- From: Anthony Grasso <anthony.grasso@cisra.canon.com.au>
- Date: Fri, 17 Oct 2008 12:11:43 +1100
- To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
- CC: www-svg@w3.org
Hi Dr. Hoffmann, The SVG Working Group discussed this issue and as a result made changes to the specification. Please see my comments below. Doug Schepers wrote: > Hi, Dr. Olaf- > > Thanks for your insightful comment. I've raised ISSUE-2062 in our > Tracker, and the SVG WG will discuss it and get back to you as soon as > possible. > > Thanks- > -Doug, on behalf of the SVG WG > > > Dr. Olaf Hoffmann wrote (on 9/20/08 9:34 AM): >> Hello SVG WG, >> >> doing some experiments with foreignObject I discovered, that there is some >> information missing in the definition or description of foreignObject. >> This should be clarified. >> >> >> 1. Compared to SVG1.1 the use of xlink:href is new, but in the attribute >> definitions is not mentioned, what should happen with the referenced >> resource (what can be almost everything according to 14.1.4 Reference >> restrictions), if a user agent decides to interprete foreignObject >> somehow. >> >> For example for a referenced XHTML document (as well as for >> embedded XHTML) Opera 9.5 decides to display the top left corner >> fragment of the referenced document into the area described by >> x, y, width, height attributes following the painters model (earlier >> other elements below, later elements on top). >> Other parts of the referenced document beyond this area are not >> accessible. >> >> My guess is too, that it is at least intended, that the referenced >> document or a fragment of it is somehow displayed inside the >> given area (following the painters model), if displayed at all. >> But then this should be mentioned in the attribute definition >> as for image, use, animate, set etc or in the general >> description of the element, as for example for audio and video. >> >> Another interpretation could be, that the xlink:href references >> an alternative view, a description (xhtml:longdesc), something >> related to the foreignObject content. Or the content of >> foreignObject could be an alternative fallback for the >> referenced document similar to the behaviour of xhtml:object. >> >> (Side note: the element animation has a similar problem, it >> is not mentioned, what the purpose of xlink:href is, however >> this can be guessed, but I would like to suggest to replace >> "The referenced SVG document represents a separate document >> which generates its own parse tree and document object model." >> with >> "The SVG document referenced with the xlink:href attribute >> represents a separate document which generates its own >> parse tree and document object model." >> to cover this problem for the animation element, a similar >> description could solve parts of problem for foreignObject as >> well). >> >> >> 2. According to the SVG1.1 usage and the example >> 23_02.svg it is possible too to put the foreign content >> directly inside the foreignObject. >> If additionally an external resource is available with >> xlink:href, what happens? What is the intended >> relation between the content and the document >> referenced by xlink:href? >> Is it an arbitrary choice of the viewer, what will be >> displayed if the viewer decides to display something >> and we assume that both contents are displayable for >> the viewer somehow? >> a) Is the foreignObject content displayed only? >> b) Is the referenced document displayed only? >> c) are both content and referenced document displayed? >> c1) is the content on top (because of the painters model and >> the xlink:href is slightly earlier in the source code than the >> content?) >> c2) is the referenced document on top? >> d) should the viewer provide an interface to select, what >> to display? >> An additional paragraph was inserted before the last paragraph in The 'foreignObject' element section [1]. The 'xlink:href' attribute of 'foreignObject' had a sentence added to the end of the paragraph [2]. >> 3. Obviously different from SVG1.1 in SVGT1.2 the >> foreignObject currently does not create its own >> viewport >> http://www.w3.org/TR/SVGMobile12/coords.html#ElementsThatEstablishViewports >> >> How is the foreign content aligned relative to the >> user coordinate system? Is there a chance for the author >> to influence, which part of the referenced content is >> displayed, if a viewer like Opera 9.5 displays only a fragment >> or is this the problem of the foreign language (for example >> XHTML, typically creating scrollbars or other mechanisms >> automatically to get access to the content of the complete >> document)? >> Is the content outside the x, y, width, height area always >> clipped or is it on the viewer to decide this or on the author >> to avoid this? >> > > The 'foreignObject' element was added to the list of elements that establish new viewports [3]. Please let us know at your earliest convenience if these changes are satisfactory. Kind Regards, Anthony Grasso. [1] http://dev.w3.org/SVG/profiles/1.2T/master/extend.html#ForeignObjectElement [2] http://dev.w3.org/SVG/profiles/1.2T/master/extend.html#ForeignObjectElementHrefAttribute [3] http://dev.w3.org/SVG/profiles/1.2T/master/coords.html#ElementsThatEstablishViewports
Received on Friday, 17 October 2008 01:12:41 UTC