Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. */ package org.apache.pdfbox.multipdf; import java.awt.geom.AffineTransform; import java.io.IOException; import java.io.OutputStream; import java.nio.charset.StandardCharsets; import java.util.Arrays; import java.util.HashSet; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.fontbox.util.BoundingBox; import org.apache.pdfbox.cos.COSArray; import org.apache.pdfbox.cos.COSBase; import org.apache.pdfbox.cos.COSDictionary; import org.apache.pdfbox.cos.COSName; import org.apache.pdfbox.cos.COSStream; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDDocumentCatalog; import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.PDResources; import org.apache.pdfbox.pdmodel.common.PDRectangle; import org.apache.pdfbox.pdmodel.common.PDStream; import org.apache.pdfbox.pdmodel.PDPageContentStream; import org.apache.pdfbox.pdmodel.PDPageContentStream.AppendMode; import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject; import org.apache.pdfbox.pdmodel.graphics.optionalcontent.PDOptionalContentGroup; import org.apache.pdfbox.pdmodel.graphics.optionalcontent.PDOptionalContentProperties; import org.apache.pdfbox.util.Matrix; /** * This class allows to import pages as Form XObjects into a document and use them to create layers * (optional content groups). It should used only on loaded documents, not on generated documents * because these can contain unfinished parts, e.g. font subsetting information. */ public class LayerUtility { private static final Log LOG = LogFactory.getLog(LayerUtility.class); private static final boolean DEBUG = true; private final PDDocument targetDoc; private final PDFCloneUtility cloner; /** * Creates a new instance. * @param document the PDF document to modify */ public LayerUtility(PDDocument document) { this.targetDoc = document; this.cloner = new PDFCloneUtility(document); } /** * Returns the PDF document we work on. * @return the PDF document */ public PDDocument getDocument() { return this.targetDoc; } /** * Some applications may not wrap their page content in a save/restore (q/Q) pair which can * lead to problems with coordinate system transformations when content is appended. This * method lets you add a q/Q pair around the existing page's content. * @param page the page * @throws IOException if an I/O error occurs */ public void wrapInSaveRestore(PDPage page) throws IOException { COSStream saveGraphicsStateStream = getDocument().getDocument().createCOSStream(); try (OutputStream saveStream = saveGraphicsStateStream.createOutputStream()) { saveStream.write("q\n".getBytes(StandardCharsets.ISO_8859_1)); } COSStream restoreGraphicsStateStream = getDocument().getDocument().createCOSStream(); try (OutputStream restoreStream = restoreGraphicsStateStream.createOutputStream()) { restoreStream.write("Q\n".getBytes(StandardCharsets.ISO_8859_1)); } //Wrap the existing page's content in a save/restore pair (q/Q) to have a controlled //environment to add additional content. COSDictionary pageDictionary = page.getCOSObject(); COSBase contents = pageDictionary.getDictionaryObject(COSName.CONTENTS); if (contents instanceof COSStream) { COSStream contentsStream = (COSStream) contents; COSArray array = new COSArray(); array.add(saveGraphicsStateStream); array.add(contentsStream); array.add(restoreGraphicsStateStream); pageDictionary.setItem(COSName.CONTENTS, array); } else if (contents instanceof COSArray) { COSArray contentsArray = (COSArray) contents; contentsArray.add(0, saveGraphicsStateStream); contentsArray.add(restoreGraphicsStateStream); } else { throw new IOException("Contents are unknown type: " + contents.getClass().getName()); } } /** * Imports a page from some PDF file as a Form XObject so it can be placed on another page * in the target document. * <p> * You may want to call {@link #wrapInSaveRestore(PDPage) wrapInSaveRestore(PDPage)} before invoking the Form XObject to * make sure that the graphics state is reset. * * @param sourceDoc the source PDF document that contains the page to be copied * @param pageNumber the page number of the page to be copied * @return a Form XObject containing the original page's content * @throws IOException if an I/O error occurs */ public PDFormXObject importPageAsForm(PDDocument sourceDoc, int pageNumber) throws IOException { PDPage page = sourceDoc.getPage(pageNumber); return importPageAsForm(sourceDoc, page); } private static final Set<String> PAGE_TO_FORM_FILTER = new HashSet<>( Arrays.asList("Group", "LastModified", "Metadata")); /** * Imports a page from some PDF file as a Form XObject so it can be placed on another page * in the target document. * <p> * You may want to call {@link #wrapInSaveRestore(PDPage) wrapInSaveRestore(PDPage)} before invoking the Form XObject to * make sure that the graphics state is reset. * * @param sourceDoc the source PDF document that contains the page to be copied * @param page the page in the source PDF document to be copied * @return a Form XObject containing the original page's content * @throws IOException if an I/O error occurs */ public PDFormXObject importPageAsForm(PDDocument sourceDoc, PDPage page) throws IOException { importOcProperties(sourceDoc); PDStream newStream = new PDStream(targetDoc, page.getContents(), COSName.FLATE_DECODE); PDFormXObject form = new