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Re: Font Metrics concerns

From: Alan Stearns <stearns@adobe.com>
Date: Tue, 10 Feb 2015 05:26:39 +0000
To: John Daggett <jdaggett@mozilla.com>, Chris Lilley <chris@w3.org>
CC: Stephen Zilles <szilles@adobe.com>, Tab Atkins Jr. <jackalmage@gmail.com>, "public-houdini@w3.org" <public-houdini@w3.org>, Bram Stein <stein@adobe.com>
Message-ID: <D0FFE082.23CDA%stearns@adobe.com>
On 2/10/15, 1:05 PM, "John Daggett" <jdaggett@mozilla.com> wrote:

>> > I don't think defining an API for font metrics is the right place to
>> > start. First off, you're really probably talking about some form of
>> > *line* metrics rather than actual font metrics.
>> 
>> The desirability of an API for linebox metrics (which is not under
>> dispute, and was also agreed to at the Houdini meeting) does not in
>> itself argue for the undesirability of a Font metrics API in addition.
>
>The argument has been made that providing font metrics is a good
>starting point and I don't think it is. If an author is trying to get
>line metrics, then *those* are the metrics for which there should be an
>API. The two should not be conflated, since there are many scenarios
>where knowing the metrics for fonts used along a line will *not* tell
>you the line metrics.

There are some cases where line metrics are needed, such as trying to
position a drop cap’s baseline with the appropriate baseline in the main
text. There are other cases where just the font metrics are required, such
as trying to size a drop cap based on cap height.

Both line metrics and font metrics will be useful. I don’t have a firm
opinion on which is the better ‘starting point’. But I do think that
progress can be made on both in parallel (line metrics should be part of
the fragment tree spec).

Thanks,

Alan

Received on Tuesday, 10 February 2015 05:27:11 UTC

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