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*Subject*: **Re: [office] How to calculate the start and end point of an elliptical arc from given angles.**

*From*:**Regina Henschel <regina.henschel@libreoffice.org>***To*: office@lists.oasis-open.org*Date*: Thu, 04 Apr 2013 14:15:09 +0200

Hi Thorsten, Thorsten Behrens schrieb:

Hi Regina, thanks for another detailed analysis here - you wrote:But the specification does not describe, how to calculate the start and end point. I have tested it with some applications and found, that actually two methods are used. (1) Used by LibreOffice 4.0 and PowerPoint 2013 Preview Draw an angle with the given value (here 30deg and 315deg). Calculate the intersection of the leg of the angle with the full ellipse (here center (3000|1000) and size (6000|2000)).That at least appears to be the simplest interpretation.

Method (2) is used for the primitive ellipse <draw:ellipse>. Also note

that those enhanced paths are more-or-less a bijection of those binary ppt autoshape things (see also 20.1.9 in ISO 29500), and keeping that mapping lossless and/or preventing excessive recalculation seems desirable.

I have no proposal, because both methods are reasonable.I wonder how wide-spread those commands are - where did you notice the difference, I presume there is a bug report somewhere?

No bug report yet.

Kind regards Regina

**References**:**How to calculate the start and end point of an elliptical arc from given angles.***From:*Regina Henschel <regina.henschel@libreoffice.org>

**Re: [office] How to calculate the start and end point of an elliptical arc from given angles.***From:*Thorsten Behrens <tbehrens@suse.com>

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