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[ink] inspecting the shared canvas

From: Al Gilman <Alfred.S.Gilman@IEEE.org>
Date: Mon, 18 Dec 2006 21:07:51 -0500
Message-Id: <p06110426c1acb61504a2@[192.168.1.100]>
To: www-multimodal@w3.org

This is not a change suggestion for the InkML specification _per se_,
but rather raising a concern that we have in accessibility that it
would seem you will also have to worry about to make Ink-using
applications consistently usable in their look and feel so as to be
accepted by users. To co-exist with other sources in a shared canvas,
you need to know what they are doing in all the dimensions of display
phenomena that you enter yourself.

InkML Reference:
http://www.w3.org/TR/2006/WD-InkML-20061023

Issue Reference:
Find "actual presentation properties" in (Member confidential link)
http://lists.w3.org/Archives/Member/w3c-wai-pf/2006OctDec/0144.html

Client-side scripts that attempt to meet accessibility guidelines by assuring
color contrast between the effects they control and the surrounding background
color of the canvas have run into problems when:

>The CSS cascade resolves to 'clear' but there is a background color or image
>that shows through -- layered by the operating system outside the control
>of the CSS-driven rendering engine.

Applications that share multi-user ink traces with platform imagery
on a common canvas will encounter similar problems. The application
will be color-coding the traces; and it will need to be concerned to
allocate colors to the traces that will not only distinguish one
trace from another but likewise be perceivable against the background
arriving on the canvas from other sources.

http://www.w3.org/TR/WCAG20/guidelines.html#visual-audio-contrast

We can't expect all the other content painting on the canvas to get
transcoded into InkML but we should expect full information in some
common canvas coordinates. In addition, one should be able to inspect
starting from the underlying object model which is the origin of
other-source canvas effects, as in HTML+CSS.

There are similar problems with locations on the canvas.  One common function
of ink traces in whiteboard usage cases is to hook something in the background
scene to attach an annotation. For this to work reliably, the final 
ink placement
of the rendered text or other DOM objects must be knowable, reliably and
accurately.

>Brad A. Myers, Choon Hong Peck, Jeffrey Nichols, Dave Kong, and Robert
>Miller. "Interacting At a Distance Using Semantic Snarfing," In Proceedings
>of Ubicomp 2001. Sept 30-Oct 2, Atlanta, Georgia. pp. 305-314.
>http://www.cs.cmu.edu/~pebbles/papers/pebblessnarfubicomp.pdf

This is not anything that impacts the definition of the Ink format, but it is
something that impacts the success of Ink-using applications.

Please join with the WAI and the Working Groups working on the DOM and
Delivery Context Interfaces to secure and ensure full and accurate access
to this information about content rendered to the canvas.

Al
Received on Tuesday, 19 December 2006 02:08:08 GMT

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