- From: David Dailey <ddailey@zoominternet.net>
- Date: Sat, 19 Apr 2014 08:23:28 -0400
- To: "'Dirk Schulze'" <dschulze@adobe.com>, "'Bjoern Hoehrmann'" <derhoermi@gmx.net>
- Cc: "'SVG public list'" <www-svg@w3.org>
Bjoern Hoehrmann <derhoermi@gmx.net> wrote: >> If `union` ignores that such a rectangle has no area then maybe, but >> that would be strange and unexpected, and I've certainly seen `union` >> implementations of geometry libraries that do not behave like that. >> Note that there is the related open issue "Issue 11: Need to define >> what the union of rectangles with no area means." Dirk replied: >Well, why wouldn't ><path d="M100,100L100,100z"/> >have a valid bounding box? You might not fill the area, but you can still stroke it or add >a marker. So it is valid. --------- Interesting discussion. I think there is logic in both points of view. Does a bounding box refer to the unions of nonzero areas or the unions of the curves? A line of zero thickness has no area, but I think most would still expect it to have a bounding box. On the other hand, when one looks at the code generated by programs, there may be extraneous points included in an SVG document. I assume that these may represent places that the artist's hand shook or accidentally clicked. They are, so far as I have seen, *never* part of the meaning of a document. If a mathematician wants to draw a set which is the union of a line with a point, the point will be made visible by giving it a non-zero radius. So, I guess I am tempted to conclude that curves of zero measure (in the sense of a zero-dimensional Hausdorff space [1]) should not contribute to the bounding box since individual points do not contribute to the visual semantics of a document. Cheers David [1] http://en.wikipedia.org/wiki/Hausdorff_measure
Received on Saturday, 19 April 2014 12:24:02 UTC