RE: [cgmo-webcgm] getObjectExtent for text

[Lofton Henderson <lofton@rockynet.com>]

Now that you mention it, that sounds right, Rob.  The reading in I.2.1 is 
suggestive.

What do others think?

Question to implementors:  if you had a Restricted Text string with 
Boxed-All, what would you use?  Would you use a bottom-to-top font metric 
(of which Rob's "grid" is an instance), or do you actually compute the 
bounding box of the text strokes?

Reference:  see CGM:1999, Figure 20, p.81

-Lofton.

At 10:57 AM 4/21/2009 -0600, Robert Orosz wrote:
>Lofton,
>
>I thought the top line was simply the top of the imaginary grid on which
>individual glyphs are defined. In other words, it is 1000 for each font if
>you use the 1000 x 1000 grid like clause I.2.3 of CGM99.
>
>Rob
>
>-----Original Message-----
>From: Lofton Henderson [mailto:lofton@rockynet.com]
>Sent: Tuesday, April 21, 2009 10:43 AM
>To: 'WebCGM'
>Subject: Re: [cgmo-webcgm] getObjectExtent for text
>
>
>Forrest, All --
>
>Good question.  If you look at p.441 of CGM:1999...
>
>1.) capheight agrees (718)
>2.) there are chars with diacritical marks, like A-umlaut.
>
>Therefore #2 implies that Top > Cap.
>
>Does anyone have the answer, what is (and where-to-find) the Top value for
>Helvetica (and the other 12 standard fonts)?
>
>Forrest, what is the difference if you use the Helvetica 'ymax'
>value?  I.e., what does the gOE text expect and what is the ymax-based
>result?
>
>-Lofton.
>
>p.s. I forgot to include this link earlier:
>[1]
>http://www.w3.org/Graphics/WebCGM/drafts/current-editor-21/WebCGM21-DOM.html
>#getObjectExtent
>
>
>At 11:17 AM 4/21/2009 -0500, Forrest Carpenter wrote:
> >All,
> >
> >For text the getObjectExtent is based on bottomline-to-topline distance of
> >the font. Is there some where this is specified for the standard WebCGM
> >fonts? We are using metrics from Microcosm (Tom Wright) for ours. For
> >Helvetica we have cap height = 718, ascender = 718 and descender = 207
>using
> >these values we match Stuart's values for the text string in the
> >getObjectExtentTransformed test. In our calculations we use the yMax value
> >for the topline calculation which for this font is 931 and gives a
>different
> >value than Stuart's. What values should be used for the topline
>calculation?
> >
> >Regards,
> >Forrest
> >
> >
> >-----Original Message-----
> >From: Galt, Stuart A [mailto:stuart.a.galt@boeing.com]
> >Sent: Monday, April 20, 2009 6:07 PM
> >To: WebCGM
> >Subject: [cgmo-webcgm] getObjectExtent and getObjectExtentTransformed
> >
> >Hello,
> >
> >I have updated the getObjectExtent.htm and the
> >getObjectExtentTransformed.htm
> >files on the FTP server.
> >
> >For both tests:
> >- I have added a try block so if the getObjectExtent() call fails then I
> >
> >   put "getObjectExtent not implemented" in the result table.
> >
> >- Changed the calculated box value for the text string to take into
> >account
> >   the decender of the 'g'
> >
> >For getObjectExtentTransformed:
> >- Changed the how far the circle was translated from 40 to 120.
> >
> >Stuart.
> >
> >--
> >Stuart Galt
> >SGML Resource Group
> >stuart.a.galt@boeing.com
> >(206) 544-3656
> >
> >
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