Created attachment 133666 [details] pdf file to trigger the bug The Arthur render backend implements the 'Miter' line join style incorrectly. You can see this with the attached test file. It contains a polygon with two corners positioned such that the miter limit is exceeded. The pdf standard requires that in such a case, the miter join is converted to a bevel join: http://www.verypdf.com/document/pdf-format-reference/pg_0217.htm The Arthur backend, however, simply shortens the miter a little bit. This results in the spike that can be seen on the screenshot.
Created attachment 133667 [details] The file as rendered by the Splash backend
Created attachment 133668 [details] The file as rendered by the Arthur backend
The fix is to use Qt::SvgMiterJoin instead of Qt::MiterJoin. It is recommended in https://bugreports.qt.io/browse/QTBUG-52640 and does indeed fix the problem. I'll attach a patch.
Created attachment 133669 [details] [review] Patch to use the correct join style
Pushed
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