Re: DOM events Re: PROPOSAL: User Agent Issue 190:

Charles,

One of the things I brought up at the WAI-PF FTF was a need to determine
the list of accessible actions mapped for a given element. That said, we
should not need to fire a specific event to activate them. We simply need
to activate them. For example, if a mouseover drops a menu item from
JavaScript there should be an action in the list of actions you mention
that describes the action and a method that enables you to activate it.
This would also help with AccessKeys. AccessKeys could key off the method
to give an item focus by default, the first activation mechanism possibly
and then the rest of a set of method(s) that would allow you to selectively
activate the function you want. The combination makes AccessKeys much more
powerful.

Today, in DOM 2, we have an DOMOnActivate event which would be fired on
activation. I would much rather find out what function was activated as
opposed to the device specific activation notification like onclick.

Does this make sense?

So, what we could have are these which is in line with alot of what you are
saying:

DOMOnFocusIn ( in DOM 2 - Merger of onMouseOver, onFocus)
DOMOnFocusOut (in DOM 2 - Merger of onMouseOut, onBlur)
DOMOnActivate (in DOM 2 - with a parameter indicating which method was
triggered or is to be triggered) We may desire pre and post notification.

DOMOnPointerMove (new - replaces onMouseMove)

DOMSelectionChange (new - for SelectionModel)

Regarding the above, would there be any reason to add event filter
capability?

Another consideration we should discuss is should we have a "default"
activation method.

Also, should a DOM element have a method to indicate if actions are mapped
to the element?

Good stuff Charles. Thanks for bringing this up again.

Rich

Rich Schwerdtfeger
Lead Architect, IBM Special Needs Systems
EMail/web: schwer@us.ibm.com http://www.austin.ibm.com/sns/rich.htm

"Two roads diverged in a wood, and I -
I took the one less traveled by, and that has made all the difference.",
Frost


Charles McCathieNevile <charles@w3.org> on 02/15/2000 01:41:33 AM

To:   Richard Schwerdtfeger/Austin/IBM@IBMUS
cc:   User Agent Guidelines Emailing List <w3c-wai-ua@w3.org>, WAI PF group
      <w3c-wai-pf@w3.org>
Subject:  DOM events Re: PROPOSAL: User Agent Issue 190:




Cross posted to Protocols & Formats and User Agent groups

I think we should take a step back and look carefully at this again.

Implementing an event model is important if we accept that the web that is
moving into the future is going to rely on scripting and dynamic
effects. Although there will be a requirement for some time to come that it
be possible to use the web without these things, I believe that by ignoring
them altogether we are hiding our heads in the sand - we must work out how
to make them accessible.

The basic requirement is to make the interactions that the user can have,
as
defined by the content itself, available to the user without requirement
for
a specific type of hardware interface. For example, relying on the presence
of a mouse, or of a visual display of a certain size, is unreasonable.

In HTML terms, what is required is that the User Agent provide some
mechanism
to programmatically trigger the event trigger attributes, and that that
function is also available in a device-independent manner to the greatest
extent possible.

One approach to this is to look at the new DOM event set, and map the
current
HTML towards that set. (For a note on why this is a good idea, read the
original HTML 4.0 specification at the relevant point...)

Here is a possible way to handle the events:

onClick, onDblClick, onKeyPress, onKeyDown, onKeyUp can all be mapped to
the
new onActivate, using a parameter where appropriate. I would suggest that
the
value of the parameter be numeric, and that we require of the DOM group
that
this event be able to take sufficient parameters to encompass a multiple
click, or differentiating between some number of different keys (I would
suggest that 10 is a better number than 2, for example)

onMouseOver, onFocus be merged to the new equivalent, and similarly with
onMouseOut and OnBlur.

onMouseMove is a bit tricky. Where mouse things are used with X,Y
parameters
there is some careful thinking needed to work in a non-visual space - in
some
cases a more object-oriented approach will solve the problem (this is a Web
Content Question), but there are cases where it is just very difficult -
the
same problem that arises in trying to deal with raster-based graphics.

I think the rest of the events can stay as they are. Gregory has already
pointed to the potential problems raised by ill-considered use of mutation
events such as onChange for submitting forms, and in any event that does
not
rely on a particular type of user interface.

To a certain extent this is going over old ground. Which I find extremely
frustrating, but think is pretty important and we still need to get it
right.

Charles McCN

On Mon, 14 Feb 2000 schwer@us.ibm.com wrote:




  This is why we were pushing the DOM2 event model as P2.

  It is unrealistic to expect the DOM WG to scrap their entire event model
  for accessibility. We should be able to improve upon it in terms of
device
  independence. Having people start developing to the DOM 2 event model
will
  not require them to rewrite the whole thing.

  I do appreciate your concerns.

  Rich

Received on Tuesday, 15 February 2000 12:09:11 UTC