Qt issue with printing landscape-oriented images

Hi!

This information may be interesting for printing stack maintainers of 
various Linus distros (Zdenek?).

I've already posted it into the OpenPrinting Telegram group, but as not 
everybody subscribed to the group, I repost it here, by Till's advise.

We've recently noticed, that the Okular (Qt-based image viewer) 
incorrectly prints images in the landscape orientation.

When printing image (see attached test.png) it sends the following 
Create-Job request, followed by the image, converted to PDF (see 
attached 00000020-data.pdf:

-----
IPP: request message:
{
     VERSION 2.0
     OPERATION Create-Job

     GROUP operation-attributes-tag
     ATTR "attributes-charset" charset: utf-8
     ATTR "attributes-natural-language" naturalLanguage: en-us
     ATTR "printer-uri" uri: ipp://localhost/printers/Kyocera_ECOSYS_M2040dn
     ATTR "requesting-user-name" nameWithoutLanguage: pzz
     ATTR "job-name" nameWithoutLanguage: bug.png

     GROUP job-attributes-tag
     ATTR "media" keyword: A4
     ATTR "sides" keyword: one-sided
     ATTR "landscape" boolean: false
     ATTR "number-up" integer: 1
     ATTR "number-up-layout" keyword: lrtb
     ATTR "job-billing" nameWithoutLanguage:
     ATTR "job-priority" integer: 50
     ATTR "job-sheets" nameWithoutLanguage: none none
}
-----

It can be reduced down to the very simple Qt example:

-----
#include <iostream>
#include <QApplication>
#include <QPrinter>
#include <QPrintDialog>
#include <QImage>
#include <QPainter>

int main(int argc, char* argv[])
{
     QApplication app(argc, argv);
     QPrinter printer;
     printer.setPageOrientation(QPageLayout::Landscape);
     QImage img("./test.png");
     img = img.scaled(printer.width(), printer.height(), 
Qt::KeepAspectRatio, Qt:
     QPainter painter(&printer);
     painter.drawImage(0, 0, img, 0, 0);
     painter.end();
     return 0;
}
-----

The problem is obviously in the ATTR "landscape" boolean: false 
attribute. This is definitely at the Qt side. Seems like all existing 
versions of Qt are affected.

We have submitted PR agains qt-base, it is pretty trivial and currently 
on review:

https://codereview.qt-project.org/c/qt/qtbase/+/624835

I believe, all more or less modern Linux distros are affected and wonder 
why nobody complained before

Note, the problem doesn't exist with old versions of the cups-filters (I 
was able to test with very old version1.28)

Looks like the landscape attribute attribute is silently ignoring by 
these old versions, and without this explicit orientation setting, 
filters set correct orientation automatically.

-- 

	Wishes, Alexander Pevzner ([email protected])