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A definition for "character cell" is not provide in the spec

From: Jonathan Watt <jwatt@jwatt.org>
Date: Wed, 07 Feb 2007 20:19:42 +0100
Message-ID: <45CA264E.2090200@jwatt.org>
To: www-svg@w3.org

Dear SVG WG,

SVG implementations seem to have diverged due to a lack of a definition for the 
term "character cell" which is used in:

   http://www.w3.org/TR/SVG11/interact.html#PointerEventsProperty

Mozilla defines this to be the rectangle that exactly fits to the edges of the 
painted area of each glyph. This might make sense in the case of text along a 
path or where each glyph is positioned individually, but in the case of a run of 
text along a straight line (without any extra character spacing) it leads to 
hit-test gaps between glyphs. Other implementations seem to use a larger box so 
they don't have these gaps. Perhaps they simply decide to use a single box 
around runs of text along a straight line? Or maybe they define "character cell" 
to be the box that is the advance of the glyph in question wide, by the largest 
font ascent to largest font decent high? (Details from other implementers would 
be welcome.)

At any rate, please define the term "character cell" so that implementors can 
eliminate this difference between their implementations.

Regards,
Jonathan
Received on Wednesday, 7 February 2007 19:19:58 GMT

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