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Fwd: SVG Path, Polyline, and Polygon data coordinates

From: Dugan Knoll <ddknoll@gmail.com>
Date: Fri, 4 Oct 2013 12:27:26 -0700
Message-ID: <CALY1syEwSOMwOw+ogFnghGKAK6OXAuw=fHsepMEA_i9u40g2=w@mail.gmail.com>
To: www-svg@w3.org
I notice in Appendix O.2.1 you mention that there is a plan to "Change
all coordinate types to <length> in preparation for referencing
css3-values."  However, the Path, Polyline, and Polygon elements do
not use the <length> BNF grammar and only allows for a numerical
value.  Shouldn't the path data be allowed to use css units such as
em, %, px, etc.?

One of the unique and powerful attributes of SVG is that it can scale
based upon the viewport of the device.   At the moment, all of the
basic shapes will allow css scaling except for the Polyline, Polygon,
and Path.  This makes it quite difficult to use all of the basic
shapes together because they cannot scale in the same manner.

For example, you could draw a triangle that extends the full length of
the screen like so:

<path d="M0%,50%L0,20L100%,20z" />

To allow for this, the BNF grammar would likely be something like this:

coordinate-pair:
    coordinate comma-wsp coordinate
    | coordinate negative-coordinate

coordinate:
    number
    | length

I've been working with SVG graphics quite a bit and this is the one
thing that was really hoping for in Version 2.  Right now the path
data type is not nearly as flexible as the rest of the shapes. This
would be a vast improvement over its current functionality.

Thanks for your time,

Dugan Knoll

Web Developer
Founder: www.svgeneration.com
Received on Sunday, 6 October 2013 19:59:41 UTC

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