Watermark.java

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/*
 * Turró i Cutiller Foundation. License notice.
 * Copyright (C) 2018 Lluis Turró Cutiller <http://www.turro.org/>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.turro.pdf;
 
import com.lowagie.text.DocumentException;
import com.lowagie.text.Element;
import com.lowagie.text.Font;
import com.lowagie.text.Image;
import com.lowagie.text.Phrase;
import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.ColumnText;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfGState;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfStamper;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
 
public class Watermark {
 
  public void addWatermark(InputStream src, OutputStream dest, WatermarkCfg watermark) throws IOException, DocumentException {
    PdfReader reader = new PdfReader(src);
    int n = reader.getNumberOfPages();
    PdfStamper stamper = new PdfStamper(reader, dest);
    stamper.setRotateContents(false);
    // transparency
    PdfGState gs1 = new PdfGState();
    gs1.setFillOpacity(0.2f);
    // properties
    PdfContentByte over;
    Rectangle pagesize;
    float x, y;
    String text[] = watermark.getText();
    Phrase p[] = new Phrase[text.length];
    if(watermark.hasText()) {
      // text watermark
      Font f = new Font(Font.HELVETICA, 30, Font.BOLD);
      for(int i = 0; i < text.length; i++) {
        p[i] = new Phrase(text[i], f);
      }
    }
    Image img = null;
    float w = 0.0F, h = 0.0F;
    if(watermark.hasImage()) {
      // image watermark
      img = Image.getInstance(watermark.getImage());
      w = img.getScaledWidth();
      h = img.getScaledHeight();
    }
    // loop over every page
    for (int i = 1; i <= n; i++) {
      pagesize = reader.getPageSize(i);
      x = (pagesize.getLeft() + pagesize.getRight()) / 2;
      y = (pagesize.getTop() + pagesize.getBottom()) / 2;
      over = stamper.getOverContent(i);
      over.saveState();
      over.setGState(gs1);
      if(p.length > 0) {
        float yp = y + ((p.length * 40) / 2);
        for(Phrase ph : p) {
          ColumnText.showTextAligned(over, Element.ALIGN_CENTER, ph, x, yp, watermark.getRotation());
          yp -= 40;
        }
      }
      if(img != null) {
        over.addImage(img, w, 0, 0, h, x - (w / 2), y - (h / 2));
      }
      over.restoreState();
    }
    stamper.close();
    reader.close();
  }
 
}