So, why can't you simply ask for the the first non-empty cell ( a new api)
in the current column in a given direction. Or the first non empty cell in
the current row (new api again) in a given direction?
Is that it or do you have other use cases?
To Dominic's point what do we do with hidden cells?
Rich Schwerdtfeger
From: James Teh <ja...@nvaccess.org>
To: Richard Schwerdtfeger/Austin/IBM@IBMUS
Cc: IAccessible2 mailing list
<accessibility-...@lists.linux-foundation.org>,
accessibility-ia2-boun...@lists.linuxfoundation.org, Dominic
Mazzoni <dmazz...@google.com>
Date: 01/05/2016 07:57 PM
Subject: Re: [Accessibility-ia2] aria-colcount and aria-rowcount
mapping, again
Precisely what you're trying to say we need to do: allow for navigation
other than row + 1 and col + 1. If we have a table which has a cell at r1c2
but no cell at r2c2 and the user navigates down by row from r1c2, how does
an AT find the next appropriate cell? There are two choices right now:
1. Keep trying IAccessibleTable2::cellAt with increasing row numbers until
we find a cell. But what if the next cell is at r1000c2 (which is entirely
possible with these new ARIA properties)? That'd mean calling cellAt 999
times.
2. Use accNavigate to walk through the rows, query the first column in each
row to get its row number, then use cellAt to get the cell n that row in
the original column. This does allow us to skip rows which have no data at
all. However, it's still horrible because:
* There might be interspersed thead/tbody/rowgroup elements, requiring
hierarchical tree traversal.
* There are still a huge number of calls.
Aside from the complexity and performance horror, it's also difficult for
implementers to grasp. They look at IA2 and see a table interface, but then
have to understand that actually, the table interface isn't enough to
navigate tables by row and column; they might actually have to do some
insane tree walking to get anything useful.
Things get even worse if you believe an AT should do something other than
skipping rows if there is no cell in the same column on the next non-empty
row. Dominic suggests we should just go to the first column. I think that
is a bad user experience and breaks a user's spatial feel of the table. So
if we want to move to the next "nearest" cell, now we can't even use cellAt
any more. We have to walk the children of every subsequent row looking for
"nearby" coordinates.
Jamie
On 6/01/2016 11:39 AM, Richard Schwerdtfeger wrote:
What are the use cases?
Rich Schwerdtfeger
Inactive hide details for James Teh ---01/05/2016
07:15:27
PM---My point is that we don't currently have a way
of
handling thisJames Teh ---01/05/2016 07:15:27 PM---My point is that
we don't currently have a way of handling this decently with IA2 and
that we need
From: James Teh <ja...@nvaccess.org>
To: Richard Schwerdtfeger/Austin/IBM@IBMUS
Cc: IAccessible2 mailing list
<accessibility-...@lists.linux-foundation.org>,
accessibility-ia2-boun...@lists.linuxfoundation.org, Dominic Mazzoni
<dmazz...@google.com>
Date: 01/05/2016 07:15 PM
Subject: Re: [Accessibility-ia2] aria-colcount and aria-rowcount
mapping, again
My point is that we don't currently have a way of handling this
decently with IA2 and that we need new API calls. Saying "just faf
around with accNavigate and try all sorts of different stuff until
you find what you want" isn't good enough IMO, not least because it's
horribly unperformant cross-proc. If we're going to have gaps at the
start/in the middle of rows, we need some sort of table navigation
function that can handle different types of navigation. Currently,
there is no such function.
Jamie
On 6/01/2016 11:00 AM, Richard Schwerdtfeger wrote:
Jamie,
I have to agree with Dominic that you have a lot of different
what ifs for determining where to go when a cell is empty. I
think you need to be able to pass a parameter that asks the
browser to go where you want based on a set of criteria.
For example, So, what if several rows are skipped? When does
the situation become problematic?
