风语者的祝福有冷却吗:读取BMP图像的JAVA类

来源:百度文库 编辑:九乡新闻网 时间:2024/03/28 23:09:51

//
//This code was taken and cleaned up from a
//Javaworld tips and tricks column
//

import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.MemoryImageSource;
import java.io.FileInputStream;
import java.io.IOException;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;

//
//really just a collection of methods to read a BMP file
//

public class BMPLoader

{

// build an int from a byte array - convert little to big endian
public static int constructInt(byte[] in, int offset) {

int ret = ((int) in[offset + 3] & 0xff);

ret = (ret << 8) | ((int) in[offset + 2] & 0xff);

ret = (ret << 8) | ((int) in[offset + 1] & 0xff);

ret = (ret << 8) | ((int) in[offset + 0] & 0xff);

return (ret);

}

// build an int from a byte array - convert little to big endian
// set high order bytes to 0xfff
public static int constructInt3(byte[] in, int offset) {

int ret = 0xff;

ret = (ret << 8) | ((int) in[offset + 2] & 0xff);

ret = (ret << 8) | ((int) in[offset + 1] & 0xff);

ret = (ret << 8) | ((int) in[offset + 0] & 0xff);

return (ret);

}

// build an int from a byte array - convert little to big endian
public static long constructLong(byte[] in, int offset) {

long ret = ((long) in[offset + 7] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 6] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 5] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 4] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 3] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 2] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 1] & 0xff);

ret |= (ret << 8) | ((long) in[offset + 0] & 0xff);

return (ret);

}


// build an double from a byte array - convert little to big endian
public static double constructDouble(byte[] in, int offset) {

long ret = constructLong(in, offset);

return (Double.longBitsToDouble(ret));

}

// build an short from a byte array - convert little to big endian
public static short constructShort(byte[] in, int offset) {

short ret = (short) ((short) in[offset + 1] & 0xff);

ret = (short) ((ret << 8) | (short) ((short) in[offset + 0] & 0xff));

return (ret);

}


// internal class representing a bitmap header structure
// with code to read it from a file
static class BitmapHeader {

public int nsize;

public int nbisize;

public int nwidth;

public int nheight;

public int nplanes;

public int nbitcount;

public int ncompression;

public int nsizeimage;

public int nxpm;

public int nypm;

public int nclrused;

public int nclrimp;

// read in the bitmap header
public void read(FileInputStream fs) throws IOException

{

final int bflen = 14; // 14 byte BITMAPFILEHEADER

byte bf[] = new byte[bflen];

fs.read(bf, 0, bflen);

final int bilen = 40; // 40-byte BITMAPINFOHEADER

byte bi[] = new byte[bilen];

fs.read(bi, 0, bilen);

// Interperet data.
nsize = constructInt(bf, 2);

// System.out.println("File type is :"+(char)bf[0]+(char)bf[1]);
// System.out.println("Size of file is :"+nsize);

nbisize = constructInt(bi, 2);

// System.out.println("Size of bitmapinfoheader is :"+nbisize);

nwidth = constructInt(bi, 4);

// System.out.println("Width is :"+nwidth);

nheight = constructInt(bi, 8);

// System.out.println("Height is :"+nheight);

nplanes = constructShort(bi, 12); //(((int)bi[13]&0xff)<<8)
// (int)bi[12]&0xff;

// System.out.println("Planes is :"+nplanes);

nbitcount = constructShort(bi, 14); //(((int)bi[15]&0xff)<<8)
// (int)bi[14]&0xff;

// System.out.println("BitCount is :"+nbitcount);

// Look for non-zero values to indicate compression
ncompression = constructInt(bi, 16);

// System.out.println("Compression is :"+ncompression);

nsizeimage = constructInt(bi, 20);

// System.out.println("SizeImage is :"+nsizeimage);

nxpm = constructInt(bi, 24);

// System.out.println("X-Pixels per meter is :"+nxpm);

nypm = constructInt(bi, 28);

// System.out.println("Y-Pixels per meter is :"+nypm);

nclrused = constructInt(bi, 32);

// System.out.println("Colors used are :"+nclrused);

nclrimp = constructInt(bi, 36);

// System.out.println("Colors important are :"+nclrimp);

}

}

public static Image read(FileInputStream fs)

{

try {

BitmapHeader bh = new BitmapHeader();

bh.read(fs);

if (bh.nbitcount == 24)

return (readMap24(fs, bh));

if (bh.nbitcount == 32)

return (readMap32(fs, bh));

if (bh.nbitcount == 8)

return (readMap8(fs, bh));

fs.close();

} catch (IOException e) {

// System.out.println("Caught exception in loadbitmap!");
}

return (null);

}

/**
*
* readMap24 internal routine to read the bytes in a 24 bit bitmap
*
*
*
* Arguments:
*
* fs - file stream
*
* bh - header struct
*
* Returns:
*
* Image Object, be sure to check for (Image)null !!!!
*
*
*
*/
protected static Image readMap32(FileInputStream fs, BitmapHeader bh)
throws IOException

{

Image image;

// No Palatte data for 24-bit format but scan lines are

// padded out to even 4-byte boundaries.

