[cairo] Problems with cairo_get_line_width and "new" semantics

Carl Worth cworth at cworth.org
Tue May 16 13:41:54 PDT 2006

On Tue, 16 May 2006 12:53:41 -0700, Carl Worth wrote:
> Oh, or maybe I'm using the wrong matrix when I'm adding the
> extra face points to the pen. Yeah, I bet that's it...

Yes, that was it. I dropped the ctm and ctm_inverse parameters from
the surface-backend-interface stroke function and just used the pen's
matrix everywhere instead. Now the image backend works just fine.

>                                              For SVG I think the path
> coordinates will have to be transformed by the inverse of then pen
> matrix since I don't think the path and pen can be transformed
> independently. I don't know if PDF will require all that or if it will
> be as simple as PS, (where we just emit the pen matrix before
> stroking).

I noticed that the PDF backend was already doing exactly what I
describe above, (transforming the path by ctm_inverse and the pen by
ctm) so switching that from the current CTM to the pen's matrix made
the "hard" case start passing for the PDF backend.

Meanwhile, the easy case and the reference for the easy case are still
failing for PDF, (which seems quite bizarre).

SVG has precisely the same failure pattern as PDF right now.

The latest code is still being pushed out to my line-width-scale


(though I'll likely rebuild the whole branch from scratch once I get
it all working---I still find that process extremely valuable every
time I do it).

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