PDFormXObject(newStream); //Copy resources PDResources pageRes = page.getResources(); PDResources formRes = new PDResources(); cloner.cloneMerge(pageRes, formRes); form.setResources(formRes); //Transfer some values from page to form transferDict(page.getCOSObject(), form.getCOSObject(), PAGE_TO_FORM_FILTER, true); Matrix matrix = form.getMatrix(); AffineTransform at = matrix.createAffineTransform(); PDRectangle mediaBox = page.getMediaBox(); PDRectangle cropBox = page.getCropBox(); PDRectangle viewBox = (cropBox != null ? cropBox : mediaBox); //Handle the /Rotation entry on the page dict int rotation = page.getRotation(); //Transform to FOP's user space //at.scale(1 / viewBox.getWidth(), 1 / viewBox.getHeight()); at.translate(mediaBox.getLowerLeftX() - viewBox.getLowerLeftX(), mediaBox.getLowerLeftY() - viewBox.getLowerLeftY()); switch (rotation) { case 90: at.scale(viewBox.getWidth() / viewBox.getHeight(), viewBox.getHeight() / viewBox.getWidth()); at.translate(0, viewBox.getWidth()); at.rotate(-Math.PI / 2.0); break; case 180: at.translate(viewBox.getWidth(), viewBox.getHeight()); at.rotate(-Math.PI); break; case 270: at.scale(viewBox.getWidth() / viewBox.getHeight(), viewBox.getHeight() / viewBox.getWidth()); at.translate(viewBox.getHeight(), 0); at.rotate(-Math.PI * 1.5); break; default: //no additional transformations necessary } //Compensate for Crop Boxes not starting at 0,0 at.translate(-viewBox.getLowerLeftX(), -viewBox.getLowerLeftY()); if (!at.isIdentity()) { form.setMatrix(at); } BoundingBox bbox = new BoundingBox(); bbox.setLowerLeftX(viewBox.getLowerLeftX()); bbox.setLowerLeftY(viewBox.getLowerLeftY()); bbox.setUpperRightX(viewBox.getUpperRightX()); bbox.setUpperRightY(viewBox.getUpperRightY()); form.setBBox(new PDRectangle(bbox)); return form; } /** * Places the given form over the existing content of the indicated page (like an overlay). * The form is enveloped in a marked content section to indicate that it's part of an * optional content group (OCG), here used as a layer. This optional group is returned and * can be enabled and disabled through methods on {@link PDOptionalContentProperties}. * <p> * You may want to call {@link #wrapInSaveRestore(PDPage) wrapInSaveRestore(PDPage)} before calling this method to make * sure that the graphics state is reset. * * @param targetPage the target page * @param form the form to place * @param transform the transformation matrix that controls the placement of your form. You'll * need this if your page has a crop box different than the media box, or if these have negative * coordinates, or if you want to scale or adjust your form. * @param layerName the name for the layer/OCG to produce * @return the optional content group that was generated for the form usage * @throws IOException if an I/O error occurs */ public PDOptionalContentGroup appendFormAsLayer(PDPage targetPage, PDFormXObject form, AffineTransform transform, String layerName) throws IOException { PDDocumentCatalog catalog = targetDoc.getDocumentCatalog(); PDOptionalContentProperties ocprops = catalog.getOCProperties(); if (ocprops == null) { ocprops = new PDOptionalContentProperties(); catalog.setOCProperties(ocprops); } if (ocprops.hasGroup(layerName)) { throw new IllegalArgumentException("Optional group (layer) already exists: " + layerName); } PDRectangle cropBox = targetPage.getCropBox(); if ((cropBox.getLowerLeftX() < 0 || cropBox.getLowerLeftY() < 0) && transform.isIdentity()) { // PDFBOX-4044 LOG.warn("Negative cropBox " + cropBox + " and identity transform may make your form invisible"); } PDOptionalContentGroup layer = new PDOptionalContentGroup(layerName); ocprops.addGroup(layer); try (PDPageContentStream contentStream = new PDPageContentStream(targetDoc, targetPage, AppendMode.APPEND, !DEBUG)) { contentStream.beginMarkedContent(COSName.OC, layer); contentStream.saveGraphicsState(); contentStream.transform(new Matrix(transform)); contentStream.drawForm(form); contentStream.restoreGraphicsState(); contentStream.endMarkedContent(); } return layer; } private void transferDict(COSDictionary orgDict, COSDictionary targetDict, Set<String> filter, boolean inclusive) throws IOException { for (Map.Entry<COSName, COSBase> entry : orgDict.entrySet()) { COSName key = entry.getKey(); if (inclusive && !filter.contains(key.getName())) { continue; } else if (!inclusive && filter.contains(key.getName())) { continue; } targetDict.setItem(key, cloner.cloneForNewDocument(entry.getValue())); } } /** * Imports OCProperties from source document to target document so hidden layers can still be * hidden after import. * * @param sourceDoc The source PDF document that contains the /OCProperties to be copied. * @throws IOException If an I/O error occurs. */ private void importOcProperties(PDDocument srcDoc) throws IOException { PDDocumentCatalog srcCatalog = srcDoc.getDocumentCatalog(); PDOptionalContentProperties srcOCProperties = srcCatalog.getOCProperties(); if (srcOCProperties == null) { return; } PDDocumentCatalog dstCatalog = targetDoc.getDocumentCatalog(); PDOptionalContentProperties dstOCProperties = dstCatalog.getOCProperties(); if (dstOCProperties == null) { dstCatalog.setOCProperties( new PDOptionalContentProperties((COSDictionary) cloner.cloneForNewDocument(srcOCProperties))); } else { cloner.cloneMerge(srcOCProperties, dstOCProperties); } } }