[Accessibility-ia2] next changes to IAccessible2

James Teh jamie at nvaccess.org
Thu Jun 9 04:08:54 PDT 2011


While I recognise the importance of media accessibility, I think special 
purpose interfaces are generally best avoided and so extreme caution 
needs to be exercised when considering them. I think we need to clearly 
determine the use cases for each interface and part thereof. My initial 
feeling is that most of this either does not belong in an accessibility 
API or can be done in a far more general way.

I don't see the need for a special interface to control media. The media 
playback controls can already be exposed as normal controls to ATs (e.g. 
buttons, sliders, etc.), just as they are now, with the application 
providing keyboard shortcuts as appropriate. Selection and toggling of 
media tracks can (and should) similarly be handled by the application 
using a standard UI.

Output of text cues can be generalised and handled using live regions.

The only piece remaining is pausing of audio while the AT reports the 
cue to the user if that reporting would overlap with another cue. This 
really does venture outside the scope of current accessibility APIs, as 
  ATs don't generally change application behaviour, but rather allow 
exposure and interaction with UI. I don't really have a good solution 
for this yet. However, the proposed solution has several problems:
1. The event could be picked up by multiple ATs, but not all of them may 
want the pause on exit behaviour. An event shouldn't generally change 
application behaviour just because an app picked it up; it should be 
passive. Also, keep in mind that many a11y clients register for all 
events, even if they don't use them all.
2. What if a user is using multiple ATs; e.g. screen reader and 
magnifier? One might issue a request to fetch the next cue, but another 
might not be finished outputting it yet.


On 8/06/2011 7:46 PM, Alexander Surkov wrote:
> Hi.
> Based on my talk with Silvia couple days ago I think I can suggest API
> for your consideration -
> https://wiki.mozilla.org/Accessibility/IA2_1.3#IAccessibleMedia_interface.
> Thank you.
> Alex.

James Teh
Vice President, Developer
NV Access Inc, ABN 61773362390
Email: jamie at nvaccess.org
Web site: http://www.nvaccess.org/

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