- From: Jon Ferraiolo <jonf@adobe.com>
- Date: Tue, 9 May 2006 16:11:15 -0700
- 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/0253.html We agree with your comment and have made editorial changes to better indicate what user agents must do. Here is the new text: ------------ 7.3 The initial coordinate system For the 'svg' element, the SVG user agent must establish an initial viewport coordinate system and an initial user coordinate system such that the two coordinates systems are identical. The origin of both coordinate systems must be at the origin of the viewport, and one unit in the initial coordinate system must equal one "pixel" (i.e., a px unit as defined in [ CSS2 lengths]) in the viewport. In most cases, such as stand-alone SVG documents or SVG document fragments embedded (by reference or inline) within XML parent documents where the parent's layout is determined by CSS [CSS2] or XSL [XSL], the SVG user agent must establish the initial viewport coordinate system (and therefore the initial user coordinate system) such that its origin is at the top/left of the viewport, with the positive x-axis pointing towards the right, the positive y-axis pointing down, and text rendered with an "upright" orientation, which means glyphs are oriented such that Roman characters and full-size ideographic characters for Asian scripts have the top edge of the corresponding glyphs oriented upwards and the right edge of the corresponding glyphs oriented to the right. If the SVG implementation is part of a user agent which supports styling XML documents using CSS2-compatible px units, then the SVG user agent should get its initial value for the size of a px unit in real world units to match the value used for other XML styling operations; otherwise, if the user agent can determine the size of a px unit from its environment, it should use that value; otherwise, it should choose an appropriate size for one px unit. In all cases, the size of a px must be in conformance with the rules described in [ CSS2 lengths]. Example 07_02 below shows that the initial coordinate system has the origin at the top/left with the x-axis pointing to the right and the y-axis pointing down. The initial user coordinate system has one user unit equal to the parent (implicit or explicit) user agent's "pixel". ------------ 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 15:36:54 +0000 (UTC) To: www-svg@w3.org Message-ID: <Pine.LNX.4.62.0512281534430.7669@dhalsim.dreamhost.com> Section 7.3 The initial coordinate system's first pargraph describes a model, but does not require implementations to use that model. Please change section 7.3 such that the paragraph makes clear testable requirements on implementations, so that it is possible to determine what user agents must do, or, alternatively, link the assertions in this section to the sections that actually contain the relevant conformance criteria that result in these assertions being true statements. -- Ian Hickson U+1047E )\._.,--....,'``. fL http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,. Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 9 May 2006 23:11:42 UTC