[OpenType] Re: [mpeg-OTspec] SVGZ in SVG+OpenType

[Sairus Patel]

Cam/Chris, could support of such encodings (gzip, deflate) be seen as
required of SVG viewers even for an "SVG Integration" such as SVG-in-OT?
Or could the encodings be restricted just to plaintext and gzipped content
for SVG-in-OT? Is there a reason to reject deflate? Perhaps all should be
allowed, and the fact that certain impls may not support all of them could
be pointed out in the spec and seen as an impl limitation. The font-making
world already has many "best/prudent practices" to keep in mind and this
will be one of them.

Vlad: if it's clear that this is a clarification, can it be added without
going through the amendment process? That would simplify things, e.g. for
developers who right now don't have a central place to find the latest
SVG-in-OT spec.

By the way, all the color formats are OpenType (well, OFF) now, and are
not Adobe/Mozilla's or Microsoft's or Google's. In my view, impls should
try to or aim to support all of them: SVG, glyph overlay, and color
bitmaps, just as impls should aim to support CFF as well as TT.

Sairus


-----Original Message-----
From: Behdad Esfahbod <behdad at behdad.org>
Reply-To: "opentype-list at indx.co.uk" <opentype-list at indx.co.uk>
Date: Sunday, October 26, 2014 at 6:04 PM
To: "listmaster at indx.co.uk" <listmaster at indx.co.uk>
Subject: [OpenType] Re: [mpeg-OTspec] SVGZ in SVG+OpenType

>Message from OpenType list:
>
>
>Thanks Chris,
>
>On 14-10-26 05:07 PM, Chris Lilley chris at w3.org [mpeg-OTspec] wrote:
>>  
>> 
>> Hello Behdad,
>> 
>> Saturday, October 25, 2014, 9:56:18 AM, you wrote:
>> 
>>> Allow gzip-compressed SVG documents where SVG documents are currently
>>> accepted.
>> 
>> This is a useful clarification. I say clarification because a
>> conforming SVG viewer is already required to accept gzip-compressed
>> content:
>> 
>> SVG implementations must correctly support gzip-encoded [RFC1952]
>> and deflate-encoded [RFC1951] data streams, for any content type
>> (including SVG, script files, images).
>
>Right.  You mentioned this before, and I tried to confirm it, but got
>confused
>and thought the requirements only affect HTTP transport.  I checked again
>now
>and see your point.
>
>This distinction is important though, because if your reasoning is to be
>followed, then deflate-encoded SVG must also be supported.
>
>However, from the point of view of SVG+OpenType specification / working
>group,
>they may not feel bound by the SVG viewer conformance requirements.
>
>Anyway, I think you know better what the implications are one way or
>another.
> In the mean time I'll go build a font, such that Jonathan can take a
>look at
>implementing it in Firefox.
>
>behdad
>
>> SVG implementations that support HTTP must support these encodings
>> according to the HTTP 1.1 specification [RFC2616]; in particular,
>> the client must specify with an "Accept-Encoding:" request header
>> [HTTP-ACCEPT-ENCODING] those encodings that it accepts, including at
>> minimum gzip and deflate, and then decompress any gzip-encoded and
>> deflate-encoded data streams that are downloaded from the server.
>> When an SVG viewer retrieves compressed content (e.g., an .svgz
>> file) over HTTP, if the "Content-Encoding" and "Transfer-Encoding"
>> response headers are missing or specify a value that does not match
>> the compression method that has been applied to the content, then
>> the SVG viewer must not render the content and must treat the
>> document as being in error.
>> 
>> http://www.w3.org/TR/SVG11/conform.html#ConformingSVGViewers
>> 
>>> As there are only one current implementations and the format is
>>>backwards
>>> compatible, it was recommended on the mailing list by Sairus to keep
>>>the table
>>> version number to the current number.
>> 
>> Yes, I think that makes sense; because arguably implementations should
>> have accepted this from the start. If they did not, they were
>> non-conforming.
>> 
>> -- 
>> Best regards,
>> Chris Lilley, Technical Director, W3C Interaction Domain
>> 
>> 
>
>-- 
>behdad
>http://behdad.org/
>
>
>
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