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Re: Some notes on SVG parsing in HTML 5

From: Simon Pieters <simonp@opera.com>
Date: Thu, 26 Feb 2009 01:04:21 +0100
To: "Cameron McCormack" <cam@mcc.id.au>
Cc: "www-archive@w3.org" <www-archive@w3.org>
Message-ID: <op.upxmhjyaidj3kv@hp-a0a83fcd39d2>
It seems I can't post to public-svg-wg so posting to www-archive for reference.


On Thu, 26 Feb 2009 00:45:49 +0100, Simon Pieters <simonp@opera.com> wrote:

> I thought I'd point out things that don't match my understanding of  
> HTML5:
>
> On Thu, 26 Feb 2009 00:14:12 +0100,  wrote:
>
>> Hello WG.
>>
>> I’ve taken a brief look at the commented out SVG parsing language in
>> HTML 5.  Below are some pertinent notes for ACTION-2395.  Something
>> being a “parse error” means that the document is non-conforming.
>
> It also means that a UA has the choise to continue parsing (using the  
> rules given in the spec) or to abort parsing.
>
>
>> Parsing this document:
>>
>>   <svg xmlns='http://www.w3.org/2000/svg'>
>>     <circle r='100'/>
>>   </svg>
>>
>> as text/html would be non-conforming, since it doesn't begin with an
>> <html> tag,
>
> No, <html> is optional, but lack of a doctype is a parse error. (Lack of  
> <title> is not a parse error but a content model error.)
>
>
>
>> Parsing this document:
>>
>>   <!DOCTYPE html>
>>   <html>
>>     <head>
>>       <title></title>
>>     </head>
>>     <body>
>>       <svg>
>>         <circle r='100'/>
>>       </svg>
>>     </body>
>>   </html>
>>
>> would be non-conforming, since the <svg> tag is missing an
>> xmlns='http://www.w3.org/2000/svg' attribute.
>
> No, xmlns is optional. If it is preset, it must have the right value,  
> though.
>
>
>> SVG Tiny 1.2 elements aren't considered, and so <textArea> will parse
>> as an HTML <textarea> element and break out of foreign content mode.
>
> <textArea> *could* be supported, though.
>
>
>> There's a comment <!--XXXSVG need to define processing for </script> to
>> match HTML5's </script> processing --> but I'm not sure what processing
>> this means.
>
> See:  
> http://www.whatwg.org/specs/web-apps/current-work/multipage/tree-construction.html#parsing-main-incdata
>
> Basically, it says how to run the script in a way that is compatible  
> with how browsers have to do it for HTML (in the face of, say, an  
> external script that document.writes another external script that  
> document.writes something).
>
>
>> In foreign content mode, a <font> start tag with a color, face or size
>> attribute will cause the document to be non-conforming.  <!-- the
>> attributes here are required so that SVG <font> will go through as SVG
>> but legacy <font>s won't -->
>
>
>> The following start tags cause a parse error inside foreign content:
>> b, big, blockquote, body, br, center, code, dd, div, dl, dt, em, embed,
>> h1, h2, h3, h4, h5, h6, head, hr, i, img, li, listing, menu, meta, nobr,
>> ol, p, pre, ruby, s, small, span, string, strike, sub, sup, tbale, tt,
>> u, ul and var.  <!-- this list was determined empirically by studying
>> over 6,000,000,000 pages that were specifically not XML pages -->
>
> They are not parse errors in <foreignContent>, <title> or <desc>,  
> though. Anywhere else (in SVG) would cause the tag to escape back to  
> HTML context.
>
> Example:
>
>    <svg> <title> <b>foo</b> </title> </svg>
>
> is parsed as expected (svg and title are SVG elements, b is an HTML  
> element), but
>
>    <svg> <g> <b>foo</b> </g> </svg>
>
> is a parse error and is parsed as if it were
>
>    <svg> <g> </g></svg><b>foo</b>
>
>



-- 
Simon Pieters
Opera Software
Received on Thursday, 26 February 2009 00:05:18 UTC

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