[Poppler-bugs] [Bug 43676] Size 0 dots are large and visible

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=43676

--- Comment #2 from Adrian Johnson <ajohnson at redneon.com> 2012-01-25 06:20:16 PST ---
Created attachment 56143
  --> https://bugs.freedesktop.org/attachment.cgi?id=56143
cairo - don't render text when text matrix is not invertable

The problem is the PDF file is using a noninvertible text matrix [0 0 0 0]. The
PDF specification has this to say about noninvertible matrices: 

   When rendering graphics objects, it is sometimes necessary for a
   conforming reader to perform the inverse of a transformation—that
   is, to find the user space coordinates that correspond to a given
   pair of device space coordinates. Not all transformations are
   invertible, however. For example, if a matrix contains a, b, c,
   and d elements that are all zero, all user coordinates map to the
   same device coordinates and there is no unique inverse transformation.
   Such noninvertible transformations are not very useful and generally
   arise from unintended operations, such as scaling by 0. Use of a
   noninvertible matrix when painting graphics objects can result
   in unpredictable behaviour.

So the correct rendering of this PDF file is undefined. However to make the
cairo output more closely emulate acroread behavior I attach a patch that
ignores text when the text matrix is noninvertible.

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