What condition do you want to be met?
e.g. a parameter that tells us what to do if an empty cell is
encountered:
GOTO_FIRST_NONEMPTY_ADJACENT_CELL
What I am getting at is what is the algorithm you want the user
agent to follow when an empty cell is encountered. Does it Vary
based on a parameter. Do you want hidden cells to be ignored?
Rich
Rich Schwerdtfeger
Inactive hide details for James Teh ---01/05/2016
04:50:38 PM---On 5/01/2016 7:53 AM, Richard Schwerdtfeger
wrote: >James Teh ---01/05/2016 04:50:38 PM---On 5/01/2016 7:53
AM, Richard Schwerdtfeger wrote: >
From: James Teh <ja...@nvaccess.org>
To: Richard Schwerdtfeger/Austin/IBM@IBMUS, Dominic Mazzoni
<dmazz...@google.com>
Cc: IAccessible2 mailing list
<accessibility-...@lists.linux-foundation.org>,
accessibility-ia2-boun...@lists.linuxfoundation.org
Date: 01/05/2016 04:50 PM
Subject: Re: [Accessibility-ia2] aria-colcount and
aria-rowcount mapping, again
On 5/01/2016 7:53 AM, Richard Schwerdtfeger wrote:
Although it is possible to have 2 cells I don't think
this even close to the norm.
Two cells was just an extreme example to demonstrate the issue.
The point is that gaps at the start or middle of a row are
problematic.
Why would we we not just have the screen reader ask to go
to a row and column number?
Because if there is a gap, incrementing row or column by one
isn't sufficient. It could be 1, 2 or an arbitrary number.
It is not difficult to ask the user agent to navigate to
compute the effective cell to the right and ask for the
user agent to navigate there.
It's probably always true that navigating to the adjacent cell
in the next column is as simple as accNavigate with
NAVDIR_NEXT. However, navigating to the adjacent cell in the
next row is not so simple. What if several rows are skipped?
We can add a parameter that states to navigate to the
first non-empty cell to the ... or whatever algorithm we
choose.
Add a parameter to what? I think this would require a new
function, which is what I was suggesting.
Dominic wrote:
Jamie, as an alternative, couldn't the screen reader try
navigating to the next / previous cell using the row,
column index, but if that fails, fall back on DOM
navigation?
For example, given a current cell (x, y), if the user
wants to go right - to the next cell in the same row, try
(x + 1, y) but if that's empty, use the accessibility
tree to navigate to the next sibling.
I suppose we could do that, but it's pretty inelegant. Oh look,
we have a table interface... but uh, sometimes it's not very
useful, so you might need to use tree navigation. It's not so
bad for columns i guess, but see below for rows.
Similarly, given (x, y) if the user wants to go down - to
the same column in the next row, try (x, y + 1), but if
that's empty, use the accessibility tree to navigate to
the next row,
Navigating to the next row has two problems:
1. It's not a simple navigation, since there might be
thead/tbody/rowgroup elements to think about. Sure, it's just a
depth-first traversal, but now we're starting to get fairly
complicated for what should be a simple operation.
2. What if the next row doesn't include that column, but there
is a row 3 rows beyond that that does? Surely we should move to
the row with the matching column. That's not possible with your
algorithm.
then try column x in that row, and if that fails,
navigate to the first cell in that row.
We never want to fall back to the first column like that. If a
user moves down a row, they expect to move down a row, not down
and across (excepting column spans).
Jamie
--
James Teh
Executive Director, NV Access Limited
Ph +61 7 3149 3306
www.nvaccess.org
Facebook: http://www.facebook.com/NVAccess
Twitter: @NVAccess
SIP: ja...@nvaccess.org
--
James Teh
Executive Director, NV Access Limited
Ph +61 7 3149 3306
www.nvaccess.org
Facebook: http://www.facebook.com/NVAccess
Twitter: @NVAccess
SIP: ja...@nvaccess.org
--
James Teh
Executive Director, NV Access Limited
Ph +61 7 3149 3306
www.nvaccess.org
Facebook: http://www.facebook.com/NVAccess
Twitter: @NVAccess
SIP: ja...@nvaccess.org
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