DWGThumbnailer.java

package jirau;

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

import de.uni_siegen.wineme.come_in.thumbnailer.thumbnailers.AbstractThumbnailer;
import de.uni_siegen.wineme.come_in.thumbnailer.util.IOUtil;
import de.uni_siegen.wineme.come_in.thumbnailer.util.ResizeImage;

public class DWGThumbnailer extends AbstractThumbnailer {

	public void generateThumbnail(File input, File output) throws IOException, de.uni_siegen.wineme.come_in.thumbnailer.ThumbnailerException {
		//GENERATE FROM EXISTING BITMAP IN DWG
		byte[] outputByte = new byte[4096];
		
		FileInputStream fis = null;
		
		try {
			fis = new FileInputStream(input);
			fis.skip(0x0D);
			fis.read(outputByte, 0, 4);
			int PosSentinel = (((outputByte[3])&0xFF)*256*256*256)+(((outputByte[2])&0xFF)*256*256)+(((outputByte[1])&0xFF)*256)+((outputByte[0])&0xFF);
			fis.skip(PosSentinel-0x0D-4+30);
			outputByte[1]=0;
			fis.read(outputByte, 0, 1);
			int TypePreview = ((outputByte[0])&0xFF);
			if (TypePreview==2) {
				fis.read(outputByte, 0, 4);
				int PosBMP = (((outputByte[3])&0xFF)*256*256*256)+(((outputByte[2])&0xFF)*256*256)+(((outputByte[1])&0xFF)*256)+((outputByte[0])&0xFF);
				fis.read(outputByte, 0, 4);
				int LenBMP = (((outputByte[3])&0xFF)*256*256*256)+(((outputByte[2])&0xFF)*256*256)+(((outputByte[1])&0xFF)*256)+((outputByte[0])&0xFF);
				fis.skip(PosBMP-(PosSentinel+30)-1-4-4+14);
				fis.read(outputByte, 0, 2);
				int biBitCount = (((outputByte[1])&0xFF)*256)+((outputByte[0])&0xFF);
				fis.skip(-16);
				int bisSize=0;
				int bfSize = 0;
				if (biBitCount<9)
					bfSize = 54 + 4 * ((int) (Math.pow(2,biBitCount))) + LenBMP ;
				else bfSize = 54 + LenBMP ;
				//WORD "BM"
				outputByte[0]=0x42;outputByte[1]=0x4D;
				//DWORD bfSize
				outputByte[2]=(byte)(bfSize&0xff);outputByte[3]=(byte)(bfSize>>8&0xff);
				outputByte[4]=(byte)(bfSize>>16&0xff);outputByte[5]=(byte)(bfSize>>>24);
				//WORD bfReserved1
				outputByte[6]=0x00;outputByte[7]=0x00;
				//WORD bfReserved2
				outputByte[8]=0x00;outputByte[9]=0x00;
				//DWORD bfOffBits
				outputByte[10]=0x36;outputByte[11]=0x04;outputByte[12]=0x00;outputByte[13]=0x00;
	
				ByteArrayOutputStream baos = new ByteArrayOutputStream();
				baos.write(outputByte,0,14);
				while((LenBMP>0) && ((bisSize=fis.read(outputByte, 0, (LenBMP>4096?4096:LenBMP))) != -1)) {
					baos.write(outputByte, 0, bisSize);
					LenBMP-=bisSize;
				}
				
				ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
	
				BufferedImage originalImage = ImageIO.read(bais);
				
				ResizeImage resizer = new ResizeImage(thumbWidth, thumbHeight);
				resizer.setInputImage(originalImage);
				resizer.writeOutput(output);
			}
		} finally {
			IOUtil.quietlyClose(fis);
		}
	}

	public String[] getAcceptedMIMETypes() {
		return new String[]{ "image/x-dwg" };
	}
		
}