Bug 105579

Summary:	pdftocairo -pdf adds adds characters
Product:	cairo	Reporter:	Jason Crain <jason>
Component:	pdf backend	Assignee:	Adrian Johnson <ajohnson>
Status:	RESOLVED MOVED	QA Contact:	cairo-bugs mailing list <cairo-bugs>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:
Attachments:	anonymized.pdf rendering of anonymized.pdf is good processed pdf from `pdftocairo -pdf` rendering or processed.pdf is bad

Description Jason Crain 2018-03-18 17:37:51 UTC

Created attachment 138181 [details]
anonymized.pdf

I received a file from gour on the poppler IRC. With recent versions of cairo, printing with evince adds some characters to the document. I don't believe I'm allowed to share the original file so I'm attaching this anonymized version.

This is reproducible through poppler's pdftocairo program. Running `pdftocairo -pdf anonymized.pdf bad.pdf` produces a pdf that shows additional characters. I traced the regression to this commit:

commit 495362279b42620071c6b46f69918ce324aee0db (refs/bisect/bad)
Author: Adrian Johnson <ajohnson@redneon.com>
Date:   Sun Sep 27 08:27:53 2015 +0930

    scaled-font-subsets: if glyph 0 used for rendering, remap to different index

    Some broken pdfs use glyph 0 in embedded fonts for rendering instead of .notdef.
    The cmap we use for embedding latin fonts does not allow rendering glyph 0. Ensure
    if glyph 0 is used, it is mapped to a non 0 glyph in the subset.

    Bug 89082

This PDF includes a character mapped to glyph index 0. It's not supposed to be visible in the document, but after `pdftocairo -pdf` conversion it is.

Comment 1 Jason Crain 2018-03-18 17:47:38 UTC

Created attachment 138182 [details]
rendering of anonymized.pdf is good

Produced by `pdftocairo -png -singlefile anonymized.pdf good`. Rendering of anonymized.pdf, before processing by `pdftocairo -pdf`, is correct.

Comment 2 Jason Crain 2018-03-18 17:49:36 UTC

Created attachment 138183 [details]
processed pdf from `pdftocairo -pdf`

PDF created by `pdftocairo -pdf anonymized.pdf processed.pdf`. The conversion process adds a character to the document.

Comment 3 Jason Crain 2018-03-18 17:51:34 UTC

Created attachment 138184 [details]
rendering or processed.pdf is bad

Produced by `pdftocairo -png -singlefile processed.pdf bad`. Rendering of processed.pdf shows a new character in the image.

Comment 4 GitLab Migration User 2018-08-25 13:27:04 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/cairo/cairo/issues/13.

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