How to Crop, Split, Remove Pages From PDFs With Java and PDFBox

If you don’t like to read large amounts of text on a screen and prefer (printing on) paper, this article will show you how to use Java to automate some useful PDF manipulations. To save paper and ink/toner, my usual workflow is to remove extra pages from PDFs, then crop the text area to make it bigger, and to remove white margins. Then I merge 2 pages per sheet and I split the doc. into multiple, smaller files, to make it easier to print on both sides if the printer doesn’t support full-duplex. I chose Java and PDFBox because they are extremely fast on large files and they have a ton of options and possibilities to integrate with other projects. Create a new Java project with Maven Let's start by creating a new Java project, named , with Maven: pdf_utils mvn archetype:generate \ -DgroupId=com.pdf.pdf_utils \ -DartifactId=pdf_utils \ -DarchetypeArtifactId=maven-archetype-quickstart \ -DarchetypeVersion=1.4 \ -DinteractiveMode=false Then, open the file and add a dependency to , in the section: pdf_utils/pom.xml PDFBox dependencies ... org.apache.pdfbox pdfbox 2.0.27 ... Also change the target & source compiler versions: org.apache.maven.plugins maven-compiler-plugin 17 17 Then rename the generated class to src/main/java/com/pdf/pdf_utils/App.java PDFUtils How to crop a PDF We will now develop a Java function that crops each page within a PDF document and saves the cropped content in a new PDF file. The cropping coordinates, specified in millimeters, will serve as inputs to the function. Add helper functions to convert between mm units Convert mm to units Extract the doc's file name Crop each page Save the result & append "-cropped" to the ouyput file's name public String cropPDFMM(float x, float y, float width, float height, String srcFilePath) throws IOException { // helper functions to convert between mm units Function mmToUnits = (Float a) -> a / 0.352778f; Function unitsToMm = (Float a) -> a * 0.352778f;

// convert mm to units float xUnits = mmToUnits.apply(x); float yUnits = mmToUnits.apply(y); float widthUnits = mmToUnits.apply(width); float heightUnits = mmToUnits.apply(height);

// extract the doc's file name File srcFile = new File(srcFilePath); String fileName = srcFile.getName(); int dotIndex = fileName.lastIndexOf('.'); String fileNameWithoutExtension = (dotIndex == -1) ? fileName : fileName.substring(0, dotIndex);

// crop each page PDDocument doc = PDDocument.load(srcFile); int nrOfPages = doc.getNumberOfPages(); PDRectangle newBox = new PDRectangle( xUnits, yUnits, widthUnits, heightUnits); for (int i = 0; i < nrOfPages; i++) { doc.getPage(i).setCropBox(newBox); }

// save the result & append -cropped to the file name File outFile = new File(fileNameWithoutExtension + "-cropped.pdf"); doc.save(outFile); doc.close(); return outFile.getCanonicalPath(); } Let's test by calling it from the function: cropPDFMM main public static void main( String[] args ) { String srcFilePath = "/Users/user/.../file.pdf"; PDFUtils app = new PDFUtils();

try { ///// crop pdf float x = 18f; float y = 20f; float width = 140f; float height = 210f; String resultFilePath = app.cropPDFMM(x, y, width, height, srcFilePath);

System.out.println( "Done!" ); } catch (Exception e) { System.out.println(e); } } You should see a file named in the current directory. file-cropped.pdf How to remove pages from a PDF To remove specific pages from a document, we can utilize an array of integer ranges. Each range consists of a start page and an end page ([startPage1, endPage1, startPage2, endPage2, ...]). The function iterates through each page of the document and checks if the page number falls outside of any of the specified ranges in the array. If a page is not within any range, it is appended to a new document. Add a helper function to test if a page is within a range Test each page number -> append it to a temp. doc Save the temp. doc. -> overwrite the input file public void removePages(String srcFilePath, Integer[] pageRanges) throws IOException { // a helper function to test if a page is within a range BiPredicate pageInInterval = (Integer page, Integer[] allPages) -> { for (int j = 0; j = startPage-1 && page < endPage) { return true; } } return false; };

File srcFile = new File(srcFilePath); PDDocument pdfDocument = PDDocument.load(srcFile); PDDocument tmpDoc = new PDDocument();

// test if a page is within a range // if not, append the page to a temp. doc. for (int i = 0; i < pdfDocument.getNumberOfPages(); i++) { if (pageInInterval.test(i, pageRanges)) { continue; } tmpDoc.addPage(pdfDocument.getPage(i)); }

