[OASIS Issue Tracker] (OFFICE-3825) How to calculate the start and end point of an elliptical arc from given angles

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

    [ https://issues.oasis-open.org/browse/OFFICE-3825?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=73075#comment-73075 ] 

Regina Henschel commented on OFFICE-3825:
-----------------------------------------

The current (master for LibreOffice 6.3) implementation uses the method (2) only for those shapes, which are imported from binary MS Office versions. Those shapes cannot be expressed in draw:enhanced-path of ODF 1.2 anyway, because they use a swing angle and the command G for this belongs to ODF 1.4ÂOFFICE-4026. For other shapes with U and T command the method (1) is used. I'm going to write a proposal for command U and T according method(1), but do not yet know when it will be finished. Setting the issue to ODF-Next for now.

> How to calculate the start and end point of an elliptical arc from given angles
> -------------------------------------------------------------------------------
>
>                 Key: OFFICE-3825
>                 URL: https://issues.oasis-open.org/browse/OFFICE-3825
>             Project: OASIS Open Document Format for Office Applications (OpenDocument) TC
>          Issue Type: Bug
>          Components: Graphics, Part 1 (Schema)
>    Affects Versions: ODF 1.2
>            Reporter: Regina Henschel
>            Priority: Major
>             Fix For: ODF-Next
>
>
> For a long description, example document and screenshots see mail https://www.oasis-open.org/apps/org/workgroup/office/email/archives/201304/msg00002.html
> This is about commands U and T in draw:enhanced-path (19.145, part 1, ODF 1.2). The arc is defined by a start and an end angle. But the specification does not say, how to create the points. There exists two reasonable methods, which are used by applications.
> (1) Intersect leg of the angle with the full ellipse.
> (2) Intersect leg of the angle with the corresponding outer circle and scale the circle then to get the ellipse.
> I think that the problem has to be discussed with OIC and people of the affected applications. I have no proposal.



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