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Fwd: [Moderator Action] marker-mid and Bezier paths

From: Dean Jackson <dean@w3.org>
Date: Fri, 24 Aug 2001 01:40:55 +1000
To: www-svg@w3.org
Message-ID: <20010824014055.A26586@grorg.org>
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----- Forwarded message from Mark Nahabedian <naha@ai.mit.edu> -----

X-Envelope-From: www-svg-request@tux.w3.org  Thu Aug 23 10:24:35 2001
Old-Date: Thu, 23 Aug 2001 10:24:25 -0400 (EDT)
From: Mark Nahabedian <naha@ai.mit.edu>
To: www-svg@w3.org
Cc: naha@ai.mit.edu
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Subject: [Moderator Action] marker-mid and Bezier paths
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I was trying to draw an arrow in the middle of a Bezier curve and the
arrow wasn't being displayed.  I naievely reported this as a bug in
Batik (http://nagoya.apache.org/bugzilla/show_bug.cgi?id=3229).

After my bug report was dismissed, I found the paragraph of the
"marker" section of the SVG spec which says

    The graphics for a marker are defined by a 'marker' element. To
    indicate that a particular 'marker' element should be rendered at
    the vertices of a particular 'path', 'line', 'polyline' or
    'polygon' element, set one or more marker properties ('marker',
    'marker-start', 'marker-mid' or 'marker-end') to reference the
    given 'marker' element.

It seems to me that restricting markers to be rendered only at path
vertices is unreasonable.  One often wants an arrow (or whatever) in
the middle of a graph arc rather than at either end.  It's
unreasonable to expect a midpoint to be synthesized for this purpose
since doing so would require one to predict all of the points along
the path and find the middle one.  This effort is typically beyond the
scope or ability of the software generating the SVG (typically in an
XSLT transformation).

----- End forwarded message -----
Received on Thursday, 23 August 2001 11:41:42 UTC

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