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[Bug 10249] Canvas requires a content selection method

From: <bugzilla@jessica.w3.org>
Date: Thu, 03 Feb 2011 17:25:48 +0000
To: public-html-a11y@w3.org
Message-Id: <E1Pl2wG-0000Yv-NZ@jessica.w3.org>

Rich Schwerdtfeger <schwer@us.ibm.com> changed:

           What    |Removed                     |Added
             Status|RESOLVED                    |REOPENED
         Resolution|NEEDSINFO                   |

--- Comment #5 from Rich Schwerdtfeger <schwer@us.ibm.com> 2011-02-03 17:25:48 UTC ---
Users will need the ability to select content in <canvas> for a broad number of
reasons and low vision users require the ability to track the selection with
their magnifiers.

As the canvas subtree is designed to represent a one for one representation of
what is drawn on the visual canvas, we do have the ability to use the <mark>
element in the canvas subtree and apply the aria-selected property to it. This
would require a small modification to the ARIA specification to make
aria-selected a global attribute. This allows us to annotate the canvas subtree
for screen reader vendors so that they can detect the selected content.

We could also use the selection range APIs from the various browsers to do the
same thing. What we still lack is the ability of the author to convey where a
user is selecting content in canvas during a point and drag operation to be
able to drive a magnifier. This requires two things:

1. Convey the caret or selection position during the selection process to a
screen magnifier so that the magnifier can zoom at the point on the screen
where the author is currently performing the selection.
2. Convey the location of selected content on the screen to a screen reader so
that it can zoom to and along the selection area. 

To address 1. we have a modification to the Canvas2DAPI that will allow an
author to update the caret or selection point for a screen magnifier during the
selection process. We are discussing whether this should belong in the
Canvas2dAPI spec. as this is also needed for SVG.

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Received on Thursday, 3 February 2011 17:25:50 UTC

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