Java tutorial
/* * Copyright 2011 Radim Hatlapatka. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * under the License. */ package cz.muni.pdfjbim; import com.itextpdf.text.DocumentException; import com.itextpdf.text.Image; import com.itextpdf.text.pdf.PRIndirectReference; import com.itextpdf.text.pdf.PdfDictionary; import com.itextpdf.text.pdf.PdfName; import com.itextpdf.text.pdf.PdfObject; import com.itextpdf.text.pdf.PdfReader; import com.itextpdf.text.pdf.PdfStamper; import com.itextpdf.text.pdf.PdfWriter; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.Iterator; import java.util.List; import java.util.Map; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * class for replacing images inside PDF document by their recompressed version * * @author Radim Hatlapatka (208155@mail.muni.cz) */ public class PdfImageReplacer { private static final Logger log = LoggerFactory.getLogger(PdfImageReplacer.class); /** * replace images by they recompressed version according to JBIG2 standard positions and image * data given in imagesData * * @param pdfName represents name of original PDF file * @param os represents output stream for writing changed PDF file * @param imagesData contains compressed images according to JBIG2 standard and informations * about them * @throws PdfRecompressionException if version of PDF is lower than 1.4 or was catch * DocumentException or IOException */ public void replaceImageUsingIText(String pdfName, OutputStream os, List<Jbig2ForPdf> imagesData) throws PdfRecompressionException { try (FileInputStream pdfInputStream = new FileInputStream(pdfName)) { replaceImageUsingIText(pdfInputStream, os, imagesData); } catch (FileNotFoundException ex) { throw new PdfRecompressionException("File " + pdfName + " doesn't exist", ex); } catch (IOException ex) { throw new PdfRecompressionException("Unable to read file " + pdfName, ex); } } /** * replace images by they recompressed version according to JBIG2 standard positions and image * data given in imagesData * * @param originalPdf represents name of original PDF file * @param os represents output stream for writing changed PDF file * @param imagesData contains compressed images according to JBIG2 standard and informations * about them * @throws PdfRecompressionException if version of PDF is lower than 1.4 or was catch * DocumentException or IOException */ public void replaceImageUsingIText(InputStream originalPdf, OutputStream os, List<Jbig2ForPdf> imagesDataList) throws PdfRecompressionException { if (originalPdf == null) { throw new NullPointerException("pdfName"); } if (os == null) { throw new NullPointerException("os"); } if (imagesDataList == null) { throw new NullPointerException("imagesData is null => nothing to recompress"); } log.info("Replacing old images in PDF with their equivalent encoded according to standard JBIG2"); PdfReader pdf; PdfStamper stp = null; try { pdf = new PdfReader(originalPdf); stp = new PdfStamper(pdf, os); PdfWriter writer = stp.getWriter(); int version; if ((version = Integer.parseInt(String.valueOf(pdf.getPdfVersion()))) < 4) { log.debug("PDF version of original PDF was {} => changing to PDF version 1.4", pdf.getPdfVersion()); writer.setPdfVersion(PdfWriter.PDF_VERSION_1_4); } for (Jbig2ForPdf imagesData : imagesDataList) { Map<PdfObjId, PdfImage> jbig2Images = imagesData.getMapOfJbig2Images(); Iterator itImages = jbig2Images.values().iterator(); String key; if (itImages.hasNext()) { PdfImage myImg = (PdfImage) itImages.next(); key = myImg.getPdfImageInformation().getKey(); } else { key = "im0"; } for (int pageNum = 1; pageNum <= pdf.getNumberOfPages(); pageNum++) { PdfDictionary pg = pdf.getPageN(pageNum); PdfDictionary resPg = (PdfDictionary) PdfReader.getPdfObject(pg.get(PdfName.RESOURCES)); PdfDictionary xobjResPg = (PdfDictionary) PdfReader.getPdfObject(resPg.get(PdfName.XOBJECT)); PdfObject obj = null; if (xobjResPg != null) { for (Iterator it = xobjResPg.getKeys().iterator(); it.hasNext();) { PdfObject pdfObjIndirect = xobjResPg.get((PdfName) it.next()); if (pdfObjIndirect.isIndirect()) { PdfDictionary pdfObj2 = (PdfDictionary) PdfReader.getPdfObject(pdfObjIndirect); PdfDictionary xobj2Res = (PdfDictionary) PdfReader .getPdfObject(pdfObj2.get(PdfName.RESOURCES)); if (xobj2Res != null) { for (Iterator it2 = xobj2Res.getKeys().iterator(); it2.hasNext();) { PdfObject resObj = xobj2Res.get((PdfName) it2.next()); } PdfDictionary xobj = (PdfDictionary) PdfReader .getPdfObject(xobj2Res.get(PdfName.XOBJECT)); if (xobj == null) { continue; } obj = xobj.get(new PdfName(key)); } else { obj = xobjResPg.get(new PdfName(key)); if (obj == null) { obj = pdfObjIndirect; } } } } } if ((obj != null) && (obj.isIndirect())) { PdfDictionary tg = (PdfDictionary) PdfReader.getPdfObject(obj); if (tg == null) { continue; } PdfName type = (PdfName) PdfReader.getPdfObject(tg.get(PdfName.SUBTYPE)); if (PdfName.IMAGE.equals(type)) { PRIndirectReference ref = (PRIndirectReference) obj; PdfObjId imId = new PdfObjId(ref.getNumber(), ref.getGeneration()); PdfImage jbImage = jbig2Images.get(imId); if (jbImage == null) { continue; } log.debug("Replacing image {}", jbImage); PdfImageInformation jbImageInfo = jbImage.getPdfImageInformation(); Image img = Image.getInstance(jbImageInfo.getWidth(), jbImageInfo.getHeight(), jbImage.getImageData(), imagesData.getGlobalData()); PdfReader.killIndirect(obj); Image maskImage = img.getImageMask(); if (maskImage != null) { writer.addDirectImageSimple(maskImage); } writer.addDirectImageSimple(img, (PRIndirectReference) obj); } } } } } catch (IOException ioEx) { throw new PdfRecompressionException(ioEx); } catch (DocumentException dEx) { throw new PdfRecompressionException(dEx); } finally { log.debug("Deleting temporary files created during process of PDF recompression"); for (Jbig2ForPdf imagesData : imagesDataList) { Tools.deleteFilesFromList(imagesData.getJbFiles().toArray(new File[0])); } try { if (stp != null) { stp.close(); } } catch (DocumentException ex) { log.error("Exception thrown while closing stream", ex); } catch (IOException ex) { log.error("Exception thrown while closing stream", ex); } } } }