Re: [PyX-user] bug report: bad bounding box

[Michael S. <m-s...@us...>]

Hello,

On 16.10.09, Alan G Isaac wrote:
> As you see, the corners are cut off of every vertex of
> the triangle.  (Current SVN.)

The effect you describe is well known. In fact, we discussed about it
many years ago and decided to leave it like it is. The problem is that
the true bounding box of a picture does depend on both the paths and
the respective linewidth. It is simple to calculate bounding boxes for
lines; for curves it is more difficult. PyX calculates these two.
Including also the linewidth and stroke effects coming from the
different linejoin parameters is really difficult. We decided not to
do this, as it would lead to a reimplementation of ghostscript.

This is why canvas.writeEPSfile and the equivalent for PDF take a
parameter "bboxenlarge". This is meant to serve as a workaround for
the above problem. It is set to 1pt by default. As you increased the
linewidth to 1cm, you should play also with this parameter.

You may also use ghostscript to calculate the true bounding box:
  gs -dNOPAUSE -q -dBATCH -sDEVICE=bbox

Michael

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