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Re: [CSSWG] Minutes and Resolutions 2010-03-17

From: Jonathan Kew <jonathan@jfkew.plus.com>
Date: Tue, 23 Mar 2010 11:52:43 +0000
Cc: fantasai <fantasai.lists@inkedblade.net>, www-style@w3.org
Message-Id: <A3724BBE-2263-44A6-8AE3-50754FC1EE5B@jfkew.plus.com>
To: John Daggett <jdaggett@mozilla.com>
On 23 Mar 2010, at 07:38, John Daggett wrote:
> 
> Taking your suggestion about reseting font-size/vertical-align, 
> here's what I would propose:
> 
> ======
> 
> Name:    character-transform
> Value:   normal | inferior | ordinal | subscript | superscript
> Initial: normal
> 
> The values 'subscript', 'superscript', 'inferior', and 'ordinal' imply
> the appropriate variant glyph is displayed when available in the font
> (OpenType features: subs, supr, sinf, ordn).  When a variant glyph is
> not available, a simulated version is synthesized using a reduced form
> of the default glyph.  Normal implies use of the default glyph at normal
> size.  When the value is anything other than 'normal', the font-size and
> vertical-align properties are set to 'inherit'.
> 
> ======
> 
> Defined this way, the semantics of using this property would never
> change simply because a font lacked subscript/superscript glyphs,
> simulated fallback would always occur when necessary.  Fallback would
> *not* be to the existing font-size/vertical-align tweak but to a
> simulated glyph that resembles what a variant glyph would typically look
> like, similar to the way simulated small-caps works today.  Not ideal in
> any way shape or form, but better than just displaying an unstyled
> default glyph and losing the semantic nature of
> subscript/superscript/etc.
> 
> Default styling for sub/sup:
> 
>  sub {
>    vertical-align: sub;
>    font-size: smaller;
>    line-height: normal;
>  }
> 
>  sup {
>    vertical-align: super;
>    font-size: smaller;
>    line-height: normal;
>  }
> 
> Using 'character-transform' instead:
> 
>  sub {
>    character-transform: subscript;
>  }
> 
>  sup {
>    character-transform: superscript;
>  }

If I'm understanding this properly, presumably I'd write something like

    sup {
        vertical-align: super;
        font-size: smaller;
        line-height: normal;
        character-transform: superscript;
    }

so as to get true superscript glyphs when using a suitable UA (and font), yet degrade gracefully on older UAs that don't recognize character-transform.

Here, new character-transform-aware UAs would replace the vertical-align and font-size settings, using 'inherit' instead. Does this apply regardless of the order? Or would later properties override earlier ones, so that

    sup {
        character-transform: superscript;
        vertical-align: super;
        font-size: smaller;
        line-height: normal;
    }

could double-superscript the text because the vertical-align/font-size override the 'inherit' setting triggered by character-transform? Or would the subsequent vertical-align/font-size settings actually override the character-transform property altogether?

JK
Received on Tuesday, 23 March 2010 11:53:28 GMT

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