import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
import java.awt.MediaTracker;
import java.awt.Container;
import java.awt.Toolkit;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.net.FileNameMap;
import java.net.URLConnection;
import javax.imageio.ImageIO;
import java.lang.Integer;

/*
	Skript zum Verkleinern von Bildern mit Hilfe
	der Klasse Bild

	args[0] - Anzahl Pixel an der laengsten Kante
	args[1] - qualitaet JPEG, z.B. 75 fuer 75%
	args[2] - Eingangsordner
	args[3] - Ausgabeordner
*/

FileNameMap fileNameMap = URLConnection.getFileNameMap();
int width = Integer.parseInt(args[0]);
int height = width;
String inDirName = args[2];
String outDirName = args[3];
File inFile = new File(inDirName);
File[] fileList = inFile.listFiles();
if(fileList != null && fileList.length > 0) {
	for(int i = 0; i < fileList.length; i++) {
		System.out.println(fileList[i].getAbsolutePath());

		File outDir = new File(outDirName);
		File outFile = new File(outDir, fileList[i].getName());
		System.out.println(outFile.getAbsolutePath());
		Image image = ImageIO.read(fileList[i]);
    MediaTracker mediaTracker = new MediaTracker(new Container());
    mediaTracker.addImage(image, 0);
    try {
      mediaTracker.waitForID(0);
      if (!mediaTracker.isErrorAny()) {

        int quality = Integer.parseInt(args[1]);
        float factor = (float) 0.0;

        BufferedImage thumbImage;
        int imageWidth = image.getWidth(null);
        int imageHeight = image.getHeight(null);
        int thumbWidth = width;
        int thumbHeight = height;
        if(imageWidth < width) {
          thumbWidth = imageWidth;
        }
        if(imageHeight < height) {
          thumbHeight = imageHeight;
        }
        double thumbRatio = (double)thumbWidth / (double)thumbHeight;
        double imageRatio = (double)imageWidth / (double)imageHeight;
        if (thumbRatio < imageRatio) {
          thumbHeight = (int)(thumbWidth / imageRatio);
        }
        else {
          thumbWidth = (int)(thumbHeight * imageRatio);
        }

        String mimeType = fileNameMap.getContentTypeFor("file://" + fileList[i].getAbsolutePath());

        // draw original image to thumbnail image object and
        // scale it to the new size on-the-fly
        if(mimeType.contains("jpeg") || mimeType.contains("png")) {
          thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
        } else {
          thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_ARGB);
        }
        Graphics2D graphics2D = thumbImage.createGraphics();
        graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);

        // 30.7.2007: sharpening hinzugefuegt (Anfang)
        //float factor = -0.15f; // minus = sharpen, plus = soften
        //float[] sharpenArray = {0, -1, 0, -1, 5, -1, 0, -1, 0};
        /*
          30.6.2013: sharpening als Weichmacher nur, wenn Bild < 400
        */
        /*if(thumbWidth < 400 || thumbHeight < 400) {
          factor = 0.1f;
        }*/

        if(factor != (float) 0.0) {
            //float[] array = {0, factor, 0, factor, 1-(factor*4), factor, 0, factor, 0};
						float[] array = new float[9];
						array[0] = 0;
						array[1] = factor;
						array[2] = 0;
						array[3] = factor;
						array[4] = 1-(factor*4);
						array[5] = factor;
						array[6] = 0;
						array[7] = factor;
						array[8] = 0;
            Kernel kernel = new Kernel(3, 3, array);
            ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
            thumbImage = cOp.filter(thumbImage, null);
        }
        // 30.7.2007: sharpening hinzugefuegt (Ende)

        String imgType;
        if(mimeType.contains("jpg")) {
          imgType = "jpg";
        } else if(mimeType.contains("jpeg")) {
          imgType = "jpg";
        } else if(mimeType.contains("png")) {
          imgType = "png";
        } else if(mimeType.contains("gif")) {
          imgType = "gif";
        } else {
          imgType = "jpg";
        }

        ImageIO.write(thumbImage, imgType, outFile);
      }
    } catch (InterruptedException ex) {
      System.out.println("Error: " + ex.getLocalizedMessage());
    }

	}
} else {
	System.out.println("fileList is null or empty");
}