- From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
- Date: Tue, 24 Jun 2014 18:03:15 +0200
- To: www-svg@w3.org
Strictly following the recommendations for SVG 1.0, SVG 1.1, SVG tiny 1.2, properties not explicitly mentioned in the recommendations are not applicable for those documents anyway. For example there are currently no properties width, height, transform etc applicable for SVG elements. If viewers ignore the recommendations, they clearly have a bug ;o) Therefore whatever is changed for SVG 2 concering attributes and properties or specifities/priorities, this should have no effect on current documents indicating to be written in one of the versions 1.x. Of course we know, that viewers tend to have lots of bugs and gaps and do not necessarily care about recommendations, documents have been written with, therefore we can be almost sure, that they will fail in the future as well, if there are backwards incompatible changes. Therefore SVG 2 has the requirement to avoid such backwards incompatible changes. This should typically mean, the working group should chose new names for new properties, which are not in conflict with old attribute names. But of course, since HTML5 drafts appeared, it is modern now for other working groups to create tag soup as well - we will see, how much this will apply for SVG 2. We know as well, that some implementors intentionally implement bugs or keep gaps open to corrupt formats - but there is not much we can do as to prefer other programs or to continue to send bug reports and explaining the purpose of recommendations. I think as well, that there is not much need to convert attributes like transform and many others to properties, because typically they are only related to content and not to styling. On the other hand it can be a simplification for authors, to be able to use CSS, if decorative alternatives really require transforms. Many are not very familiar with XSL(T) to apply this instead of CSS, if they really have to modify elements or attributes for styling reasons. And my assumption is, if an author really applies a stylesheet to an SVG document or a mixtures of SVG and XHTML, the risk is pretty low, that accidently new CSS features are applied to SVG documents of version 1.x Why should authors do this? Typically authors know as well, that most viewers have no version specific implementations and fail therefore for backwards incompatible changes in recommendations, therefore they will simply not add new features to old documents or to old stylesheets without checking carefully for such viewer bugs. And for SVG 2 documents they should know, that attributes converted to properties are changeable due to stylesheets, therefore no problem to be selective enough to avoid unintended conflicts. I think, often it is not very useful to change attributes to properties, but sometimes it has usecases and the risk of nonesense presentation for old files is low. But there is a big risk, that due to the abuse of stylesheets, there will be no meaningful primary presentation (without CSS interpretation) anymore, if programs like inkscape insist to use the style attribute for everything, that can be expressed as a property. Such abuse of the style attribute for nonesense is already today a much bigger risk for the audience to get inaccessible, meaningless documents. Therefore clearly one should not promote to use the style attribute at all or something like this with similar high specifity/priority. Instead it is important to explain authors, that they always have to clean up files produced by programs like inkscape to get rid of style attributes in published documents. Changing the specifity/priorities of presentation attributes within the CSS cascade together with the known bug of most viewers not to care about format versions indicated in documents, means always, that most future viewers will fail for old documents, which use external CSS files to provide alternative views with different styling. Therefore in practice your suggestion causes trouble for old documents if implemented in those viewers with versionless interpretations - the opposite of your intentions. In current documents there is no need for the !important rule, fortunately! And hopefully in the future there will be still no need to use this - this is mainly a feature, if already something went wrong, this should not be the normal way to provide styling for SVG documents in the future. Olaf
Received on Tuesday, 24 June 2014 16:03:44 UTC