[Development] Qt PDF as a new TP module for Qt 5.14

Allan Sandfeld Jensen kde at carewolf.com
Tue Aug 13 22:15:37 CEST 2019

On Tuesday, 13 August 2019 22:03:17 CEST Lisandro Damián Nicanor Pérez Meyer 
> Hi!
> On Mon, 12 Aug 2019 at 09:39, Kai Köhne <Kai.Koehne at qt.io> wrote:
> [snip]
> > Qt PDF is so far a Qt labs module [1]. It allows Qt applications to
> > render/view PDF's in QWidget based applications [2], and is built on top
> > of PDFium. However, development has been stagnant, also because it is
> > built on top of a rather old version of PDFium.
> > 
> > Why wasn't PDFium updated? PDFium got merged into Chromium a while ago,
> > and is nowadays built as part of Chromium, using their build system (gn).
> > Updating qtpdf.git to ship with latest PDFium would require quite some
> > work, and keeping it up to date would require continuous work, too - work
> > that nobody was willing to invest into so far.
> > 
> > But it turns out that, since Qt 5.11, we have PDFium already in our
> > sources, and we're actually also building it! It's part of the Qt
> > WebEngine libs that use it for PDF rendering in HTML. So technically, you
> > can already render PDF's by loading them into a Qt WebEngine page.
> > Anyhow, not everybody wants to ship a web browser for 'just' rendering
> > PDF's [3] ...
> So maintaining it under it's build system it's troublesome, but
> letting other people do it in yet another build system is ok. Sorry,
> that sounds fishy.
> PDF libraries tend to be a common source of CVEs, so whichever library
> is used it should be certainly easy to update without the need of a
> third party acting as a proxy.

We get the security patches from Chromium, and need them to patch them in 
QtWebEngine anyway. QtPdf will get those security patches for free through the 
work we need to do anyway for QtWebEngine.

The model is suggested because it would be both the most secure and the least 
amount of work.


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