[gs-bugs] [Bug 698369] - MuPDF - Incorrect rendering of closed path when start and end very close

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698369

Bug ID: 698369
Summary: Incorrect rendering of closed path when start and end
very close
Product: MuPDF
Version: unspecified
Hardware: PC
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: P4
Component: mupdf
Assignee: mupdf-***@artifex.com
Reporter: ***@gmail.com
QA Contact: gs-***@ghostscript.com
Word Size: ---

Created attachment 14085
--> http://bugs.ghostscript.com/attachment.cgi?id=14085&action=edit
minimal PDF file demonstrating the bug

In the attached minimal PDF file, I built a closed path where the start and end
points are very close to one another. Closing the path generates a strange
horizontal line which is not supposed to be there.

The file can be generated using "mutool create" using the file "broken.txt"
which I will attach to the issue.

I will also attach renderings of produced and expected outputs, created with
"mutool draw".

I originally encountered this issue using a drawing I created using the IPE
editor.

This bug applies to version 1.11 of MuPDF, which I couldn't find in the version
list of the Bugzilla form.

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698369

--- Comment #1 from ***@gmail.com ---
Created attachment 14086
--> http://bugs.ghostscript.com/attachment.cgi?id=14086&action=edit
command file for "mutool create" to produce broken.pdf

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698369

--- Comment #2 from ***@gmail.com ---
Created attachment 14087
--> http://bugs.ghostscript.com/attachment.cgi?id=14087&action=edit
produced vs. expected rendering

[b***@artifex.com]

http://bugs.ghostscript.com/show_bug.cgi?id=698369

Robin Watts <***@artifex.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |***@artifex.com
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED

--- Comment #3 from Robin Watts <***@artifex.com> ---
Fixed in:

commit a8047c876f7f82cbce82c5210a865991f83caa26
Author: Robin Watts <***@artifex.com>
Date: Thu Nov 9 15:54:15 2017 +0000

Bug 698369: Fix stroking issue when closepath is infinitessimal.

If the move due to a closepath is infinitessimal, fz_stroke_lineto
skips it as it cannot accurately figure out what the direction is.

It appears we have had some code in fz_stroke_closepath to cope
with exactly this case, but it does the wrong thing. This dates
back all the way to the initial import of the code, so presumably
it worked at some point, and stopped working somewhere along the
line.

Thanks for the report!