On Thursday, August 12, 2010, 10:58:35 PM, Tab wrote: TAJ> 2010/8/7 Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>: Fantasai said: >>>Going forward, if SVG needs coordinate units in addition to CSS lengths >>>for SVG 2.0, we could define an actual unit identifier for them. Maybe >>>"cu" for "coordinate system units". That would be massively incompatible with all deployed content. Co-ordinate pairs are used *all over the place* in SVG. >>> Unit identifiers are an important >>>extension point in CSS syntax; we should take advantage of that. >> This unit is already defined, it is called 'px'. This corresponds to one >> unit in the local coordinate system and is implicated, if a length value >> has no unit identifier. And in the absence of any other transform, or zoom. TAJ> This is not at all compatible with CSS. 'px' has a very specific TAJ> meaning, and it is not dependent on the local coordinate system. TAJ> Modulo visual-warping effects like zoom: and some transform: values, In other words, modulo the local to global coordinate system transform of svg, ... TAJ> 1px is 1/96 of 1in. Now that the CSS WG has (mostly) settled on that definition (several times) this year, yes. Previously, it was some tiny fraction of a degree (originally, the angle subtended by one device pixel on Hakon's old Sun monitor at a reading distance of one Hakon arm. Honestly.) TAJ> The LCS-dependent lengths that SVG employs are a different unit than 'px'. Agreed. Slapping a unit identifier onto SVG lengths and coordinates really doesn't help here except for making everyting more verbose and incompatible. -- Chris Lilley mailto:chris@w3.org Technical Director, Interaction Domain W3C Graphics Activity Lead Co-Chair, W3C Hypertext CGReceived on Thursday, 12 August 2010 21:49:24 UTC
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