Issue with PDF printing via cairo library – Proposed Patch

[Vladimir Gribko]

Hello cairo developers,

I am a C++ developer at CIB software GmbH, and we use cairo for rendering and printing PDF documents within our product, CIB pdf toolbox 2.
Recently, we encountered an issue when printing certain PDF with the "Microsoft Print to PDF" printer: the output PDF appeared distorted.
We couldn't find a problem in our code, and for further testing we printed this PDF, using the well-known open-source utility pdftocairo:

> pdftocairo.exe -print -printer "Microsoft Print to PDF" input.pdf output.pdf

We observed the same result with pdftocairo and therefore suspected a problem in the cairo code.

Upon analyzing the problem, we identified two issues within the function _cairo_win32_printing_surface_paint_recording_pattern():

1. The use of an uninitialized variable, is_subsurface.
2. Displaced ClipPath for the pattern being printed, which leads to the distorted output.

We have developed a patch addressing these two issues and would like to propose it for inclusion in the cairo code.
Additionally, I have attached the minimized input.pdf and the distorted output.pdf obtained with pdftocairo.
So, please review and share your feedback.

Thank you for your attention.

Best regards,
Vladimir Gribko.
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