- From: Simon Harper <simon.harper@manchester.ac.uk>
- Date: Thu, 20 Aug 2009 15:31:40 +0100
- To: "Jim Allan" <jimallan@tsbvi.edu>
- Cc: "'UAWG list'" <w3c-wai-ua@w3.org>
In this case should we not think about possible scenarios for UAs to generate missing fallback content. Maybe a set of examples, principles, etc so there is at least some consistency? Cheers Si. ======================= Simon Harper University of Manchester (UK) Human Centred Web Lab: http://hcw.cs.manchester.ac.uk My Site: http://hcw.cs.manchester.ac.uk/people/harper/ My Diary (Web): http://hcw.cs.manchester.ac.uk/people/harper/ phpicalendar/week.php My Diary (Subscribe): http://hcw.cs.manchester.ac.uk/diaries/harper/ SimonHarper.ics On 20 Aug 2009, at 15:11, Jim Allan wrote: > PF is already on this. Interestingly, HTML5 is as much a > specification for > designing a user agent as it is a language spec. Viewed in that > light, it > could prove useful to UAWG as a jumping off point for filling-in > accessibility gaps. One area to fill in would be the notion of > fallback > content. The user should have access to the fallback regardless of > the state > of the parent element. In other words, the user should have access > to the > fallback content whether canvas scripting is on or off, or other > conditions. > > The question becomes, will UA developers actually implement these > items. > Canvas will still work even if the user has no access to the fallback > content. This is the status quo with 'objects' now (Flash, video > players, > etc.). They all function, yet the user has no easy access to fallback > content. > > Jim > >> -----Original Message----- >> From: w3c-wai-ua-request@w3.org [mailto:w3c-wai-ua-request@w3.org] On > Behalf >> Of Simon Harper >> Sent: Thursday, August 20, 2009 3:10 AM >> To: Jim Allan >> Cc: 'UAWG list' >> Subject: Re: The Canvas 2D API 1.0 Specification >> >> It seems then that the accessibility interface to canvas is the bit >> we should be working on as canvas seems like a mini-ua? We should >> start to make suggestions and give solutions to the html5 people IMO. >> >> >> Cheers >> Si. >> >> ======================= >> >> Simon Harper >> University of Manchester (UK) >> >> Human Centred Web Lab: http://hcw.cs.manchester.ac.uk >> >> My Site: http://hcw.cs.manchester.ac.uk/people/harper/ >> >> My Diary (Web): http://hcw.cs.manchester.ac.uk/people/harper/ >> phpicalendar/week.php >> My Diary (Subscribe): http://hcw.cs.manchester.ac.uk/diaries/harper/ >> SimonHarper.ics >> >> >> >> >> >> On 19 Aug 2009, at 18:53, Jim Allan wrote: >> >>> Thanks Simon. It's a nice statement. We all know, if a developer >>> can do >>> something they will. >>> >>> One troubling bit is >>>> When authors use the canvas interface element, they must also >>>> provide >>>> content that, when presented to the user, conveys essentially the >>>> same function or purpose as the bitmap canvas. This content may be >>>> placed as content of the canvas interface element. The contents of >>>> the canvas interface element, if any, are the element's fallback >>>> content. >>> >>> UAAG20 has >>> 3.1.1 Notification of Alternative Content: Provide a global option >>> for the >>> user to be notified of alternatives to rendered content (e.g., >>> short text >>> alternatives, long descriptions, captions). >>> >>> 3.1.2 Configurable Default Rendering: Provide the user with the >>> global >>> option to set which type of alternative to render by default. If the >>> alternative content has a different height and/or width, then the >>> user agent >>> will reflow the viewport. (Level A) >>> >>> We had similar stuff in UAAG10. However no User Agents have yet >>> implemented >>> a way to easily get to the internal element "fall back content". >>> >>> Another troubling item is >>>> In interactive visual media, if scripting is enabled for the canvas >>>> interface element, the canvas interface element represents an >>>> embedded element with a dynamically created image. >>> >>> This implies there is separate scripting for canvas. Separate from >>> javascript? A different instance? How does a user (or agent) turn >>> off >>> scripting for just canvas? >>> >>> Jim >>> >>>> -----Original Message----- >>>> From: w3c-wai-ua-request@w3.org [mailto:w3c-wai-ua- >>>> request@w3.org] On >>> Behalf >>>> Of Simon Harper >>>> Sent: Wednesday, August 19, 2009 10:46 AM >>>> To: UAWG list >>>> Subject: The Canvas 2D API 1.0 Specification >>>> >>>> I was monitoring xtech and saw this going through >>>> >>>> http://dev.w3.org/html5/canvas-api/canvas-2d-api.html >>>> >>>> >>>> which says.. >>>> >>>> 5. Accessibility Considerations >>>> >>>> Authors should not use the canvas interface element in a document >>>> when a more suitable element is available. For example, it is >>>> inappropriate to use a canvas interface element to render a page >>>> heading: if the desired presentation of the heading is graphically >>>> intense, it should be marked up using appropriate elements >>>> (typically >>>> h1) and then styled using CSS and supporting technologies such as >>>> XBL. >>>> >>>> When authors use the canvas interface element, they must also >>>> provide >>>> content that, when presented to the user, conveys essentially the >>>> same function or purpose as the bitmap canvas. This content may be >>>> placed as content of the canvas interface element. The contents of >>>> the canvas interface element, if any, are the element's fallback >>>> content. >>>> >>>> In interactive visual media, if scripting is enabled for the canvas >>>> interface element, the canvas interface element represents an >>>> embedded element with a dynamically created image. >>>> >>>> In non-interactive, static, visual media, if the canvas interface >>>> element has been previously painted on (e.g. if the page was viewed >>>> in an interactive visual medium and is now being printed, or if >>>> some >>>> script that ran during the page layout process painted on the >>>> element), then the canvas interface element represents embedded >>>> content with the current image and size. Otherwise, the element >>>> represents its fallback content instead. >>>> >>>> In non-visual media, and in visual media if scripting is >>>> disabled for >>>> the canvas interface element, the canvas interface element >>>> represents >>>> its fallback content instead. >>>> >>>> >>>> >>>> they say... >>>> >>>> Techniques and additional APIs to make specific uses of canvas >>>> interface elements more widely accessible are under discussion, and >>>> will be reflected in this draft as progress is made. >>>> >>>> I wonder what these are? >>>> >>>> >>>> Cheers >>>> Si. >>>> >>>> ======================= >>>> >>>> Simon Harper >>>> University of Manchester (UK) >>>> >>>> Human Centred Web Lab: http://hcw.cs.manchester.ac.uk >>>> >>>> My Site: http://hcw.cs.manchester.ac.uk/people/harper/ >>>> >>>> My Diary (Web): http://hcw.cs.manchester.ac.uk/people/harper/ >>>> phpicalendar/week.php >>>> My Diary (Subscribe): http://hcw.cs.manchester.ac.uk/diaries/ >>>> harper/ >>>> SimonHarper.ics >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >> > >
Received on Thursday, 20 August 2009 14:32:13 UTC