//    ImageToBmp


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

public class ImageToBmp {

    public static void imageToBmpFile(BufferedImage image, File outputfile) throws Exception {
        byte[] bmpdata=imageToBmpFileBytes(image);
        writeFile(outputfile,bmpdata);
    }

    public static void imagePixelsToBmpFile(int[] pixels, int width, int height, File outputfile) throws Exception {
        byte[] bmpdata=imagePixelsToBmpFileBytes(pixels,width,height);
        writeFile(outputfile,bmpdata);
    }

    public static byte[] imageToBmpFileBytes(BufferedImage image) {
        int width=image.getWidth(),
            height=image.getHeight();
        int[] pixels=image.getRGB(0,0,width,height,null,0,width);
        byte[] bmpdata=imagePixelsToBmpFileBytes(pixels,width,height);
        return bmpdata;
    }
    
    public static byte[] imagePixelsToBmpFileBytes(int[] pixels, int width, int height) {
        // Variables
        int rowlength=((width*3-1)/4+1)*4,
            filesize=54+height*rowlength;
        byte[] data=new byte[filesize];
        // File Header
        setValue(data,0,2,0x4d42);
        setValue(data,2,4,filesize);
        setValue(data,6,2,0);
        setValue(data,8,2,0);
        setValue(data,10,4,0x36);
        // DIB Header
        setValue(data,14,4,0x28); // Header size
        setValue(data,18,4,width);
        setValue(data,22,4,height);
        setValue(data,26,2,1);
        setValue(data,28,2,0x18); // Bits per pixel
        setValue(data,30,4,0); // No compression
        setValue(data,34,4,height*rowlength);
        setValue(data,38,4,0);
        setValue(data,42,4,0);
        setValue(data,46,4,0);
        setValue(data,50,4,0);
        // Image data
        int padding=rowlength-width*3,
            offset=54;
        for (int y=height-1; y>=0; y--) {
            for (int x=0; x<width; x++) {
                setValue(data,offset,3,(pixels[y*width+x]&0x00FFFFFF));
                offset+=3;
            }
            if (padding>0) {
                setValue(data,offset,padding,0);
                offset+=padding;
            }
        }
        // Return bytedata
        return data;
    }

    private static void setValue(byte[] data, int offset, int length, int value) {
        if (length==1) {
            data[offset]=getByte(value);
            return;
        }
        if (length==2) {
            data[offset]=getByte(value&0xFF);
            data[offset+1]=getByte((value&0xFF00)>>8);
            return;
        }
        if (length==3) {
            data[offset]=getByte(value&0xFF);
            data[offset+1]=getByte((value&0xFF00)>>8);
            data[offset+2]=getByte((value&0xFF0000)>>16);
            return;
        }
        if (length==4) {
            data[offset]=getByte(value&0xFF);
            data[offset+1]=getByte((value&0xFF00)>>8);
            data[offset+2]=getByte((value&0xFF0000)>>16);
            data[offset+3]=getByte((value&0xFF000000)>>24);
            return;
        }
        System.out.println("ImageToBmp.setValue(...,"+offset+","+length+","+value+"): Invalid length");
        System.exit(1);
    }

    private static byte getByte(int value) {
        if (value<=127) {
            return (byte)(value);
        } else {
            return (byte)(value-256);
        }
    }

    private static void writeFile(File file, byte[] data) throws Exception {
        FileOutputStream output=new FileOutputStream(file);
        output.write(data);
        output.flush();
        output.close();
    }

}