PDFOne (for Java)
Create, edit, view, print & enhance PDF documents and forms in Java SE/EE

Compatibility

J2SE J2EE Windows Linux Mac (OS X)

Home » Newsletter » February 2016

There is a question on StackOverFlow.com asking if there was a way to replace an image in a PDF file. PDFOne can parse through all content elements in a page and identify content like text, images, shapes, form fields, and annotations. PDFOne can delete form fields and annotations and redact text, but deleting images and shapes (path elements) is not supported yet. A quick-and-dirty solution would be draw another image after identify the bounding box of the existing image.

In this document, an old logo image was replaced with a new logo.

First, the index of the the images that need to be replaced was identified. For that, this code snippet extracts all images from the PDF document.

import java.io.File;
import java.util.ArrayList;

import javax.imageio.ImageIO;

import com.gnostice.pdfone.PDFOne;
import com.gnostice.pdfone.PdfDocument;
import com.gnostice.pdfone.PdfPageElement;
import com.gnostice.pdfone.PdfPageImageElement;

public class replaceImage {

  public static void main(String[] args) {

    ArrayList oImageList;

    try {
      PdfDocument doc = new PdfDocument();

      doc.load("sample_doc.pdf");
      oImageList = (ArrayList) doc.getPageElements(
          "1-", PdfPageElement.ELEMENT_TYPE_IMAGE);

      if (oImageList.size() > 0) {
        for (int i = 0; i < oImageList.size(); i++) {
          ImageIO.write(
              oImageList.get(i).getImage(),
              "png",
              new File("image" + i + ".png"));
        }
        doc.save("new-doc.pdf");

      } else {
        System.out.println("No images");
      }

      doc.close();

    } catch (Exception e) {
      System.out.println("Error in replaceImage.java");
      System.out.println(e.getMessage());
    }
  }
}

The output folder tells you the index of the images that need to be replaced.

The above code snippet was then modified to add draw new logo image wherever the old logo appeared.

import java.util.ArrayList;

import com.gnostice.pdfone.PDFOne;
import com.gnostice.pdfone.PdfDocument;
import com.gnostice.pdfone.PdfImage;
import com.gnostice.pdfone.PdfPage;
import com.gnostice.pdfone.PdfPageElement;
import com.gnostice.pdfone.PdfPageImageElement;

public class replaceImage {

  public static void main(String[] args) {

    ArrayList oImageList;

    try {
      PdfDocument doc = new PdfDocument();

      doc.load("sample_doc.pdf");
      oImageList =
          (ArrayList) doc.getPageElements(
              "1-",
              PdfPageElement.ELEMENT_TYPE_IMAGE);

      if (oImageList.size() > 0) {
        for (int i = 0; i < oImageList.size(); i++) {
          if ((i == 0) || (i == 3) || (i == 6)) {
            PdfPageImageElement oPageImage = oImageList.get(i);
            PdfImage pi = PdfImage
                .create("new-logo.png");

            PdfPage pg = doc.getPage(oPageImage.getPageNum());
            pg.drawImage(pi, oPageImage.getX(), oPageImage.getY());            

          }
          // ImageIO.write(
          //    oImageList.get(i).getImage(), 
          //    "png", 
          //    new File("image" + i + ".png"));
        }
        doc.save("new-doc.pdf");

      } else {
        System.out.println("No images");
      }

      doc.close();

    } catch (Exception e) {
      System.out.println("Error in replaceImage.java");
      System.out.println(e.getMessage());
    }
  }
}