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Re: [SVGMobile12] SVGT12-207: Incorrect assertion in section 7.1 regarding information provided to the UA

From: Jon Ferraiolo <jonf@adobe.com>
Date: Tue, 9 May 2006 16:11:15 -0700
Message-ID: <6ECA24BE410D994496A2AE995367C5C8AED907@namail3.corp.adobe.com>
To: "Ian Hickson" <ian@hixie.ch>
Cc: <www-svg@w3.org>

Ian,
This is the official response from the SVG WG to your Last Call comment
at the following URL:
  http://lists.w3.org/Archives/Public/www-svg/2005Dec/0250.html

We agree with your comment and removed much of the text in section 7.1
as you suggested under option #1 so that we could leave a bare-bones
introduction of concepts and terms and remove any potential redundancy
with text found later in the chapter. Section 7.1 now reads as follows:

------------
7.1 Introduction

For all media, the SVG canvas describes "the space where the SVG content
is rendered." The canvas is infinite for each dimension of the space,
but rendering occurs relative to a finite rectangular region of the
canvas. This finite rectangular region is called the SVG viewport. For
visual media [  CSS2-VISUAL], the SVG viewport is the viewing area where
the user sees the SVG content.

The size of the SVG viewport (i.e., its width and height) is determined
by a negotiation process (see Establishing the size of the initial
viewport) between the SVG document fragment and its parent (real or
implicit). Once the viewport is established, the SVG user agent must
establish the initial viewport coordinate system and the initial user
coordinate system (see Initial coordinate system). The viewport
coordinate system is also called viewport space and the user coordinate
system is also called user space.

A new user space (i.e., a new current coordinate system) can be
established at any place within an SVG document fragment by specifying
transformations in the form of transformation matrices or simple
transformation operations such as rotation, skewing, scaling and
translation (see Coordinate system transformations). Establishing new
user spaces via coordinate system transformations are fundamental
operations to 2D graphics and represent the usual method of controlling
the size, position, rotation and skew of graphic objects.

New viewports also can be established. By establishing a new viewport,
one can provide a new reference rectangle for "fitting" a graphic into a
particular rectangular area. ("Fit" means that a given graphic is
transformed in such a way that its bounding box in user space aligns
exactly with the edges of a given viewport.) 
------------

Thank you very much for your thorough review and excellent feedback.
Please tell us within two weeks if you are not satisfied with this
response.

Jon Ferraiolo
SVG WG

--------------

From: Ian Hickson <ian@hixie.ch> 
Date: Wed, 28 Dec 2005 15:07:15 +0000 (UTC)
To: www-svg@w3.org 
Message-ID: <Pine.LNX.4.62.0512281449040.7669@dhalsim.dreamhost.com> 


Section 7.1 Introduction [to Coordinate Systems, Transformations and 
Units] states that user agents are provided with three items of 
information (given in the bulleted list in that section). However, this
does not appear to be necessarily a true statement. In particular, there

does not seem to be any requirement anywhere that leads to this
statement 
being true.

The 7.1 Introduction section refers to 7.2 The initial viewport,
possibly 
implying that that section defines where the information from these
bullet 
points arises. However, section 7.2 is also free from any conformance 
requirements that would result in this, except for the one requirement 
that does indeed result in this when the SVG is in a CSS context.

Please correct chapter 7 sections 7.1 and 7.2 as follows. Either:

1. Remove the large amounts of non-normative, confusing, and potentially

   incorrect prose, leaving merely the one normative requirement and 
   optionally a clear description of its consequences, or

2. Rephrase the sections such that they have precise conformance 
   requirements for the case where SVG is used in a CSS context (the one

   current conformance requirement handles this correctly and can be
kept) 
   and the case where CSS is not used (e.g. because SVG is being used in

   a standalone context); then, remove all the confusing text that
asserts 
   or describes the consequences of the (currently largely implied)
model.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 9 May 2006 23:11:32 GMT

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