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suggested change to scrollPathIntoView

From: Richard Schwerdtfeger <schwer@us.ibm.com>
Date: Mon, 23 Dec 2013 16:12:13 -0600
To: Canvas <public-canvas-api@w3.org>
Cc: "Jay Munro" <jaymunro@microsoft.com>, "Rik Cabanier" <cabanier@gmail.com>, "Jatinder Mann" <jmann@microsoft.com>, "Dominic Mazzoni" <dmazzoni@google.com>
Message-ID: <OF0A9771A6.88302FDB-ON86257C4A.00674A64-86257C4A.0079F7A0@us.ibm.com>


Notional Child was deemed confusing to the editors so,

I started making the the changes to scrollPathIntoView below. What confuses
me a bit is does the function actually mean to take an element that has an
exact location that matches the rectangle or should it actually meant that
any descendant that has a location that intersects the path be scrolled
into view? , ... Or should it mean any element contained entirely within
the rectangle should be scrolled into view? To me it does not make sense to
have the author remember the location of the element.


The scrollPathIntoView() method, when invoked, must run the following
steps:
   1.	Let the specified rectangle be the rectangle of the bounding box of
      the intended path.
   2.	Let rendered fallback element a be descendant of the canvas element
      having an assigned location using drawSystemFocusRing(). Through the
      assignment these elements represent rendered descendants of the
      canvas element whose dimensions are those of the specified rectangle.
   3.	Scroll the rendered fallback element into view with the align to top
      flag set.
   4.	Inform the user that the caret and/or selection cover the specified
      rectangle of the canvas. User agents may wait until the next time the
      event loop reaches its "update the rendering" step to optionally
      inform the user.


"Inform the user", as used in this section, could mean calling a system
accessibility API, which would notify assistive technologies such as
magnification tools. To properly drive magnification based on a focus
change, a system accessibility API driving a screen magnifier needs the
bounds for the newly focused object. The methods above are intended to
enable this by allowing the user agent to report the bounding box of the
path used to render the focus ring as the bounds of the element element
passed as an argument, if that element is focused, and the bounding box of
the area to which the user agent is scrolling as the bounding box of the
current selection.

Rich Schwerdtfeger
Received on Monday, 23 December 2013 22:12:49 UTC

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