Created attachment 120544 [details]
Sample PDF for testing

Split from https://bugs.kde.org/show_bug.cgi?id=406237

SUMMARY
When selecting "Print original size" as the scaling setting, the document is shifted down and left, rather than being cropped.

STEPS TO REPRODUCE
1. Open any PDF (such as the one attached)
2. Open the Print menu, choose a paper size smaller than the one of the original document, and select "Print original size" as the scaling mode.
3. Click "Print."

OBSERVED RESULT
The document's contents are shifted down and left to fit the printer's margins.

EXPECTED RESULT
The document's contents are overlayed with a blank margin prior to being sent tot the print driver.

SOFTWARE/OS VERSIONS
KDE Frameworks Version: 5.58.0
Qt Version: 5.12.3

ADDITIONAL INFORMATION
The current system for this kind of printing may even have problems for RTL languages (I do not know since I have not tested this). I think a simpler, more elegant solution would be to replace this scaling mode with one called "Crop to fit printable area." This new scaling mode would add blank margins to the PDF before sending it to the print driver, rather than allowing the printer to figure out that it can't print part of the document. I'm not sure how useful that would be in practice compared to the "Fit to full page" scale mode.