[cairo] correct arc_to error bound calculation

Carl Worth cworth at cworth.org
Mon Aug 22 11:20:02 PDT 2005

On Sun, 14 Aug 2005 23:47:06 +0200, Bertram Felgenhauer wrote:
> here is a patch that does three things:
> 1st. it splits out the major axis calculation from cairo-pen.c
> 2nd. it corrects a mistake in that calculation.
> 3rd. it makes arc_to_error base its calculation on this major axis
> calculation instead of the bogus use of Eigen values.

Hi Bertram,

Thanks for this patch. I've gone through it and it all seems
correct. I'd like to see a few changes before it is committed though:

1) The bug fix of (2) above should be committed independently from the
   code re-shuffling.

2) The math in the comment should be rewritten using row-vector
   notation so that the bug fix is more obvious

3) Perhaps a,b,c,d should be initialized with  _cairo_matrix_get_affine

4) The relevant portions of the comment should move with the code
   rather than one comment pointing to a comment in another file.

5) The _cairo_matrix_unit_circle_major_axis function should be
   adjusted to accept a radius and then be renamed to:


> The Eigen value calculation has no users after this patch is
> applied and could be removed.

6) Yes, that should be done as well.

Thanks again!


PS. Independent pieces of the above should be committed
independently. Did you get CVS commit access yet? That would help
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