-bit or 8-bit Windows Bitmap, aborting...");
       image = (Image)null;
     }

     fs.close();
     return image;

   } catch(Exception e){
     e.printStackTrace();
     System.out.println("Caught exception in loadbitmap!");
   }
   return(Image)null;
 }

 public static int[] getPixels(Image parImage, int parWidth, int parHeight){
   int[] bitmap = new int[parWidth * parHeight];
   PixelGrabber pg = new PixelGrabber(parImage, 0, 0, parWidth, parHeight,
                                      bitmap, 0, parWidth);
   try{
     pg.grabPixels();
   } catch(InterruptedException e){
     e.printStackTrace();
   }
   return bitmap;
 }
}