What thirdparty packages are used in Qt5 PDF module for display of PDF files?

[JoeCFD]

I only want to display PDF files with Qt5 PDF module.

from here: https://wiki.qt.io/Handling_PDF
The QtPDF module is a wrapper around PDFium with Apache License Version 2.0. It will look good to use Qt PDF module as LGPL. But some other packages(GPL) are listed as well. Does this module use other packages. I am a bit confused. Has anyone had looked into this? In theory, Qt5 PDF module has to be GPL if any GPL package is used inside, right?

[sierdzio]

@JoeCFD here is the official documentation page: https://doc.qt.io/qt-6/qtpdf-licensing.html and it says the module can be used under LGPL. The list under additional licenses is empty - either it really is so or it is a documentation bug.

[JoeCFD]

@sierdzio I saw that one as well. It seems this module uses third party package for rendering. You are right. This could be a doc bug. And this module can not be LGPL.

[SGaist]

@JoeCFD From the licensing page, the only third party is pdfium which a quick look at the project's sources confirm.

The pdfium project is Apache 2.0 licensed so the module can be LGPL.

[JoeCFD]

@SGaist I ldd all libs of pdf module and did not see they are linked to any GPL libs. I also could not see any Qt plugin which includes libs like poppler or xpdf. Will try an example and strace it to find out all related links. Thanks.

[SGaist]

@JoeCFD I think you may have misunderstood the content of the page. The third party libraries listed there are just alternatives to QtPDF that you can use in place of it. Those are not extra/optional dependencies of the QtPDF module.

[JoeCFD]

@SGaist I want to make sure it is the case that except PDFium no libs of other third parties are involved .

[SGaist]

@JoeCFD You can see it in the code source directly as well as the CMakeLists.txt files of the module.