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Re: Gzipped svg files in the local filesystem

From: Cameron McCormack <cam@mcc.id.au>
Date: Mon, 8 Nov 2010 09:42:31 +1300
To: Erik Dahlstrom <ed@opera.com>
Cc: public-svg-wg@w3.org
Message-ID: <20101107204231.GA20905@wok.mcc.id.au>
Hi Erik.

Erik Dahlstrom:
> I've been looking at the 1.1 and 1.2T specifications for conformance
> criteria for svg viewer UA:s in particular when encountering an
> *.svgz file in the local filesystem. I can't find a requirement for
> such files to be displayed - surely the intention isn't that such
> files must cause an error message to appear in the UA?

Is there any requirement for a Conforming SVG Viewer to support file:
URIs at all?  Actually I can see in conform.html “SVG implementations
that support HTTP must…” so I suppose HTTP isn’t even required!

> Reading [1] it seems clear that *.svgz files don't fulfill the
> requirements for being a "conforming standalone svg stand-alone
> file". Should there be a similar conformance class for svgz files
> (along with clear requirements for displaying such files), or is
> wasting diskspace considered to be a good thing?


> Incidentally it would also mean that e.g Inkscape and Illustrator are
> not "Conforming SVG Generators".

Well, they can also save non-compressed SVG files, so presumably that’s
sufficient for them to be conforming?

> Here's my proposed new wording (to be added to the confomance
> criteria appendix):
> [[ Conforming Compressed SVG Stand-Alone Files
> A file is a Conforming Compressed SVG Stand-Alone File if:
> - the first bytes of the file are 0x1F8b (the fixed ID1 and ID2
> fields from the gzip file format header, as defined in RFC1952),
> - the file extension is "svgz",
> - the decompressed contents of the file fulfills all the
> requirements for "Conforming SVG Stand-Alone Files".
> ]]

Incidentally, I’ve always found the extension .svgz to be annoying.
gzip and gunzip expect a .gz extension, unless you use the -S ""
command line argument.  So I tend to name my files .svg.gz.

> and changing G.6 to be:
> [[ Conforming SVG Generators
> A Conforming SVG Generator is a program which:
> - always creates at least one of Conforming SVG Document Fragments,
> Conforming Compressed SVG Stand-Alone Files or Conforming SVG
> Stand-Alone Files.
> - does not create non-conforming SVG document fragments of any of
> the above types.
> ]]

I find the second point there a bit strange.  Consider an authoring tool
that supports HTML and SVG authoring: does its ability to generate HTML
files, which presumably count as “non-conforming SVG document
fragments”, render it a non-conforming SVG Generator?

Maybe there should be a definition for “non-conforming SVG document
fragment” then, but I am not sure what it would be.

> Finally add a clause that requires either "Conforming SVG
> Interpreters" or "Conforming SVG Viewers" to support "Conforming
> Compressed SVG Stand-Alone Files".

Cameron McCormack ≝ http://mcc.id.au/
Received on Sunday, 7 November 2010 20:43:15 UTC

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