- From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
- Date: Wed, 28 Jul 2010 12:04:19 +0200
- To: public-fx@w3.org
Hello, due to my (animation) tests I created in the last weeks, no viewer is currently completely right if an author really uses a mixture of units in an SVG document, especially not within animation. Most viewers create completely nonsense for different reasons and bugs. For authors it is hardly to predict, what is displayed, if units are used within SVG documents. Therefore the best approach for authors is, what is already the only way for the tiny profiles: use only local units. If one needs an absolute size or one in em, ex, percentage for the complete SVG document, one should use a viewBox and the corresponding unit only within the values of width and height of the root svg element. Even this causes problems with some viewers, at least if other units are used than px or percentage. If an author uses units within an SVG document, it is predictable, that the results from different viewers are quite different, some not usable for the audience at all. This problem is much worse for SVG than for (X)HTML+CSS, because (X)HTML has some amount of self-adjustment and another mechanism to be scalable than SVG - and in doubt for (X)HTML+CSS the audience can simply switch off the decorative CSS, if it causes too many problems. It is typically not a good idea for SVG to switch off somehow presentation attributes (apart from the problem, that this is not possible). This indicates already, that the seemingly simple unit issue is a big barrier for an arbitrary SVG implementor. To be usable and predictable for authors, there is a practically zero tolerance for bugs. For authors additional units mainly blow up the source code of documents and the complexity for the document is increased. On the other hand there are not much benefits for authors with other than local units, relative (to the boundingBox) units and percentages within SVG with the exception of width and height of the root svg element. Olaf
Received on Wednesday, 28 July 2010 10:10:36 UTC