int xwidth = bh.nsizeimage / bh.nheight;

int ndata[] = new int[bh.nheight * bh.nwidth];

byte brgb[] = new byte[bh.nwidth * 4 * bh.nheight];

fs.read(brgb, 0, bh.nwidth * 4 * bh.nheight);

int nindex = 0;

for (int j = 0; j < bh.nheight; j++)

{

for (int i = 0; i < bh.nwidth; i++)

{

ndata[bh.nwidth * (bh.nheight - j - 1) + i] = constructInt3(
brgb, nindex);

nindex += 4;

}

}

image = Toolkit.getDefaultToolkit().createImage

(new MemoryImageSource(bh.nwidth, bh.nheight,

ndata, 0, bh.nwidth));

fs.close();

return (image);

}

/**
*
* readMap24 internal routine to read the bytes in a 24 bit bitmap
*
*
*
* Arguments:
*
* fs - file stream
*
* bh - header struct
*
* Returns:
*
* Image Object, be sure to check for (Image)null !!!!
*
*
*
*/
protected static Image readMap24(FileInputStream fs, BitmapHeader bh)
throws IOException

{

Image image;

// No Palatte data for 24-bit format but scan lines are

// padded out to even 4-byte boundaries.

int npad = (bh.nsizeimage / bh.nheight) - bh.nwidth * 3;

int ndata[] = new int[bh.nheight * bh.nwidth];

byte brgb[] = new byte[(bh.nwidth + npad) * 3 * bh.nheight];

fs.read(brgb, 0, (bh.nwidth + npad) * 3 * bh.nheight);

int nindex = 0;

for (int j = 0; j < bh.nheight; j++)

{

for (int i = 0; i < bh.nwidth; i++)

{

ndata[bh.nwidth * (bh.nheight - j - 1) + i] = constructInt3(
brgb, nindex);

nindex += 3;

}

nindex += npad;

}

image = Toolkit.getDefaultToolkit().createImage

(new MemoryImageSource(bh.nwidth, bh.nheight,

ndata, 0, bh.nwidth));

fs.close();

return (image);

}

/**
*
* readMap8 internal routine to read the bytes in a 8 bit bitmap
*
*
*
* Arguments:
*
* fs - file stream
*
* bh - header struct
*
* Returns:
*
* Image Object, be sure to check for (Image)null !!!!
*
*
*
*/
protected static Image readMap8(FileInputStream fs, BitmapHeader bh)
throws IOException

{

Image image;

// 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 (bh.nclrused > 0)

{

nNumColors = bh.nclrused;

}

else

{

nNumColors = (1 & 0xff) << bh.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 (bh.nsizeimage == 0)

{

bh.nsizeimage = ((((bh.nwidth * bh.nbitcount) + 31) & ~31) >> 3);

bh.nsizeimage *= bh.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] = constructInt3(bpalette, nindex8);

nindex8 += 4;

}

// Read the image data (actually indices into the palette)

// Scan lines are still padded out to even 4-byte

// boundaries.

int npad8 = (bh.nsizeimage / bh.nheight) - bh.nwidth;

// System.out.println("nPad is:"+npad8);

int ndata8[] = new int[bh.nwidth * bh.nheight];

byte bdata[] = new byte[(bh.nwidth + npad8) * bh.nheight];

fs.read(bdata, 0, (bh.nwidth + npad8) * bh.nheight);

nindex8 = 0;

for (int j8 = 0; j8 < bh.nheight; j8++)

{

for (int i8 = 0; i8 < bh.nwidth; i8++)

{

ndata8[bh.nwidth * (bh.nheight - j8 - 1) + i8] =

npalette[((int) bdata[nindex8] & 0xff)];

nindex8++;

}

nindex8 += npad8;

}

image = Toolkit.getDefaultToolkit().createImage

(new MemoryImageSource(bh.nwidth, bh.nheight,

ndata8, 0, bh.nwidth));

return (image);

}

/**
*
* load method - see read for details
*
*
*
* Arguments:
*
* sdir and sfile are the result of the FileDialog()
*
* getDirectory() and getFile() methods.
*
*
*
* Returns:
*
* Image Object, be sure to check for (Image)null !!!!
*
*
*
*/
public static Image load(String sdir, String sfile) {

return (load(sdir + sfile));

}

/**
*
* load method - see read for details
*
*
*
* Arguments:
*
* sdir - full path name
*
*
*
* Returns:
*
* Image Object, be sure to check for (Image)null !!!!
*
*
*
*/
public static Image load(String sdir)

{

try

{

FileInputStream fs = new FileInputStream(sdir);

return (read(fs));

}

catch (IOException ex) {

return (null);

}

}

public static void main(String[] args) throws IOException

{

if (args.length == 0) {

System.out.println("Usage >java BMPLoader ImageFile.bmp");

System.exit(0);

}

FileInputStream in = new FileInputStream(args[0]);

Image TheImage = read(in);

JFrame TheFrame = new JFrame(args[0]);

JLabel TheLabel = new JLabel(new ImageIcon(TheImage));

TheFrame.getContentPane().add(new JScrollPane(TheLabel));

TheFrame.setSize(300, 300);

TheFrame.setVisible(true);

}
//end class BMPLoader
}