[PDFBOX-5664] 3.0.0: PDFCloneUtility needs a protected constructor to be useable outside of PDFBox when using Java 9 JPMS

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0 PDFBox
• Fix Version/s: 3.0.1 PDFBox, 4.0.0
• Component/s: Utilities
• External issue URL: https://github.com/rototor/pdfbox-graphics2d/issues/56
• Assignee: Andreas Lehmkühler
• Reporter: Emmeran Seehuber
• Created: 22/Aug/23 06:09
• Updated: 30/Nov/23 21:19
• Resolved: 24/Oct/23 05:35

Description

The constructor of PDFCloneUtility is package private. I did not have a problem with this, because I did an ugly workaround in my pdfbox-graphics2d 3.0.0 branch. I created a derived class InternalDeprecatedCOSCloner in the org.apache.pdfbox.multipdf package inside my project. And could access the constructor.

This works fine as long as you don't plan to use the JPMS modules introduced with Java 9. Which I personally don't plan every to do.

But it seems Apache POI is going to use those JPMS modules, at least fanningpj is trying to get POI working with PDFBox 3.0.0 and my pdfbox-graphics2d with version 3.0.0. And now he gets a not so nice 
 
/Users/pj.fanning/svn/poi/poi-ooxml/src/main/java9/module-info.java:18: error: module org.apache.poi.ooxml reads package org.apache.pdfbox.multipdf from both de.rototor.pdfbox.graphics2d and org.apache.pdfbox

As the - to be honest rather dirty - workaround done be me no longer works with JPMS...

You can find the concrete usage for the cloner here https://github.com/rototor/pdfbox-graphics2d/blob/master/graphics2d/src/main/java/de/rototor/pdfbox/graphics2d/PdfBoxGraphics2DPaintApplier.java. Just search for PDFCloneUtility. I use it to clone PDShading when I'm "rewriting" PDFs. I.e. I use PDFBox to draw on my Graphics2D adapter to create new PDFs and filter / change stuff in the PDF on the fly. Mostly to split PDFs for Seperation colors and such stuff.

Just making the PDFClonerUtility constructor public again would of course work. But I'm not sure that this is the right solution. AFAIR it was made package private because of many problems of users which did not really understand what this class was for.

Maybe a solution could be to make the constructor protected and create a package private getCloner() factory method? That would allow me to derive from the class from outside the original package but would also prevent people who don't know for sure that they really want to use this class from using it.