Created attachment 87877 [details]
This PDF triggers a cairo error

The attached PDF is a single page containing an XObject which prints a Knockout transparency group, which itself prints a non-Knockout transparency group.  It is not properly drawn using evince because of a cairo error.

In greater details:

With this PDF, in cairo_surface_create_similar_clip, the surface resulting from:

  result = cairo_surface_create_similar (target, content, width, height);

is defined with a negative height.  This in turn leads to the following Cairo error when drawing the group:

  BAD status: invalid value (typically too big) for the size of the input (surface, pattern, etc.)

I'm not sure what the comment:

  //XXX: negative matrix

in the body of the function is refering to, but indeed, there's a sign problem.


Adding abs(...) around the two substractions (CairoOutputDev.cc:1425 and next) does the trick --- the PDF is rendered correctly ---, but I'm not sure this is the right fix.

(Using git poppler)