// save the temporary doc. tmpDoc.save(new File(srcFilePath)); tmpDoc.close(); pdfDocument.close(); } Let's test it by calling in the main function: removePages ///// remove pages app.removePages(resultFilePath, new Integer[] {1, 21, 376, 428}); It will overwrite the input (cropped) file. How to split a PDF We will now introduce a function that enables the splitting of a PDF into multiple separate PDFs, with each resulting file containing a specified number of pages. The function expects two inputs: the path to the source PDF document and the desired number of pages in each split file. Extract source file's name for each nrOfPages append them to a temporary document save the temp doc with the source file's name + index public void splitPDF(String srcFilePath, int nrOfPages) throws IOException { // extract file's name File srcFile = new File(srcFilePath); String fileName = srcFile.getName(); int dotIndex = fileName.lastIndexOf('.'); String fileNameWithoutExtension = (dotIndex == -1) ? fileName : fileName.substring(0, dotIndex);

PDDocument pdfDocument = PDDocument.load(srcFile);

// extract every nrOfPages to a temporary document // append an index to its name and save it for (int i = 1; i < pdfDocument.getNumberOfPages(); i+=nrOfPages) { Splitter splitter = new Splitter();

int fromPage = i; int toPage = i+nrOfPages; splitter.setStartPage(fromPage); splitter.setEndPage(toPage); splitter.setSplitAtPage(toPage - fromPage );

List lst = splitter.split(pdfDocument);

PDDocument pdfDocPartial = lst.get(0); File f = new File(fileNameWithoutExtension + "-" + i + ".pdf"); pdfDocPartial.save(f); pdfDocPartial.close(); } pdfDocument.close(); } Here is the full function: main() public static void main( String[] args ){ String srcFilePath = "/Users/user/pdfs/file.pdf"; PDFUtils app = new PDFUtils();

try { ///// crop pdf float x = 18f; float y = 20f; float width = 140f; float height = 210f; String resultFilePath = app.cropPDFMM(x, y, width, height, srcFilePath);

///// remove pages app.removePages(resultFilePath, new Integer[] {1, 21, 376, 428}); ///// split pages app.splitPDF(resultFilePath, 20);

System.out.println( "Done!" ); } catch (Exception e) { System.out.println(e); } } Merge 2 pages per sheet (2up) This function is inspired from . https://stackoverflow.com/questions/12093408/pdfbox-merge-2-portrait-pages-onto-a-single-side-by-side-landscape-page Create a temporary document Iterate over the pages of the original doc. -> get the left & right pages Create a new "output" page with the right dimensions Append the left page at (0,0) Append the right page, translated to (left page's width, 0) Save the temp. doc -> overwrite the source file public void mergePages(String srcFilePath) throws IOException {

// SOURCE: https://stackoverflow.com/questions/12093408/pdfbox-merge-2-portrait-pages-onto-a-single-side-by-side-landscape-page File srcFile = new File(srcFilePath); PDDocument pdfDocument = PDDocument.load(srcFile); PDDocument outPdf = new PDDocument();

for (int i = 0; i < pdfDocument.getNumberOfPages(); i+=2) { PDPage page1 = pdfDocument.getPage(i); PDPage page2 = pdfDocument.getPage(i+1); PDRectangle pdf1Frame = page1.getCropBox(); PDRectangle pdf2Frame = page2.getCropBox(); PDRectangle outPdfFrame = new PDRectangle(pdf1Frame.getWidth()+pdf2Frame.getWidth(), Math.max(pdf1Frame.getHeight(), pdf2Frame.getHeight()));

// Create output page with calculated frame and add it to the document COSDictionary dict = new COSDictionary(); dict.setItem(COSName.TYPE, COSName.PAGE); dict.setItem(COSName.MEDIA_BOX, outPdfFrame); dict.setItem(COSName.CROP_BOX, outPdfFrame); dict.setItem(COSName.ART_BOX, outPdfFrame); PDPage newP = new PDPage(dict); outPdf.addPage(newP);

// Source PDF pages has to be imported as form XObjects to be able to insert them at a specific point in the output page LayerUtility layerUtility = new LayerUtility(outPdf); PDFormXObject formPdf1 = layerUtility.importPageAsForm(pdfDocument, page1); PDFormXObject formPdf2 = layerUtility.importPageAsForm(pdfDocument, page2);

AffineTransform afLeft = new AffineTransform(); layerUtility.appendFormAsLayer(newP, formPdf1, afLeft, "left" + i); AffineTransform afRight = AffineTransform.getTranslateInstance(pdf1Frame.getWidth(), 0.0); layerUtility.appendFormAsLayer(newP, formPdf2, afRight, "right" + i); }

outPdf.save(srcFile); outPdf.close(); pdfDocument.close(); } Update to test it: main() ... ///// 2 pages per sheet app.mergePages(resultFilePath); ... Here is the full list of imports: package com.pdf.pdf_utils;

import org.apache.pdfbox.cos.COSDictionary; import org.apache.pdfbox.cos.COSName; import org.apache.pdfbox.multipdf.LayerUtility; import org.apache.pdfbox.multipdf.Splitter; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.pdmodel.PDPage; import org.apache.pdfbox.pdmodel.common.PDRectangle; import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject;

import java.awt.geom.AffineTransform; import java.io.File; import java.io.IOException; import java.util.List; import java.util.function.BiPredicate; import java.util.function.Function; The source code is available . here Also published . here