W3C home > Mailing lists > Public > www-svg@w3.org > January 2013

Promoting more SVG attributes into properties

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 23 Jan 2013 10:54:38 -0800
Message-ID: <CAAWBYDBAFvoKWY-WrERbRhnUpeMdA51bFrQemkzH-D3oTLp9cg@mail.gmail.com>
To: www-svg <www-svg@w3.org>
The CSSWG today resolved to allow more SVG attributes into CSS
properties, as requested by the SVGWG.  Starting from the list at
<http://dev.w3.org/SVG/proposals/css-animation/animation-proposal.html#def_attributes>,
we removed all the attributes that only have meaning within filters,
and agreed to add the rest.

This leaves us with the following list of attributes being promoted to
properties:

cx, cy, dx, dy, fx, fy, height, width, offset, r, rx, ry, x, x1, x2,
y, y1, y2 and maybe d

(d is a harder one - I *really* want it, but the syntax isn't
compatible with CSS right now, and would require a reparse step to
make it meaningful - for example, the valid path string "M0,0h1v1h1v1"
produces three tokens in the CSS parser - IDENT(M0) COMMA DIMENSION(0,
h1v1h1v1).  Are we interested in pursuing a more CSS-compatible syntax
for path data?  Please say yes - I *really* want to be able to use
units in path data, as I was *just* working on something made harder
and uglier by that lack.)

We accepted them as-is, without any name changes.  As these are
properties, they parse with the usual CSS rules, which means no
unitless lengths.

The only issue is still that of collisions between attributes with the
same name but different values, such as "x" on <rect> and <text>.  We
can't reject mismatches at parse-time, like we usually do, because you
can't tell whether it's wrong until you try to apply it.  There are a
few ways to resolve this:

1. If the wrong syntax is used on a given element, treat it like an
invalid variables, and just use the initial value for the property.

2. Restrict the property to a single syntax that works on both
instances.  For example, for the 'x' property, only allow a single
length.  If you want to specify multiple lengths for a <text> element,
you need to use the attribute form.

I'm ambivalent on which solution to use.  If the WG has opinions, or a
third option, let us know!

~TJ
Received on Wednesday, 23 January 2013 18:55:33 GMT

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