/*
 * This class is part of the book "iText in Action - 2nd Edition"
 * written by Bruno Lowagie (ISBN: 9781935182610)
 * For more info, go to: http://itextpdf.com/examples/
 * This example only works with the AGPL version of iText.
 */
package part4.chapter16;

import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

import com.itextpdf.text.DocumentException;
import com.itextpdf.text.pdf.PRStream;
import com.itextpdf.text.pdf.PdfName;
import com.itextpdf.text.pdf.PdfNumber;
import com.itextpdf.text.pdf.PdfObject;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.parser.PdfImageObject;

public class ResizeImage {

	/** The resulting PDF file. */
    public static String RESULT = "results/part4/chapter16/resized_image.pdf";
    /** The multiplication factor for the image. */
    public static float FACTOR = 0.5f;
    
    /**
     * Manipulates a PDF file src with the file dest as result
     * @param src the original PDF
     * @param dest the resulting PDF
     * @throws IOException
     * @throws DocumentException 
     */
    public void manipulatePdf(String src, String dest) throws IOException, DocumentException {
        PdfName key = new PdfName("ITXT_SpecialId");
        PdfName value = new PdfName("123456789");
        // Read the file
        PdfReader reader = new PdfReader(SpecialId.RESULT);
        int n = reader.getXrefSize();
        PdfObject object;
        PRStream stream;
        // Look for image and manipulate image stream
        for (int i = 0; i < n; i++) {
            object = reader.getPdfObject(i);
            if (object == null || !object.isStream())
                continue;
            stream = (PRStream)object;
            if (value.equals(stream.get(key))) {
                PdfImageObject image = new PdfImageObject(stream);
                BufferedImage bi = image.getBufferedImage();
                if (bi == null) continue;
                int width = (int)(bi.getWidth() * FACTOR);
                int height = (int)(bi.getHeight() * FACTOR);
                BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
                AffineTransform at = AffineTransform.getScaleInstance(FACTOR, FACTOR);
                Graphics2D g = img.createGraphics();
                g.drawRenderedImage(bi, at);
                ByteArrayOutputStream imgBytes = new ByteArrayOutputStream();
                ImageIO.write(img, "JPG", imgBytes);
                stream.clear();
                stream.setData(imgBytes.toByteArray(), false, PRStream.NO_COMPRESSION);
                stream.put(PdfName.TYPE, PdfName.XOBJECT);
                stream.put(PdfName.SUBTYPE, PdfName.IMAGE);
                stream.put(key, value);
                stream.put(PdfName.FILTER, PdfName.DCTDECODE);
                stream.put(PdfName.WIDTH, new PdfNumber(width));
                stream.put(PdfName.HEIGHT, new PdfNumber(height));
                stream.put(PdfName.BITSPERCOMPONENT, new PdfNumber(8));
                stream.put(PdfName.COLORSPACE, PdfName.DEVICERGB);
            }
        }
        // Save altered PDF
        PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(RESULT));
        stamper.close();
        reader.close();
    }

    /**
     * Main method.
     *
     * @param    args    no arguments needed
     * @throws DocumentException 
     * @throws IOException
     */
    public static void main(String[] args) throws IOException, DocumentException {
        new SpecialId().createPdf(SpecialId.RESULT);
        new ResizeImage().manipulatePdf(SpecialId.RESULT, RESULT);
    }
}