[mpeg-OTspec] comments re SVG table in the OFF draft

[Levantovsky, Vladimir]

Thank you Jonathan,

What you're proposing makes perfect sense but I also wonder if, in light of the changes proposed by Cameron for UA style sheet we should also extend the language of your proposed second sentence to say that "The use of SVG text elements _and/or SVG foreign objects_ within these glyph descriptions is prohibited."

Best regards,
Vladimir


> -----Original Message-----
> From: mpeg-OTspec at yahoogroups.com [mailto:mpeg-OTspec at yahoogroups.com]
> On Behalf Of Jonathan Kew
> Sent: Tuesday, March 11, 2014 11:37 AM
> To: OTspec <mpeg-OTspec at yahoogroups.com>
> Subject: [mpeg-OTspec] comments re SVG table in the OFF draft
> 
> A few comments on the current 3rd ed. working draft:
> 
> - - - - -
> 
> First, the opening sentence in section "5.5.1 SVG - The SVG (Scalable
> Vector Graphics) table" seems problematic to me:
> 
> <quote>
> This table contains SVG [16] descriptions for some or all of the glyphs
> in the font, the use of SVG text elements for outline fill is
> prohibited.
> </quote>
> 
> This would read much better if split into two sentences, not joined by
> a comma. And second, shouldn't the use of SVG text elements be
> prohibited for -any- purpose within the glyphs (not only for outline
> fill)? If we want to avoid glyph descriptions referring to external
> fonts, we can't allow SVG text elements to be stroked or used as
> clipping paths, for example.
> 
> So I suggest changing this to something like:
> 
> <proposed>
> This table contains SVG [16] descriptions for some or all of the glyphs
> in the font. The use of SVG text elements within these glyph
> descriptions is prohibited.
> </proposed>
> 
> - - - - -
> 
> Further, we should specify what happens if an SVG text element is found
> (despite being prohibited): is that element ignored, but the remainder
> of the glyph rendered normally, or do we consider the entire glyph
> description invalid, and ignore it, falling back to a TrueType or CFF
> glyph?
> 
> Offhand, I'm inclined to favor the former: require the renderer to
> ignore the SVG text element(s), but proceed to do its best to render
> any other content. So I'd suggest an additional sentence such as:
> 
> <proposed>
> If any SVG text element is encountered within a glyph description, it
> MUST be ignored by the renderer.
> </proposed>
> 
> - - - - -
> 
> Finally, forwarding a comment from Cameron McCormack regarding the
> description of "Glyph Rendering":
> 
> <forwarded>
>      I don't think that added rule in the UA style sheet,
> 
>        :root {
>          font-size: 0 !important;
>        }
> 
>      is sufficient, since font-size can be specified on an element in
> the document.  The importance of the rule doesn't inherit.
> 
>      Instead, I think this would work:
> 
>        @namespace svg url(http://www.w3.org/2000/svg);
> 
>        svg|text, svg|foreignObject {
>          display: none !important;
>        }
> 
>      Using |display: none| seems like a clearer description of what's
> going on, and should have the same effect as |font-size: 0|.
> </forwarded>
> 
> This seems like a good change we should make to the draft.
> 
> 
> JK
> 
> 
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