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HTML+SVG use cases

From: Jeff Schiller <codedread@gmail.com>
Date: Mon, 27 Jun 2005 15:29:06 -0500
Message-ID: <da131fde0506271329598f35b7@mail.gmail.com>
To: public-cdf@w3.org

I understand from an email conversation with Chris Lilley that the
initial version of CDF will stick to the HTML + SVG through <object>
use case.  I would also like to understand what is the CDF WG position
on the following important (for SVG) use cases and whether there
should be interaction between the CDF and SVG WGs on these two cases:

a) HTML + SVG through <img>

b) HTML/CSS + SVG through background-image, list-image, etc

The above two represent very important inroads for SVG to be widely
used on the internet without the strict requirement of XHTML.  For the
most part, <img> can be replaced by <object> tags (and provide
fallback content), but there is no suitable replacement for CSS
background-image, and this would be a nice effect to have on the web
today (no better way to handle "rounded corners").

Indications by Chris are that the above two use cases are covered by
the SVG spec but only in one paragraph that I know of at the end of
SVG 1.1 Full Appendix G:

"If the user agent includes an HTML or XHTML viewing capability or can
apply CSS/XSL styling properties to XML documents, then a Conforming
SVG Viewer must support resources of MIME type "image/svg+xml"
wherever raster image external resources can be used, such as in the
HTML or XHTML 'img' element and in CSS/XSL properties that can refer
to raster image resources (e.g., 'background-image')."

What is not clear by this how the SVG content is to be handled.  Is it
frozen (as if a raster image) or can it be scripted?  If it's a
background image, surely the SVG needs to scale appropriately in the
case of a window resize.  Can the SVG image interact with other DOM
events (like mouse, keyboard if focus is given) from the parent HTML,
etc?

Also, in HTML there is currently no way to have a scalable background,
but with SVG this would be a piece of cake.  What stands in the way is
clearly specifying the behavior in various cases.  For instance, if
the html:img height/weight attributes are not specified (i.e. the SVG
document should be displayed at its "native" resolution, but what if
SVG document does not have width/height or is a percentage?)

Of course the HTML spec does not have considerations for these cases
because the only image type was simple raster formats.  Thus, browser
developers have no real clue how to handle these cases and so they
don't.  And SVG languishes on the internet...

If the CDF WG feels this falls strictly into the SVG WG camp, please
forward this mail along, but I feel that there is considerable overlap
here.

Thanks,
Jeff Schiller
Received on Monday, 27 June 2005 20:29:44 GMT

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